WWW.MOTOROLA.COM/SEMICONDUCTORS
M68HC08
Microcontrollers
MC68HC908SR12/D
Rev. 4, 2/2002
MC68HC908SR12
MC68HC08SR12
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Technical Data
3
MC68HC908SR12
MC68HC08SR12
Technical Data
Motorola reserves the right to make changes without further notice to any products
herein. Motorola makes no warranty, representation or guarantee regarding the
suitability of its products for any particular purpose, nor does Motorola assume any
liability arising out of the application or use of any product or circuit, and specifically
disclaims any and all liability, including without limitation consequential or incidental
damages. "Typical" parameters which may be provided in Motorola data sheets and/or
specifications can and do vary in different applications and actual performance may
vary over time. All operating parameters, including "Typicals" must be validated for
each customer application by customer's technical experts. Motorola does not convey
any license under its patent rights nor the rights of others. Motorola products are not
designed, intended, or authorized for use as components in systems intended for
surgical implant into the body, or other applications intended to support or sustain life,
or for any other application in which the failure of the Motorola product could create a
situation where personal injury or death may occur. Should Buyer purchase or use
Motorola products for any such unintended or unauthorized application, Buyer shall
indemnify and hold Motorola and its officers, employees, subsidiaries, affiliates, and
distributors harmless against all claims, costs, damages, and expenses, and
reasonable attorney fees arising out of, directly or indirectly, any claim of personal
injury or death associated with such unintended or unauthorized use, even if such claim
alleges that Motorola was negligent regarding the design or manufacture of the part.
Motorola, Inc. is an Equal Opportunity/Affirmative Action Employer.
Motorola and the Stylized M logo are registered in the U.S. Patent and Trademark Office.
digital dna is a trademark of Motorola, Inc.
Motorola, Inc., 2002
Technical Data
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
4
Technical Data
MOTOROLA
To provide the most up-to-date information, the revision of our
documents on the World Wide Web will be the most current. Your printed
copy may be an earlier revision. To verify you have the latest information
available, refer to:
http://www.motorola.com/semiconductors/
The following revision history table summarizes changes contained in
this document. For your convenience, the page number designators
have been linked to the appropriate location.
Revision History
Date
Revision
Level
Description
Page
Number(s)
February,
2002
4
PTB0/SDA0, PTB1/SCL0, PTB2/SDA1/TxD, and
PTB3/SCL1/RxD pins -- clarified these open-drain pins
throughout this document.
323, 254, 293
8.4.6 Programming the PLL
-- deleted redundant step in
programming the PLL.
120
Figure 10-1 . Monitor Mode Circuit
-- corrected connections
for PTA1 and PTA2.
167
Table 10-1 . Monitor Mode Signal Requirements and Options
-- clarified clock input requirements for monitor mode entry.
169
Section 11. Timer Interface Module (TIM)
-- timer
discrepancies corrected throughout this section.
181
18.5.1 Port C Data Register (PTC)
and
18.5.2 Data Direction
Register C (DDRC)
-- added notes for PTC6 and PTC7 on
42-pin package.
327, 329
Figure 19-3 . IRQ2 Block Diagram
and
19.5 IRQ1 and IRQ2
Pins
-- corrected IRQ2 for BIH and BIL instructions.
338, 339
Table 24-4 . 5V DC Electrical Characteristics
and
Table 24-5 .
3V DC Electrical Characteristics
-- added additional I
DD
measurements.
374, 376
Table 24-13 . Current Detection Electrical Characteristics
--
updated trip point values.
382
Appendix A. MC68HC08SR12
-- added appendix for ROM part:
MC68HC08SR12.
393
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
List of Sections
5
Technical Data -- MC68HC908SR12MC68HC08SR12
List of Sections
Section 1. General Description . . . . . . . . . . . . . . . . . . . . 35
Section 2. Memory Map . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Section 3. Random-Access Memory (RAM) . . . . . . . . . . 61
Section 4. FLASH Memory . . . . . . . . . . . . . . . . . . . . . . . . 63
Section 5. Configuration and Mask Option Registers
(CONFIG & MOR) . . . . . . . . . . . . . . . . . . . . . . 73
Section 6. Central Processor Unit (CPU) . . . . . . . . . . . . 81
Section 7. Oscillator (OSC) . . . . . . . . . . . . . . . . . . . . . . 101
Section 8. Clock Generator Module (CGM) . . . . . . . . . . 111
Section 9. System Integration Module (SIM) . . . . . . . . 141
Section 10. Monitor ROM (MON) . . . . . . . . . . . . . . . . . . 165
Section 11. Timer Interface Module (TIM) . . . . . . . . . . . 181
Section 12. Timebase Module (TBM) . . . . . . . . . . . . . . . 205
Section 13. Pulse Width Modulator (PWM) . . . . . . . . . . 211
Section 14. Analog Module . . . . . . . . . . . . . . . . . . . . . . 221
Section 15. Analog-to-Digital Converter (ADC) . . . . . . 231
Section 16. Serial Communications Interface (SCI) . . . 251
Section 17. Multi-Master IIC Interface (MMIIC) . . . . . . . 291
Section 18. Input/Output (I/O) Ports . . . . . . . . . . . . . . . 317
Section 19. External Interrupt (IRQ) . . . . . . . . . . . . . . . 335
List of Sections
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
6
List of Sections
MOTOROLA
Section 20. Keyboard Interrupt Module (KBI). . . . . . . . 343
Section 21. Computer Operating Properly (COP) . . . . 351
Section 22. Low-Voltage Inhibit (LVI) . . . . . . . . . . . . . . 357
Section 23. Break Module (BRK) . . . . . . . . . . . . . . . . . . 363
Section 24. Electrical Specifications . . . . . . . . . . . . . . . 371
Section 25. Mechanical Specifications . . . . . . . . . . . . . 387
Section 26. Ordering Information . . . . . . . . . . . . . . . . . 391
Appendix A. MC68HC08SR12 . . . . . . . . . . . . . . . . . . . . 393
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Table of Contents
7
Technical Data -- MC68HC908SR12MC68HC08SR12
Table of Contents
Section 1. General Description
1.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
1.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.4
MCU Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
1.5
Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
1.6
Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
1.6.1
Power Supply Pins (V
DD
and V
SS
) . . . . . . . . . . . . . . . . . . . . 42
1.6.2
Oscillator Pins (OSC1 and OSC2) . . . . . . . . . . . . . . . . . . . . 42
1.6.3
External Reset Pin (RST) . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
1.6.4
External Interrupt Pin (IRQ1) . . . . . . . . . . . . . . . . . . . . . . . . 43
1.6.5
Analog Power Supply Pin (V
DDA
) . . . . . . . . . . . . . . . . . . . . . 43
1.6.6
Analog Ground Pin (V
SSA
) . . . . . . . . . . . . . . . . . . . . . . . . . . 43
1.6.7
ADC Voltage Low Reference Pin (V
REFL
) . . . . . . . . . . . . . . 43
1.6.8
ADC Voltage High Reference Pin (V
REFH
). . . . . . . . . . . . . . 43
1.6.9
External Filter Capacitor Pin (CGMXFC) . . . . . . . . . . . . . . . 43
1.6.10
Analog Input Pins (OPIN1/ATD0, OPIN2/ATD1, V
SSAM
) . . . 44
1.6.11
Port A Input/Output (I/O) Pins (PTA7PTA0) . . . . . . . . . . . . 44
1.6.12
Port B I/O Pins (PTB6PTB0) . . . . . . . . . . . . . . . . . . . . . . . 44
1.6.13
Port C I/O Pins (PTC7PTC0) . . . . . . . . . . . . . . . . . . . . . . . 44
1.6.14
Port D I/O Pins (PTD7/KBI7PTD0/KBI0) . . . . . . . . . . . . . . 44
Section 2. Memory Map
2.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
2.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
2.3
Unimplemented Memory Locations . . . . . . . . . . . . . . . . . . . . . 45
Table of Contents
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
8
Table of Contents
MOTOROLA
2.4
Reserved Memory Locations . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2.5
Input/Output (I/O) Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Section 3. Random-Access Memory (RAM)
3.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Section 4. FLASH Memory
4.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
4.4
FLASH Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
4.5
FLASH Page Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.6
FLASH Mass Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.7
FLASH Program Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.8
FLASH Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.8.1
FLASH Block Protect Register . . . . . . . . . . . . . . . . . . . . . . .70
Section 5. Configuration and Mask Option Registers
(CONFIG & MOR)
5.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
5.4
Configuration Register 1 (CONFIG1) . . . . . . . . . . . . . . . . . . . .75
5.5
Configuration Register 2 (CONFIG2) . . . . . . . . . . . . . . . . . . . .77
5.6
Mask Option Register (MOR) . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Table of Contents
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Table of Contents
9
Section 6. Central Processor Unit (CPU)
6.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
6.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
6.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.4
CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.4.1
Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83
6.4.2
Index Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
6.4.3
Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
6.4.4
Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.4.5
Condition Code Register . . . . . . . . . . . . . . . . . . . . . . . . . . .85
6.5
Arithmetic/Logic Unit (ALU) . . . . . . . . . . . . . . . . . . . . . . . . . . .88
6.6
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
6.6.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
6.6.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.7
CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.8
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.9
Opcode Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Section 7. Oscillator (OSC)
7.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
7.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
7.3
Clock Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103
7.3.1
CGM Reference Clock Selection . . . . . . . . . . . . . . . . . . . . 104
7.3.2
TBM Reference Clock Selection . . . . . . . . . . . . . . . . . . . . 105
7.4
Internal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
7.5
RC Oscillator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
7.6
X-tal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
7.7
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
7.7.1
Crystal Amplifier Input Pin (OSC1). . . . . . . . . . . . . . . . . . . 108
7.7.2
Crystal Amplifier Output Pin (OSC2) . . . . . . . . . . . . . . . . . 109
Table of Contents
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
10
Table of Contents
MOTOROLA
7.7.3
Oscillator Enable Signal (SIMOSCEN). . . . . . . . . . . . . . . . 109
7.7.4
CGM Oscillator Clock (CGMXCLK) . . . . . . . . . . . . . . . . . . 109
7.7.5
CGM Reference Clock (CGMRCLK) . . . . . . . . . . . . . . . . . 109
7.7.6
Oscillator Clock to Time Base Module (OSCCLK) . . . . . . . 109
7.8
Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109
7.8.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
7.8.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
7.9
Oscillator During Break Mode. . . . . . . . . . . . . . . . . . . . . . . . . 110
Section 8. Clock Generator Module (CGM)
8.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
8.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
8.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
8.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
8.4.1
Oscillator Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
8.4.2
Phase-Locked Loop Circuit (PLL) . . . . . . . . . . . . . . . . . . .116
8.4.3
PLL Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
8.4.4
Acquisition and Tracking Modes . . . . . . . . . . . . . . . . . . . . 118
8.4.5
Manual and Automatic PLL Bandwidth Modes. . . . . . . . . . 118
8.4.6
Programming the PLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
8.4.7
Special Programming Exceptions . . . . . . . . . . . . . . . . . . .124
8.4.8
Base Clock Selector Circuit . . . . . . . . . . . . . . . . . . . . . . . . 124
8.4.9
CGM External Connections . . . . . . . . . . . . . . . . . . . . . . . . 125
8.5
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
8.5.1
External Filter Capacitor Pin (CGMXFC) . . . . . . . . . . . . . . 126
8.5.2
PLL Analog Power Pin (V
DDA
) . . . . . . . . . . . . . . . . . . . . . . 126
8.5.3
PLL Analog Ground Pin (V
SSA
) . . . . . . . . . . . . . . . . . . . . . 126
8.5.4
Oscillator Output Frequency Signal (CGMXCLK) . . . . . . . 126
8.5.5
CGM Reference Clock (CGMRCLK) . . . . . . . . . . . . . . . . . 126
8.5.6
CGM VCO Clock Output (CGMVCLK) . . . . . . . . . . . . . . . . 127
8.5.7
CGM Base Clock Output (CGMOUT). . . . . . . . . . . . . . . . . 127
8.5.8
CGM CPU Interrupt (CGMINT) . . . . . . . . . . . . . . . . . . . . . 127
8.6
CGM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127
8.6.1
PLL Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Table of Contents
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Table of Contents
11
8.6.2
PLL Bandwidth Control Register . . . . . . . . . . . . . . . . . . . . 130
8.6.3
PLL Multiplier Select Registers . . . . . . . . . . . . . . . . . . . . . 132
8.6.4
PLL VCO Range Select Register . . . . . . . . . . . . . . . . . . . . 133
8.6.5
PLL Reference Divider Select Register . . . . . . . . . . . . . . . 134
8.7
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.8
Special Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.8.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.8.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
8.8.3
CGM During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . 136
8.9
Acquisition/Lock Time Specifications . . . . . . . . . . . . . . . . . . .137
8.9.1
Acquisition/Lock Time Definitions. . . . . . . . . . . . . . . . . . . . 137
8.9.2
Parametric Influences on Reaction Time . . . . . . . . . . . . . . 137
8.9.3
Choosing a Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Section 9. System Integration Module (SIM)
9.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
9.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
9.3
SIM Bus Clock Control and Generation . . . . . . . . . . . . . . . . . 144
9.3.1
Bus Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
9.3.2
Clock Start-up from POR or LVI Reset. . . . . . . . . . . . . . . . 145
9.3.3
Clocks in Stop Mode and Wait Mode . . . . . . . . . . . . . . . . . 146
9.4
Reset and System Initialization. . . . . . . . . . . . . . . . . . . . . . . . 146
9.4.1
External Pin Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
9.4.2
Active Resets from Internal Sources . . . . . . . . . . . . . . . . . 147
9.4.2.1
Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
9.4.2.2
Computer Operating Properly (COP) Reset. . . . . . . . . . 149
9.4.2.3
Illegal Opcode Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
9.4.2.4
Illegal Address Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
9.4.2.5
Low-Voltage Inhibit (LVI) Reset . . . . . . . . . . . . . . . . . . . 150
9.4.2.6
Monitor Mode Entry Module Reset. . . . . . . . . . . . . . . . . 150
9.5
SIM Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
9.5.1
SIM Counter During Power-On Reset . . . . . . . . . . . . . . . . 151
9.5.2
SIM Counter During Stop Mode Recovery . . . . . . . . . . . . . 151
9.5.3
SIM Counter and Reset States. . . . . . . . . . . . . . . . . . . . . .151
Table of Contents
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
12
Table of Contents
MOTOROLA
9.6
Exception Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
9.6.1
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
9.6.1.1
Hardware Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
9.6.1.2
SWI Instruction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
9.6.1.3
Interrupt Status Registers . . . . . . . . . . . . . . . . . . . . . . . 155
9.6.1.4
Interrupt Status Register 1 . . . . . . . . . . . . . . . . . . . . . . . 155
9.6.1.5
Interrupt Status Register 2 . . . . . . . . . . . . . . . . . . . . . . . 157
9.6.1.6
Interrupt Status Register 3 . . . . . . . . . . . . . . . . . . . . . . . 157
9.6.2
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
9.6.3
Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .158
9.6.4
Status Flag Protection in Break Mode . . . . . . . . . . . . . . . . 158
9.7
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159
9.7.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
9.7.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
9.8
SIM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
9.8.1
SIM Break Status Register . . . . . . . . . . . . . . . . . . . . . . . . . 162
9.8.2
SIM Reset Status Register . . . . . . . . . . . . . . . . . . . . . . . . 163
9.8.3
SIM Break Flag Control Register . . . . . . . . . . . . . . . . . . . . 164
Section 10. Monitor ROM (MON)
10.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
10.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
10.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
10.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
10.4.1
Entering Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
10.4.2
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172
10.4.3
Break Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172
10.4.4
Baud Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
10.4.5
Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
10.5
Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Table of Contents
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Table of Contents
13
Section 11. Timer Interface Module (TIM)
11.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
11.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
11.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
11.4
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
11.5
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
11.5.1
TIM Counter Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
11.5.2
Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
11.5.3
Output Compare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
11.5.3.1
Unbuffered Output Compare . . . . . . . . . . . . . . . . . . . . . 188
11.5.3.2
Buffered Output Compare . . . . . . . . . . . . . . . . . . . . . . . 189
11.5.4
Pulse Width Modulation (PWM) . . . . . . . . . . . . . . . . . . . . . 189
11.5.4.1
Unbuffered PWM Signal Generation . . . . . . . . . . . . . . . 190
11.5.4.2
Buffered PWM Signal Generation . . . . . . . . . . . . . . . . . 191
11.5.4.3
PWM Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
11.6
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
11.7
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .193
11.7.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
11.7.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
11.8
TIM During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . 194
11.9
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
11.10 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
11.10.1 TIM Status and Control Register . . . . . . . . . . . . . . . . . . . . 196
11.10.2 TIM Counter Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
11.10.3 TIM Counter Modulo Registers . . . . . . . . . . . . . . . . . . . . . 199
11.10.4 TIM Channel Status and Control Registers . . . . . . . . . . . .200
11.10.5 TIM Channel Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Section 12. Timebase Module (TBM)
12.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
12.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Table of Contents
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
14
Table of Contents
MOTOROLA
12.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
12.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
12.5
Timebase Register Description. . . . . . . . . . . . . . . . . . . . . . . . 207
12.6
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
12.7
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .209
12.7.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
12.7.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
Section 13. Pulse Width Modulator (PWM)
13.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
13.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
13.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
13.4
PWM Period and Resolution. . . . . . . . . . . . . . . . . . . . . . . . . . 214
13.5
PWM Automatic Phase Control . . . . . . . . . . . . . . . . . . . . . . . 215
13.6
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .216
13.7
Wait Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
13.8
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
13.9
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
13.10 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
13.10.1 PWM Control Register (PWMCR) . . . . . . . . . . . . . . . . . . .217
13.10.2 PWM Clock Control Register (PWMCCR) . . . . . . . . . . . . . 218
13.10.3 PWM Data Registers (PWMDR0PWMDR2) . . . . . . . . . . 219
13.10.4 PWM Phase Control Register . . . . . . . . . . . . . . . . . . . . . . 220
Section 14. Analog Module
14.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
14.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
14.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
14.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
Table of Contents
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Table of Contents
15
14.4.1
On-Chip Temperature Sensor . . . . . . . . . . . . . . . . . . . . . . 223
14.4.2
Two-Stage Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
14.4.3
Amplifier Response Time . . . . . . . . . . . . . . . . . . . . . . . . . . 224
14.4.4
Current Flow Detection Amplifier . . . . . . . . . . . . . . . . . . . . 225
14.4.5
Current Flow Detect Output . . . . . . . . . . . . . . . . . . . . . . . . 225
14.5
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
14.6
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .225
14.6.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
14.6.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
14.7
Analog Module I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . 226
14.7.1
Analog Module Control Register (AMCR) . . . . . . . . . . . . . 226
14.7.2
Analog Module Gain Control Register (AMGCR) . . . . . . . .227
14.7.3
Analog Module Status and Control Register (AMSCR) . . . 228
Section 15. Analog-to-Digital Converter (ADC)
15.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
15.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
15.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
15.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
15.4.1
ADC Port I/O Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
15.4.2
Voltage Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
15.4.3
Conversion Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
15.4.4
Continuous Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
15.4.5
Auto-scan Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
15.4.6
Result Justification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
15.4.7
Data Register Interlocking . . . . . . . . . . . . . . . . . . . . . . . . . 239
15.4.8
Monotonicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .239
15.5
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
15.6
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .239
15.6.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
15.6.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
15.7
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
15.7.1
ADC Voltage In (V
ADIN
) . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
Table of Contents
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
16
Table of Contents
MOTOROLA
15.7.2
ADC Analog Power Pin (V
DDA
) . . . . . . . . . . . . . . . . . . . . . 240
15.7.3
ADC Analog Ground Pin (V
SSA
) . . . . . . . . . . . . . . . . . . . . . 240
15.7.4
ADC Voltage Reference High Pin (V
REFH
). . . . . . . . . . . . . 241
15.7.5
ADC Voltage Reference Low Pin (V
REFL
) . . . . . . . . . . . . . 241
15.8
I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
15.8.1
ADC Status and Control Register. . . . . . . . . . . . . . . . . . . . 242
15.8.2
ADC Clock Control Register. . . . . . . . . . . . . . . . . . . . . . . . 244
15.8.3
ADC Data Register 0 (ADRH0 and ADRL0). . . . . . . . . . . . 246
15.8.4
ADC Auto-Scan Mode Data Registers (ADRL1ADRL3). . 248
15.8.5
ADC Auto-Scan Control Register (ADASCR). . . . . . . . . . . 248
Section 16. Serial Communications Interface (SCI)
16.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
16.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
16.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
16.4
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
16.5
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
16.5.1
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .257
16.5.2
Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
16.5.2.1
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
16.5.2.2
Character Transmission . . . . . . . . . . . . . . . . . . . . . . . . . 259
16.5.2.3
Break Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
16.5.2.4
Idle Characters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
16.5.2.5
Inversion of Transmitted Output. . . . . . . . . . . . . . . . . . . 261
16.5.2.6
Transmitter Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . 261
16.5.3
Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
16.5.3.1
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
16.5.3.2
Character Reception . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
16.5.3.3
Data Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
16.5.3.4
Framing Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
16.5.3.5
Baud Rate Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
16.5.3.6
Receiver Wakeup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
16.5.3.7
Receiver Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . .270
16.5.3.8
Error Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
Table of Contents
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Table of Contents
17
16.6
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .271
16.6.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
16.6.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
16.7
SCI During Break Module Interrupts. . . . . . . . . . . . . . . . . . . . 272
16.8
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
16.8.1
TxD (Transmit Data). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
16.8.2
RxD (Receive Data) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
16.9
I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
16.9.1
SCI Control Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
16.9.2
SCI Control Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
16.9.3
SCI Control Register 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
16.9.4
SCI Status Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .282
16.9.5
SCI Status Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .286
16.9.6
SCI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
16.9.7
SCI Baud Rate Register . . . . . . . . . . . . . . . . . . . . . . . . . . . 288
Section 17. Multi-Master IIC Interface (MMIIC)
17.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291
17.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
17.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
17.4
I/O Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
17.5
Multi-Master IIC System Configuration . . . . . . . . . . . . . . . . . . 295
17.6
Multi-Master IIC Bus Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 295
17.6.1
START Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
17.6.2
Slave Address Transmission . . . . . . . . . . . . . . . . . . . . . . . 296
17.6.3
Data Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
17.6.4
Repeated START Signal . . . . . . . . . . . . . . . . . . . . . . . . . .297
17.6.5
STOP Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .297
17.6.6
Arbitration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . .297
17.6.7
Clock Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
17.6.8
Handshaking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
17.6.9
Packet Error Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
17.7
MMIIC I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
Table of Contents
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
18
Table of Contents
MOTOROLA
17.7.1
MMIIC Address Register (MMADR) . . . . . . . . . . . . . . . . . . 299
17.7.2
MMIIC Control Register 1 (MMCR1) . . . . . . . . . . . . . . . . . 301
17.7.3
MMIIC Control Register 2 (MMCR2) . . . . . . . . . . . . . . . . . 303
17.7.4
MMIIC Status Register (MMSR). . . . . . . . . . . . . . . . . . . . . 305
17.7.5
MMIIC Data Transmit Register (MMDTR) . . . . . . . . . . . . . 307
17.7.6
MMIIC Data Receive Register (MMDRR). . . . . . . . . . . . . . 308
17.7.7
MMIIC CRC Data Register (MMCRCDR). . . . . . . . . . . . . . 309
17.7.8
MMIIC Frequency Divider Register (MMFDR) . . . . . . . . . . 310
17.8
Program Algorithm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
17.8.1
Data Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312
17.9
SMBus Protocols with PEC and without PEC. . . . . . . . . . . . . 313
17.9.1
Quick Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
17.9.2
Send Byte. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
17.9.3
Receive Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
17.9.4
Write Byte/Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
17.9.5
Read Byte/Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
17.9.6
Process Call . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .315
17.9.7
Block Read/Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
17.10 SMBus Protocol Implementation . . . . . . . . . . . . . . . . . . . . . . 316
Section 18. Input/Output (I/O) Ports
18.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
18.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
18.3
Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
18.3.1
Port A Data Register (PTA) . . . . . . . . . . . . . . . . . . . . . . . . 320
18.3.2
Data Direction Register A (DDRA) . . . . . . . . . . . . . . . . . . . 321
18.3.3
Port A LED Control Register (LEDA) . . . . . . . . . . . . . . . . . 323
18.4
Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
18.4.1
Port B Data Register (PTB) . . . . . . . . . . . . . . . . . . . . . . . . 324
18.4.2
Data Direction Register B (DDRB) . . . . . . . . . . . . . . . . . . . 325
18.5
Port C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
18.5.1
Port C Data Register (PTC) . . . . . . . . . . . . . . . . . . . . . . . . 327
18.5.2
Data Direction Register C (DDRC). . . . . . . . . . . . . . . . . . . 329
18.5.3
Port C LED Control Register (LEDC) . . . . . . . . . . . . . . . . . 330
Table of Contents
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Table of Contents
19
18.6
Port D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
18.6.1
Port D Data Register (PTD) . . . . . . . . . . . . . . . . . . . . . . . . 331
18.6.2
Data Direction Register D (DDRD). . . . . . . . . . . . . . . . . . . 332
Section 19. External Interrupt (IRQ)
19.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
19.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
19.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
19.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
19.5
IRQ1 and IRQ2 Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338
19.6
IRQ Module During Break Interrupts . . . . . . . . . . . . . . . . . . .339
19.7
IRQ Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
19.7.1
IRQ1 Status and Control Register . . . . . . . . . . . . . . . . . . .340
19.7.2
IRQ2 Status and Control Register . . . . . . . . . . . . . . . . . . .341
Section 20. Keyboard Interrupt Module (KBI)
20.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343
20.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343
20.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
20.4
I/O Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
20.5
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
20.5.1
Keyboard Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347
20.6
Keyboard Interrupt Registers . . . . . . . . . . . . . . . . . . . . . . . . . 347
20.6.1
Keyboard Status and Control Register. . . . . . . . . . . . . . . . 348
20.6.2
Keyboard Interrupt Enable Register . . . . . . . . . . . . . . . . . . 349
20.7
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .349
20.8
Wait Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349
20.9
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349
20.10 Keyboard Module During Break Interrupts . . . . . . . . . . . . . . .350
Table of Contents
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
20
Table of Contents
MOTOROLA
Section 21. Computer Operating Properly (COP)
21.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351
21.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351
21.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352
21.4
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
21.4.1
ICLK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
21.4.2
STOP Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
21.4.3
COPCTL Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
21.4.4
Power-On Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
21.4.5
Internal Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354
21.4.6
Reset Vector Fetch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354
21.4.7
COPD (COP Disable) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .354
21.4.8
COPRS (COP Rate Select) . . . . . . . . . . . . . . . . . . . . . . . . 354
21.5
COP Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355
21.6
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355
21.7
Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355
21.8
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .355
21.8.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356
21.8.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356
21.9
COP Module During Break Mode . . . . . . . . . . . . . . . . . . . . . .356
Section 22. Low-Voltage Inhibit (LVI)
22.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
22.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
22.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
22.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
22.4.1
Polled LVI Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359
22.4.2
Forced Reset Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 360
22.4.3
Voltage Hysteresis Protection . . . . . . . . . . . . . . . . . . . . . . 360
22.4.4
LVI Trip Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360
22.5
LVI Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
Table of Contents
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Table of Contents
21
22.6
LVI Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
22.7
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .361
22.7.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362
22.7.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362
Section 23. Break Module (BRK)
23.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363
23.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363
23.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364
23.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364
23.4.1
Flag Protection During Break Interrupts . . . . . . . . . . . . . . .366
23.4.2
CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . 366
23.4.3
TIM1 and TIM2 During Break Interrupts . . . . . . . . . . . . . . .366
23.4.4
COP During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . 366
23.5
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .366
23.5.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366
23.5.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367
23.6
Break Module Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .367
23.6.1
Break Status and Control Register. . . . . . . . . . . . . . . . . . . 367
23.6.2
Break Address Registers . . . . . . . . . . . . . . . . . . . . . . . . . .368
23.6.3
SIM Break Status Register . . . . . . . . . . . . . . . . . . . . . . . . . 368
23.6.4
SIM Break Flag Control Register . . . . . . . . . . . . . . . . . . . . 370
Section 24. Electrical Specifications
24.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371
24.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372
24.3
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . .372
24.4
Functional Operating Range. . . . . . . . . . . . . . . . . . . . . . . . . . 373
24.5
Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373
24.6
5.0V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . 374
24.7
3.0V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . 376
Table of Contents
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
22
Table of Contents
MOTOROLA
24.8
5.0V Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
24.9
3.0V Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
24.10 5.0V Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 378
24.11 3.0V Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 379
24.12 5.0V ADC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . 380
24.13 3.0V ADC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . 381
24.14 Analog Module Electrical Characteristics . . . . . . . . . . . . . . . . 382
24.14.1 Temperature Sensor Electrical Characteristics . . . . . . . . . 382
24.14.2 Current Detection Electrical Characteristics. . . . . . . . . . . . 382
24.14.3 Two-Stage Amplifier Electrical Characteristics. . . . . . . . . . 382
24.15 Timer Interface Module Characteristics . . . . . . . . . . . . . . . . . 383
24.16 MMIIC Electrical Characteristics. . . . . . . . . . . . . . . . . . . . . . . 383
24.17 CGM Electrical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . 385
24.18 FLASH Memory Characteristics . . . . . . . . . . . . . . . . . . . . . . . 386
Section 25. Mechanical Specifications
25.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387
25.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387
25.3
48-Pin Plastic Low Quad Flat Pack (LQFP) . . . . . . . . . . . . . . 388
25.4
42-Pin Shrink Dual In-Line Package (SDIP) . . . . . . . . . . . . . . 389
Section 26. Ordering Information
26.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391
26.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391
26.3
MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391
Table of Contents
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Table of Contents
23
Appendix A. MC68HC08SR12
A.1
Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393
A.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
A.3
MCU Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
A.4
Memory Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
A.5
Mask Option Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
A.6
Reserved Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
A.7
Monitor ROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
A.8
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
A.8.1
Memory Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
A.9
ROM Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398
Table of Contents
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
24
Table of Contents
MOTOROLA
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
List of Figures
25
Technical Data -- MC68HC908SR12MC68HC08SR12
List of Figures
Figure
Title
Page
1-1
MC68HC908SR12 Block Diagram . . . . . . . . . . . . . . . . . . . . . . 39
1-2
48-Pin LQFP Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . 40
1-3
42-Pin SDIP Pin Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . 41
1-4
Power Supply Bypassing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2-1
Memory Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2-2
Control, Status, and Data Registers . . . . . . . . . . . . . . . . . . . . . 48
4-1
FLASH I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . 64
4-2
FLASH Control Register (FLCR) . . . . . . . . . . . . . . . . . . . . . . . 65
4-3
FLASH Programming Flowchart . . . . . . . . . . . . . . . . . . . . . . . . 69
4-4
FLASH Block Protect Register (FLBPR). . . . . . . . . . . . . . . . . . 70
4-5
FLASH Block Protect Start Address . . . . . . . . . . . . . . . . . . . . . 70
5-1
CONFIG and MOR Register Summary. . . . . . . . . . . . . . . . . . . 74
5-2
Configuration Register 1 (CONFIG1) . . . . . . . . . . . . . . . . . . . .75
5-3
Configuration Register 2 (CONFIG2) . . . . . . . . . . . . . . . . . . . .77
5-4
Mask Option Register (MOR) . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6-1
CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
6-2
Accumulator (A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
6-3
Index Register (H:X) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
6-4
Stack Pointer (SP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85
6-5
Program Counter (PC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6-6
Condition Code Register (CCR) . . . . . . . . . . . . . . . . . . . . . . . . 86
7-1
Oscillator Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . 103
7-2
Mask Option Register (MOR) . . . . . . . . . . . . . . . . . . . . . . . . . 104
7-3
Configuration Register 2 (CONFIG2) . . . . . . . . . . . . . . . . . . .105
7-4
Internal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
List of Figures
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
26
List of Figures
MOTOROLA
Figure
Title
Page
7-5
RC Oscillator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
7-6
Crystal Oscillator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
8-1
CGM Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
8-2
CGM I/O Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . . 115
8-3
CGM External Connections . . . . . . . . . . . . . . . . . . . . . . . . . .125
8-4
PLL Control Register (PCTL) . . . . . . . . . . . . . . . . . . . . . . . . . 128
8-5
PLL Bandwidth Control Register (PBWCR) . . . . . . . . . . . . . . 131
8-6
PLL Multiplier Select Register High (PMSH) . . . . . . . . . . . . . 132
8-7
PLL Multiplier Select Register Low (PMSL) . . . . . . . . . . . . . . 132
8-8
PLL VCO Range Select Register (PMRS) . . . . . . . . . . . . . . . 133
8-9
PLL Reference Divider Select Register (PMDS) . . . . . . . . . . 134
8-10
PLL Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139
9-1
SIM Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
9-2
SIM I/O Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . 144
9-3
CGM Clock Signals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
9-4
External Reset Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
9-5
Internal Reset Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
9-6
Sources of Internal Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
9-7
POR Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
9-8
Interrupt Entry Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
9-9
Interrupt Recovery Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
9-10
Interrupt Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
9-11
Interrupt Recognition Example . . . . . . . . . . . . . . . . . . . . . . . . 154
9-12
Interrupt Status Register 1 (INT1). . . . . . . . . . . . . . . . . . . . . .155
9-13
Interrupt Status Register 2 (INT2). . . . . . . . . . . . . . . . . . . . . .157
9-14
Interrupt Status Register 3 (INT3). . . . . . . . . . . . . . . . . . . . . .157
9-15
Wait Mode Entry Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159
9-16
Wait Recovery from Interrupt or Break . . . . . . . . . . . . . . . . . . 160
9-17
Wait Recovery from Internal Reset. . . . . . . . . . . . . . . . . . . . . 160
9-18
Stop Mode Entry Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161
9-19
Stop Mode Recovery from Interrupt or Break . . . . . . . . . . . . . 161
9-20
SIM Break Status Register (SBSR) . . . . . . . . . . . . . . . . . . . . 162
9-21
SIM Reset Status Register (SRSR) . . . . . . . . . . . . . . . . . . . . 163
9-22
SIM Break Flag Control Register (SBFCR) . . . . . . . . . . . . . . 164
List of Figures
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
List of Figures
27
Figure
Title
Page
10-1
Monitor Mode Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
10-2
Low-Voltage Monitor Mode Entry Flowchart. . . . . . . . . . . . . . 171
10-3
Monitor Data Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
10-4
Break Transaction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
10-5
Read Transaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
10-6
Write Transaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
10-7
Stack Pointer at Monitor Mode Entry . . . . . . . . . . . . . . . . . . .178
10-8
Monitor Mode Entry Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . 179
11-1
TIM Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
11-2
TIM I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
11-3
PWM Period and Pulse Width . . . . . . . . . . . . . . . . . . . . . . . . 190
11-4
TIM Status and Control Register (TSC) . . . . . . . . . . . . . . . . . 196
11-5
TIM Counter Registers High (TCNTH) . . . . . . . . . . . . . . . . . . 198
11-6
TIM Counter Registers Low (TCNTL) . . . . . . . . . . . . . . . . . . . 198
11-7
TIM Counter Modulo Register High (TMODH) . . . . . . . . . . . .199
11-8
TIM Counter Modulo Register Low (TMODL) . . . . . . . . . . . . . 199
11-9
TIM Channel 0 Status and Control Register (TSC0) . . . . . . . 200
11-10 TIM Channel 1 Status and Control Register (TSC1) . . . . . . . 200
11-11 CHxMAX Latency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
11-12 TIM Channel 0 Register High (TCH0H) . . . . . . . . . . . . . . . . . 204
11-13 TIM Channel 0 Register Low (TCH0L) . . . . . . . . . . . . . . . . . . 204
11-14 TIM Channel 1 Register High (TCH1H) . . . . . . . . . . . . . . . . . 204
11-15 TIM Channel 1 Register Low (TCH1L) . . . . . . . . . . . . . . . . . . 204
12-1
Timebase Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
12-2
Timebase Control Register (TBCR) . . . . . . . . . . . . . . . . . . . . 207
13-1
PWM I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . 212
13-2
PWM Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
13-3
PWM Output Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
13-4
PWM Automatic Phase Control . . . . . . . . . . . . . . . . . . . . . . . 215
13-5
PWM Control Register (PWMCR). . . . . . . . . . . . . . . . . . . . . .217
13-6
PWM Clock Control Register (PWMCCR) . . . . . . . . . . . . . . . 218
13-7
PWM Data Register 0 (PWMDR0) . . . . . . . . . . . . . . . . . . . . . 219
13-8
PWM Data Register 1 (PWMDR1) . . . . . . . . . . . . . . . . . . . . . 219
List of Figures
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
28
List of Figures
MOTOROLA
Figure
Title
Page
13-9
PWM Data Register 2 (PWMDR2) . . . . . . . . . . . . . . . . . . . . . 219
13-10 PWM Phase Control Register (PWMPCR) . . . . . . . . . . . . . . .220
14-1
Analog Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . 222
14-2
Analog Module I/O Register Summary . . . . . . . . . . . . . . . . . . 223
14-3
Analog Module Control Register (AMCR). . . . . . . . . . . . . . . . 226
14-4
Analog Module Gain Control Register (AMGCR) . . . . . . . . . . 227
14-5
Analog Module Status and Control Register (AMSCR) . . . . .229
15-1
ADC I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . .233
15-2
ADC Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
15-3
ADC Status and Control Register (ADSCR) . . . . . . . . . . . . . . 242
15-4
ADC Clock Control Register (ADICLK). . . . . . . . . . . . . . . . . . 244
15-5
ADRH0 and ADRL0 in 8-Bit Truncated Mode. . . . . . . . . . . . . 246
15-6
ADRH0 and ADRL0 in Right Justified Mode. . . . . . . . . . . . . . 246
15-7
ADRH0 and ADRL0 in Left Justified Mode . . . . . . . . . . . . . . .247
15-8
ADRH0 and ADRL0 in Left Justified Sign Data Mode . . . . . . 247
15-9
ADC Data Register Low 1 to 3 (ADRL1ADRL3) . . . . . . . . . . 248
15-10 ADC Scan Control Register (ADASCR) . . . . . . . . . . . . . . . . . 248
16-1
SCI Module Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . 255
16-2
SCI I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
16-3
SCI Data Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
16-4
SCI Transmitter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .258
16-5
SCI Receiver Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . 263
16-6
Receiver Data Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . .264
16-7
Slow Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
16-8
Fast Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .268
16-9
SCI Control Register 1 (SCC1). . . . . . . . . . . . . . . . . . . . . . . . 274
16-10 SCI Control Register 2 (SCC2). . . . . . . . . . . . . . . . . . . . . . . . 277
16-11 SCI Control Register 3 (SCC3). . . . . . . . . . . . . . . . . . . . . . . . 279
16-12 SCI Status Register 1 (SCS1) . . . . . . . . . . . . . . . . . . . . . . . . 282
16-13 Flag Clearing Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . .285
16-14 SCI Status Register 2 (SCS2) . . . . . . . . . . . . . . . . . . . . . . . . 286
16-15 SCI Data Register (SCDR) . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
16-16 SCI Baud Rate Register (SCBR) . . . . . . . . . . . . . . . . . . . . . . 288
List of Figures
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
List of Figures
29
Figure
Title
Page
17-1
MMIIC I/O Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . 294
17-2
Multi-Master IIC Bus Transmission Signal Diagram . . . . . . . .295
17-3
Clock Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
17-4
MMIIC Address Register (MMADR) . . . . . . . . . . . . . . . . . . . . 299
17-5
MMIIC Control Register 1 (MMCR1). . . . . . . . . . . . . . . . . . . . 301
17-6
MMIIC Control Register 2 (MMCR2). . . . . . . . . . . . . . . . . . . . 303
17-7
MMIIC Status Register (MMSR) . . . . . . . . . . . . . . . . . . . . . . . 305
17-8
MMIIC Data Transmit Register (MMDTR) . . . . . . . . . . . . . . . 307
17-9
MMIIC Data Receive Register (MMDRR) . . . . . . . . . . . . . . . . 308
17-10 MMIIC CRC Data Register (MMCRCDR) . . . . . . . . . . . . . . . . 309
17-11 MMIIC Frequency Divider Register (MMFDR) . . . . . . . . . . . .310
17-12 Data Transfer Sequences for Master/Slave
Transmit/Receive Modes . . . . . . . . . . . . . . . . . . . . . . . . . . 312
17-13 Quick Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
17-14 Send Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
17-15 Receive Byte. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
17-16 Write Byte/Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
17-17 Read Byte/Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
17-18 Process Call . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
17-19 Block Read/Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
17-20 SMBus Protocol Implementation . . . . . . . . . . . . . . . . . . . . . . 316
18-1
I/O Port Register Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . 318
18-2
Port A Data Register (PTA) . . . . . . . . . . . . . . . . . . . . . . . . . .320
18-3
Data Direction Register A (DDRA) . . . . . . . . . . . . . . . . . . . . . 321
18-4
Port A I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
18-5
Port A LED Control Register (LEDA) . . . . . . . . . . . . . . . . . . .323
18-6
Port B Data Register (PTB) . . . . . . . . . . . . . . . . . . . . . . . . . .324
18-7
Data Direction Register B (DDRB) . . . . . . . . . . . . . . . . . . . . . 325
18-8
Port B I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326
18-9
Port C Data Register (PTC) . . . . . . . . . . . . . . . . . . . . . . . . . .327
18-10 Data Direction Register B (DDRB) . . . . . . . . . . . . . . . . . . . . . 329
18-11 Port C I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329
18-12 Port A LED Control Register (LEDA) . . . . . . . . . . . . . . . . . . .330
18-13 Port D Data Register (PTD) . . . . . . . . . . . . . . . . . . . . . . . . . .331
18-14 Data Direction Register D (DDRD) . . . . . . . . . . . . . . . . . . . . . 332
18-15 Port D I/O Circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332
List of Figures
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
30
List of Figures
MOTOROLA
Figure
Title
Page
19-1
External Interrupt I/O Register Summary . . . . . . . . . . . . . . . . 336
19-2
IRQ1 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337
19-3
IRQ2 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338
19-4
IRQ1 Status and Control Register (INTSCR1) . . . . . . . . . . . . 340
19-5
IRQ2 Status and Control Register (INTSCR2) . . . . . . . . . . . . 341
20-1
KBI I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
20-2
Keyboard Interrupt Block Diagram . . . . . . . . . . . . . . . . . . . . . 345
20-3
Keyboard Status and Control Register (KBSCR) . . . . . . . . . . 348
20-4
Keyboard Interrupt Enable Register (KBIER) . . . . . . . . . . . . . 349
21-1
COP Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352
21-2
Configuration Register 1 (CONFIG1) . . . . . . . . . . . . . . . . . . .354
21-3
COP Control Register (COPCTL) . . . . . . . . . . . . . . . . . . . . . .355
22-1
LVI I/O Register Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
22-2
LVI Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
22-3
LVI Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
23-1
Break Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . 365
23-2
Break Module I/O Register Summary . . . . . . . . . . . . . . . . . . . 365
23-3
Break Status and Control Register (BRKSCR). . . . . . . . . . . . 367
23-4
Break Address Register High (BRKH) . . . . . . . . . . . . . . . . . . 368
23-5
Break Address Register Low (BRKL) . . . . . . . . . . . . . . . . . . . 368
23-6
SIM Break Status Register (SBSR) . . . . . . . . . . . . . . . . . . . . 369
23-7
SIM Break Flag Control Register (SBFCR) . . . . . . . . . . . . . . 370
24-1
RC vs. Bus Frequency (5V @25
C) . . . . . . . . . . . . . . . . . . . . 378
24-2
RC vs. Bus Frequency (3V @25
C) . . . . . . . . . . . . . . . . . . . . 379
24-3
MMIIC Signal Timings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383
25-1
48-Pin Plastic Low Quad Flat Pack (LQFP) . . . . . . . . . . . . . . 388
25-2
42-Pin Shrink Dual In-Line Package (SDIP) . . . . . . . . . . . . . . 389
A-1
MC68HC08SR12 Block Diagram . . . . . . . . . . . . . . . . . . . . . 395
A-2
MC68HC08SR12 Memory Map . . . . . . . . . . . . . . . . . . . . . . 396
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
List of Tables
31
Technical Data -- MC68HC908SR12MC68HC08SR12
List of Tables
Table
Title
Page
2-1
Vector Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
5-1
CGMXCLK Clock Selection . . . . . . . . . . . . . . . . . . . . . . . . . . .80
6-1
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6-2
Opcode Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
7-1
CGMXCLK Clock Selection . . . . . . . . . . . . . . . . . . . . . . . . . .104
7-2
Timebase Module Reference Clock Selection . . . . . . . . . . . .105
8-1
Numeric Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123
8-3
VPR1 and VPR0 Programming . . . . . . . . . . . . . . . . . . . . . . . 130
8-2
PRE1 and PRE0 Programming . . . . . . . . . . . . . . . . . . . . . . . 130
9-1
Signal Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
9-2
PIN Bit Set Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .147
9-3
Interrupt Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
10-1
Monitor Mode Signal Requirements and Options . . . . . . . . . . 169
10-2
Mode Differences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
10-3
Monitor Baud Rate Selection . . . . . . . . . . . . . . . . . . . . . . . . . 173
10-4
READ (Read Memory) Command . . . . . . . . . . . . . . . . . . . . . 175
10-5
WRITE (Write Memory) Command. . . . . . . . . . . . . . . . . . . . . 175
10-7
IWRITE (Indexed Write) Command . . . . . . . . . . . . . . . . . . . . 176
10-6
IREAD (Indexed Read) Command . . . . . . . . . . . . . . . . . . . . . 176
10-8
READSP (Read Stack Pointer) Command . . . . . . . . . . . . . . .177
10-9
RUN (Run User Program) Command . . . . . . . . . . . . . . . . . . . 177
11-1
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
11-2
Prescaler Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
List of Tables
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
32
List of Tables
MOTOROLA
Table
Title
Page
11-3
Mode, Edge, and Level Selection . . . . . . . . . . . . . . . . . . . . . .202
12-1
Timebase Rate Selection for OSCCLK = 32.768 kHz . . . . . . 207
13-1
PTC0 Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
13-2
PWM Counter Clock Prescaler Selection . . . . . . . . . . . . . . . . 219
14-1
Analog Module Power Control . . . . . . . . . . . . . . . . . . . . . . . . 226
14-2
Amplifier Channel Select Control bits . . . . . . . . . . . . . . . . . . . 227
14-3
Analog Module Gain Values . . . . . . . . . . . . . . . . . . . . . . . . . . 228
14-4
Analog Module Clock Divider Select. . . . . . . . . . . . . . . . . . . . 229
15-1
MUX Channel Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
15-2
ADC Clock Divide Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
15-3
ADC Mode Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
15-4
Auto-scan Mode Channel Select . . . . . . . . . . . . . . . . . . . . . . 248
16-1
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
16-2
Start Bit Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
16-3
Data Bit Recovery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
16-4
Stop Bit Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
16-5
Character Format Selection . . . . . . . . . . . . . . . . . . . . . . . . . .276
16-6
SCI Baud Rate Prescaling . . . . . . . . . . . . . . . . . . . . . . . . . . . 288
16-7
SCI Baud Rate Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
16-8
SCI Baud Rate Selection Examples . . . . . . . . . . . . . . . . . . . . 290
17-1
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294
17-2
MMIIC Baud Rate Selection . . . . . . . . . . . . . . . . . . . . . . . . . . 310
18-1
Port Control Register Bits Summary. . . . . . . . . . . . . . . . . . . . 319
18-2
Port A Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322
18-3
PTB2 and PTB3 Pin Configurations . . . . . . . . . . . . . . . . . . . . 325
18-4
Port B Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 326
18-5
PTC0 Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328
18-6
Port C Pin Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
18-7
Port D Pin Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333
List of Tables
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
List of Tables
33
Table
Title
Page
20-1
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
22-1
LVIOUT Bit Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
24-1
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . .372
24-2
Operating Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373
24-3
Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373
24-4
5V DC Electrical Characteristics. . . . . . . . . . . . . . . . . . . . . . . 374
24-5
3V DC Electrical Characteristics. . . . . . . . . . . . . . . . . . . . . . . 376
24-6
5V Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
24-7
3V Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
24-8
5V Oscillator Specifications . . . . . . . . . . . . . . . . . . . . . . . . . .378
24-9
3V Oscillator Specifications . . . . . . . . . . . . . . . . . . . . . . . . . .379
24-10 5V ADC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . 380
24-11 3V ADC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . 381
24-12 Temperature Sensor Electrical Characteristics . . . . . . . . . . . 382
24-13 Current Detection Electrical Characteristics . . . . . . . . . . . . . . 382
24-14 Two-Stage Amplifier Electrical Characteristics . . . . . . . . . . . . 382
24-15 MMIIC DC Electrical Characteristics. . . . . . . . . . . . . . . . . . . . 383
24-16 MMIIC Interface Input/Output Signal Timing. . . . . . . . . . . . . . 384
24-17 FLASH Memory Electrical Characteristics . . . . . . . . . . . . . . . 386
26-1
MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391
A-1
Summary of MC68HC08SR12 and
MC68HC908SR12 Differences . . . . . . . . . . . . . . . . . . . . . 394
A-2
MC68HC08SR12 Order Numbers . . . . . . . . . . . . . . . . . . . . . 398
List of Tables
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
34
List of Tables
MOTOROLA
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
General Description
35
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 1. General Description
1.1 Contents
1.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
1.4
MCU Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
1.5
Pin Assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
1.6
Pin Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
1.6.1
Power Supply Pins (V
DD
and V
SS
) . . . . . . . . . . . . . . . . . . . . 42
1.6.2
Oscillator Pins (OSC1 and OSC2) . . . . . . . . . . . . . . . . . . . . 42
1.6.3
External Reset Pin (RST) . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
1.6.4
External Interrupt Pin (IRQ1) . . . . . . . . . . . . . . . . . . . . . . . . 43
1.6.5
Analog Power Supply Pin (V
DDA
) . . . . . . . . . . . . . . . . . . . . . 43
1.6.6
Analog Ground Pin (V
SSA
) . . . . . . . . . . . . . . . . . . . . . . . . . . 43
1.6.7
ADC Voltage Low Reference Pin (V
REFL
) . . . . . . . . . . . . . . 43
1.6.8
ADC Voltage High Reference Pin (V
REFH
). . . . . . . . . . . . . . 43
1.6.9
External Filter Capacitor Pin (CGMXFC) . . . . . . . . . . . . . . . 43
1.6.10
Analog Input Pins (OPIN1/ATD0, OPIN2/ATD1, V
SSAM
) . . . 44
1.6.11
Port A Input/Output (I/O) Pins (PTA7PTA0) . . . . . . . . . . . . 44
1.6.12
Port B I/O Pins (PTB6PTB0) . . . . . . . . . . . . . . . . . . . . . . . 44
1.6.13
Port C I/O Pins (PTC7PTC0) . . . . . . . . . . . . . . . . . . . . . . . 44
1.6.14
Port D I/O Pins (PTD7/KBI7PTD0/KBI0) . . . . . . . . . . . . . . 44
General Description
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
36
General Description
MOTOROLA
1.2 Introduction
The MC68HC908SR12 is a member of the low-cost, high-performance
M68HC08 Family of 8-bit microcontroller units (MCUs). The M68HC08
Family is based on the customer-specified integrated circuit (CSIC)
design strategy. All MCUs in the family use the enhanced M68HC08
central processor unit (CPU08) and are available with a variety of
modules, memory sizes and types, and package types.
1.3 Features
Features of the MC68HC908SR12 include the following:
High-performance M68HC08 architecture
Fully upward-compatible object code with M6805, M146805, and
M68HC05 Families
Maximum internal bus frequency:
8-MHz at 5V operating voltage
4-MHz at 3V operating voltage
Clock input options:
RC-oscillator
32kHz crystal-oscillator with 32MHz internal phase-lock-loop
12k-bytes user program FLASH memory with security
1
feature
512 bytes of on-chip RAM
Two 16-bit, 2-channel timer interface modules (TIM1 and TIM2)
with selectable input capture, output compare, and PWM
capability on each channel
Timebase module
3-channel, 8-bit high speed PWM (125kHz) with independent
counters and automatic phase control
Serial communications interface module (SCI)
1. No security feature is absolutely secure. However, Motorola's strategy is to make reading or
copying the FLASH difficult for unauthorized users.
General Description
Features
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
General Description
37
System Management Bus (SMBus), version 1.0/1.1
(Multi-master IIC bus)
14-channel, 10-bit analog-to-digital converter (ADC), with
auto-scan mode for 4 channels
Current sensor with programmable amplifier
Temperature sensor (20
C to +70
C)
IRQ1 external interrupt pin with integrated pullup
IRQ2 external interrupt pin with programmable pullup
8-bit keyboard wakeup port with integrated pullup
31 general-purpose input/output (I/O) pins and 2 dedicated pins:
31 shared-function I/O pins
Two dedicated analog input pins
Low-power design (fully static with Stop and Wait modes)
Master reset pin (with integrated pullup) and power-on reset
System protection features
Optional computer operating properly (COP) reset
Low-voltage detection with optional reset
Illegal opcode detection with reset
Illegal address detection with reset
48-pin low quad flat pack (LQFP) and 42-pin shrink dual-in-line
package (SDIP)
Specific features of the MC68HC908SR12 in 42-pin SDIP are:
29 general-purpose l/Os only
11-channel ADC only
Features of the CPU08 include the following:
Enhanced HC05 programming model
Extensive loop control functions
16 addressing modes (eight more than the HC05)
General Description
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
38
General Description
MOTOROLA
16-bit Index register and stack pointer
Memory-to-memory data transfers
Fast 8
8 multiply instruction
Fast 16/8 divide instruction
Binary-coded decimal (BCD) instructions
Optimization for controller applications
Efficient C language support
1.4 MCU Block Diagram
Figure 1-1
shows the structure of the MC68HC908SR12.
MC6
8
HC9
08S
R12
MC6
8
HC08
S
R1
2
--
Rev
.
4.0
T
ech
n
i
c
a
l
Da
ta
MO
T
O
RO
LA
G
ene
r
a
l D
e
s
c
r
i
p
t
io
n
3
9
Ge
n
e
ra
l
De
sc
rip
t
i
o
n
MCU Bl
oc
k
D
i
ag
r
a
m
Figure 1-1. MC68HC908SR12 Block Diagram
CLOCK GENERATOR MODULE
SYSTEM INTEGRATION
MODULE
TIMEBASE
2-CHANNEL TIMER INTERFACE
MODULE 2
LOW-VOLTAGE
INHIBIT MODULE
8-BIT KEYBOARD
ARITHMETIC/LOGIC
UNIT (ALU)
CPU
REGISTERS
M68HC08 CPU
CONTROL AND STATUS REGISTERS -- 96 BYTES
USER FLASH -- 12,288 BYTES
USER RAM -- 512 BYTES
MONITOR ROM -- 368 BYTES
USER FLASH VECTORS -- 38 BYTES
EXTERNAL IRQ
MODULE
DD
RB
PO
RT
B
INTERNAL BUS
OSC1
OSC2
CGMXFC
* RST
* IRQ1
MODULE
INTERRUPT MODULE
COMPUTER OPERATING
PROPERLY MODULE
V
REFH
PTB6/IRQ2
PTB5/T2CH1
PTB4/T2CH0
PTB3//SCL1/RxD
PTB2/SDA1/TxD
PTB1/SCL0
PTB0/SDA0
V
REFL
2-CHANNEL TIMER INTERFACE
MODULE 1
PHASE-LOCKED LOOP
SERIAL COMMUNICATIONS
INTERFACE MODULE
POWER-ON RESET
MODULE
POWER
V
SS
V
DD
V
SSA
V
DDA
* Pin contains integrated pullup device.
** Pin contains configurable pullup device.
*** Pin contains integrated pullup device for KBI functions.
Pin is open-drain when configured as output.
High current drive pin (for LED).
# Pin not bonded on 42-pin SDIP.
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
PULSE WIDTH MODULATOR
MODULE
PO
RTA
DD
RA
PTA5/ATD7 PTA0/ATD2
DD
RC
PO
RT
C
PTC7/ATD12
#
PTC6/ATD11
#
PTC5/ATD10
PTC4/ATD9
PTC3/ATD8
PTC2/PWM2
PTC1/PWM1
PTC0/PWM0/CD
PO
RT
D
DD
RD
PTD7/KBI7 PTD0/KBI0 ***
** IRQ2
MULTI-MASTER IIC (SMBUS)
INTERFACE MODULE
ANALOG
MODULE
OPIN1/ATD0
#
OPIN2/ATD1
PTA7/T1CH1
PTA6/T1CH0
V
SSAM
X-TAL OSCILLATOR
RC OSCILLATOR
INTERNAL OSCILLATOR
OSCILLATORS AND
General Description
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
40
General Description
MOTOROLA
1.5 Pin Assignments
Figure 1-2. 48-Pin LQFP Pin Assignments
VSSA
48
47
46
45
44
43
42
41
40
39
1
2
3
4
5
6
7
8
9
10
14
15
16
17
18
19
20
21
22
36
32
31
30
29
28
27
26
13
PTC3/ATD8
IRQ1
PTD2/KBI2
RST
NC
PTD0/KBI0
VDD
OSC1
OSC2
VSS
PTD1/KBI1
PT
D
4
/KBI4
PTB2/SDA1
/
Tx
D
PTB1
/SCL0
PT
B0/SDA0
PTB3/SCL
1/Rx
D
PT
D
5
/KBI5
PTC2/PW
M
2
PTC1/PW
M
1
PTC0
/PW
M
0
/
CD
PTA7
/T1CH1
PT
D
6
/KBI6
OPIN2/ATD1
VREFL
VREFH
OPIN1/ATD0
VSSAM
PTA6/T1CH0
PTB6/IRQ2
PTB4/T2CH0
PTA0/ATD2
PTC7/ATD12
PTB5/T2CH1
CGM
X
F
C
12
PTD3/KBI3
25
PTD7/KBI7
11
24
NC
23
35
34
33
VDDA
PTC6/
A
TD11
PTC5/
A
TD10
PTC4/
A
TD9
PTA1
/ATD3
PTA2
/ATD4
PTA3
/ATD5
PTA4
/ATD6
NC
PTA5
/ATD7
37
38
NC: No connection
General Description
Pin Functions
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
General Description
41
Figure 1-3. 42-Pin SDIP Pin Assignment
1.6 Pin Functions
Description of pin functions are provided here.
21
22
PTD5/KBI5
PTD4/KBI4
PTC2/PWM2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
PTC1/PWM1
PTC0/PWM0/CD
PTB2/SDA1/TxD
PTB1/SCL0
PTB0/SDA0
PTC3/ATD8
PTD2/KBI2
RST
PTD3/KBI3
PTA0/ATD2
VREFL
VREFH
PTA1/ATD3
PTA2/ATD4
PTA3/ATD5
PTA4/ATD6
VSSA
PTB5/T2CH1
PTB4/T2CH0
PTD7/KBI7
PTA6/T1CH0
PTB6/IRQ2
PTC5/ATD10
VDDA
OPIN1/ATD0
VSSAM
PTC4/ATD9
PTA5/ATD7
CGMXFC
PTD0/KBI0
VDD
OSC1
OSC2
VSS
PTD1/KBI1
IRQ1
PTA7/T1CH1
20
23
PTD6/KBI6
PTB3/SCL1/RxD
Pins not available on 42-pin package
Internal connection
OPIN2/ATD1
Unconnected
PTC6/ATD11
Unconnected
PTC7/ATD12
Unconnected
General Description
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
42
General Description
MOTOROLA
1.6.1 Power Supply Pins (V
DD
and V
SS
)
V
DD
and V
SS
are the power supply and ground pins. The MCU operates
from a single power supply.
Fast signal transitions on MCU pins place high, short-duration current
demands on the power supply. To prevent noise problems, take special
care to provide power supply bypassing at the MCU as
Figure 1-4
shows. Place the C1 bypass capacitor as close to the MCU as possible.
Use a high-frequency-response ceramic capacitor for C1. C2 is an
optional bulk current bypass capacitor for use in applications that require
the port pins to source high current levels.
Figure 1-4. Power Supply Bypassing
V
SS
must be grounded for proper MCU operation.
1.6.2 Oscillator Pins (OSC1 and OSC2)
The OSC1 and OSC2 pins are the connections for the on-chip oscillator
circuit. See
Section 7. Oscillator (OSC)
and
Section 8. Clock
Generator Module (CGM)
.
MCU
V
DD
C2
C1
0.1
F
V
SS
V
DD
+
NOTE: Component values shown
represent typical applications.
General Description
Pin Functions
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
General Description
43
1.6.3 External Reset Pin (RST)
A logic 0 on the RST pin forces the MCU to a known start-up state. RST
is bidirectional, allowing a reset of the entire system. It is driven low when
any internal reset source is asserted. This pin contains an internal pullup
resistor. See
Section 9. System Integration Module (SIM)
.
1.6.4 External Interrupt Pin (IRQ1)
IRQ1 is an asynchronous external interrupt pin. This pin contains an
internal pullup resistor. See
Section 19. External Interrupt (IRQ)
.
1.6.5 Analog Power Supply Pin (V
DDA
)
V
DDA
is the power supply pin for the analog circuits of the MCU.
1.6.6 Analog Ground Pin (V
SSA
)
V
SSA
is the power supply ground pin for the analog circuits of the MCU.
It should be decoupled as per the V
SS
digital ground pin.
1.6.7 ADC Voltage Low Reference Pin (V
REFL
)
V
REFL
is the voltage input pin for the ADC voltage low reference. See
Section 15. Analog-to-Digital Converter (ADC)
.
1.6.8 ADC Voltage High Reference Pin (V
REFH
)
V
REFH
is the voltage input pin for the ADC voltage high reference. See
Section 15. Analog-to-Digital Converter (ADC)
.
1.6.9 External Filter Capacitor Pin (CGMXFC)
CGMXFC is an external filter capacitor connection for the CGM. See
Section 8. Clock Generator Module (CGM)
.
General Description
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
44
General Description
MOTOROLA
1.6.10 Analog Input Pins (OPIN1/ATD0, OPIN2/ATD1, V
SSAM
)
OPIN1/ATD0 and OPIN2/ATD1 are input pins to the analog module and
ADC and V
SSAM
is the negative reference input. See
Section 14.
Analog Module
and
Section 15. Analog-to-Digital Converter (ADC)
.
1.6.11 Port A Input/Output (I/O) Pins (PTA7
PTA0)
PTA7PTA0 are special function, bidirectional port pins.
PTA7/T1CH1PTA6/T1CH0 are shared with the TIM1, and
PTA5/ATD7PTA0/ATD2 are shared with the ADC. See
Section 18.
Input/Output (I/O) Ports
,
Section 11. Timer Interface Module (TIM)
,
and
Section 15. Analog-to-Digital Converter (ADC)
.
1.6.12 Port B I/O Pins (PTB6PTB0)
PTB6PTB0 are special function, bidirectional port pins. PTB6/IRQ2 is
shared with the IRQ2 input, PTB5/T2CH1PTB4/T2CH0 are shared with
the TIM2, PTB3/SCL1/RxDPTB2/SDA1/TxD are shared with the
MMIIC and SCI, and PTB1/SCL0PTB0/SDA0 are shared with the
MMIIC. See
Section 18. Input/Output (I/O) Ports
,
Section 19.
External Interrupt (IRQ)
,
Section 11. Timer Interface Module (TIM)
,
Section 16. Serial Communications Interface (SCI)
, and
Section 17.
Multi-Master IIC Interface (MMIIC)
.
1.6.13 Port C I/O Pins (PTC7PTC0)
PTC7PTC0 are special function, bidirectional port pins.
PTC7/ATD12PTC3/ATD8 are shared with the ADC,
PTC2/PWM2PTC1/PWM1 are shared with the PWM, and
PTC0/PWM0/CD is shared with the PWM and analog module. See
Section 18. Input/Output (I/O) Ports
,
Section 15. Analog-to-Digital
Converter (ADC)
,
Section 13. Pulse Width Modulator (PWM)
, and
Section 14. Analog Module
.
1.6.14 Port D I/O Pins (PTD7/KBI7PTD0/KBI0)
PTD7PTD0 are general-purpose bidirectional port pins with keyboard
wakeup function. See
Section 18. Input/Output (I/O) Ports
and
Section 20. Keyboard Interrupt Module (KBI)
.
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Memory Map
45
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 2. Memory Map
2.1 Contents
2.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
2.3
Unimplemented Memory Locations . . . . . . . . . . . . . . . . . . . . . 45
2.4
Reserved Memory Locations . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2.5
Input/Output (I/O) Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2.2 Introduction
The CPU08 can address 64k-bytes of memory space. The memory
map, shown in
Figure 2-1
, includes:
12,288 bytes of user FLASH memory
512 bytes of random-access memory (RAM)
38 bytes of user-defined vectors
368 bytes of monitor ROM
2.3 Unimplemented Memory Locations
Accessing an unimplemented location can cause an illegal address
reset. In the memory map (
Figure 2-1
) and in register figures in this
document, unimplemented locations are shaded.
Memory Map
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
46
Memory Map
MOTOROLA
2.4 Reserved Memory Locations
Accessing a reserved location can have unpredictable effects on MCU
operation. In the
Figure 2-1
and in register figures in this document,
reserved locations are marked with the word Reserved or with the
letter R.
2.5 Input/Output (I/O) Section
Most of the control, status, and data registers are in the zero page
$0000$005F. Additional I/O registers have the following addresses:
$FE00; SIM break status register, SBSR
$FE01; SIM reset status register, SRSR
$FE03; SIM break flag control register, SBFCR
$FE04; Interrupt status register 1, INT1
$FE05; Interrupt status register 2, INT2
$FE06; Interrupt status register 3, INT3
$FE07; Reserved
$FE08; FLASH control register, FLCR
$FE09; FLASH block protect register, FLBPR
$FE0A; Reserved
$FE0B; Reserved
$FE0C; break address register high, BRKH
$FE0D; break address register low, BRKL
$FE0E; break status and control register, BRKSCR
$FE0F; LVI status register, LVISR
$FF80; Mask option register, MOR
$FFFF; COP control register, COPCTL
Data registers are shown in
Figure 2-2
,
Table 2-1
is a list of vector
locations.
Memory Map
Input/Output (I/O) Section
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Memory Map
47
$0000
$005F
I/O Registers
96 Bytes
$0060
$025F
RAM
512 Bytes
$0260
$BFFF
Unimplemented
48,544 Bytes
$C000
$EFFF
FLASH Memory
12,288 Bytes
$F000
$FDFF
Unimplemented
3,584 Bytes
$FE00
SIM Break Status Register (SBSR)
$FE01
SIM Reset Status Register (SRSR)
$FE02
Reserved
$FE03
SIM Break Flag Control Register (SBFCR)
$FE04
Interrupt Status Register 1 (INT1)
$FE05
Interrupt Status Register 2 (INT2)
$FE06
Interrupt Status Register 3 (INT3)
$FE07
Reserved
$FE08
FLASH Control Register (FLCR)
$FE09
FLASH Block Protect Register (FLBPR)
$FE0A
Reserved
$FE0B
Reserved
$FE0C
Break Address Register High (BRKH)
$FE0D
Break Address Register Low (BRKL)
$FE0E
Break Status and Control Register (BRKSCR)
$FE0F
LVI Status Register (LVISR)
$FE10
$FF7F
Monitor ROM
368 Bytes
$FF80
Mask Option Register
$FF81
$FFD9
Reserved
89 Bytes
$FFDA
$FFFF
FLASH Vectors
38 Bytes
Figure 2-1. Memory Map
Memory Map
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
48
Memory Map
MOTOROLA
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0000
Port A Data Register
(PTA)
Read:
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
Write:
Reset:
U
U
U
U
U
U
U
U
$0001
Port B Data Register
(PTB)
Read:
0
PTB6
PTB5
PTB4
PTB3
PTB2
PTB1
PTB0
Write:
Reset:
0
U
U
U
U
U
U
U
$0002
Port C Data Register
(PTC)
Read:
PTC7
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1
PTC0
Write:
Reset:
U
U
U
U
U
U
U
U
$0003
Port D Data Register
(PTD)
Read:
PTD7
PTD6
PTD5
PTD4
PTD3
PTD2
PTD1
PTD0
Write:
Reset:
U
U
U
U
U
U
U
U
$0004
Data Direction Register A
(DDRA)
Read:
DDRA7
DDRA6
DDRA5
DDRA4
DDRA3
DDRA2
DDRA1
DDRA0
Write:
Reset:
0
0
0
0
0
0
0
0
$0005
Data Direction Register B
(DDRB)
Read:
0
DDRB6
DDRB5
DDRB4
DDRB3
DDRB2
DDRB1
DDRB0
Write:
Reset:
0
0
0
0
0
0
0
0
$0006
Data Direction Register C
(DDRC)
Read:
DDRC7
DDRC6
DDRC5
DDRC4
DDRC3
DDRC2
DDRC1
DDRC0
Write:
Reset:
0
0
0
0
0
0
0
0
$0007
Data Direction Register D
(DDRD)
Read:
DDRD7
DDRD6
DDRD5
DDRD4
DDRD3
DDRD2
DDRD1
DDRD0
Write:
Reset:
0
0
0
0
0
0
0
0
$0008
Unimplemented
Read:
Write:
Reset:
$0009
Unimplemented
Read:
Write:
Reset:
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 1 of 12)
Memory Map
Input/Output (I/O) Section
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Memory Map
49
$000A
Unimplemented
Read:
Write:
Reset:
$000B
Unimplemented
Read:
Write:
Reset:
$000C
Port-A LED Control
Register
(LEDA)
Read:
0
0
LEDA5
LEDA4
LEDA3
LEDA2
LEDA1
LEDA0
Write:
Reset:
0
0
0
0
0
0
0
0
$000D
Port-C LED Control
Register
(LEDC)
Read:
LEDC7
LEDC6
LEDC5
LEDC4
LEDC3
0
0
0
Write:
Reset:
0
0
0
0
0
0
0
0
$000E
Analog Module Control
Register
(AMCR)
Read:
PWR1
PWR0
OPCH1
OPCH0
AMIEN
DO2
DO1
DO0
Write:
Reset:
0
0
0
0
0
0
0
0
$000F
Analog Module Gain
Control Register
(AMGCR)
Read:
GAINB3
GAINB2
GAINB1
GAINB0
GAINA3
GAINA2
GAINA1
GAINA0
Write:
Reset:
0
0
0
0
0
0
0
0
$0010
Analog Module Status and
Control Register
(AMSCR)
Read:
AMCDIV1 AMCDIV0
0
OPIF
0
DOF
0
CDIF
Write:
OPIFR
CDIFR
Reset:
0
0
U
0
0
0
U
0
$0011
Unimplemented
Read:
Write:
Reset:
$0012
Unimplemented
Read:
Write:
Reset:
$0013
SCI Control Register 1
(SCC1)
Read:
LOOPS
ENSCI
TXINV
M
WAKE
ILTY
PEN
PTY
Write:
Reset:
0
0
0
0
0
0
0
0
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 2 of 12)
Memory Map
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
50
Memory Map
MOTOROLA
$0014
SCI Control Register 2
(SCC2)
Read:
SCTIE
TCIE
SCRIE
ILIE
TE
RE
RWU
SBK
Write:
Reset:
0
0
0
0
0
0
0
0
$0015
SCI Control Register 3
(SCC3)
Read:
R8
T8
DMARE
DMATE
ORIE
NEIE
FEIE
PEIE
Write:
Reset:
U
U
0
0
0
0
0
0
$0016
SCI Status Register 1
(SCS1)
Read:
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
Write:
Reset:
1
1
0
0
0
0
0
0
$0017
SCI Status Register 2
(SCS2)
Read:
0
0
0
0
0
0
BKF
RPF
Write:
Reset:
0
0
0
0
0
0
0
0
$0018
SCI Data Register
(SCDR)
Read:
R7
R6
R5
R4
R3
R2
R1
R0
Write:
T7
T6
T5
T4
T3
T2
T1
T0
Reset:
U
U
U
U
U
U
U
U
$0019
SCI Baud Rate Register
(SCBR)
Read:
0
0
SCP1
SCP0
R
SCR2
SCR1
SCR0
Write:
Reset:
0
0
0
0
0
0
0
$001A
Keyboard Status and
Control Register
(KBSCR)
Read:
0
0
0
0
KEYF
0
IMASKK
MODEK
Write:
ACKK
Reset:
0
0
0
0
0
0
0
0
$001B
Keyboard Interrupt Enable
Register
(KBIER)
Read:
KBIE7
KBIE6
KBIE5
KBIE4
KBIE3
KBIE2
KBIE1
KBIE0
Write:
Reset:
0
0
0
0
0
0
0
0
$001C
IRQ2 Status and Control
Register
(INTSCR2)
Read:
0
PTBPUE6
0
0
IRQ2F
0
IMASK2
MODE2
Write:
ACK2
Reset:
0
0
0
0
0
0
0
0
$001D
Configuration Register 2
(CONFIG2)
Read:
STOP_
ICLKEN
STOP_
RCLKEN
STOP_
XCLKEN
OSCCLK1 OSCCLK0
0
CDOEN
SCIBDSRC
Write:
Reset:
0
0
0
0
0
0
0
0
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 3 of 12)
Memory Map
Input/Output (I/O) Section
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Memory Map
51
$001E
IRQ1 Status and Control
Register
(INTSCR1)
Read:
0
0
0
0
IRQ1F
0
IMASK1
MODE1
Write:
ACK1
Reset:
0
0
0
0
0
0
0
0
$001F
Configuration Register 1
(CONFIG1)
Read:
COPRS
LVISTOP LVIRSTD LVIPWRD LVI5OR3
SSREC
STOP
COPD
Write:
Reset:
0
0
0
0
0
0
0
0
One-time writable register after each reset.
$0020
Timer 1 Status and
Control Register
(T1SC)
Read:
TOF
TOIE
TSTOP
0
0
PS2
PS1
PS0
Write:
0
TRST
Reset:
0
0
1
0
0
0
0
0
$0021
Timer 1 Counter
Register High
(T1CNTH)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
0
0
0
0
0
0
0
0
$0022
Timer 1 Counter
Register Low
(T1CNTL)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
0
0
0
0
0
0
0
0
$0023
Timer 1 Counter Modulo
Register High
(T1MODH)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
1
1
1
1
1
1
1
1
$0024
Timer 1 Counter Modulo
Register Low
(T1MODL)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
1
1
1
1
1
1
1
1
$0025
Timer 1 Channel 0 Status
and Control Register
(T1SC0)
Read:
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
TOV0
CH0MAX
Write:
0
Reset:
0
0
0
0
0
0
0
0
$0026
Timer 1 Channel 0
Register High
(T1CH0H)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
X
X
X
X
X
X
X
X
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 4 of 12)
Memory Map
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
52
Memory Map
MOTOROLA
$0027
Timer 1 Channel 0
Register Low
(T1CH0L)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
X
X
X
X
X
X
X
X
$0028
Timer 1 Channel 1 Status
and Control Register
(T1SC1)
Read:
CH1F
CH1IE
0
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
Write:
0
Reset:
0
0
0
0
0
0
0
0
$0029
Timer 1 Channel 1
Register High
(T1CH1H)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
X
X
X
X
X
X
X
X
$002A
Timer 1 Channel 1
Register Low
(T1CH1L)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
X
X
X
X
X
X
X
X
$002B
Timer 2 Status and
Control Register
(T2SC)
Read:
TOF
TOIE
TSTOP
0
0
PS2
PS1
PS0
Write:
0
TRST
Reset:
0
0
1
0
0
0
0
0
$002C
Timer 2 Counter
Register High
(T2CNTH)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
0
0
0
0
0
0
0
0
$002D
Timer 2 Counter
Register Low
(T2CNTL)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
0
0
0
0
0
0
0
0
$002E
Timer 2 Counter Modulo
Register High
(T2MODH)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
1
1
1
1
1
1
1
1
$002F
Timer 2 Counter Modulo
Register Low
(T2MODL)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
1
1
1
1
1
1
1
1
$0030
Timer 2 Channel 0 Status
and Control Register
(T2SC0)
Read:
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
TOV0
CH0MAX
Write:
0
Reset:
0
0
0
0
0
0
0
0
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 5 of 12)
Memory Map
Input/Output (I/O) Section
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Memory Map
53
$0031
Timer 2 Channel 0
Register High
(T2CH0H)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
X
X
X
X
X
X
X
X
$0032
Timer 2 Channel 0
Register Low
(T2CH0L)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
X
X
X
X
X
X
X
X
$0033
Timer 2 Channel 1 Status
and Control Register
(T2SC1)
Read:
CH1F
CH1IE
0
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
Write:
0
Reset:
0
0
0
0
0
0
0
0
$0034
Timer 2 Channel 1
Register High
(T2CH1H)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
X
X
X
X
X
X
X
X
$0035
Timer 2 Channel 1
Register Low
(T2CH1L)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
X
X
X
X
X
X
X
X
$0036
PLL Control Register
(PTCL)
Read:
PLLIE
PLLF
PLLON
BCS
PRE1
PRE0
VPR1
VPR0
Write:
Reset:
0
0
1
0
0
0
0
0
$0037
PLL Bandwidth Control
Register
(PBWC)
Read:
AUTO
LOCK
ACQ
0
0
0
0
R
Write:
Reset:
0
0
0
0
0
0
0
$0038
PLL Multiplier Select
Register High
(PMSH)
Read:
0
0
0
0
MUL11
MUL10
MUL9
MUL8
Write:
Reset:
0
0
0
0
0
0
0
0
$0039
PLL Multiplier Select
Register Low
(PMSL)
Read:
MUL7
MUL6
MUL5
MUL4
MUL3
MUL2
MUL1
MUL0
Write:
Reset:
0
1
0
0
0
0
0
0
$003A
PLL VCO Range Select
Register
(PMRS)
Read:
VRS7
VRS6
VRS5
VRS4
VRS3
VRS2
VRS1
VRS0
Write:
Reset:
0
1
0
0
0
0
0
0
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 6 of 12)
Memory Map
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
54
Memory Map
MOTOROLA
$003B
PLL Reference Divider
Select Register
(PMDS)
Read:
0
0
0
0
RDS3
RDS2
RDS1
RDS0
Write:
Reset:
0
0
0
0
0
0
0
1
$003C
Unimplemented
Read:
Write:
Reset:
$003D
Unimplemented
Read:
Write:
Reset:
$003E
Unimplemented
Read:
Write:
Reset:
$003F
Unimplemented
Read:
Write:
Reset:
$0040
Unimplemented
Read:
Write:
Reset:
$0041
Unimplemented
Read:
Write:
Reset:
$0042
Unimplemented
Read:
Write:
Reset:
$0043
Unimplemented
Read:
Write:
Reset:
$0044
Unimplemented
Read:
Write:
Reset:
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 7 of 12)
Memory Map
Input/Output (I/O) Section
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Memory Map
55
$0045
Unimplemented
Read:
Write:
Reset:
$0046
Timebase Control
Register
(TBCR)
Read:
TBIF
TBR2
TBR1
TBR0
0
TBIE
TBON
R
Write:
TACK
Reset:
0
0
0
0
0
0
0
$0047
Unimplemented
Read:
Write:
Reset:
$0048
MMIIC Address Register
(MMADR)
Read:
MMAD7
MMAD6
MMAD5
MMAD4
MMAD3
MMAD2
MMAD1
MMEXTAD
Write:
Reset:
1
0
1
0
0
0
0
0
$0049
MMIIC Control Register 1
(MMCR1)
Read:
MMEN
MMIEN
0
0
MMTXAK REPSEN
MMCRCBYTE
SDASCL1
Write:
MMCLRBB
Reset:
0
0
0
0
0
0
0
0
$004A
MMIIC Control Register 2
(MMCR2)
Read: MMALIF MMNAKIF
MMBB
MMAST
MMRW
0
0
MMCRCEF
Write:
0
0
Reset:
0
0
0
0
0
0
0
Unaffected
$004B
MMIIC Status Register
(MMSR)
Read: MMRXIF
MMTXIF
MMATCH
MMSRW MMRXAK
MMCRCBF
MMTXBE MMRXBF
Write:
0
0
Reset:
0
0
0
0
1
0
1
0
$004C
MMIIC Data Transmit
Register
(MMDTR)
Read:
MMTD7
MMTD6
MMTD5
MMTD4
MMTD3
MMTD2
MMTD1
MMTD0
Write:
Reset:
0
0
0
0
0
0
0
0
$004D
MMIIC Data Receive
Register
(MDDRR)
Read: MMRD7
MMRD6
MMRD5
MMRD4
MMRD3
MMRD2
MMRD1
MMRD0
Write:
Reset:
0
0
0
0
0
0
0
0
$004E
MMIIC CRC Data Register
(MMCRDR)
Read:
MMCRCD7 MMCRCD6 MMCRCD5 MMCRCD4 MMCRCD3 MMCRCD2 MMCRCD1 MMCRCD0
Write:
Reset:
0
0
0
0
0
0
0
0
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 8 of 12)
Memory Map
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
56
Memory Map
MOTOROLA
$004F
MMIIC Frequency Divider
Register
(MMFDR)
Read:
0
0
0
0
0
MMBR2
MMBR1
MMBR0
Write:
Reset:
0
0
0
0
0
1
0
0
$0050
Reserved
Read:
R
R
R
R
R
R
R
R
Write:
Reset:
$0051
PWM Control Register
(PWMCR)
Read:
PWMEN2 PWMEN1 PWMEN0
0
0
PCH2
PCH1
PCH0
Write:
Reset:
0
0
0
0
0
0
0
0
$0052
PWM Clock Control
Register
(PWMCCR)
Read:
PCLKSEL
0
0
0
0
0
PCLK1
PCLK0
Write:
Reset:
0
0
0
0
0
0
0
0
$0053
PWM Data Register 0
(PWMDR0)
Read:
0PWMD7 0PWMD6 0PWMD5 0PWMD4 0PWMD3 0PWMD2 0PWMD1 0PWMD0
Write:
Reset:
0
0
0
0
0
0
0
0
$0054
PWM Data Register 1
(PWMDR1)
Read:
1PWMD7 1PWMD6 1PWMD5 1PWMD4 1PWMD3 1PWMD2 1PWMD1 1PWMD0
Write:
Reset:
0
0
0
0
0
0
0
0
$0055
PWM Data Register 2
(PWMDR2)
Read:
2PWMD7 2PWMD6 2PWMD5 2PWMD4 2PWMD3 2PWMD2 2PWMD1 2PWMD0
Write:
Reset:
0
0
0
0
0
0
0
0
$0056
PWM Phase Control
Register
(PWMPCR)
Read:
PHEN
PHD6
PHD5
PHD4
PHD3
PHD2
PHD1
PHD0
Write:
Reset:
0
0
0
0
0
0
0
0
$0057
ADC Status and Control
Register
(ADSCR)
Read:
COCO
AIEN
ADCO
ADCH4
ADCH3
ADCH2
ADCH1
ADCH0
Write:
Reset:
0
0
0
1
1
1
1
1
$0058
ADC Clock Control
Register
(ADICLK)
Read:
ADIV2
ADIV1
ADIV0
ADICLK
MODE1
MODE0
0
0
Write:
R
Reset:
0
0
0
0
0
1
0
0
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 9 of 12)
Memory Map
Input/Output (I/O) Section
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Memory Map
57
$0059
ADC Data Register High 0
(ADRH0)
Read:
ADx
ADx
ADx
ADx
ADx
ADx
ADx
ADx
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005A
ADC Data Register Low 0
(ADRL0)
Read:
ADx
ADx
ADx
ADx
ADx
ADx
ADx
ADx
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005B
ADC Data Register Low 1
(ADRL1)
Read:
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005C
ADC Data Register Low 2
(ADRL3)
Read:
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005D
ADC Data Register Low 3
(ADRL3)
Read:
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005E
ADC Auto-scan Control
Register
(ADASCR)
Read:
0
0
0
0
0
AUTO1
AUTO0
ASCAN
Write:
Reset:
0
0
0
0
0
0
0
0
$005F
Unimplemented
Read:
Write:
Reset:
$FE00
SIM Break Status Register
(SBSR)
Read:
R
R
R
R
R
R
SBSW
R
Write:
Note
Reset:
0
Note: Writing a logic 0 clears SBSW.
$FE01
SIM Reset Status Register
(SRSR)
Read:
POR
PIN
COP
ILOP
ILAD
0
LVI
0
Write:
POR:
1
0
0
0
0
0
0
0
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 10 of 12)
Memory Map
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
58
Memory Map
MOTOROLA
$FE02
Reserved
Read:
R
R
R
R
R
R
R
R
Write:
Reset:
$FE03
SIM Break Flag Control
Register
(SBFCR)
Read:
BCFE
R
R
R
R
R
R
R
Write:
Reset:
0
$FE04
Interrupt Status Register 1
(INT1)
Read:
IF6
IF5
IF4
IF3
IF2
IF1
0
0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$FE05
Interrupt Status Register 2
(INT2)
Read:
IF14
IF13
IF12
IF11
IF10
IF9
IF8
IF7
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$FE06
Interrupt Status Register 3
(INT3)
Read:
0
0
0
0
0
IF17
IF16
IF15
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$FE07
Reserved
Read:
R
R
R
R
R
R
R
R
Write:
Reset:
$FE08
FLASH Control Register
(FLCR)
Read:
0
0
0
0
HVEN
MASS
ERASE
PGM
Write:
Reset:
0
0
0
0
0
0
0
0
$FE09
FLASH Block Protect
Register (FLBPR)
Read:
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
Write:
Reset:
0
0
0
0
0
0
0
0
$FE0A
Reserved
Read:
R
R
R
R
R
R
R
R
Write:
Reset:
$FE0B
Reserved
Read:
R
R
R
R
R
R
R
R
Write:
Reset:
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 11 of 12)
Memory Map
Input/Output (I/O) Section
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Memory Map
59
$FE0C
Break Address Register
High
(BRKH)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
0
0
0
0
0
0
0
0
$FE0D
Break Address Register
Low
(BRKL)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
0
0
0
0
0
0
0
0
$FE0E
Break Status and Control
Register
(BRKSCR)
Read:
BRKE
BRKA
0
0
0
0
0
0
Write:
Reset:
0
0
0
0
0
0
0
0
$FE0F
Low-Voltage Inhibit Status
Register
(LVISR)
Read: LVIOUT
0
0
0
0
0
0
0
Write:
Reset:
0
0
0
0
0
0
0
0
$FF80
Mask Option Register
(MOR)*
Read:
OSCSEL1 OSCSEL0
R
R
R
R
R
R
Write:
Erased:
1
1
1
1
1
1
1
1
Reset:
U
U
U
U
U
U
U
U
* MOR is a non-volatile FLASH register; write by programming.
$FFFF
COP Control Register
(COPCTL)
Read:
Low byte of reset vector
Write:
Writing clears COP counter (any value)
Reset:
U
U
U
U
U
U
U
U
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
U = Unaffected
X = Indeterminate
= Unimplemented
R
= Reserved
Figure 2-2. Control, Status, and Data Registers (Sheet 12 of 12)
Memory Map
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
60
Memory Map
MOTOROLA
.
Table 2-1. Vector Addresses
Vector Priority
Vector
Address
Vector
Lowest
IF17
$FFDA
Timebase Module Interrupt Vector (High)
$FFDB
Timebase Module Interrupt Vector (Low)
IF16
$FFDC
Analog Module Interrupt Vector (High)
$FFDD
Analog Module Interrupt Vector (Low)
IF15
$FFDE
ADC Conversion Complete Vector (High)
$FFDF
ADC Conversion Complete Vector (Low)
IF14
$FFE0
Keyboard Vector (High)
$FFE1
Keyboard Vector (Low)
IF13
$FFE2
SCI Transmit Vector (High)
$FFE3
SCI Transmit Vector (Low)
IF12
$FFE4
SCI Receive Vector (High)
$FFE5
SCI Receive Vector (Low)
IF11
$FFE6
SCI Error Vector (High)
$FFE7
SCI Error Vector (Low)
IF10
$FFE8
MMIIC Interrupt Vector (High)
$FFE9
MMIIC Interrupt Vector (Low)
IF9
$FFEA
TIM2 Overflow Vector (High)
$FFEB
TIM2 Overflow Vector (Low)
IF8
$FFEC
TIM2 Channel 1 Vector (High)
$FFED
TIM2 Channel 1 Vector (Low)
IF7
$FFEE
TIM2 Channel 0 Vector (High)
$FFEF
TIM2 Channel 0 Vector (Low)
IF6
$FFF0
TIM1 Overflow Vector (High)
$FFF1
TIM1 Overflow Vector (Low)
IF5
$FFF2
TIM1 Channel 1 Vector (High)
$FFF3
TIM1 Channel 1 Vector (Low)
IF4
$FFF4
TIM1 Channel 0 Vector (High)
$FFF5
TIM1 Channel 0 Vector (Low)
IF3
$FFF6
PLL Vector (High)
$FFF7
PLL Vector (Low)
IF2
$FFF8
IRQ2 Vector (High)
$FFF9
IRQ2 Vector (Low)
IF1
$FFFA
IRQ1 Vector (High)
$FFFB
IRQ1 Vector (Low)
--
$FFFC
SWI Vector (High)
$FFFD
SWI Vector (Low)
--
$FFFE
Reset Vector (High)
Highest
$FFFF
Reset Vector (Low)
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Random-Access Memory (RAM)
61
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 3. Random-Access Memory (RAM)
3.1 Contents
3.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3.2 Introduction
This section describes the 512 bytes of RAM (random-access memory).
3.3 Functional Description
Addresses $0060 through $025F are RAM locations. The location of the
stack RAM is programmable. The 16-bit stack pointer allows the stack to
be anywhere in the 64K-byte memory space.
NOTE:
For correct operation, the stack pointer must point only to RAM
locations.
Within page zero are 160 bytes of RAM. Because the location of the
stack RAM is programmable, all page zero RAM locations can be used
for I/O control and user data or code. When the stack pointer is moved
from its reset location at $00FF out of page zero, direct addressing mode
instructions can efficiently access all page zero RAM locations. Page
zero RAM, therefore, provides ideal locations for frequently accessed
global variables.
Before processing an interrupt, the CPU uses five bytes of the stack to
save the contents of the CPU registers.
NOTE:
For M6805 compatibility, the H register is not stacked.
Random-Access Memory (RAM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
62
Random-Access Memory (RAM)
MOTOROLA
During a subroutine call, the CPU uses two bytes of the stack to store
the return address. The stack pointer decrements during pushes and
increments during pulls.
NOTE:
Be careful when using nested subroutines. The CPU may overwrite data
in the RAM during a subroutine or during the interrupt stacking
operation.
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
FLASH Memory
63
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 4. FLASH Memory
4.1 Contents
4.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
4.4
FLASH Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
4.5
FLASH Page Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.6
FLASH Mass Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.7
FLASH Program Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
4.8
FLASH Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.8.1
FLASH Block Protect Register . . . . . . . . . . . . . . . . . . . . . . .70
4.2 Introduction
This section describes the operation of the embedded FLASH memory.
This memory can be read, programmed, and erased from a single
external supply. The program and erase operations are enabled through
the use of an internal charge pump.
FLASH Memory
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
64
FLASH Memory
MOTOROLA
4.3 Functional Description
The FLASH memory consists of an array of 12,288 bytes for user
memory plus a block of 38 bytes for user interrupt vectors and one byte
for the mask option register. An erased bit reads as logic 1 and a
programmed bit reads as a logic 0. The FLASH memory page size is
defined as 128 bytes, and is the minimum size that can be erased in a
page erase operation. Program and erase operations are facilitated
through control bits in FLASH control register (FLCR). The address
ranges for the FLASH memory are:
$C000$EFFF; user memory, 12,288 bytes
$FFDA$FFFF; user interrupt vectors, 38 bytes
$FF80; mask option register
Programming tools are available from Motorola. Contact your local
Motorola representative for more information.
NOTE:
A security feature prevents viewing of the FLASH contents.
1
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$FE08
FLASH Control Register
(FLCR)
Read:
0
0
0
0
HVEN
MASS
ERASE
PGM
Write:
Reset:
0
0
0
0
0
0
0
0
$FE09
FLASH Block Protect
Register (FLBPR)
Read:
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 4-1. FLASH I/O Register Summary
1. No security feature is absolutely secure. However, Motorola's strategy is to make reading or
copying the FLASH difficult for unauthorized users.
FLASH Memory
FLASH Control Register
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
FLASH Memory
65
4.4 FLASH Control Register
The FLASH control register (FLCR) controls FLASH program and erase
operations.
HVEN -- High Voltage Enable Bit
This read/write bit enables the charge pump to drive high voltages for
program and erase operations in the array. HVEN can only be set if
either PGM = 1 or ERASE = 1 and the proper sequence for program
or erase is followed.
1 = High voltage enabled to array and charge pump on
0 = High voltage disabled to array and charge pump off
MASS -- Mass Erase Control Bit
This read/write bit configures the memory for mass erase operation or
block erase operation when the ERASE bit is set.
1 = Mass Erase operation selected
0 = Block Erase operation selected
ERASE -- Erase Control Bit
This read/write bit configures the memory for erase operation.
ERASE is interlocked with the PGM bit such that both bits cannot be
equal to 1 or set to 1 at the same time.
1 = Erase operation selected
0 = Erase operation not selected
PGM -- Program Control Bit
This read/write bit configures the memory for program operation.
PGM is interlocked with the ERASE bit such that both bits cannot be
equal to 1 or set to 1 at the same time.
1 = Program operation selected
0 = Program operation not selected
Address:
$FE08
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
HVEN
MASS
ERASE
PGM
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 4-2. FLASH Control Register (FLCR)
FLASH Memory
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
66
FLASH Memory
MOTOROLA
4.5 FLASH Page Erase Operation
Use the following procedure to erase a page of FLASH memory. A page
consists of 128 consecutive bytes starting from addresses $xx00 or
$xx80. The 38-byte user interrupt vectors area also forms a page. The
38-byte user interrupt vectors cannot be erased by the page erase
operation because of security reasons. Mass erase is required to erase
this page.
1. Set the ERASE bit and clear the MASS bit in the FLASH control
register.
2. Write any data to any FLASH address within the page address
range desired.
3. Wait for a time, t
nvs
(10
s).
4. Set the HVEN bit.
5. Wait for a time, t
Erase
(1ms).
6. Clear the ERASE bit.
7. Wait for a time, t
nvh
(5
s).
8. Clear the HVEN bit.
9. After time, t
rcv
(1
s), the memory can be accessed again in read
mode.
NOTE:
Programming and erasing of FLASH locations cannot be performed by
executing code from the FLASH memory; the code must be executed
from RAM. While these operations must be performed in the order as
shown, but other unrelated operations may occur between the steps.
FLASH Memory
FLASH Mass Erase Operation
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
FLASH Memory
67
4.6 FLASH Mass Erase Operation
Use the following procedure to erase the entire FLASH memory to read
as logic 1:
1. Set both the ERASE bit and the MASS bit in the FLASH control
register.
2. Write any data to any FLASH address within the FLASH memory
address range.
3. Wait for a time, t
nvs
(10
s).
4. Set the HVEN bit.
5. Wait for a time t
MErase
(4ms).
6. Clear the ERASE bit.
7. Wait for a time, t
nvhl
(100
s).
8. Clear the HVEN bit.
9. After time, t
rcv
(1
s), the memory can be accessed again in read
mode.
NOTE:
Programming and erasing of FLASH locations cannot be performed by
executing code from the FLASH memory; the code must be executed
from RAM. While these operations must be performed in the order as
shown, but other unrelated operations may occur between the steps.
FLASH Memory
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
68
FLASH Memory
MOTOROLA
4.7 FLASH Program Operation
Programming of the FLASH memory is done on a row basis. A row
consists of 64 consecutive bytes starting from addresses $xx00, $xx40,
$xx80, or $xxC0. The procedure for programming a row of the FLASH
memory is outlined below:
1. Set the PGM bit. This configures the memory for program
operation and enables the latching of address and data for
programming.
2. Write any data to any FLASH address within the row address
range desired.
3. Wait for a time, t
nvs
(10
s).
4. Set the HVEN bit.
5. Wait for a time, t
pgs
(5
s).
6. Write data to the FLASH address to be programmed.
7. Wait for time, t
Prog
(30
s).
8. Repeat step 6 and 7 until all the bytes within the row are
programmed.
9. Clear the PGM bit.
10. Wait for time, t
nvh
(5
s).
11. Clear the HVEN bit.
12. After time, t
rcv
(1
s), the memory can be accessed again in read
mode.
This program sequence is repeated throughout the memory until all data
is programmed.
NOTE:
Programming and erasing of FLASH locations cannot be performed by
executing code from the FLASH memory; the code must be executed
from RAM. While these operations must be performed in the order as
shown, but other unrelated operations may occur between the steps. Do
not exceed t
Prog
maximum. See
24.18 FLASH Memory
Characteristics
.
FLASH Memory
FLASH Program Operation
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
FLASH Memory
69
Figure 4-3
shows a flowchart representation for programming the
FLASH memory.
Figure 4-3. FLASH Programming Flowchart
Set HVEN bit
Write any data to any FLASH address
within the row address range desired
Wait for a time, t
nvs
Set PGM bit
Wait for a time, t
pgs
Write data to the FLASH address
to be programmed
Wait for a time, t
Prog
Clear PGM bit
Wait for a time, t
nvh
Clear HVEN bit
Wait for a time, t
rcv
Completed
programming
this row?
Y
N
End of Programming
The time between each FLASH address change (step 6 to step 6), or
must not exceed the maximum programming
time, t
Prog
max.
the time between the last FLASH address programmed
to clearing PGM bit (step 6 to step 9)
NOTE:
1
2
3
4
5
6
7
9
10
11
12
Algorithm for programming
a row (64 bytes) of FLASH memory
This row program algorithm assumes the row/s
to be programmed are initially erased.
FLASH Memory
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
70
FLASH Memory
MOTOROLA
4.8 FLASH Protection
Due to the ability of the on-board charge pump to erase and program the
FLASH memory in the target application, provision is made to protect
pages of memory from unintentional erase or program operations due to
system malfunction. This protection is done by use of a FLASH block
protect register (FLBPR). The FLBPR determines the range of the
FLASH memory which is to be protected. The range of the protected
area starts from a location defined by FLBPR and ends to the bottom of
the FLASH memory ($FFFF). When the memory is protected, the HVEN
bit cannot be set in either ERASE or PROGRAM operations.
NOTE:
When the FLBPR is cleared (all 0's), the entire FLASH memory is
protected from being programmed and erased. When all the bits are set,
the entire FLASH memory is accessible for program and erase.
4.8.1 FLASH Block Protect Register
The FLASH block protect register is implemented as an 8-bit I/O register.
The content of this register determine the starting location of the
protected range within the FLASH memory.
BPR[7:0] -- FLASH Block Protect Register Bit7 to Bit 0
BPR[7:1] represent bits [13:7] of a 16-bit memory address. Bits
[15:14] are logic 1s and bits [6:0] are logic 0s.
Figure 4-5. FLASH Block Protect Start Address
Address:
$FE09
Bit 7
6
5
4
3
2
1
Bit 0
Read:
BPR7
BPR6
BPR5
BPR4
BPR3
BPR2
BPR1
BPR0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 4-4. FLASH Block Protect Register (FLBPR)
16-bit memory address
Start address of FLASH block protect
1 1
0 0 0 0 0 0 0
BPR[7:1]
FLASH Memory
FLASH Protection
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
FLASH Memory
71
BPR0 is used only for BPR[7:0] = $FF, for no block protection.
The resultant 16-bit address is used for specifying the start address
of the FLASH memory for block protection. The FLASH is protected
from this start address to the end of FLASH memory, at $FFFF. With
this mechanism, the protect start address can be XX00 or XX80 (at
page boundaries) within the FLASH memory.
Examples of protect start address:
BPR[7:0]
Start of Address of Protect Range
$00 or $01
$C000 (1100 0000 0000 0000)
The entire FLASH memory is protected.
$02 or $03
$C080 (1100 0000 1000 0000)
$04 or $05
$C100 (1100 0001 0000 0000)
$06 or $07
$C180 (1100 0001 1000 0000)
$08 or $09
$C200 (1100 0010 0000 0000)
and so on...
$F8 or $F9
$FE00 (1111 1110 0000 0000)
$FA or $FB
$FE80 (1111 1110 1000 0000)
$FC or $FD
$FF00 (1111 1111 0000 0000)
$FE
$FF80 (1111 1111 1000 0000)
$FF
The entire FLASH memory is not protected.
Note:
The end address of the protected range is always $FFFF.
FLASH Memory
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
72
FLASH Memory
MOTOROLA
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Configuration and Mask Option Registers (CONFIG & MOR)
73
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 5. Configuration and Mask Option Registers
(CONFIG & MOR)
5.1 Contents
5.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
5.4
Configuration Register 1 (CONFIG1) . . . . . . . . . . . . . . . . . . . .75
5.5
Configuration Register 2 (CONFIG2) . . . . . . . . . . . . . . . . . . . .77
5.6
Mask Option Register (MOR) . . . . . . . . . . . . . . . . . . . . . . . . . . 79
5.2 Introduction
This section describes the configuration registers, CONFIG1 and
CONFIG2; and the mask option register, MOR.
The configuration registers enable or disable these options:
Computer operating properly module (COP)
COP timeout period (2
18
2
4
or 2
13
2
4
ICLK cycles)
Low-voltage inhibit (LVI) module power
LVI module reset
LVI module in stop mode
LVI module voltage trip point selection
STOP instruction
Stop mode recovery time (32 ICLK cycles or 4096 ICLK cycles)
Oscillator (internal, RC, and crystal) during stop mode
Serial communications interface clock source (CGMXCLK or f
BUS
)
Current detect output pin
Configuration and Mask Option
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
74
Configuration and Mask Option Registers (CONFIG & MOR)
MOTOROLA
The mask option register selects one of the following oscillator options
as the MCU reference clock:
Internal oscillator
RC oscillator
Crystal oscillator
5.3 Functional Description
The configuration registers and the mask option register are used in the
initialization of various options. These two types of registers are
configured differently:
Configuration registers -- Write-once registers after reset
Mask option register -- FLASH register (write by programming)
The configuration registers can be written once after each reset. All of
the configuration register bits are cleared during reset. Since the various
options affect the operation of the MCU, it is recommended that these
registers be written immediately after reset. The configuration registers
are located at $001D and $001F. The configurations register may be
read at anytime.
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$001D
Configuration Register 2
(CONFIG2)
Read:
STOP_
ICLKEN
STOP_
RCLKEN
STOP_
XCLKEN
OSCCLK1 OSCCLK0
0
CDOEN
SCIBDSRC
Write:
Reset:
0
0
0
0
0
0
0
0
$001F
Configuration Register 1
(CONFIG1)
Read:
COPRS
LVISTOP LVIRSTD LVIPWRD LVI5OR3
SSREC
STOP
COPD
Write:
Reset:
0
0
0
0
0
0
0
0
$FF80
Mask Option Register
(MOR)*
Read:
OSCSEL1 OSCSEL0
R
R
R
R
R
R
Write:
Erased:
1
1
1
1
1
1
1
1
* FLASH register.
Reset:
U
U
U
U
U
U
U
U
One-time writable register after each reset.
Reset by POR only.
= Unimplemented
R
= Reserved
Figure 5-1. CONFIG and MOR Register Summary
Configuration and Mask Option Registers (CONFIG & MOR)
Configuration Register 1 (CONFIG1)
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Configuration and Mask Option Registers (CONFIG & MOR)
75
NOTE:
The options except LVI5OR3 are one-time writable by the user after
each reset. The LVI5OR3 bit is one-time writable by the user only after
each POR (power-on reset). The CONFIG registers are not in the
FLASH memory but are special registers containing one-time writable
latches after each reset. Upon a reset, the CONFIG registers default to
predetermined settings as shown in
Figure 5-2
and
Figure 5-3
.
The mask option register (MOR) is used for selecting one of the three
clock options for the MCU. The MOR is a byte located in FLASH
memory, and is written to by a FLASH programming routine.
5.4 Configuration Register 1 (CONFIG1)
COPRS -- COP Rate Select
COPRS selects the COP time-out period. Reset clears COPRS. (See
Section 21. Computer Operating Properly (COP)
.)
1 = COP time out period = 2
13
2
4
ICLK cycles
0 = COP time out period = 2
18
2
4
ICLK cycles
LVISTOP -- LVI Enable in Stop Mode
When the LVIPWRD bit is clear, setting the LVISTOP bit enables the
LVI to operate during stop mode. Reset clears LVISTOP. (See
Section 22. Low-Voltage Inhibit (LVI)
.)
1 = LVI enabled during stop mode
0 = LVI disabled during stop mode
Address:
$001F
Bit 7
6
5
4
3
2
1
Bit 0
Read:
COPRS
LVISTOP LVIRSTD LVIPWRD LVI5OR3
SSREC
STOP
COPD
Write:
Reset:
0
0
0
0
0*
0
0
0
* Reset by POR only.
Figure 5-2. Configuration Register 1 (CONFIG1)
Configuration and Mask Option
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
76
Configuration and Mask Option Registers (CONFIG & MOR)
MOTOROLA
LVIRSTD -- LVI Reset Disable
LVIRSTD disables the reset signal from the LVI module. (See
Section 22. Low-Voltage Inhibit (LVI)
.)
1 = LVI module resets disabled
0 = LVI module resets enabled
LVIPWRD -- LVI Power Disable Bit
LVIPWRD disables the LVI module. (See
Section 22. Low-Voltage
Inhibit (LVI)
.)
1 = LVI module power disabled
0 = LVI module power enabled
LVI5OR3 -- LVI 5V or 3V Operating Mode
LVI5OR3 selects the voltage operating mode of the LVI module. (See
Section 22. Low-Voltage Inhibit (LVI)
.) The voltage mode selected
for the LVI should match the operating V
DD
.
See Section 24.
Electrical Specifications
for the LVI voltage trip points for each of
the modes.
1 = LVI operates in 5V mode
0 = LVI operates in 3V mode
SSREC -- Short Stop Recovery
SSREC enables the CPU to exit stop mode with a delay of 32 ICLK
cycles instead of a 4096 ICLK cycle delay.
1 = Stop mode recovery after 32 ICLK cycles
0 = Stop mode recovery after 4096 ICLK cycles
NOTE:
Exiting stop mode by pulling reset will result in the long stop recovery.
If using an external crystal oscillator, and it is disabled during stop mode
(STOP_XCLKEN=0), do not set the SSREC bit.
NOTE:
When the LVI is disabled in stop mode (LVISTOP=0), the system
stabilization time for long stop recovery (4096 ICLK cycles) gives a delay
longer than the LVI's turn-on time. There is no period where the MCU is
not protected from a low power condition. However, when using the
short stop recovery configuration option, the 32 ICLK delay is less than
the LVI's turn-on time and there exists a period in start-up where the LVI
is not protecting the MCU.
Configuration and Mask Option Registers (CONFIG & MOR)
Configuration Register 2 (CONFIG2)
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Configuration and Mask Option Registers (CONFIG & MOR)
77
STOP -- STOP Instruction Enable
STOP enables the STOP instruction.
1 = STOP instruction enabled
0 = STOP instruction treated as illegal opcode
COPD -- COP Disable Bit
COPD disables the COP module. (See
Section 21. Computer
Operating Properly (COP)
.)
1 = COP module disabled
0 = COP module enabled
5.5 Configuration Register 2 (CONFIG2)
STOP_ICLKEN -- Internal Oscillator Stop Mode Disable
STOP_ICLKEN disables the internal oscillator during stop mode.
Setting the STOP_ICLKEN bit disables the oscillator during stop
mode. (See
7.4 Internal Oscillator
).
Reset clears this bit.
1 = Internal oscillator disabled during stop mode
0 = Internal oscillator enabled to operate during stop mode
STOP_RCLKEN -- RC Oscillator Stop Mode Enable
STOP_RCLKEN enables the RC oscillator to continue operating
during stop mode. Setting the STOP_RCLKEN bit allows the
oscillator to operate continuously even during stop mode. This is
useful for driving the timebase module to allow it to generate periodic
wake up while in stop mode. (See
Section 8. Clock Generator
Module (CGM)
and subsection
8.8.2 Stop Mode
.)
Reset clears this bit.
1 = RC oscillator enabled to operate during stop mode
0 = RC oscillator disabled during stop mode
Address:
$001D
Bit 7
6
5
4
3
2
1
Bit 0
Read:
STOP_
ICLKEN
STOP_
RCLKEN
STOP_
XCLKEN
OSCCLK1 OSCCLK0
0
CDOEN
SCIBDSRC
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 5-3. Configuration Register 2 (CONFIG2)
Configuration and Mask Option
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
78
Configuration and Mask Option Registers (CONFIG & MOR)
MOTOROLA
STOP_XCLKEN -- Crystal Oscillator Stop Mode Enable
STOP_XCLKEN enables the crystal (x-tal) oscillator to continue
operating during stop mode. Setting the STOP_XCLKEN bit allows
the x-tal oscillator to operate continuously even during stop mode.
This is useful for driving the timebase module to allow it to generate
periodic wake up while in stop mode. (See
Section 8. Clock
Generator Module (CGM)
and subsection
8.8.2 Stop Mode
.)
Reset clears this bit.
1 = X-tal oscillator enabled to operate during stop mode
0 = X-tal oscillator disabled during stop mode
OSCCLK1, OSCCLK0 -- Oscillator Output Control Bits
OSCCLK1 and OSCCLK0 select which oscillator output to be driven
out as OSCCLK to the timebase module (TBM). Reset clears these
two bits.
CDOEN -- Current-Flow Detect Output Enable
CDOEN enables the port pin PC0/PWM0/CD as the CD output pin for
the current detect flag (CDIF) from the analog module. Reset clears
the CDOEN bit.
1 = PCO/PWMO/CD pin enabled as CD output pin,
PTC0 and PWM0 functions are disabled.
0 = PTC0/PWM/CD pin disabled as CD output pin,
PTC0 or PWM0 functions are available; see
18.5.1 Port C
Data Register (PTC)
.
OSCCLK1
OSCCLK0
Timebase Clock Source
0
0
Internal oscillator (ICLK)
0
1
RC oscillator (RCCLK)
1
0
X-tal oscillator (XTAL)
1
1
Not used
Configuration and Mask Option Registers (CONFIG & MOR)
Mask Option Register (MOR)
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Configuration and Mask Option Registers (CONFIG & MOR)
79
SCIBDSRC -- SCI Baud Rate Clock Source
SCIBDSRC selects the clock source used for the SCI. The setting of
this bit affects the frequency at which the SCI operates.
1 = Internal data bus clock, f
BUS
, is used as clock source for SCI
0 = Oscillator clock, CGMXCLK, is used as clock source for SCI
5.6 Mask Option Register (MOR)
The mask option register (MOR) is used for selecting one of the three
clock options for the MCU. The MOR is a byte located in FLASH
memory, and is written to by a FLASH programming routine.
OSCSEL1, OSCSEL0 -- Oscillator Selection Bits
OSCSEL1 and OSCSEL0 select which oscillator is used for the MCU
CGMXCLK clock. The erase state of these two bits is logic 1. These
bits are unaffected by reset. (See
Table 5-1
).
Bits 50 -- Should be left as 1's.
Address:
$FF80
Bit 7
6
5
4
3
2
1
Bit 0
Read:
OSCSEL1 OSCSEL0
R
R
R
R
R
R
Write:
Erased:
1
1
1
1
1
1
1
1
Reset:
U
U
U
U
U
U
U
U
R
= Reserved
Figure 5-4. Mask Option Register (MOR)
Configuration and Mask Option
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
80
Configuration and Mask Option Registers (CONFIG & MOR)
MOTOROLA
NOTE:
The internal oscillator is a free running oscillator and is available after
each POR or reset. It is turned-off in stop mode by clearing the
STOP_ICLKEN bit in CONFIG2.
Table 5-1. CGMXCLK Clock Selection
OSCSEL1
OSCSEL0
CGMXCLK
OSC2 pin
Comments
0
0
--
--
Not used
0
1
ICLK
f
BUS
Internal oscillator generates the CGMXCLK.
1
0
RCCLK
f
BUS
RC oscillator generates the CGMXCLK.
Internal oscillator is available after each POR
or reset.
1
1
X-TAL
Inverting
output of
XTAL
X-tal oscillator generates the CGMXCLK.
Internal oscillator is available after each POR
or reset.
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Central Processor Unit (CPU)
81
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 6. Central Processor Unit (CPU)
6.1 Contents
6.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
6.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.4
CPU Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.4.1
Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83
6.4.2
Index Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
6.4.3
Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
6.4.4
Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.4.5
Condition Code Register . . . . . . . . . . . . . . . . . . . . . . . . . . .85
6.5
Arithmetic/Logic Unit (ALU) . . . . . . . . . . . . . . . . . . . . . . . . . . .88
6.6
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
6.6.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
6.6.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.7
CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.8
Instruction Set Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.9
Opcode Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.2 Introduction
The M68HC08 CPU (central processor unit) is an enhanced and fully
object-code-compatible version of the M68HC05 CPU. The CPU08
Reference Manual (Motorola document order number CPU08RM/AD)
contains a description of the CPU instruction set, addressing modes,
and architecture.
Central Processor Unit (CPU)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
82
Central Processor Unit (CPU)
MOTOROLA
6.3 Features
Object code fully upward-compatible with M68HC05 Family
16-bit stack pointer with stack manipulation instructions
16-bit index register with x-register manipulation instructions
8-MHz CPU internal bus frequency
64K-byte program/data memory space
16 addressing modes
Memory-to-memory data moves without using accumulator
Fast 8-bit by 8-bit multiply and 16-bit by 8-bit divide instructions
Enhanced binary-coded decimal (BCD) data handling
Modular architecture with expandable internal bus definition for
extension of addressing range beyond 64K-bytes
Low-power stop and wait modes
6.4 CPU Registers
Figure 6-1
shows the five CPU registers. CPU registers are not part of
the memory map.
Central Processor Unit (CPU)
CPU Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Central Processor Unit (CPU)
83
Figure 6-1. CPU Registers
6.4.1 Accumulator
The accumulator is a general-purpose 8-bit register. The CPU uses the
accumulator to hold operands and the results of arithmetic/logic
operations.
ACCUMULATOR (A)
INDEX REGISTER (H:X)
STACK POINTER (SP)
PROGRAM COUNTER (PC)
CONDITION CODE REGISTER (CCR)
CARRY/BORROW FLAG
ZERO FLAG
NEGATIVE FLAG
INTERRUPT MASK
HALF-CARRY FLAG
TWO'S COMPLEMENT OVERFLOW FLAG
V 1 1 H
I
N Z C
H
X
0
0
0
0
7
15
15
15
7
0
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Write:
Reset:
Unaffected by reset
Figure 6-2. Accumulator (A)
Central Processor Unit (CPU)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
84
Central Processor Unit (CPU)
MOTOROLA
6.4.2 Index Register
The 16-bit index register allows indexed addressing of a 64K-byte
memory space. H is the upper byte of the index register, and X is the
lower byte. H:X is the concatenated 16-bit index register.
In the indexed addressing modes, the CPU uses the contents of the
index register to determine the conditional address of the operand.
The index register can serve also as a temporary data storage location.
6.4.3 Stack Pointer
The stack pointer is a 16-bit register that contains the address of the next
location on the stack. During a reset, the stack pointer is preset to
$00FF. The reset stack pointer (RSP) instruction sets the least
significant byte to $FF and does not affect the most significant byte. The
stack pointer decrements as data is pushed onto the stack and
increments as data is pulled from the stack.
In the stack pointer 8-bit offset and 16-bit offset addressing modes, the
stack pointer can function as an index register to access data on the
stack. The CPU uses the contents of the stack pointer to determine the
conditional address of the operand.
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Bit
0
Read:
Write:
Reset:
0
0
0
0
0
0
0
0
X
X
X
X
X
X
X
X
X = Indeterminate
Figure 6-3. Index Register (H:X)
Central Processor Unit (CPU)
CPU Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Central Processor Unit (CPU)
85
NOTE:
The location of the stack is arbitrary and may be relocated anywhere in
RAM. Moving the SP out of page 0 ($0000 to $00FF) frees direct
address (page 0) space. For correct operation, the stack pointer must
point only to RAM locations.
6.4.4 Program Counter
The program counter is a 16-bit register that contains the address of the
next instruction or operand to be fetched.
Normally, the program counter automatically increments to the next
sequential memory location every time an instruction or operand is
fetched. Jump, branch, and interrupt operations load the program
counter with an address other than that of the next sequential location.
During reset, the program counter is loaded with the reset vector
address located at $FFFE and $FFFF. The vector address is the
address of the first instruction to be executed after exiting the reset state.
6.4.5 Condition Code Register
The 8-bit condition code register contains the interrupt mask and five
flags that indicate the results of the instruction just executed. Bits 6 and
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Bit
0
Read:
Write:
Reset:
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Figure 6-4. Stack Pointer (SP)
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Bit
0
Read:
Write:
Reset:
Loaded with Vector from $FFFE and $FFFF
Figure 6-5. Program Counter (PC)
Central Processor Unit (CPU)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
86
Central Processor Unit (CPU)
MOTOROLA
5 are set permanently to logic 1. The following paragraphs describe the
functions of the condition code register.
V -- Overflow Flag
The CPU sets the overflow flag when a two's complement overflow
occurs. The signed branch instructions BGT, BGE, BLE, and BLT use
the overflow flag.
1 = Overflow
0 = No overflow
H -- Half-Carry Flag
The CPU sets the half-carry flag when a carry occurs between
accumulator bits 3 and 4 during an add-without-carry (ADD) or add-
with-carry (ADC) operation. The half-carry flag is required for binary-
coded decimal (BCD) arithmetic operations. The DAA instruction uses
the states of the H and C flags to determine the appropriate correction
factor.
1 = Carry between bits 3 and 4
0 = No carry between bits 3 and 4
Bit 7
6
5
4
3
2
1
Bit 0
Read:
V
1
1
H
I
N
Z
C
Write:
Reset:
X
1
1
X
1
X
X
X
X = Indeterminate
Figure 6-6. Condition Code Register (CCR)
Central Processor Unit (CPU)
CPU Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Central Processor Unit (CPU)
87
I -- Interrupt Mask
When the interrupt mask is set, all maskable CPU interrupts are
disabled. CPU interrupts are enabled when the interrupt mask is
cleared. When a CPU interrupt occurs, the interrupt mask is set
automatically after the CPU registers are saved on the stack, but
before the interrupt vector is fetched.
1 = Interrupts disabled
0 = Interrupts enabled
NOTE:
To maintain M6805 Family compatibility, the upper byte of the index
register (H) is not stacked automatically. If the interrupt service routine
modifies H, then the user must stack and unstack H using the PSHH and
PULH instructions.
After the I bit is cleared, the highest-priority interrupt request is
serviced first.
A return-from-interrupt (RTI) instruction pulls the CPU registers from
the stack and restores the interrupt mask from the stack. After any
reset, the interrupt mask is set and can be cleared only by the clear
interrupt mask software instruction (CLI).
N -- Negative flag
The CPU sets the negative flag when an arithmetic operation, logic
operation, or data manipulation produces a negative result, setting bit
7 of the result.
1 = Negative result
0 = Non-negative result
Z -- Zero flag
The CPU sets the zero flag when an arithmetic operation, logic
operation, or data manipulation produces a result of $00.
1 = Zero result
0 = Non-zero result
Central Processor Unit (CPU)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
88
Central Processor Unit (CPU)
MOTOROLA
C -- Carry/Borrow Flag
The CPU sets the carry/borrow flag when an addition operation
produces a carry out of bit 7 of the accumulator or when a subtraction
operation requires a borrow. Some instructions -- such as bit test and
branch, shift, and rotate -- also clear or set the carry/borrow flag.
1 = Carry out of bit 7
0 = No carry out of bit 7
6.5 Arithmetic/Logic Unit (ALU)
The ALU performs the arithmetic and logic operations defined by the
instruction set.
Refer to the CPU08 Reference Manual (Motorola document order
number CPU08RM/AD) for a description of the instructions and
addressing modes and more detail about the architecture of the CPU.
6.6 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-consumption
standby modes.
6.6.1 Wait Mode
The WAIT instruction:
Clears the interrupt mask (I bit) in the condition code register,
enabling interrupts. After exit from wait mode by interrupt, the I bit
remains clear. After exit by reset, the I bit is set.
Disables the CPU clock
Central Processor Unit (CPU)
CPU During Break Interrupts
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Central Processor Unit (CPU)
89
6.6.2 Stop Mode
The STOP instruction:
Clears the interrupt mask (I bit) in the condition code register,
enabling external interrupts. After exit from stop mode by external
interrupt, the I bit remains clear. After exit by reset, the I bit is set.
Disables the CPU clock
After exiting stop mode, the CPU clock begins running after the oscillator
stabilization delay.
6.7 CPU During Break Interrupts
If a break module is present on the MCU, the CPU starts a break
interrupt by:
Loading the instruction register with the SWI instruction
Loading the program counter with $FFFC:$FFFD or with
$FEFC:$FEFD in monitor mode
The break interrupt begins after completion of the CPU instruction in
progress. If the break address register match occurs on the last cycle of
a CPU instruction, the break interrupt begins immediately.
A return-from-interrupt instruction (RTI) in the break routine ends the
break interrupt and returns the MCU to normal operation if the break
interrupt has been deasserted.
6.8 Instruction Set Summary
6.9 Opcode Map
See
Table 6-2
.
Central Processor Unit (CPU)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
90
Central Processor Unit (CPU)
MOTOROLA
Table 6-1. Instruction Set Summary
Source
Form
Operation
Description
Effect on
CCR
Addr
e
s
s
Mo
d
e
Opc
o
de
O
p
eran
d
Cycl
es
V H I N Z C
ADC #opr
ADC opr
ADC opr
ADC opr,X
ADC opr,X
ADC ,X
ADC opr,SP
ADC opr,SP
Add with Carry
A
(A) + (M) + (C)
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A9
B9
C9
D9
E9
F9
9EE9
9ED9
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
ADD #opr
ADD opr
ADD opr
ADD opr,X
ADD opr,X
ADD ,X
ADD opr,SP
ADD opr,SP
Add without Carry
A
(A) + (M)
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
AB
BB
CB
DB
EB
FB
9EEB
9EDB
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
AIS #opr
Add Immediate Value (Signed) to SP
SP
(SP) + (16 M)
IMM
A7
ii 2
AIX #opr
Add Immediate Value (Signed) to H:X
H:X
(H:X) + (16 M)
IMM
AF
ii
2
AND #opr
AND opr
AND opr
AND opr,X
AND opr,X
AND ,X
AND opr,SP
AND opr,SP
Logical AND
A
(A) & (M)
0
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A4
B4
C4
D4
E4
F4
9EE4
9ED4
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
ASL opr
ASLA
ASLX
ASL opr,X
ASL ,X
ASL opr,SP
Arithmetic Shift Left
(Same as LSL)
DIR
INH
INH
IX1
IX
SP1
38
48
58
68
78
9E68
dd
ff
ff
4
1
1
4
3
5
ASR opr
ASRA
ASRX
ASR opr,X
ASR opr,X
ASR opr,SP
Arithmetic Shift Right
DIR
INH
INH
IX1
IX
SP1
37
47
57
67
77
9E67
dd
ff
ff
4
1
1
4
3
5
BCC rel
Branch if Carry Bit Clear
PC
(PC) + 2 + rel ? (C) = 0
REL
24
rr
3
BCLR n, opr
Clear Bit n in M
Mn
0
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
11
13
15
17
19
1B
1D
1F
dd
dd
dd
dd
dd
dd
dd
dd
4
4
4
4
4
4
4
4
C
b0
b7
0
b0
b7
C
Central Processor Unit (CPU)
Opcode Map
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Central Processor Unit (CPU)
91
BCS rel
Branch if Carry Bit Set (Same as BLO)
PC
(PC) + 2 + rel ? (C) = 1
REL
25
rr
3
BEQ rel
Branch if Equal
PC
(PC) + 2 + rel ? (Z) = 1
REL
27
rr
3
BGE opr
Branch if Greater Than or Equal To
(Signed Operands)
PC
(PC) + 2 + rel ? (N
V
) =
0
REL
90
rr
3
BGT opr
Branch if Greater Than (Signed
Operands)
PC
(PC) + 2 +rel ? (Z)
| (N
V
) =
0 REL
92
rr
3
BHCC rel
Branch if Half Carry Bit Clear
PC
(PC) + 2 + rel ? (H) = 0
REL
28
rr
3
BHCS rel
Branch if Half Carry Bit Set
PC
(PC) + 2 + rel ? (H) = 1
REL
29
rr
3
BHI rel
Branch if Higher
PC
(PC) + 2 + rel ? (C) | (Z) = 0
REL
22
rr
3
BHS rel
Branch if Higher or Same
(Same as BCC)
PC
(PC) + 2 + rel ? (C) = 0
REL
24
rr
3
BIH rel
Branch if IRQ Pin High
PC
(PC) + 2 + rel ? IRQ = 1
REL
2F
rr
3
BIL rel
Branch if IRQ Pin Low
PC
(PC) + 2 + rel ? IRQ = 0
REL
2E
rr
3
BIT #opr
BIT opr
BIT opr
BIT opr,X
BIT opr,X
BIT ,X
BIT opr,SP
BIT opr,SP
Bit Test
(A) & (M)
0
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A5
B5
C5
D5
E5
F5
9EE5
9ED5
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
BLE opr
Branch if Less Than or Equal To
(Signed Operands)
PC
(PC) + 2 +rel ? (Z)
| (N
V
) =
1 REL
93
rr
3
BLO rel
Branch if Lower (Same as BCS)
PC
(PC) + 2 + rel ? (C) = 1
REL
25
rr
3
BLS rel
Branch if Lower or Same
PC
(PC) + 2 + rel ? (C) | (Z) = 1
REL
23
rr
3
BLT opr
Branch if Less Than (Signed Operands)
PC
(PC) + 2 + rel ? (N
V
) =
1
REL
91
rr
3
BMC rel
Branch if Interrupt Mask Clear
PC
(PC) + 2 + rel ? (I) = 0
REL
2C
rr
3
BMI rel
Branch if Minus
PC
(PC) + 2 + rel ? (N) = 1
REL
2B
rr
3
BMS rel
Branch if Interrupt Mask Set
PC
(PC) + 2 + rel ? (I) = 1
REL
2D
rr
3
BNE rel
Branch if Not Equal
PC
(PC) + 2 + rel ? (Z) = 0
REL
26
rr
3
BPL rel
Branch if Plus
PC
(PC) + 2 + rel ? (N) = 0
REL
2A
rr
3
BRA rel
Branch Always
PC
(PC) + 2 + rel
REL
20
rr
3
Table 6-1. Instruction Set Summary (Continued)
Source
Form
Operation
Description
Effect on
CCR
Addr
e
s
s
Mo
d
e
Opc
o
de
O
p
eran
d
Cycl
es
V H I N Z C
Central Processor Unit (CPU)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
92
Central Processor Unit (CPU)
MOTOROLA
BRCLR n,opr,rel Branch if Bit n in M Clear
PC
(PC) + 3 + rel ? (Mn) = 0
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
01
03
05
07
09
0B
0D
0F
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
5
5
5
5
5
5
5
5
BRN rel
Branch Never
PC
(PC) + 2
REL
21
rr
3
BRSET n,opr,rel Branch if Bit n in M Set
PC
(PC) + 3 + rel ? (Mn) = 1
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
00
02
04
06
08
0A
0C
0E
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
dd rr
5
5
5
5
5
5
5
5
BSET n,opr
Set Bit n in M
Mn
1
DIR (b0)
DIR (b1)
DIR (b2)
DIR (b3)
DIR (b4)
DIR (b5)
DIR (b6)
DIR (b7)
10
12
14
16
18
1A
1C
1E
dd
dd
dd
dd
dd
dd
dd
dd
4
4
4
4
4
4
4
4
BSR rel
Branch to Subroutine
PC
(PC) + 2; push (PCL)
SP
(SP) 1; push (PCH)
SP
(SP) 1
PC
(PC) + rel
REL
AD
rr
4
CBEQ opr,rel
CBEQA #opr,rel
CBEQX #opr,rel
CBEQ opr,X+,rel
CBEQ X+,rel
CBEQ opr,SP,rel
Compare and Branch if Equal
PC
(PC) + 3 + rel ? (A) (M) = $00
PC
(PC) + 3 + rel ? (A) (M) = $00
PC
(PC) + 3 + rel ? (X) (M) = $00
PC
(PC) + 3 + rel ? (A) (M) = $00
PC
(PC) + 2 + rel ? (A) (M) = $00
PC
(PC) + 4 + rel ? (A) (M) = $00
DIR
IMM
IMM
IX1+
IX+
SP1
31
41
51
61
71
9E61
dd rr
ii rr
ii rr
ff rr
rr
ff rr
5
4
4
5
4
6
CLC
Clear Carry Bit
C
0
0 INH
98
1
CLI
Clear Interrupt Mask
I
0
0 INH
9A
2
CLR opr
CLRA
CLRX
CLRH
CLR opr,X
CLR ,X
CLR opr,SP
Clear
M
$00
A
$00
X
$00
H
$00
M
$00
M
$00
M
$00
0 0 1
DIR
INH
INH
INH
IX1
IX
SP1
3F
4F
5F
8C
6F
7F
9E6F
dd
ff
ff
3
1
1
1
3
2
4
Table 6-1. Instruction Set Summary (Continued)
Source
Form
Operation
Description
Effect on
CCR
Addr
e
s
s
Mo
d
e
Opc
o
de
O
p
eran
d
Cycl
es
V H I N Z C
Central Processor Unit (CPU)
Opcode Map
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Central Processor Unit (CPU)
93
CMP #opr
CMP opr
CMP opr
CMP opr,X
CMP opr,X
CMP ,X
CMP opr,SP
CMP opr,SP
Compare A with M
(A) (M)
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A1
B1
C1
D1
E1
F1
9EE1
9ED1
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
COM opr
COMA
COMX
COM opr,X
COM ,X
COM opr,SP
Complement (One's Complement)
M
(M) = $FF (M)
A
(A) = $FF (M)
X
(X) = $FF (M)
M
(M) = $FF (M)
M
(M) = $FF (M)
M
(M) = $FF (M)
0
1
DIR
INH
INH
IX1
IX
SP1
33
43
53
63
73
9E63
dd
ff
ff
4
1
1
4
3
5
CPHX #opr
CPHX opr
Compare H:X with M
(H:X) (M:M + 1)
IMM
DIR
65
75
ii ii+1
dd
3
4
CPX #opr
CPX opr
CPX opr
CPX ,X
CPX opr,X
CPX opr,X
CPX opr,SP
CPX opr,SP
Compare X with M
(X) (M)
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A3
B3
C3
D3
E3
F3
9EE3
9ED3
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
DAA
Decimal Adjust A
(A)
10
U
INH
72
2
DBNZ opr,rel
DBNZA rel
DBNZX rel
DBNZ opr,X,rel
DBNZ X,rel
DBNZ opr,SP,rel
Decrement and Branch if Not Zero
A
(A) 1 or M
(M) 1 or X
(X) 1
PC
(PC) + 3 + rel ? (result)
0
PC
(PC) + 2 + rel ? (result)
0
PC
(PC) + 2 + rel ? (result)
0
PC
(PC) + 3 + rel ? (result)
0
PC
(PC) + 2 + rel ? (result)
0
PC
(PC) + 4 + rel ? (result)
0
DIR
INH
INH
IX1
IX
SP1
3B
4B
5B
6B
7B
9E6B
dd rr
rr
rr
ff rr
rr
ff rr
5
3
3
5
4
6
DEC opr
DECA
DECX
DEC opr,X
DEC ,X
DEC opr,SP
Decrement
M
(M) 1
A
(A) 1
X
(X) 1
M
(M) 1
M
(M) 1
M
(M) 1
DIR
INH
INH
IX1
IX
SP1
3A
4A
5A
6A
7A
9E6A
dd
ff
ff
4
1
1
4
3
5
DIV
Divide
A
(H:A)/(X)
H
Remainder
INH
52
7
Table 6-1. Instruction Set Summary (Continued)
Source
Form
Operation
Description
Effect on
CCR
Addr
e
s
s
Mo
d
e
Opc
o
de
O
p
eran
d
Cycl
es
V H I N Z C
Central Processor Unit (CPU)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
94
Central Processor Unit (CPU)
MOTOROLA
EOR #opr
EOR opr
EOR opr
EOR opr,X
EOR opr,X
EOR ,X
EOR opr,SP
EOR opr,SP
Exclusive OR M with A
A
(A
M)
0
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A8
B8
C8
D8
E8
F8
9EE8
9ED8
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
INC opr
INCA
INCX
INC opr,X
INC ,X
INC opr,SP
Increment
M
(M) + 1
A
(A) + 1
X
(X) + 1
M
(M) + 1
M
(M) + 1
M
(M) + 1
DIR
INH
INH
IX1
IX
SP1
3C
4C
5C
6C
7C
9E6C
dd
ff
ff
4
1
1
4
3
5
JMP opr
JMP opr
JMP opr,X
JMP opr,X
JMP ,X
Jump
PC
Jump Address
DIR
EXT
IX2
IX1
IX
BC
CC
DC
EC
FC
dd
hh ll
ee ff
ff
2
3
4
3
2
JSR opr
JSR opr
JSR opr,X
JSR opr,X
JSR ,X
Jump to Subroutine
PC
(PC) + n (n = 1, 2, or 3)
Push (PCL); SP
(SP) 1
Push (PCH); SP
(SP) 1
PC
Unconditional Address
DIR
EXT
IX2
IX1
IX
BD
CD
DD
ED
FD
dd
hh ll
ee ff
ff
4
5
6
5
4
LDA #opr
LDA opr
LDA opr
LDA opr,X
LDA opr,X
LDA ,X
LDA opr,SP
LDA opr,SP
Load A from M
A
(M)
0
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A6
B6
C6
D6
E6
F6
9EE6
9ED6
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
LDHX #opr
LDHX opr
Load H:X from M
H:X
(
M:M
+ 1
)
0
IMM
DIR
45
55
ii jj
dd
3
4
LDX #opr
LDX opr
LDX opr
LDX opr,X
LDX opr,X
LDX ,X
LDX opr,SP
LDX opr,SP
Load X from M
X
(M)
0
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
AE
BE
CE
DE
EE
FE
9EEE
9EDE
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
LSL opr
LSLA
LSLX
LSL opr,X
LSL ,X
LSL opr,SP
Logical Shift Left
(Same as ASL)
DIR
INH
INH
IX1
IX
SP1
38
48
58
68
78
9E68
dd
ff
ff
4
1
1
4
3
5
Table 6-1. Instruction Set Summary (Continued)
Source
Form
Operation
Description
Effect on
CCR
Addr
e
s
s
Mo
d
e
Opc
o
de
O
p
eran
d
Cycl
es
V H I N Z C
C
b0
b7
0
Central Processor Unit (CPU)
Opcode Map
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Central Processor Unit (CPU)
95
LSR opr
LSRA
LSRX
LSR opr,X
LSR ,X
LSR opr,SP
Logical Shift Right
0
DIR
INH
INH
IX1
IX
SP1
34
44
54
64
74
9E64
dd
ff
ff
4
1
1
4
3
5
MOV opr,opr
MOV opr,X+
MOV #opr,opr
MOV X+,opr
Move
(M)
Destination
(M)
Source
H:X
(H:X) + 1 (IX+D, DIX+)
0
DD
DIX+
IMD
IX+D
4E
5E
6E
7E
dd dd
dd
ii dd
dd
5
4
4
4
MUL
Unsigned multiply
X:A
(X)
(A)
0 0 INH
42
5
NEG opr
NEGA
NEGX
NEG opr,X
NEG ,X
NEG opr,SP
Negate (Two's Complement)
M
(M) = $00 (M)
A
(A) = $00 (A)
X
(X) = $00 (X)
M
(M) = $00 (M)
M
(M) = $00 (M)
DIR
INH
INH
IX1
IX
SP1
30
40
50
60
70
9E60
dd
ff
ff
4
1
1
4
3
5
NOP
No Operation
None
INH
9D
1
NSA
Nibble Swap A
A
(A[3:0]:A[7:4])
INH
62
3
ORA #opr
ORA opr
ORA opr
ORA opr,X
ORA opr,X
ORA ,X
ORA opr,SP
ORA opr,SP
Inclusive OR A and M
A
(A) | (M)
0
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
AA
BA
CA
DA
EA
FA
9EEA
9EDA
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
PSHA
Push A onto Stack
Push (A); SP
(SP) 1
INH
87
2
PSHH
Push H onto Stack
Push (H); SP
(SP) 1
INH
8B
2
PSHX
Push X onto Stack
Push (X); SP
(SP) 1
INH
89
2
PULA
Pull A from Stack
SP
(SP + 1); Pull
(
A
)
INH
86
2
PULH
Pull H from Stack
SP
(SP + 1); Pull
(
H
)
INH
8A
2
PULX
Pull X from Stack
SP
(SP + 1); Pull
(
X
)
INH
88
2
ROL opr
ROLA
ROLX
ROL opr,X
ROL ,X
ROL opr,SP
Rotate Left through Carry
DIR
INH
INH
IX1
IX
SP1
39
49
59
69
79
9E69
dd
ff
ff
4
1
1
4
3
5
Table 6-1. Instruction Set Summary (Continued)
Source
Form
Operation
Description
Effect on
CCR
Addr
e
s
s
Mo
d
e
Opc
o
de
O
p
eran
d
Cycl
es
V H I N Z C
b0
b7
C
0
C
b0
b7
Central Processor Unit (CPU)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
96
Central Processor Unit (CPU)
MOTOROLA
ROR opr
RORA
RORX
ROR opr,X
ROR ,X
ROR opr,SP
Rotate Right through Carry
DIR
INH
INH
IX1
IX
SP1
36
46
56
66
76
9E66
dd
ff
ff
4
1
1
4
3
5
RSP
Reset Stack Pointer
SP
$FF
INH
9C
1
RTI
Return from Interrupt
SP
(SP) + 1; Pull (CCR)
SP
(SP) + 1; Pull (A)
SP
(SP) + 1; Pull (X)
SP
(SP) + 1; Pull (PCH)
SP
(SP) + 1; Pull (PCL)
INH
80
7
RTS
Return from Subroutine
SP
SP + 1
;
Pull
(
PCH)
SP
SP + 1; Pull (PCL)
INH
81
4
SBC #opr
SBC opr
SBC opr
SBC opr,X
SBC opr,X
SBC ,X
SBC opr,SP
SBC opr,SP
Subtract with Carry
A
(A) (M) (C)
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A2
B2
C2
D2
E2
F2
9EE2
9ED2
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
SEC
Set Carry Bit
C
1
1 INH
99
1
SEI
Set Interrupt Mask
I
1
1 INH
9B
2
STA opr
STA opr
STA opr,X
STA opr,X
STA ,X
STA opr,SP
STA opr,SP
Store A in M
M
(A)
0
DIR
EXT
IX2
IX1
IX
SP1
SP2
B7
C7
D7
E7
F7
9EE7
9ED7
dd
hh ll
ee ff
ff
ff
ee ff
3
4
4
3
2
4
5
STHX opr
Store H:X in M
(M:M + 1)
(H:X)
0
DIR
35
dd
4
STOP
Enable IRQ Pin; Stop Oscillator
I
0; Stop Oscillator
0 INH
8E
1
STX opr
STX opr
STX opr,X
STX opr,X
STX ,X
STX opr,SP
STX opr,SP
Store X in M
M
(X)
0
DIR
EXT
IX2
IX1
IX
SP1
SP2
BF
CF
DF
EF
FF
9EEF
9EDF
dd
hh ll
ee ff
ff
ff
ee ff
3
4
4
3
2
4
5
Table 6-1. Instruction Set Summary (Continued)
Source
Form
Operation
Description
Effect on
CCR
Addr
e
s
s
Mo
d
e
Opc
o
de
O
p
eran
d
Cycl
es
V H I N Z C
b0
b7
C
Central Processor Unit (CPU)
Opcode Map
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Central Processor Unit (CPU)
97
SUB #opr
SUB opr
SUB opr
SUB opr,X
SUB opr,X
SUB ,X
SUB opr,SP
SUB opr,SP
Subtract A
(A) (M)
IMM
DIR
EXT
IX2
IX1
IX
SP1
SP2
A0
B0
C0
D0
E0
F0
9EE0
9ED0
ii
dd
hh ll
ee ff
ff
ff
ee ff
2
3
4
4
3
2
4
5
SWI
Software Interrupt
PC
(PC) + 1; Push (PCL)
SP
(SP) 1; Push (PCH)
SP
(SP) 1; Push (X)
SP
(SP) 1; Push (A)
SP
(SP) 1; Push (CCR)
SP
(SP) 1; I
1
PCH
Interrupt Vector High Byte
PCL
Interrupt Vector Low Byte
1 INH
83
9
TAP
Transfer A to CCR
CCR
(A)
INH
84
2
TAX
Transfer A to X
X
(A)
INH
97
1
TPA
Transfer CCR to A
A
(CCR)
INH
85
1
TST opr
TSTA
TSTX
TST opr,X
TST ,X
TST opr,SP
Test for Negative or Zero
(A) $00 or (X) $00 or (M) $00
0
DIR
INH
INH
IX1
IX
SP1
3D
4D
5D
6D
7D
9E6D
dd
ff
ff
3
1
1
3
2
4
TSX
Transfer SP to H:X
H:X
(SP) + 1
INH
95
2
TXA
Transfer X to A
A
(X)
INH
9F
1
TXS
Transfer H:X to SP
(SP)
(H:X) 1
INH
94
2
Table 6-1. Instruction Set Summary (Continued)
Source
Form
Operation
Description
Effect on
CCR
Addr
e
s
s
Mo
d
e
Opc
o
de
O
p
eran
d
Cycl
es
V H I N Z C
Central Processor Unit (CPU)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
98
Central Processor Unit (CPU)
MOTOROLA
A
Accumulator
n
Any bit
C
Carry/borrow bit
opr
Operand (one or two bytes)
CCR
Condition code register
PC
Program counter
dd
Direct address of operand
PCH Program counter high byte
dd rr
Direct address of operand and relative offset of branch instruction
PCL Program counter low byte
DD
Direct to direct addressing mode
REL Relative addressing mode
DIR
Direct addressing mode
rel
Relative program counter offset byte
DIX+
Direct to indexed with post increment addressing mode
rr
Relative program counter offset byte
ee ff
High and low bytes of offset in indexed, 16-bit offset addressing
SP1 Stack pointer, 8-bit offset addressing mode
EXT
Extended addressing mode
SP2 Stack pointer 16-bit offset addressing mode
ff
Offset byte in indexed, 8-bit offset addressing
SP
Stack pointer
H
Half-carry bit
U
Undefined
H
Index register high byte
V
Overflow bit
hh ll
High and low bytes of operand address in extended addressing
X
Index register low byte
I
Interrupt mask
Z
Zero bit
ii
Immediate operand byte
&
Logical AND
IMD
Immediate source to direct destination addressing mode
|
Logical OR
IMM
Immediate addressing mode
Logical EXCLUSIVE OR
INH
Inherent addressing mode
( )
Contents of
IX
Indexed, no offset addressing mode
( )
Negation (two's complement)
IX+
Indexed, no offset, post increment addressing mode
#
Immediate value
IX+D
Indexed with post increment to direct addressing mode
Sign extend
IX1
Indexed, 8-bit offset addressing mode
Loaded with
IX1+
Indexed, 8-bit offset, post increment addressing mode
?
If
IX2
Indexed, 16-bit offset addressing mode
:
Concatenated with
M
Memory location
Set or cleared
N
Negative bit
--
Not affected
Table 6-1. Instruction Set Summary (Continued)
Source
Form
Operation
Description
Effect on
CCR
Addr
e
s
s
Mo
d
e
Opc
o
de
O
p
eran
d
Cycl
es
V H I N Z C
MC6
8
HC9
08S
R12
MC6
8
HC08
S
R1
2
--
Rev
.
4.0
T
ech
n
i
c
a
l
Da
ta
MO
T
O
RO
LA
Cen
t
r
a
l Pr
oc
es
so
r
Unit
(
C
PU)
9
9
Cen
t
r
a
l P
r
oc
es
so
r
Unit
(
C
PU)
Op
co
d
e
M
a
p
Table 6-2. Opcode Map
Bit Manipulation
Branch
Read-Modify-Write
Control
Register/Memory
DIR
DIR
REL
DIR
INH
INH
IX1
SP1
IX
INH
INH
IMM
DIR
EXT
IX2
SP2
IX1
SP1
IX
0
1
2
3
4
5
6
9E6
7
8
9
A
B
C
D
9ED
E
9EE
F
0
5
BRSET0
3
DIR
4
BSET0
2
DIR
3
BRA
2
REL
4
NEG
2
DIR
1
NEGA
1
INH
1
NEGX
1
INH
4
NEG
2
IX1
5
NEG
3
SP1
3
NEG
1
IX
7
RTI
1
INH
3
BGE
2
REL
2
SUB
2
IMM
3
SUB
2
DIR
4
SUB
3
EXT
4
SUB
3
IX2
5
SUB
4
SP2
3
SUB
2
IX1
4
SUB
3
SP1
2
SUB
1
IX
1
5
BRCLR0
3
DIR
4
BCLR0
2
DIR
3
BRN
2
REL
5
CBEQ
3
DIR
4
CBEQA
3
IMM
4
CBEQX
3
IMM
5
CBEQ
3 IX1+
6
CBEQ
4
SP1
4
CBEQ
2
IX+
4
RTS
1
INH
3
BLT
2
REL
2
CMP
2
IMM
3
CMP
2
DIR
4
CMP
3
EXT
4
CMP
3
IX2
5
CMP
4
SP2
3
CMP
2
IX1
4
CMP
3
SP1
2
CMP
1
IX
2
5
BRSET1
3
DIR
4
BSET1
2
DIR
3
BHI
2
REL
5
MUL
1
INH
7
DIV
1
INH
3
NSA
1
INH
2
DAA
1
INH
3
BGT
2
REL
2
SBC
2
IMM
3
SBC
2
DIR
4
SBC
3
EXT
4
SBC
3
IX2
5
SBC
4
SP2
3
SBC
2
IX1
4
SBC
3
SP1
2
SBC
1
IX
3
5
BRCLR1
3
DIR
4
BCLR1
2
DIR
3
BLS
2
REL
4
COM
2
DIR
1
COMA
1
INH
1
COMX
1
INH
4
COM
2
IX1
5
COM
3
SP1
3
COM
1
IX
9
SWI
1
INH
3
BLE
2
REL
2
CPX
2
IMM
3
CPX
2
DIR
4
CPX
3
EXT
4
CPX
3
IX2
5
CPX
4
SP2
3
CPX
2
IX1
4
CPX
3
SP1
2
CPX
1
IX
4
5
BRSET2
3
DIR
4
BSET2
2
DIR
3
BCC
2
REL
4
LSR
2
DIR
1
LSRA
1
INH
1
LSRX
1
INH
4
LSR
2
IX1
5
LSR
3
SP1
3
LSR
1
IX
2
TAP
1
INH
2
TXS
1
INH
2
AND
2
IMM
3
AND
2
DIR
4
AND
3
EXT
4
AND
3
IX2
5
AND
4
SP2
3
AND
2
IX1
4
AND
3
SP1
2
AND
1
IX
5
5
BRCLR2
3
DIR
4
BCLR2
2
DIR
3
BCS
2
REL
4
STHX
2
DIR
3
LDHX
3
IMM
4
LDHX
2
DIR
3
CPHX
3
IMM
4
CPHX
2
DIR
1
TPA
1
INH
2
TSX
1
INH
2
BIT
2
IMM
3
BIT
2
DIR
4
BIT
3
EXT
4
BIT
3
IX2
5
BIT
4
SP2
3
BIT
2
IX1
4
BIT
3
SP1
2
BIT
1
IX
6
5
BRSET3
3
DIR
4
BSET3
2
DIR
3
BNE
2
REL
4
ROR
2
DIR
1
RORA
1
INH
1
RORX
1
INH
4
ROR
2
IX1
5
ROR
3
SP1
3
ROR
1
IX
2
PULA
1
INH
2
LDA
2
IMM
3
LDA
2
DIR
4
LDA
3
EXT
4
LDA
3
IX2
5
LDA
4
SP2
3
LDA
2
IX1
4
LDA
3
SP1
2
LDA
1
IX
7
5
BRCLR3
3
DIR
4
BCLR3
2
DIR
3
BEQ
2
REL
4
ASR
2
DIR
1
ASRA
1
INH
1
ASRX
1
INH
4
ASR
2
IX1
5
ASR
3
SP1
3
ASR
1
IX
2
PSHA
1
INH
1
TAX
1
INH
2
AIS
2
IMM
3
STA
2
DIR
4
STA
3
EXT
4
STA
3
IX2
5
STA
4
SP2
3
STA
2
IX1
4
STA
3
SP1
2
STA
1
IX
8
5
BRSET4
3
DIR
4
BSET4
2
DIR
3
BHCC
2
REL
4
LSL
2
DIR
1
LSLA
1
INH
1
LSLX
1
INH
4
LSL
2
IX1
5
LSL
3
SP1
3
LSL
1
IX
2
PULX
1
INH
1
CLC
1
INH
2
EOR
2
IMM
3
EOR
2
DIR
4
EOR
3
EXT
4
EOR
3
IX2
5
EOR
4
SP2
3
EOR
2
IX1
4
EOR
3
SP1
2
EOR
1
IX
9
5
BRCLR4
3
DIR
4
BCLR4
2
DIR
3
BHCS
2
REL
4
ROL
2
DIR
1
ROLA
1
INH
1
ROLX
1
INH
4
ROL
2
IX1
5
ROL
3
SP1
3
ROL
1
IX
2
PSHX
1
INH
1
SEC
1
INH
2
ADC
2
IMM
3
ADC
2
DIR
4
ADC
3
EXT
4
ADC
3
IX2
5
ADC
4
SP2
3
ADC
2
IX1
4
ADC
3
SP1
2
ADC
1
IX
A
5
BRSET5
3
DIR
4
BSET5
2
DIR
3
BPL
2
REL
4
DEC
2
DIR
1
DECA
1
INH
1
DECX
1
INH
4
DEC
2
IX1
5
DEC
3
SP1
3
DEC
1
IX
2
PULH
1
INH
2
CLI
1
INH
2
ORA
2
IMM
3
ORA
2
DIR
4
ORA
3
EXT
4
ORA
3
IX2
5
ORA
4
SP2
3
ORA
2
IX1
4
ORA
3
SP1
2
ORA
1
IX
B
5
BRCLR5
3
DIR
4
BCLR5
2
DIR
3
BMI
2
REL
5
DBNZ
3
DIR
3
DBNZA
2
INH
3
DBNZX
2
INH
5
DBNZ
3
IX1
6
DBNZ
4
SP1
4
DBNZ
2
IX
2
PSHH
1
INH
2
SEI
1
INH
2
ADD
2
IMM
3
ADD
2
DIR
4
ADD
3
EXT
4
ADD
3
IX2
5
ADD
4
SP2
3
ADD
2
IX1
4
ADD
3
SP1
2
ADD
1
IX
C
5
BRSET6
3
DIR
4
BSET6
2
DIR
3
BMC
2
REL
4
INC
2
DIR
1
INCA
1
INH
1
INCX
1
INH
4
INC
2
IX1
5
INC
3
SP1
3
INC
1
IX
1
CLRH
1
INH
1
RSP
1
INH
2
JMP
2
DIR
3
JMP
3
EXT
4
JMP
3
IX2
3
JMP
2
IX1
2
JMP
1
IX
D
5
BRCLR6
3
DIR
4
BCLR6
2
DIR
3
BMS
2
REL
3
TST
2
DIR
1
TSTA
1
INH
1
TSTX
1
INH
3
TST
2
IX1
4
TST
3
SP1
2
TST
1
IX
1
NOP
1
INH
4
BSR
2
REL
4
JSR
2
DIR
5
JSR
3
EXT
6
JSR
3
IX2
5
JSR
2
IX1
4
JSR
1
IX
E
5
BRSET7
3
DIR
4
BSET7
2
DIR
3
BIL
2
REL
5
MOV
3
DD
4
MOV
2 DIX+
4
MOV
3
IMD
4
MOV
2 IX+D
1
STOP
1
INH
*
2
LDX
2
IMM
3
LDX
2
DIR
4
LDX
3
EXT
4
LDX
3
IX2
5
LDX
4
SP2
3
LDX
2
IX1
4
LDX
3
SP1
2
LDX
1
IX
F
5
BRCLR7
3
DIR
4
BCLR7
2
DIR
3
BIH
2
REL
3
CLR
2
DIR
1
CLRA
1
INH
1
CLRX
1
INH
3
CLR
2
IX1
4
CLR
3
SP1
2
CLR
1
IX
1
WAIT
1
INH
1
TXA
1
INH
2
AIX
2
IMM
3
STX
2
DIR
4
STX
3
EXT
4
STX
3
IX2
5
STX
4
SP2
3
STX
2
IX1
4
STX
3
SP1
2
STX
1
IX
INH Inherent
REL Relative
SP1 Stack Pointer, 8-Bit Offset
IMM Immediate
IX
Indexed, No Offset
SP2 Stack Pointer, 16-Bit Offset
DIR Direct
IX1
Indexed, 8-Bit Offset
IX+
Indexed, No Offset with
EXT Extended
IX2
Indexed, 16-Bit Offset
Post Increment
DD
Direct-Direct
IMD Immediate-Direct
IX1+ Indexed, 1-Byte Offset with
IX+D Indexed-Direct
DIX+ Direct-Indexed
Post Increment
*
Pre-byte for stack pointer indexed instructions
0
High Byte of Opcode in Hexadecimal
Low Byte of Opcode in Hexadecimal
0
5
BRSET0
3
DIR
Cycles
Opcode Mnemonic
Number of Bytes / Addressing Mode
MSB
LSB
MSB
LSB
Central Processor Unit (CPU)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
100
Central Processor Unit (CPU)
MOTOROLA
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Oscillator (OSC)
101
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 7. Oscillator (OSC)
7.1 Contents
7.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
7.3
Clock Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103
7.3.1
CGM Reference Clock Selection . . . . . . . . . . . . . . . . . . . . 104
7.3.2
TBM Reference Clock Selection . . . . . . . . . . . . . . . . . . . . 105
7.4
Internal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
7.5
RC Oscillator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
7.6
X-tal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
7.7
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
7.7.1
Crystal Amplifier Input Pin (OSC1). . . . . . . . . . . . . . . . . . . 108
7.7.2
Crystal Amplifier Output Pin (OSC2) . . . . . . . . . . . . . . . . . 109
7.7.3
Oscillator Enable Signal (SIMOSCEN). . . . . . . . . . . . . . . . 109
7.7.4
CGM Oscillator Clock (CGMXCLK) . . . . . . . . . . . . . . . . . . 109
7.7.5
CGM Reference Clock (CGMRCLK) . . . . . . . . . . . . . . . . . 109
7.7.6
Oscillator Clock to Time Base Module (OSCCLK) . . . . . . . 109
7.8
Low Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109
7.8.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
7.8.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
7.9
Oscillator During Break Mode. . . . . . . . . . . . . . . . . . . . . . . . . 110
Oscillator (OSC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
102
Oscillator (OSC)
MOTOROLA
7.2 Introduction
The oscillator module provides the reference clock for the clock
generator module (CGM), the timebase module (TBM), and other MCU
sub-systems.
The oscillator module consist of three types of oscillator circuits:
Internal oscillator
RC oscillator
Crystal (x-tal) oscillator
The reference clock for the CGM and other MCU sub-systems is
selected by:
MC68HC908SR12 -- FLASH device -- oscillator selected by
programming the mask option register located at $FF80.
MC68HC08SR12 -- ROM device -- oscillator selected by ROM-
mask layer at factory.
The reference clock for the timebase module (TBM) is selected by the
two bits, OSCCLK1 and OSCCLK0, in the CONFIG2 register.
The internal oscillator runs continuously after a POR or reset, and is
always available. The RC and crystal oscillator cannot run concurrently;
one is disabled while the other is selected; because the RC and x-tal
circuits share the same OSC1 pin.
Figure 7-1
. shows the block diagram of the oscillator module.
Oscillator (OSC)
Clock Selection
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Oscillator (OSC)
103
Figure 7-1. Oscillator Module Block Diagram
7.3 Clock Selection
Reference clocks are selectable for the following sub-systems:
CGMXCLK and CGMRCLK -- Reference clock for clock
generator module (CGM) and other MCU sub-systems other than
TBM and COP. This is the main reference clock for the MCU.
OSCCLK -- Reference clock for timebase module (TBM).
X-TAL OSCILLATOR
RC OSCILLATOR
INTERNAL OSCILLATOR
MUX
OSC1
OSC2
BUS CLOCK
From SIM
MUX
XCLK
RCCLK
ICLK
OSCCLK0
OSCCLK1
OSCSEL0
OSCSEL1
OSCCLK
To TBM
CGMXCLK
CGMRCLK
To CGM and others
MOR
CONFIG2
To CGM PLL
X
RC
I
X
RC
I
To SIM
(and COP)
Oscillator (OSC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
104
Oscillator (OSC)
MOTOROLA
7.3.1 CGM Reference Clock Selection
The clock generator module (CGM) reference clock (CGMXCLK) is the
reference clock input to the MCU. It is selected by programming two bits
in a FLASH memory location; the mask option register (MOR), at $FF80.
See
5.6 Mask Option Register (MOR)
.
NOTE:
On the ROM device, the oscillator is selected by a ROM-mask layer at
factory.
NOTE:
The internal oscillator is a free running oscillator and is available after
each POR or reset. It is turned-off in stop mode by clearing the
STOP_ICLKEN bit in CONFIG2.
Address:
$FF80
Bit 7
6
5
4
3
2
1
Bit 0
Read:
OSCSEL1 OSCSEL0
R
R
R
R
R
R
Write:
Erased:
1
1
1
1
1
1
1
1
Reset:
U
U
U
U
U
U
U
U
R
= Reserved
Figure 7-2. Mask Option Register (MOR)
Table 7-1. CGMXCLK Clock Selection
OSCSEL1
OSCSEL0
CGMXCLK
OSC2 Pin
Comments
0
0
--
--
Not used
0
1
ICLK
f
BUS
Internal oscillator generates the CGMXCLK.
1
0
RCCLK
f
BUS
RC oscillator generates the CGMXCLK.
Internal oscillator is available after each POR
or reset.
1
1
XCLK
Inverting
output of
X-TAL
X-tal oscillator generates the CGMXCLK.
Internal oscillator is available after each POR
or reset.
Oscillator (OSC)
Internal Oscillator
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Oscillator (OSC)
105
7.3.2 TBM Reference Clock Selection
The timebase module reference clock (OSCCLK) is selected by
configuring two bits in the CONFIG2 register, at $001D. See
5.5
Configuration Register 2 (CONFIG2)
.
NOTE:
The RCCLK or XCLK is only available if that clock is selected as the
CGM reference clock, whereas the ICLK is always available.
7.4 Internal Oscillator
The internal oscillator clock (ICLK) is a free running 24kHz clock that
requires no external components. It can be selected as the CGMXCLK
for the CGM and MCU sub-systems; and the OSCCLK clock for the
TBM. The ICLK is also the reference clock input to the computer
operating properly (COP) module.
Due to the simplicity of the internal oscillator, it does not have the
accuracy and stability of the RC oscillator or the x-tal oscillator.
Therefore, the ICLK is not suitable where an accurate bus clock is
required and it should not be used as the CGMRCLK to the CGM PLL.
Address:
$001D
Bit 7
6
5
4
3
2
1
Bit 0
Read:
STOP_
ICLKEN
STOP_
RCLKEN
STOP_
XCLKEN
OSCCLK1 OSCCLK0
0
CDOEN
SCIBDSRC
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 7-3. Configuration Register 2 (CONFIG2)
Table 7-2. Timebase Module Reference Clock Selection
OSCCLK1
OSCCLK0
Timebase Clock Source
0
0
Internal oscillator (ICLK)
0
1
RC oscillator (RCCLK)
1
0
X-tal oscillator (XCLK)
1
1
Not used
Oscillator (OSC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
106
Oscillator (OSC)
MOTOROLA
The internal oscillator by default is always available and is free running
after POR or reset. It can be stopped in Stop mode by setting the
STOP_ICLKEN bit before executing the STOP instruction.
Figure 7-4
shows the logical representation of components of the
internal oscillator circuitry.
Figure 7-4. Internal Oscillator
7.5 RC Oscillator
The RC oscillator circuit is designed for use with external R and C to
provide a clock source with tolerance less than 10%.
In its typical configuration, the RC oscillator requires two external
components, one R and one C. Component values should have a
tolerance of 1% or less, to obtain a clock source with less than 10%
tolerance. The oscillator configuration uses two components:
C
EXT
R
EXT
INTERNAL OSCILLATOR
EN
SIMOSCEN
STOP_ICLKEN
CONFIG2
ICLK
MCU
From SIM
To Clock Selection MUX
BUS CLOCK
From SIM
OSC2
and COP
Oscillator (OSC)
X-tal Oscillator
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Oscillator (OSC)
107
Figure 7-5. RC Oscillator
7.6 X-tal Oscillator
The X-tal oscillator circuit is designed for use with an external crystal or
ceramic resonator to provide an accurate clock source.
In its typical configuration, the X-tal oscillator is connected in a Pierce
oscillator configuration, as shown in
Figure 7-6
. This figure shows only
the logical representation of the internal components and may not
represent actual circuitry. The oscillator configuration uses five
components:
Crystal, X
1
Fixed capacitor, C
1
Tuning capacitor, C
2
(can also be a fixed capacitor)
Feedback resistor, R
B
Series resistor, R
S
(optional)
R
EXT
C
EXT
V
DD
MCU
OSC1
SIMOSCEN
From SIM
STOP_RCLKEN
CONFIG2
RC OSCILLATOR
EN
See
Section 24.
for component value requirements.
BUS CLOCK
From SIM
OSC2
RCCLK
To Clock Selection MUX
Oscillator (OSC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
108
Oscillator (OSC)
MOTOROLA
Figure 7-6. Crystal Oscillator
The series resistor (R
S
) is included in the diagram to follow strict Pierce
oscillator guidelines and may not be required for all ranges of operation,
especially with high frequency crystals. Refer to the crystal
manufacturer's data for more information.
7.7 I/O Signals
The following paragraphs describe the oscillator I/O signals.
7.7.1 Crystal Amplifier Input Pin (OSC1)
OSC1 pin is an input to the crystal oscillator amplifier or the input to the
RC oscillator circuit.
C
1
C
2
R
B
X
1
R
S
*
*R
S
can be zero (shorted) when used with higher-frequency crystals.
MCU
Refer to manufacturer's data.
OSC2
OSC1
See
Section 24.
for component value requirements.
SIMOSCEN
From SIM
STOP_XCLKEN
CONFIG2
XCLK
To Clock Selection MUX
Oscillator (OSC)
Low Power Modes
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Oscillator (OSC)
109
7.7.2 Crystal Amplifier Output Pin (OSC2)
When the x-tal oscillator is selected, OSC2 pin is the output of the crystal
oscillator inverting amplifier.
When the RC oscillator or internal oscillator is selected, OSC2 pin is the
output of the internal bus clock.
7.7.3 Oscillator Enable Signal (SIMOSCEN)
The SIMOSCEN signal from the system integration module (SIM)
enables/disables the x-tal oscillator, the RC-oscillator, or the internal
oscillator circuit.
7.7.4 CGM Oscillator Clock (CGMXCLK)
The CGMXCLK clock is output from the x-tal oscillator, RC oscillator or
the internal oscillator. This clock drives to CGM and other MCU sub-
systems.
7.7.5 CGM Reference Clock (CGMRCLK)
This is buffered signal of CGMXCLK, it is used by the CGM as the
phase-locked-loop (PLL) reference clock.
7.7.6 Oscillator Clock to Time Base Module (OSCCLK)
The OSCCLK is the reference clock that drives the timebase module.
See
Section 12. Timebase Module (TBM)
.
7.8 Low Power Modes
The WAIT and STOP instructions put the MCU in low-power
consumption standby modes.
Oscillator (OSC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
110
Oscillator (OSC)
MOTOROLA
7.8.1 Wait Mode
The WAIT instruction has no effect on the oscillator module. CGMXCLK
continues to drive to the clock generator module, and OSCCLK
continues to drive the timebase module.
7.8.2 Stop Mode
The STOP instruction disables the x-tal or the RC oscillator circuit, and
hence the CGMXCLK clock stops running. For continuous x-tal or RC
oscillator operation in stop mode, set the STOP_XCLKEN (for x-tal) or
STOP_RCLKEN (for RC) bit to logic 1 before entering stop mode.
The internal oscillator clock continues operation in stop mode. It can be
disabled by setting the STOP_ICLKEN bit to logic 1 before entering stop
mode.
7.9 Oscillator During Break Mode
The oscillator continues to drive CGMXCLK when the device enters the
break state.
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
111
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 8. Clock Generator Module (CGM)
8.1 Contents
8.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
8.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
8.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
8.4.1
Oscillator Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
8.4.2
Phase-Locked Loop Circuit (PLL) . . . . . . . . . . . . . . . . . . .116
8.4.3
PLL Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
8.4.4
Acquisition and Tracking Modes . . . . . . . . . . . . . . . . . . . . 118
8.4.5
Manual and Automatic PLL Bandwidth Modes. . . . . . . . . . 118
8.4.6
Programming the PLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
8.4.7
Special Programming Exceptions . . . . . . . . . . . . . . . . . . .124
8.4.8
Base Clock Selector Circuit . . . . . . . . . . . . . . . . . . . . . . . . 124
8.4.9
CGM External Connections . . . . . . . . . . . . . . . . . . . . . . . . 125
8.5
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
8.5.1
External Filter Capacitor Pin (CGMXFC) . . . . . . . . . . . . . . 126
8.5.2
PLL Analog Power Pin (V
DDA
) . . . . . . . . . . . . . . . . . . . . . . 126
8.5.3
PLL Analog Ground Pin (V
SSA
) . . . . . . . . . . . . . . . . . . . . . 126
8.5.4
Oscillator Output Frequency Signal (CGMXCLK) . . . . . . . 126
8.5.5
CGM Reference Clock (CGMRCLK) . . . . . . . . . . . . . . . . . 126
8.5.6
CGM VCO Clock Output (CGMVCLK) . . . . . . . . . . . . . . . . 127
8.5.7
CGM Base Clock Output (CGMOUT). . . . . . . . . . . . . . . . . 127
8.5.8
CGM CPU Interrupt (CGMINT) . . . . . . . . . . . . . . . . . . . . . 127
8.6
CGM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127
8.6.1
PLL Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
8.6.2
PLL Bandwidth Control Register . . . . . . . . . . . . . . . . . . . . 130
8.6.3
PLL Multiplier Select Registers . . . . . . . . . . . . . . . . . . . . . 132
8.6.4
PLL VCO Range Select Register . . . . . . . . . . . . . . . . . . . . 133
8.6.5
PLL Reference Divider Select Register . . . . . . . . . . . . . . . 134
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
112
Clock Generator Module (CGM)
MOTOROLA
8.7
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.8
Special Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.8.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.8.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
8.8.3
CGM During Break Interrupts. . . . . . . . . . . . . . . . . . . . . . . 136
8.9
Acquisition/Lock Time Specifications . . . . . . . . . . . . . . . . . . .137
8.9.1
Acquisition/Lock Time Definitions. . . . . . . . . . . . . . . . . . . . 137
8.9.2
Parametric Influences on Reaction Time . . . . . . . . . . . . . . 137
8.9.3
Choosing a Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
8.2 Introduction
This section describes the clock generator module (CGM). The CGM
generates the base clock signal, CGMOUT, which is based on either the
oscillator clock divided by two or the divided phase-locked loop (PLL)
clock, CGMPCLK, divided by two. CGMOUT is the clock from which the
SIM derives the system clocks, including the bus clock, which is at a
frequency of CGMOUT2. The PLL clock, CGMVCLK (an integer
multiple of CGMPCLK) provides clock reference for the PWM and
analog modules.
The PLL is a frequency generator designed for use with a low frequency
crystal (typically 32.768kHz) to generate a base frequency and dividing
to a maximum bus frequency of 8MHz.
Clock Generator Module (CGM)
Features
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
113
8.3 Features
Features of the CGM include:
Phase-locked loop with output frequency in integer multiples of an
integer dividend of the crystal reference
Low-frequency crystal operation with low-power operation and
high-output frequency resolution
Programmable prescaler for power-of-two increases in frequency
Programmable hardware voltage-controlled oscillator (VCO) for
low-jitter operation
Automatic bandwidth control mode for low-jitter operation
Automatic frequency lock detector
CPU interrupt on entry or exit from locked condition
Configuration register bit to allow oscillator operation during stop
mode
8.4 Functional Description
The CGM consists of three major sub-modules:
Oscillator module -- The oscillator module generates the constant
reference frequency clock, CGMRCLK (buffered CGMXCLK).
Phase-locked loop (PLL) -- The PLL generates the
programmable VCO frequency clock, CGMVCLK, and the divided,
CGMPCLK. The CGMVCLK provides the input reference clock to
the PWM and analog modules.
Base clock selector circuit -- This software-controlled circuit
selects either CGMXCLK divided by two or the divided VCO clock,
CGMPCLK, divided by two as the base clock, CGMOUT. The SIM
derives the system clocks from either CGMOUT or CGMXCLK.
Figure 8-1
shows the structure of the CGM.
Figure 8-2
is a summary of the CGM registers.
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
114
Clock Generator Module (CGM)
MOTOROLA
Figure 8-1. CGM Block Diagram
BCS
PHASE
DETECTOR
LOOP
FILTER
FREQUENCY
DIVIDER
VOLTAGE
CONTROLLED
OSCILLATOR
AUTOMATIC
MODE
CONTROL
LOCK
DETECTOR
CLOCK
CGMXCLK
CGMOUT
CGMVDV
CGMVCLK
INTERRUPT
CONTROL
CGMINT
CGMRDV
PLL ANALOG
2
CGMRCLK
SELECT
CIRCUIT
V
DDA
CGMXFC
V
SSA
LOCK
AUTO
ACQ
VPR[1:0]
PLLIE
PLLF
MUL[11:0]
REFERENCE
DIVIDER
VRS[7:0]
FREQUENCY
DIVIDER
PRE[1:0]
T0 ADC, Analog Module
PHASE-LOCKED LOOP (PLL)
A
B
1
S*
*WHEN S = 1,
CGMOUT = B
SIMDIV2
From SIM
To SIM
To SIM
RDS[3:0]
R
CGMPCLK
SIMOSCEN
OSCILLATOR (OSC) MODULE
OSC2
OSCSEL[1:0]
OSCCLK[1:0]
OSC1
From SIM
ICLK
CGMRCLK
INTERNAL OSCILLATOR
RC OSCILLATOR
CRYSTAL OSCILLATOR
MUX
See
Section 7. Oscillator (OSC)
.
N
OSCCLK
To Timebase Module (TBM)
To PWM,
To SIM (and COP)
Analog Module
L
2
P
2
E
Clock Generator Module (CGM)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
115
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0036
PLL Control Register
(PTCL)
Read:
PLLIE
PLLF
PLLON
BCS
PRE1
PRE0
VPR1
VPR0
Write:
Reset:
0
0
1
0
0
0
0
0
$0037
PLL Bandwidth Control
Register
(PBWC)
Read:
AUTO
LOCK
ACQ
0
0
0
0
R
Write:
Reset:
0
0
0
0
0
0
0
$0038
PLL Multiplier Select
Register High
(PMSH)
Read:
0
0
0
0
MUL11
MUL10
MUL9
MUL8
Write:
Reset:
0
0
0
0
0
0
0
0
$0039
PLL Multiplier Select
Register Low
(PMSL)
Read:
MUL7
MUL6
MUL5
MUL4
MUL3
MUL2
MUL1
MUL0
Write:
Reset:
0
1
0
0
0
0
0
0
$003A
PLL VCO Range Select
Register
(PMRS)
Read:
VRS7
VRS6
VRS5
VRS4
VRS3
VRS2
VRS1
VRS0
Write:
Reset:
0
1
0
0
0
0
0
0
$003B
PLL Reference Divider
Select Register
(PMDS)
Read:
0
0
0
0
RDS3
RDS2
RDS1
RDS0
Write:
Reset:
0
0
0
0
0
0
0
1
= Unimplemented
R
= Reserved
NOTES:
1. When AUTO = 0, PLLIE is forced clear and is read-only.
2. When AUTO = 0, PLLF and LOCK read as clear.
3. When AUTO = 1, ACQ is read-only.
4. When PLLON = 0 or VRS7:VRS0 = $0, BCS is forced clear and is read-only.
5. When PLLON = 1, the PLL programming register is read-only.
6. When BCS = 1, PLLON is forced set and is read-only.
Figure 8-2. CGM I/O Register Summary
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
116
Clock Generator Module (CGM)
MOTOROLA
8.4.1 Oscillator Module
The oscillator module provides two clock outputs CGMXCLK and
CGMRCLK to the CGM module. CGMXCLK when selected, is driven to
SIM module to generate the system bus clock. CGMRCLK is used by the
phase-lock-loop to provide a higher frequency system bus clock and the
reference clock for the PWM and analog modules. The oscillator module
also provides the reference clock for the timebase module (TBM). See
Section 7. Oscillator (OSC)
for detailed oscillator circuit description.
See
Section 12. Timebase Module (TBM)
for detailed description on
TBM. See
Section 13. Pulse Width Modulator (PWM)
for detailed
description on PWM module.
8.4.2 Phase-Locked Loop Circuit (PLL)
The PLL is a frequency generator that can operate in either acquisition
mode or tracking mode, depending on the accuracy of the output
frequency. The PLL can change between acquisition and tracking
modes either automatically or manually.
8.4.3 PLL Circuits
The PLL consists of these circuits:
Voltage-controlled oscillator (VCO)
Reference divider
Frequency pre-scaler
Modulo VCO frequency divider
Phase detector
Loop filter
Lock detector
Clock Generator Module (CGM)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
117
The operating range of the VCO is programmable for a wide range of
frequencies and for maximum immunity to external noise, including
supply and CGMXFC noise. The VCO frequency is bound to a range
from roughly one-half to twice the center-of-range frequency, f
VRS
.
Modulating the voltage on the CGMXFC pin changes the frequency
within this range. By design, f
VRS
is equal to the nominal center-of-range
frequency, f
NOM
, (38.4 kHz) times a linear factor, L, and a power-of-two
factor, E, or (L
2
E
)f
NOM
.
CGMRCLK is the PLL reference clock, a buffered version of CGMXCLK.
CGMRCLK runs at a frequency, f
RCLK
, and is fed to the PLL through a
programmable modulo reference divider, which divides f
RCLK
by a
factor, R. The divider's output is the final reference clock, CGMRDV,
running at a frequency, f
RDV
= f
RCLK
/R. With an external crystal
(30kHz100kHz), always set R = 1 for specified performance. With an
external high-frequency clock source, use R to divide the external
frequency to between 30kHz and 100kHz.
The VCO's output clock, CGMVCLK, running at a frequency, f
VCLK
, is
fed back through a programmable pre-scaler divider and a
programmable modulo divider. The pre-scaler divides the VCO clock by
a power-of-two factor P (the CGMPCLK) and the modulo divider reduces
the VCO clock by a factor, N. The dividers' output is the VCO feedback
clock, CGMVDV, running at a frequency, f
VDV
= f
VCLK
/(N
2
P
). (See
8.4.6 Programming the PLL
for more information.)
The phase detector then compares the VCO feedback clock, CGMVDV,
with the final reference clock, CGMRDV. A correction pulse is generated
based on the phase difference between the two signals. The loop filter
then slightly alters the DC voltage on the external capacitor connected
to CGMXFC based on the width and direction of the correction pulse.
The filter can make fast or slow corrections depending on its mode,
described in
8.4.4 Acquisition and Tracking Modes
. The value of the
external capacitor and the reference frequency determines the speed of
the corrections and the stability of the PLL.
The lock detector compares the frequencies of the VCO feedback clock,
CGMVDV, and the final reference clock, CGMRDV. Therefore, the
speed of the lock detector is directly proportional to the final reference
frequency, f
RDV
. The circuit determines the mode of the PLL and the lock
condition based on this comparison.
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
118
Clock Generator Module (CGM)
MOTOROLA
8.4.4 Acquisition and Tracking Modes
The PLL filter is manually or automatically configurable into one of two
operating modes:
Acquisition mode -- In acquisition mode, the filter can make large
frequency corrections to the VCO. This mode is used at PLL start
up or when the PLL has suffered a severe noise hit and the VCO
frequency is far off the desired frequency. When in acquisition
mode, the ACQ bit is clear in the PLL bandwidth control register.
(See
8.6.2 PLL Bandwidth Control Register
.)
Tracking mode -- In tracking mode, the filter makes only small
corrections to the frequency of the VCO. PLL jitter is much lower
in tracking mode, but the response to noise is also slower. The
PLL enters tracking mode when the VCO frequency is nearly
correct, such as when the PLL is selected as the base clock
source. (See
8.4.8 Base Clock Selector Circuit
.) The PLL is
automatically in tracking mode when not in acquisition mode or
when the ACQ bit is set.
8.4.5 Manual and Automatic PLL Bandwidth Modes
The PLL can change the bandwidth or operational mode of the loop filter
manually or automatically. Automatic mode is recommended for most
users.
In automatic bandwidth control mode (AUTO = 1), the lock detector
automatically switches between acquisition and tracking modes.
Automatic bandwidth control mode also is used to determine when the
VCO clock, CGMVCLK, is safe to use as the source for the base clock,
CGMOUT. (See
8.6.2 PLL Bandwidth Control Register
.) If PLL
interrupts are enabled, the software can wait for a PLL interrupt request
and then check the LOCK bit. If interrupts are disabled, software can poll
the LOCK bit continuously (during PLL start-up, usually) or at periodic
intervals. In either case, when the LOCK bit is set, the VCO clock is safe
to use as the source for the base clock. (See
8.4.8 Base Clock Selector
Circuit
.) If the VCO is selected as the source for the base clock and the
LOCK bit is clear, the PLL has suffered a severe noise hit and the
software must take appropriate action, depending on the application.
(See
8.7 Interrupts
for information and precautions on using interrupts.)
Clock Generator Module (CGM)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
119
The following conditions apply when the PLL is in automatic bandwidth
control mode:
The ACQ bit (See
8.6.2 PLL Bandwidth Control Register
.) is a
read-only indicator of the mode of the filter. (See
8.4.4
Acquisition and Tracking Modes
.)
The ACQ bit is set when the VCO frequency is within a certain
tolerance and is cleared when the VCO frequency is out of a
certain tolerance. (See
8.9 Acquisition/Lock Time
Specifications
for more information.)
The LOCK bit is a read-only indicator of the locked state of the
PLL.
The LOCK bit is set when the VCO frequency is within a certain
tolerance and is cleared when the VCO frequency is out of a
certain tolerance. (See
8.9 Acquisition/Lock Time
Specifications
for more information.)
CPU interrupts can occur if enabled (PLLIE = 1) when the PLL's
lock condition changes, toggling the LOCK bit. (See
8.6.1 PLL
Control Register
.)
The PLL also may operate in manual mode (AUTO = 0). Manual mode
is used by systems that do not require an indicator of the lock condition
for proper operation. Such systems typically operate well below
f
BUSMAX
.
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
120
Clock Generator Module (CGM)
MOTOROLA
The following conditions apply when in manual mode:
ACQ is a writable control bit that controls the mode of the filter.
Before turning on the PLL in manual mode, the ACQ bit must be
clear.
Before entering tracking mode (ACQ = 1), software must wait a
given time, t
ACQ
(See
8.9 Acquisition/Lock Time
Specifications
.), after turning on the PLL by setting PLLON in the
PLL control register (PCTL).
Software must wait a given time, t
AL
, after entering tracking mode
before selecting the PLL as the clock source to CGMOUT
(BCS = 1).
The LOCK bit is disabled.
CPU interrupts from the CGM are disabled.
8.4.6 Programming the PLL
The following procedure shows how to program the PLL.
NOTE:
The round function in the following equations means that the real
number should be rounded to the nearest integer number.
1. Choose the desired bus frequency, f
BUSDES
, or the desired VCO
frequency, f
VCLKDES
; and then solve for the other.
The relationship between f
BUS
and f
VCLK
is governed by the
equation:
where P is the power of two multiplier, and can be 0, 1, 2, or 3
2. Choose a practical PLL reference frequency, f
RCLK
, and the
reference clock divider, R. Typically, the reference is 32.768kHz
and R = 1.
Frequency errors to the PLL are corrected at a rate of f
RCLK
/R. For
stability and lock time reduction, this rate must be as fast as
possible. The VCO frequency must be an integer multiple of this
rate.
f
VCLK
2
P
f
CGMPCLK
2
P
4
f
BUS
=
=
Clock Generator Module (CGM)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
121
The relationship between the VCO frequency, f
VCLK
, and the
reference frequency, f
RCLK
,
is
where N is the integer range multiplier, between 1 and 4095.
In cases where desired bus frequency has some tolerance,
choose f
RCLK
to a value determined either by other module
requirements (such as modules which are clocked by CGMXCLK),
cost requirements, or ideally, as high as the specified range
allows. See
Section 24. Electrical Specifications
. Choose the
reference divider, R = 1.
When the tolerance on the bus frequency is tight, choose f
RCLK
to
an integer divisor of f
BUSDES
, and R = 1. If f
RCLK
cannot meet this
requirement, use the following equation to solve for R with
practical choices of f
RCLK
, and choose the f
RCLK
that gives the
lowest R.
3. Calculate N:
4. Calculate and verify the adequacy of the VCO and bus
frequencies f
VCLK
and f
BUS
.
f
VC LK
2
P
N
R
----------- f
RCL K
(
)
=
R
round R
MAX
f
VCL KDES
f
RCL K
--------------------------
integer
f
VCLKDES
f
RCLK
--------------------------
=
N
round
R
f
VCLKDES
f
RC LK
2
P
-------------------------------------
=
f
BUS
f
VCLK
2
P
4
-----------
=
f
VC LK
2
P
N
R
----------- f
RCL K
(
)
=
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
122
Clock Generator Module (CGM)
MOTOROLA
5. Select the VCO's power-of-two range multiplier E, according to
this table:
6. Select a VCO linear range multiplier, L, where f
NOM
= 38.4kHz
7. Calculate and verify the adequacy of the VCO programmed
center-of-range frequency, f
VRS
. The center-of-range frequency is
the midpoint between the minimum and maximum frequencies
attainable by the PLL.
For proper operation,
8. Verify the choice of P, R, N, E, and L by comparing f
VCLK
to f
VRS
and f
VCLKDES
. For proper operation, f
VCLK
must be within the
application's tolerance of f
VCLKDES
, and f
VRS
must be as close as
possible to f
VCLK.
NOTE:
Exceeding the recommended maximum bus frequency or VCO
frequency can crash the MCU.
Frequency Range
E
0 < f
VCLK
< 9,830,400
0
9,830,400
f
VCLK
< 19,660,800
1
19,660,800
f
VCLK
< 39,321,600
2
NOTE: Do not program E to a value of 3.
L
round
f
VCLK
2
E
f
N OM
--------------------------
=
f
VRS
L
2
E
(
)
f
NOM
=
f
VRS
f
VCL K
f
NOM
2
E
2
--------------------------
Clock Generator Module (CGM)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
123
9. Program the PLL registers accordingly:
a. In the PRE bits of the PLL control register (PCTL), program
the binary equivalent of P.
b. In the VPR bits of the PLL control register (PCTL), program
the binary equivalent of E.
c. In the PLL multiplier select register low (PMSL) and the PLL
multiplier select register high (PMSH), program the binary
equivalent of N.
d. In the PLL VCO range select register (PMRS), program the
binary coded equivalent of L.
e. In the PLL reference divider select register (PMDS), program
the binary coded equivalent of R.
NOTE:
The values for P, E, N, L, and R can only be programmed when the PLL
is off (PLLON = 0).
Table 8-1
provides numeric examples (numbers are in hexadecimal
notation):
Table 8-1. Numeric Examples
CGMVCLK
CGMPCLK
f
BUS
f
RCLK
R
N
P
E
L
8.0 MHz
8.0 MHz
2.0 MHz
32.768 kHz
1
F5
0
0
D1
9.8304 MHz
9.8304 MHz
2.4576 MHz
32.768 kHz
1
12C
0
1
80
10.0 MHz
10.0 MHz
2.5 MHz
32.768 kHz
1
132
0
1
83
16 MHz
16 MHz
4.0 MHz
32.768 kHz
1
1E9
0
1
D1
19.6608 MHz
19.6608 MHz
4.9152 MHz
32.768 kHz
1
258
0
2
80
20 MHz
20 MHz
5.0 MHz
32.768 kHz
1
263
0
2
82
29.4912 MHz
29.4912 MHz
7.3728 MHz
32.768 kHz
1
384
0
2
C0
32 MHz
32 MHz
8.0 MHz
32.768 kHz
1
3D1
0
2
D0
32 MHz
16 MHz
4.0 MHz
32.768 kHz
1
1E9
1
2
D0
32 MHz
8 MHz
2.0 MHz
32.768 kHz
1
F5
2
2
D0
32 MHz
4 MHz
1.0 MHz
32.768 kHz
1
7B
3
2
D0
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
124
Clock Generator Module (CGM)
MOTOROLA
8.4.7 Special Programming Exceptions
The programming method described in
8.4.6 Programming the PLL
does not account for three possible exceptions. A value of 0 for R, N, or
L is meaningless when used in the equations given. To account for these
exceptions:
A 0 value for R or N is interpreted exactly the same as a value of 1.
A 0 value for L disables the PLL and prevents its selection as the
source for the base clock.
(See
8.4.8 Base Clock Selector Circuit
.)
8.4.8 Base Clock Selector Circuit
This circuit is used to select either the oscillator clock, CGMXCLK, or the
divided VCO clock, CGMPCLK, as the source of the base clock,
CGMOUT. The two input clocks go through a transition control circuit
that waits up to three CGMXCLK cycles and three CGMPCLK cycles to
change from one clock source to the other. During this time, CGMOUT
is held in stasis. The output of the transition control circuit is then divided
by two to correct the duty cycle. Therefore, the bus clock frequency,
which is one-half of the base clock frequency, is one-fourth the
frequency of the selected clock (CGMXCLK or CGMPCLK).
The BCS bit in the PLL control register (PCTL) selects which clock drives
CGMOUT. The divided VCO clock cannot be selected as the base clock
source if the PLL is not turned on. The PLL cannot be turned off if the
divided VCO clock is selected. The PLL cannot be turned on or off
simultaneously with the selection or deselection of the divided VCO
clock. The divided VCO clock also cannot be selected as the base clock
source if the factor L is programmed to a 0. This value would set up a
condition inconsistent with the operation of the PLL, so that the PLL
would be disabled and the oscillator clock would be forced as the source
of the base clock.
Clock Generator Module (CGM)
I/O Signals
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
125
8.4.9 CGM External Connections
In its typical configuration, the CGM requires up to four external
components.
Figure 8-3
shows the external components for the PLL:
Bypass capacitor, C
BYP
Filter network
Care should be taken with PCB routing in order to minimize signal cross
talk and noise. (See
8.9 Acquisition/Lock Time Specifications
for
routing information, filter network and its effects on PLL performance.)
Figure 8-3. CGM External Connections
8.5 I/O Signals
The following paragraphs describe the CGM I/O signals.
C
BYP
Note: Filter network in box can be replaced with a 0.47
F capacitor, but will degrade stability.
10 k
0.01
F
0.033
F
0.1
F
V
SSA
V
DDA
CGMXFC
V
DD
MCU
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
126
Clock Generator Module (CGM)
MOTOROLA
8.5.1 External Filter Capacitor Pin (CGMXFC)
The CGMXFC pin is required by the loop filter to filter out phase
corrections. An external filter network is connected to this pin. (See
Figure 8-3
.)
NOTE:
To prevent noise problems, the filter network should be placed as close
to the CGMXFC pin as possible, with minimum routing distances and no
routing of other signals across the network.
8.5.2 PLL Analog Power Pin (V
DDA
)
V
DDA
is a power pin used by the analog portions of the PLL. Connect the
V
DDA
pin to the same voltage potential as the V
DD
pin.
NOTE:
Route V
DDA
carefully for maximum noise immunity and place bypass
capacitors as close as possible to the package.
8.5.3 PLL Analog Ground Pin (V
SSA
)
V
SSA
is a ground pin used by the analog portions of the PLL. Connect
the V
SSA
pin to the same voltage potential as the V
SS
pin.
NOTE:
Route V
SSA
carefully for maximum noise immunity and place bypass
capacitors as close as possible to the package.
8.5.4 Oscillator Output Frequency Signal (CGMXCLK)
CGMXCLK is the oscillator output signal. It runs at the full speed of the
oscillator, and is generated directly from the crystal oscillator circuit, the
RC oscillator circuit, or the internal oscillator circuit.
8.5.5 CGM Reference Clock (CGMRCLK)
CGMRCLK is a buffered version of CGMXCLK, this clock is the
reference clock for the phase-locked-loop circuit.
Clock Generator Module (CGM)
CGM Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
127
8.5.6 CGM VCO Clock Output (CGMVCLK)
CGMVCLK is the clock output from the VCO. This clock can be used by
the pulse width modulator (PWM) module to generate high frequency
PWM signals. This clock is also used by the analog module as a
reference for signal sampling.
8.5.7 CGM Base Clock Output (CGMOUT)
CGMOUT is the clock output of the CGM. This signal goes to the SIM,
which generates the MCU clocks. CGMOUT is a 50 percent duty cycle
clock running at twice the bus frequency. CGMOUT is software
programmable to be either the oscillator output, CGMXCLK, divided by
two or the divided VCO clock, CGMPCLK, divided by two.
8.5.8 CGM CPU Interrupt (CGMINT)
CGMINT is the interrupt signal generated by the PLL lock detector.
8.6 CGM Registers
The following registers control and monitor operation of the CGM:
PLL control register (PCTL)
(See
8.6.1 PLL Control Register
.)
PLL bandwidth control register (PBWC)
(See
8.6.2 PLL Bandwidth Control Register
.)
PLL multiplier select registers (PMSH and PMSL)
(See
8.6.3 PLL Multiplier Select Registers
.)
PLL VCO range select register (PMRS)
(See
8.6.4 PLL VCO Range Select Register
.)
PLL reference divider select register (PMDS)
(See
8.6.5 PLL Reference Divider Select Register
.)
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
128
Clock Generator Module (CGM)
MOTOROLA
8.6.1 PLL Control Register
The PLL control register (PCTL) contains the interrupt enable and flag
bits, the on/off switch, the base clock selector bit, the prescaler bits, and
the VCO power-of-two range selector bits.
PLLIE -- PLL Interrupt Enable Bit
This read/write bit enables the PLL to generate an interrupt request
when the LOCK bit toggles, setting the PLL flag, PLLF. When the
AUTO bit in the PLL bandwidth control register (PBWC) is clear,
PLLIE cannot be written and reads as logic 0. Reset clears the PLLIE
bit.
1 = PLL interrupts enabled
0 = PLL interrupts disabled
PLLF -- PLL Interrupt Flag Bit
This read-only bit is set whenever the LOCK bit toggles. PLLF
generates an interrupt request if the PLLIE bit also is set. PLLF
always reads as logic 0 when the AUTO bit in the PLL bandwidth
control register (PBWC) is clear. Clear the PLLF bit by reading the
PLL control register. Reset clears the PLLF bit.
1 = Change in lock condition
0 = No change in lock condition
NOTE:
Do not inadvertently clear the PLLF bit. Any read or read-modify-write
operation on the PLL control register clears the PLLF bit.
Address:
$0036
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PLLIE
PLLF
PLLON
BCS
PRE1
PRE0
VPR1
VPR0
Write:
Reset:
0
0
1
0
0
0
0
0
=
Unimplemented
Figure 8-4. PLL Control Register (PCTL)
Clock Generator Module (CGM)
CGM Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
129
PLLON -- PLL On Bit
This read/write bit activates the PLL and enables the VCO clock,
CGMVCLK. PLLON cannot be cleared if the VCO clock is driving the
base clock, CGMOUT (BCS = 1). (See
8.4.8 Base Clock Selector
Circuit
.) Reset sets this bit so that the loop can stabilize as the MCU
is powering up.
1 = PLL on
0 = PLL off
BCS -- Base Clock Select Bit
This read/write bit selects either the oscillator output, CGMXCLK, or
the divided VCO clock, CGMPCLK, as the source of the CGM output,
CGMOUT. CGMOUT frequency is one-half the frequency of the
selected clock. BCS cannot be set while the PLLON bit is clear. After
toggling BCS, it may take up to three CGMXCLK and three
CGMPCLK cycles to complete the transition from one source clock to
the other. During the transition, CGMOUT is held in stasis. (See
8.4.8
Base Clock Selector Circuit
.) Reset clears the BCS bit.
1 = CGMPCLK divided by two drives CGMOUT
0 = CGMXCLK divided by two drives CGMOUT
NOTE:
PLLON and BCS have built-in protection that prevents the base clock
selector circuit from selecting the VCO clock as the source of the base
clock if the PLL is off. Therefore, PLLON cannot be cleared when BCS
is set, and BCS cannot be set when PLLON is clear. If the PLL is off
(PLLON = 0), selecting CGMPCLK requires two writes to the PLL control
register. (See
8.4.8 Base Clock Selector Circuit
.)
PRE1 and PRE0 -- Prescaler Program Bits
These read/write bits control a prescaler that selects the prescaler
power-of-two multiplier, P. (See
8.4.3 PLL Circuits
and
8.4.6
Programming the PLL
.) PRE1 and PRE0 cannot be written when
the PLLON bit is set. Reset clears these bits.
These prescaler bits affects the relationship between the VCO clock
and the final system bus clock.
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
130
Clock Generator Module (CGM)
MOTOROLA
VPR1 and VPR0 -- VCO Power-of-Two Range Select Bits
These read/write bits control the VCO's hardware power-of-two range
multiplier E that, in conjunction with L (See
8.4.3 PLL Circuits
,
8.4.6
Programming the PLL
, and
8.6.4 PLL VCO Range Select
Register
.) controls the hardware center-of-range frequency, f
VRS
.
VPR1:VPR0 cannot be written when the PLLON bit is set. Reset
clears these bits.
8.6.2 PLL Bandwidth Control Register
The PLL bandwidth control register (PBWC):
Selects automatic or manual (software-controlled) bandwidth
control mode
Indicates when the PLL is locked
In automatic bandwidth control mode, indicates when the PLL is in
acquisition or tracking mode
In manual operation, forces the PLL into acquisition or tracking
mode
Table 8-2. PRE1 and PRE0 Programming
PRE1 and PRE0
P
Prescaler Multiplier
00
0
1
01
1
2
10
2
4
11
3
8
Table 8-3. VPR1 and VPR0 Programming
VPR1 and VPR0
E
VCO Power-of-Two
Range Multiplier
00
0
1
01
1
2
10
2
4
NOTE: Do not program E to a value of 3.
Clock Generator Module (CGM)
CGM Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
131
AUTO -- Automatic Bandwidth Control Bit
This read/write bit selects automatic or manual bandwidth control.
When initializing the PLL for manual operation (AUTO = 0), clear the
ACQ bit before turning on the PLL. Reset clears the AUTO bit.
1 = Automatic bandwidth control
0 = Manual bandwidth control
LOCK -- Lock Indicator Bit
When the AUTO bit is set, LOCK is a read-only bit that becomes set
when the VCO clock, CGMVCLK, is locked (running at the
programmed frequency). When the AUTO bit is clear, LOCK reads as
logic 0 and has no meaning. The write one function of this bit is
reserved for test, so this bit must always be written a 0. Reset clears
the LOCK bit.
1 = VCO frequency correct or locked
0 = VCO frequency incorrect or unlocked
ACQ -- Acquisition Mode Bit
When the AUTO bit is set, ACQ is a read-only bit that indicates
whether the PLL is in acquisition mode or tracking mode. When the
AUTO bit is clear, ACQ is a read/write bit that controls whether the
PLL is in acquisition or tracking mode.
In automatic bandwidth control mode (AUTO = 1), the last-written
value from manual operation is stored in a temporary location and is
recovered when manual operation resumes. Reset clears this bit,
enabling acquisition mode.
1 = Tracking mode
0 = Acquisition mode
Address:
$0037
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AUTO
LOCK
ACQ
0
0
0
0
R
Write:
Reset:
0
0
0
0
0
0
0
=
Unimplemented
R
=
Reserved
Figure 8-5. PLL Bandwidth Control Register (PBWCR)
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
132
Clock Generator Module (CGM)
MOTOROLA
8.6.3 PLL Multiplier Select Registers
The PLL multiplier select registers (PMSH and PMSL) contain the
programming information for the modulo feedback divider.
MUL[11:0] -- Multiplier Select Bits
These read/write bits control the modulo feedback divider that selects
the VCO frequency multiplier N. (See
8.4.3 PLL Circuits
and
8.4.6
Programming the PLL
.) A value of $0000 in the multiplier select
registers configure the modulo feedback divider the same as a value
of $0001. Reset initializes the registers to $0040 for a default multiply
value of 64.
NOTE:
The multiplier select bits have built-in protection such that they cannot
be written when the PLL is on (PLLON = 1).
Address:
$0038
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
MUL11
MUL10
MUL9
MUL8
Write:
Reset:
0
0
0
0
0
0
0
0
=
Unimplemented
Figure 8-6. PLL Multiplier Select Register High (PMSH)
Address:
$0039
Bit 7
6
5
4
3
2
1
Bit 0
Read:
MUL7
MUL6
MUL5
MUL4
MUL3
MUL2
MUL1
MUL0
Write:
Reset:
0
1
0
0
0
0
0
0
Figure 8-7. PLL Multiplier Select Register Low (PMSL)
Clock Generator Module (CGM)
CGM Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
133
8.6.4 PLL VCO Range Select Register
The PLL VCO range select register (PMRS) contains the programming
information required for the hardware configuration of the VCO.
VRS[7:0] -- VCO Range Select Bits
These read/write bits control the hardware center-of-range linear
multiplier L which, in conjunction with E (See
8.4.3 PLL Circuits
,
8.4.6 Programming the PLL
, and
8.6.1 PLL Control Register
.),
controls the hardware center-of-range frequency, f
VRS
. VRS[7:0]
cannot be written when the PLLON bit in the PCTL is set. (See
8.4.7
Special Programming Exceptions
.) A value of $00 in the VCO
range select register disables the PLL and clears the BCS bit in the
PLL control register (PCTL). (See
8.4.8 Base Clock Selector Circuit
and
8.4.7 Special Programming Exceptions
.). Reset initializes the
register to $40 for a default range multiply value of 64.
NOTE:
The VCO range select bits have built-in protection such that they cannot
be written when the PLL is on (PLLON = 1) and such that the VCO clock
cannot be selected as the source of the base clock (BCS = 1) if the VCO
range select bits are all clear.
The PLL VCO range select register must be programmed correctly.
Incorrect programming can result in failure of the PLL to achieve lock.
Address:
$003A
Bit 7
6
5
4
3
2
1
Bit 0
Read:
VRS7
VRS6
VRS5
VRS4
VRS3
VRS2
VRS1
VRS0
Write:
Reset:
0
1
0
0
0
0
0
0
Figure 8-8. PLL VCO Range Select Register (PMRS)
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
134
Clock Generator Module (CGM)
MOTOROLA
8.6.5 PLL Reference Divider Select Register
The PLL reference divider select register (PMDS) contains the
programming information for the modulo reference divider.
RDS[3:0] -- Reference Divider Select Bits
These read/write bits control the modulo reference divider that selects
the reference division factor, R. (See
8.4.3 PLL Circuits
and
8.4.6
Programming the PLL
.) RDS[3:0] cannot be written when the
PLLON bit in the PCTL is set. A value of $00 in the reference divider
select register configures the reference divider the same as a value of
$01. (See
8.4.7 Special Programming Exceptions
.) Reset
initializes the register to $01 for a default divide value of 1.
NOTE:
The reference divider select bits have built-in protection such that they
cannot be written when the PLL is on (PLLON = 1).
NOTE:
The default divide value of 1 is recommended for all applications.
Address:
$003B
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
RDS3
RDS2
RDS1
RDS0
Write:
Reset:
0
0
0
0
0
0
0
1
=
Unimplemented
Figure 8-9. PLL Reference Divider Select Register (PMDS)
Clock Generator Module (CGM)
Interrupts
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
135
8.7 Interrupts
When the AUTO bit is set in the PLL bandwidth control register (PBWC),
the PLL can generate a CPU interrupt request every time the LOCK bit
changes state. The PLLIE bit in the PLL control register (PCTL) enables
CPU interrupts from the PLL. PLLF, the interrupt flag in the PCTL,
becomes set whether interrupts are enabled or not. When the AUTO bit
is clear, CPU interrupts from the PLL are disabled and PLLF reads as
logic 0.
Software should read the LOCK bit after a PLL interrupt request to see
if the request was due to an entry into lock or an exit from lock. When the
PLL enters lock, the divided VCO clock, CGMPCLK, divided by two can
be selected as the CGMOUT source by setting BCS in the PCTL. When
the PLL exits lock, the VCO clock frequency is corrupt, and appropriate
precautions should be taken. If the application is not frequency sensitive,
interrupts should be disabled to prevent PLL interrupt service routines
from impeding software performance or from exceeding stack
limitations.
NOTE:
Software can select the CGMPCLK divided by two as the CGMOUT
source even if the PLL is not locked (LOCK = 0). Therefore, software
should make sure the PLL is locked before setting the BCS bit.
8.8 Special Modes
The WAIT instruction puts the MCU in low power-consumption standby
modes.
8.8.1 Wait Mode
The WAIT instruction does not affect the CGM. Before entering wait
mode, software can disengage and turn off the PLL by clearing the BCS
and PLLON bits in the PLL control register (PCTL) to save power. Less
power-sensitive applications can disengage the PLL without turning it
off, so that the PLL clock is immediately available at WAIT exit. This
would be the case also when the PLL is to wake the MCU from wait
mode, such as when the PLL is first enabled and waiting for LOCK or
LOCK is lost.
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
136
Clock Generator Module (CGM)
MOTOROLA
8.8.2 Stop Mode
If the oscillator stop mode enable bit (STOP_ICLKEN, STOP_RCLKEN,
or STOP_XCLKEN in CONFIG2 register) for the selected oscillator is
configured to disabled the oscillator in stop mode, then the STOP
instruction disables the CGM (oscillator and phase locked loop) and
holds low all CGM outputs (CGMOUT, CGMVCLK, CGMPCLK, and
CGMINT).
If the STOP instruction is executed with the divided VCO clock,
CGMPCLK, divided by two driving CGMOUT, the PLL automatically
clears the BCS bit in the PLL control register (PCTL), thereby selecting
the oscillator clock, CGMXCLK, divided by two as the source of
CGMOUT. When the MCU recovers from STOP, the crystal clock
divided by two drives CGMOUT and BCS remains clear.
If the oscillator stop mode enable bit is configured for continuous
oscillator operation in stop mode, then the phase locked loop is shut off
but the CGMXCLK will continue to drive the SIM and other MCU sub-
systems.
8.8.3 CGM During Break Interrupts
The system integration module (SIM) controls whether status bits in
other modules can be cleared during the break state. The BCFE bit in
the SIM break flag control register (SBFCR) enables software to clear
status bits during the break state. (See
9.8.3 SIM Break Flag Control
Register
.)
To allow software to clear status bits during a break interrupt, write a
logic 1 to the BCFE bit. If a status bit is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect the PLLF bit during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), software can read and write
the PLL control register during the break state without affecting the PLLF
bit.
Clock Generator Module (CGM)
Acquisition/Lock Time Specifications
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
137
8.9 Acquisition/Lock Time Specifications
The acquisition and lock times of the PLL are, in many applications, the
most critical PLL design parameters. Proper design and use of the PLL
ensures the highest stability and lowest acquisition/lock times.
8.9.1 Acquisition/Lock Time Definitions
Typical control systems refer to the acquisition time or lock time as the
reaction time, within specified tolerances, of the system to a step input.
In a PLL, the step input occurs when the PLL is turned on or when it
suffers a noise hit. The tolerance is usually specified as a percent of the
step input or when the output settles to the desired value plus or minus
a percent of the frequency change. Therefore, the reaction time is
constant in this definition, regardless of the size of the step input. For
example, consider a system with a 5 percent acquisition time tolerance.
If a command instructs the system to change from 0Hz to 1MHz, the
acquisition time is the time taken for the frequency to reach
1MHz
50kHz. 50kHz = 5% of the 1MHz step input. If the system is
operating at 1MHz and suffers a 100kHz noise hit, the acquisition time
is the time taken to return from 900kHz to 1MHz
5kHz. 5kHz = 5% of
the 100kHz step input.
Other systems refer to acquisition and lock times as the time the system
takes to reduce the error between the actual output and the desired
output to within specified tolerances. Therefore, the acquisition or lock
time varies according to the original error in the output. Minor errors may
not even be registered. Typical PLL applications prefer to use this
definition because the system requires the output frequency to be within
a certain tolerance of the desired frequency regardless of the size of the
initial error.
8.9.2 Parametric Influences on Reaction Time
Acquisition and lock times are designed to be as short as possible while
still providing the highest possible stability. These reaction times are not
constant, however. Many factors directly and indirectly affect the
acquisition time.
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
138
Clock Generator Module (CGM)
MOTOROLA
The most critical parameter which affects the reaction times of the PLL
is the reference frequency, f
RDV
. This frequency is the input to the phase
detector and controls how often the PLL makes corrections. For stability,
the corrections must be small compared to the desired frequency, so
several corrections are required to reduce the frequency error.
Therefore, the slower the reference the longer it takes to make these
corrections. This parameter is under user control via the choice of crystal
frequency f
XCLK
and the R value programmed in the reference divider.
(See
8.4.3 PLL Circuits
,
8.4.6 Programming the PLL
, and
8.6.5 PLL
Reference Divider Select Register
.)
Another critical parameter is the external filter network. The PLL
modifies the voltage on the VCO by adding or subtracting charge from
capacitors in this network. Therefore, the rate at which the voltage
changes for a given frequency error (thus change in charge) is
proportional to the capacitance. The size of the capacitor also is related
to the stability of the PLL. If the capacitor is too small, the PLL cannot
make small enough adjustments to the voltage and the system cannot
lock. If the capacitor is too large, the PLL may not be able to adjust the
voltage in a reasonable time. (See
8.9.3 Choosing a Filter
.)
Also important is the operating voltage potential applied to V
DDA
. The
power supply potential alters the characteristics of the PLL. A fixed value
is best. Variable supplies, such as batteries, are acceptable if they vary
within a known range at very slow speeds. Noise on the power supply is
not acceptable, because it causes small frequency errors which
continually change the acquisition time of the PLL.
Temperature and processing also can affect acquisition time because
the electrical characteristics of the PLL change. The part operates as
specified as long as these influences stay within the specified limits.
External factors, however, can cause drastic changes in the operation of
the PLL. These factors include noise injected into the PLL through the
filter capacitor, filter capacitor leakage, stray impedances on the circuit
board, and even humidity or circuit board contamination.
Clock Generator Module (CGM)
Acquisition/Lock Time Specifications
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Clock Generator Module (CGM)
139
8.9.3 Choosing a Filter
As described in
8.9.2 Parametric Influences on Reaction Time
, the
external filter network is critical to the stability and reaction time of the
PLL. The PLL is also dependent on reference frequency and supply
voltage.
Either of the filter networks in
Figure 8-10
is recommended when using
a 32.768kHz reference clock (CGMRCLK).
Figure 8-10
(a) is used for
applications requiring better stability.
Figure 8-10
(b) is used in low-cost
applications where stability is not critical.
Figure 8-10. PLL Filter
10 k
0.01
F
0.033
F
V
SSA
0.47
F
V
SSA
(a)
(b)
CGMXFC
CGMXFC
Clock Generator Module (CGM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
140
Clock Generator Module (CGM)
MOTOROLA
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
System Integration Module (SIM)
141
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 9. System Integration Module (SIM)
9.1 Contents
9.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
9.3
SIM Bus Clock Control and Generation . . . . . . . . . . . . . . . . . 144
9.3.1
Bus Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
9.3.2
Clock Start-up from POR or LVI Reset. . . . . . . . . . . . . . . . 145
9.3.3
Clocks in Stop Mode and Wait Mode . . . . . . . . . . . . . . . . . 146
9.4
Reset and System Initialization. . . . . . . . . . . . . . . . . . . . . . . . 146
9.4.1
External Pin Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
9.4.2
Active Resets from Internal Sources . . . . . . . . . . . . . . . . . 147
9.4.2.1
Power-On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
9.4.2.2
Computer Operating Properly (COP) Reset. . . . . . . . . . 149
9.4.2.3
Illegal Opcode Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
9.4.2.4
Illegal Address Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
9.4.2.5
Low-Voltage Inhibit (LVI) Reset . . . . . . . . . . . . . . . . . . . 150
9.4.2.6
Monitor Mode Entry Module Reset. . . . . . . . . . . . . . . . . 150
9.5
SIM Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
9.5.1
SIM Counter During Power-On Reset . . . . . . . . . . . . . . . . 151
9.5.2
SIM Counter During Stop Mode Recovery . . . . . . . . . . . . . 151
9.5.3
SIM Counter and Reset States. . . . . . . . . . . . . . . . . . . . . .151
9.6
Exception Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
9.6.1
Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
9.6.1.1
Hardware Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
9.6.1.2
SWI Instruction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
9.6.1.3
Interrupt Status Registers . . . . . . . . . . . . . . . . . . . . . . . 155
9.6.1.4
Interrupt Status Register 1 . . . . . . . . . . . . . . . . . . . . . . . 155
9.6.1.5
Interrupt Status Register 2 . . . . . . . . . . . . . . . . . . . . . . . 157
9.6.1.6
Interrupt Status Register 3 . . . . . . . . . . . . . . . . . . . . . . . 157
9.6.2
Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
9.6.3
Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .158
System Integration Module (SIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
142
System Integration Module (SIM)
MOTOROLA
9.6.4
Status Flag Protection in Break Mode . . . . . . . . . . . . . . . . 158
9.7
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159
9.7.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
9.7.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
9.8
SIM Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
9.8.1
SIM Break Status Register . . . . . . . . . . . . . . . . . . . . . . . . . 162
9.8.2
SIM Reset Status Register . . . . . . . . . . . . . . . . . . . . . . . . 163
9.8.3
SIM Break Flag Control Register . . . . . . . . . . . . . . . . . . . . 164
9.2 Introduction
This section describes the system integration module (SIM). Together
with the CPU, the SIM controls all MCU activities. A block diagram of the
SIM is shown in
Figure 9-1
.
Table 9-1
is a summary of the SIM
input/output (I/O) registers. The SIM is a system state controller that
coordinates CPU and exception timing. The SIM is responsible for:
Bus clock generation and control for CPU and peripherals:
Stop/wait/reset/break entry and recovery
Internal clock control
Master reset control, including power-on reset (POR) and COP
timeout
Interrupt control:
Acknowledge timing
Arbitration control timing
Vector address generation
CPU enable/disable timing
Modular architecture expandable to 128 interrupt sources
Table 9-1
shows the internal signal names used in this section.
System Integration Module (SIM)
Introduction
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
System Integration Module (SIM)
143
Figure 9-1. SIM Block Diagram
STOP/WAIT
CLOCK
CONTROL
CLOCK GENERATORS
POR CONTROL
RESET PIN CONTROL
SIM RESET STATUS REGISTER
INTERRUPT CONTROL
AND PRIORITY DECODE
MODULE STOP
MODULE WAIT
CPU STOP (FROM CPU)
CPU WAIT (FROM CPU)
SIMOSCEN (TO CGM, OSC)
CGMOUT (FROM CGM)
INTERNAL CLOCKS
MASTER
RESET
CONTROL
RESET
PIN LOGIC
LVI (FROM LVI MODULE)
ILLEGAL OPCODE (FROM CPU)
ILLEGAL ADDRESS (FROM ADDRESS
MAP DECODERS)
COP (FROM COP MODULE)
INTERRUPT SOURCES
CPU INTERFACE
RESET
CONTROL
SIM
COUNTER
COP CLOCK
ICLK (FROM OSC)
2
V
DD
INTERNAL
PULLUP
DEVICE
Table 9-1. Signal Name Conventions
Signal Name
Description
ICLK
Internal oscillator clock
CGMXCLK
Selected oscillator clock from oscillator module
CGMVCLK, CGMPCLK
PLL output and the divided PLL output
CGMOUT
CGMPCLK-based or oscillator-based clock output from CGM module
(Bus clock = CGMOUT
2)
IAB
Internal address bus
IDB
Internal data bus
PORRST
Signal from the power-on reset module to the SIM
IRST
Internal reset signal
R/W
Read/write signal
System Integration Module (SIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
144
System Integration Module (SIM)
MOTOROLA
9.3 SIM Bus Clock Control and Generation
The bus clock generator provides system clock signals for the CPU and
peripherals on the MCU. The system clocks are generated from an
incoming clock, CGMOUT, as shown in
Figure 9-3
. This clock can come
from either the oscillator module or from the on-chip PLL. (See
Section
8. Clock Generator Module (CGM)
.)
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$FE00
SIM Break Status Register
(SBSR)
Read:
R
R
R
R
R
R
SBSW
R
Write:
Note
Reset:
0
Note: Writing a logic 0 clears SBSW.
$FE01
SIM Reset Status Register
(SRSR)
Read:
POR
PIN
COP
ILOP
ILAD
0
LVI
0
Write:
POR:
1
0
0
0
0
0
0
0
$FE03
SIM Break Flag Control
Register
(SBFCR)
Read:
BCFE
R
R
R
R
R
R
R
Write:
Reset:
0
$FE04
Interrupt Status Register 1
(INT1)
Read:
IF6
IF5
IF4
IF3
IF2
IF1
0
0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$FE05
Interrupt Status Register 2
(INT2)
Read:
IF14
IF13
IF12
IF11
IF10
IF9
IF8
IF7
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$FE06
Interrupt Status Register 3
(INT3)
Read:
0
0
0
0
0
IF17
IF16
IF15
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 9-2. SIM I/O Register Summary
System Integration Module (SIM)
SIM Bus Clock Control and Generation
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
System Integration Module (SIM)
145
Figure 9-3. CGM Clock Signals
9.3.1 Bus Timing
In user mode, the internal bus frequency is either the oscillator output
(CGMXCLK) divided by four or the divided PLL output (CGMPCLK)
divided by four.
9.3.2 Clock Start-up from POR or LVI Reset
When the power-on reset module or the low-voltage inhibit module
generates a reset, the clocks to the CPU and peripherals are inactive
and held in an inactive phase until after the 4096 ICLK cycle POR
timeout has completed. The RST pin is driven low by the SIM during this
entire period. The IBUS clocks start upon completion of the timeout.
2
BUS CLOCK
GENERATORS
SYSTEM INTEGRATION MODULE
MONITOR MODE
USER MODE
SIMOSCEN
OSCILLATOR (OSC) MODULE
OSC2
OSC1
PHASE-LOCKED LOOP (PLL)
CGMXCLK
CGMRCLK
IT12
CGMOUT
SIMDIV2
PTC1
TO TIM, ADC
STOP MODE CLOCK
TO REST
OF MCU
IT23
TO REST
OF MCU
ENABLE SIGNALS
FROM CONFIG2
ICLK
TO TBM
OSCCLK
CGMVCLK
TO PWM
SIM COUNTER
System Integration Module (SIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
146
System Integration Module (SIM)
MOTOROLA
9.3.3 Clocks in Stop Mode and Wait Mode
Upon exit from stop mode by an interrupt, break, or reset, the SIM allows
ICLK to clock the SIM counter. The CPU and peripheral clocks do not
become active until after the stop delay timeout. This timeout is
selectable as 4096 or 32 ICLK cycles. (See
9.7.2 Stop Mode
.)
In wait mode, the CPU clocks are inactive. The SIM also produces two
sets of clocks for other modules. Refer to the wait mode subsection of
each module to see if the module is active or inactive in wait mode.
Some modules can be programmed to be active in wait mode.
9.4 Reset and System Initialization
The MCU has these reset sources:
Power-on reset module (POR)
External reset pin (RST)
Computer operating properly module (COP)
Low-voltage inhibit module (LVI)
Illegal opcode
Illegal address
All of these resets produce the vector $FFFE:$FFFF ($FEFE:$FEFF in
monitor mode) and assert the internal reset signal (IRST). IRST causes
all registers to be returned to their default values and all modules to be
returned to their reset states.
An internal reset clears the SIM counter (see 9.5 SIM Counter), but an
external reset does not. Each of the resets sets a corresponding bit in
the SIM reset status register (SRSR). (See
9.8 SIM Registers
.)
System Integration Module (SIM)
Reset and System Initialization
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
System Integration Module (SIM)
147
9.4.1 External Pin Reset
The RST pin circuit includes an internal pull-up device. Pulling the
asynchronous RST pin low halts all processing. The PIN bit of the SIM
reset status register (SRSR) is set as long as RST is held low for a
minimum of 67 ICLK cycles, assuming that neither the POR nor the LVI
was the source of the reset. See
Table 9-2
for details.
Figure 9-4
shows the relative timing.
Figure 9-4. External Reset Timing
9.4.2 Active Resets from Internal Sources
All internal reset sources actively pull the RST pin low for 32 ICLK cycles
to allow resetting of external peripherals. The internal reset signal IRST
continues to be asserted for an additional 32 cycles (see Figure 9-5). An
internal reset can be caused by an illegal address, illegal opcode, COP
timeout, LVI, or POR (see Figure 9-6).
NOTE:
For LVI or POR resets, the SIM cycles through 4096 + 32 ICLK cycles
during which the SIM forces the RST pin low. The internal reset signal
then follows the sequence from the falling edge of RST shown in
Figure 9-5
.
Table 9-2. PIN Bit Set Timing
Reset Type
Number of Cycles Required to Set PIN
POR/LVI
4163 (4096 + 64 + 3)
All others
67 (64 + 3)
RST
IAB
PC
VECT H
VECT L
ICLK
System Integration Module (SIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
148
System Integration Module (SIM)
MOTOROLA
Figure 9-5. Internal Reset Timing
The COP reset is asynchronous to the bus clock.
Figure 9-6. Sources of Internal Reset
The active reset feature allows the part to issue a reset to peripherals
and other chips within a system built around the MCU.
9.4.2.1 Power-On Reset
When power is first applied to the MCU, the power-on reset module
(POR) generates a pulse to indicate that power-on has occurred. The
external reset pin (RST) is held low while the SIM counter counts out
4096 + 32 ICLK cycles. Thirty-two ICLK cycles later, the CPU and
memories are released from reset to allow the reset vector sequence to
occur.
At power-on, these events occur:
A POR pulse is generated.
The internal reset signal is asserted.
The SIM enables CGMOUT.
Internal clocks to the CPU and modules are held inactive for 4096
ICLK cycles to allow stabilization of the oscillator.
The RST pin is driven low during the oscillator stabilization time.
The POR bit of the SIM reset status register (SRSR) is set and all
other bits in the register are cleared.
IRST
RST
RST PULLED LOW BY MCU
IAB
32 CYCLES
32 CYCLES
VECTOR HIGH
ICLK
ILLEGAL ADDRESS RST
ILLEGAL OPCODE RST
COPRST
LVI
POR
INTERNAL RESET
System Integration Module (SIM)
Reset and System Initialization
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
System Integration Module (SIM)
149
Figure 9-7. POR Recovery
9.4.2.2 Computer Operating Properly (COP) Reset
An input to the SIM is reserved for the COP reset signal. The overflow of
the COP counter causes an internal reset and sets the COP bit in the
SIM reset status register (SRSR). The SIM actively pulls down the RST
pin for all internal reset sources.
To prevent a COP module timeout, write any value to location $FFFF.
Writing to location $FFFF clears the COP counter and bits 12 through 5
of the SIM counter. The SIM counter output, which occurs at least every
2
13
2
4
ICLK cycles, drives the COP counter. The COP should be
serviced as soon as possible out of reset to guarantee the maximum
amount of time before the first timeout.
The COP module is disabled if the RST pin or the IRQ1 pin is held at
V
TST
while the MCU is in monitor mode. The COP module can be
disabled only through combinational logic conditioned with the high
voltage signal on the RST or the IRQ1 pin. This prevents the COP from
becoming disabled as a result of external noise. During a break state,
V
TST
on the RST pin disables the COP module.
PORRST
OSC1
ICLK
CGMOUT
RST
IAB
4096
CYCLES
32
CYCLES
32
CYCLES
$FFFE
$FFFF
IRST
System Integration Module (SIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
150
System Integration Module (SIM)
MOTOROLA
9.4.2.3 Illegal Opcode Reset
The SIM decodes signals from the CPU to detect illegal instructions. An
illegal instruction sets the ILOP bit in the SIM reset status register
(SRSR) and causes a reset.
If the stop enable bit, STOP, in the mask option register is logic 0, the
SIM treats the STOP instruction as an illegal opcode and causes an
illegal opcode reset. The SIM actively pulls down the RST pin for all
internal reset sources.
9.4.2.4 Illegal Address Reset
An opcode fetch from an unmapped address generates an illegal
address reset. The SIM verifies that the CPU is fetching an opcode prior
to asserting the ILAD bit in the SIM reset status register (SRSR) and
resetting the MCU. A data fetch from an unmapped address does not
generate a reset. The SIM actively pulls down the RST pin for all internal
reset sources.
9.4.2.5 Low-Voltage Inhibit (LVI) Reset
The low-voltage inhibit module (LVI) asserts its output to the SIM when
the V
DD
voltage falls to the LVI
TRIPF
voltage. The LVI bit in the SIM reset
status register (SRSR) is set, and the external reset pin (RST) is held low
while the SIM counter counts out 4096 + 32 ICLK cycles. Thirty-two ICLK
cycles later, the CPU is released from reset to allow the reset vector
sequence to occur. The SIM actively pulls down the RST pin for all
internal reset sources.
9.4.2.6 Monitor Mode Entry Module Reset
The monitor mode entry module reset asserts its output to the SIM when
monitor mode is entered in the condition where the reset vectors are
blank ($FF). (See
Section 10. Monitor ROM (MON)
.) When MODRST
gets asserted, an internal reset occurs. The SIM actively pulls down the
RST pin for all internal reset sources.
System Integration Module (SIM)
SIM Counter
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
System Integration Module (SIM)
151
9.5 SIM Counter
The SIM counter is used by the power-on reset module (POR) and in
stop mode recovery to allow the oscillator time to stabilize before
enabling the internal bus (IBUS) clocks. The SIM counter also serves as
a prescaler for the computer operating properly module (COP). The SIM
counter overflow supplies the clock for the COP module. The SIM
counter is 12 bits long and is clocked by the falling edge of ICLK.
9.5.1 SIM Counter During Power-On Reset
The power-on reset module (POR) detects power applied to the MCU.
At power-on, the POR circuit asserts the signal PORRST. Once the SIM
is initialized, it enables the clock generation module (CGM) to drive the
bus clock state machine.
9.5.2 SIM Counter During Stop Mode Recovery
The SIM counter also is used for stop mode recovery. The STOP
instruction clears the SIM counter. After an interrupt, break, or reset, the
SIM senses the state of the short stop recovery bit, SSREC, in the
configuration register 1 (CONFIG1). If the SSREC bit is a logic 1, then
the stop recovery is reduced from the normal delay of 4096 ICLK cycles
down to 32 ICLK cycles. This is ideal for applications using canned
oscillators that do not require long start-up times from stop mode.
External crystal applications should use the full stop recovery time, that
is, with SSREC cleared.
9.5.3 SIM Counter and Reset States
External reset has no effect on the SIM counter. (
See 9.7.2 Stop Mode
for details.) The SIM counter is free-running after all reset states. (See
9.4.2 Active Resets from Internal Sources
for counter control and
internal reset recovery sequences.)
System Integration Module (SIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
152
System Integration Module (SIM)
MOTOROLA
9.6 Exception Control
Normal, sequential program execution can be changed in three different
ways:
Interrupts:
Maskable hardware CPU interrupts
Non-maskable software interrupt instruction (SWI)
Reset
Break interrupts
9.6.1 Interrupts
At the beginning of an interrupt, the CPU saves the CPU register
contents on the stack and sets the interrupt mask (I bit) to prevent
additional interrupts. At the end of an interrupt, the RTI instruction
recovers the CPU register contents from the stack so that normal
processing can resume.
Figure 9-8
shows interrupt entry timing, and
Figure 9-9
shows interrupt recovery timing.
Figure 9-8. Interrupt Entry Timing
Figure 9-9. Interrupt Recovery Timing
MODULE
IDB
R/W
INTERRUPT
DUMMY
SP
SP 1
SP 2
SP 3
SP 4
VECT H
VECT L
START ADDR
IAB
DUMMY
PC 1[7:0] PC 1[15:8]
X
A
CCR
V DATA H
V DATA L
OPCODE
I-BIT
MODULE
IDB
R/W
INTERRUPT
SP 4
SP 3
SP 2
SP 1
SP
PC
PC + 1
IAB
CCR
A
X
PC 1[15:8] PC 1[7:0]
OPCODE
OPERAND
I-BIT
System Integration Module (SIM)
Exception Control
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
System Integration Module (SIM)
153
Interrupts are latched, and arbitration is performed in the SIM at the start
of interrupt processing. The arbitration result is a constant that the CPU
uses to determine which vector to fetch. Once an interrupt is latched by
the SIM, no other interrupt can take precedence, regardless of priority,
until the latched interrupt is serviced (or the I bit is cleared).
(See
Figure 9-10
.)
Figure 9-10. Interrupt Processing
NO
NO
NO
YES
NO
NO
YES
YES
AS MANY INTERRUPTS
I BIT SET?
FROM RESET
BREAK
I-BIT SET?
IRQ1
INTERRUPT?
SWI
INSTRUCTION?
RTI
INSTRUCTION?
FETCH NEXT
INSTRUCTION
UNSTACK CPU REGISTERS
STACK CPU REGISTERS
SET I-BIT
LOAD PC WITH INTERRUPT VECTOR
EXECUTE INSTRUCTION
YES
YES
AS EXIST ON CHIP
INTERRUPT?
System Integration Module (SIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
154
System Integration Module (SIM)
MOTOROLA
9.6.1.1 Hardware Interrupts
A hardware interrupt does not stop the current instruction. Processing of
a hardware interrupt begins after completion of the current instruction.
When the current instruction is complete, the SIM checks all pending
hardware interrupts. If interrupts are not masked (I bit clear in the
condition code register) and if the corresponding interrupt enable bit is
set, the SIM proceeds with interrupt processing; otherwise, the next
instruction is fetched and executed.
If more than one interrupt is pending at the end of an instruction
execution, the highest priority interrupt is serviced first.
Figure 9-11
demonstrates what happens when two interrupts are pending. If an
interrupt is pending upon exit from the original interrupt service routine,
the pending interrupt is serviced before the LDA instruction is executed.
Figure 9-11
Interrupt Recognition Example
The LDA opcode is prefetched by both the INT1 and INT2 RTI
instructions. However, in the case of the INT1 RTI prefetch, this is a
redundant operation.
NOTE:
To maintain compatibility with the M6805 Family, the H register is not
pushed on the stack during interrupt entry. If the interrupt service routine
modifies the H register or uses the indexed addressing mode, software
should save the H register and then restore it prior to exiting the routine.
CLI
LDA
INT1
PULH
RTI
INT2
BACKGROUND
#$FF
PSHH
INT1 INTERRUPT SERVICE ROUTINE
PULH
RTI
PSHH
INT2 INTERRUPT SERVICE ROUTINE
ROUTINE
System Integration Module (SIM)
Exception Control
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
System Integration Module (SIM)
155
9.6.1.2 SWI Instruction
The SWI instruction is a non-maskable instruction that causes an
interrupt regardless of the state of the interrupt mask (I bit) in the
condition code register.
NOTE:
A software interrupt pushes PC onto the stack. A software interrupt does
not push PC 1, as a hardware interrupt does.
9.6.1.3 Interrupt Status Registers
The flags in the interrupt status registers identify maskable interrupt
sources.
Table 9-3
summarizes the interrupt sources and the interrupt
status register flags that they set. The interrupt status registers can be
useful for debugging.
9.6.1.4 Interrupt Status Register 1
IF6IF1 -- Interrupt Flags 61
These flags indicate the presence of interrupt requests from the
sources shown in
Table 9-3
.
1 = Interrupt request present
0 = No interrupt request present
Bit 0 and Bit 1 -- Always read 0
Address:
$FE04
Bit 7
6
5
4
3
2
1
Bit 0
Read:
IF6
IF5
IF4
IF3
IF2
IF1
0
0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
R
= Reserved
Figure 9-12. Interrupt Status Register 1 (INT1)
System Integration Module (SIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
156
System Integration Module (SIM)
MOTOROLA
Table 9-3. Interrupt Sources
Priority
INT
Flag
Vector
Address
Interrupt Source
Lowest
IF17
$FFDA
Timebase Module
$FFDB
IF16
$FFDC
Analog Module
$FFDD
IF15
$FFDE
ADC Conversion Complete
$FFDF
IF14
$FFE0
Keyboard
$FFE1
IF13
$FFE2
SCI Transmit
$FFE3
IF12
$FFE4
SCI Receive
$FFE5
IF11
$FFE6
SCI Error
$FFE7
IF10
$FFE8
MMIIC
$FFE9
IF9
$FFEA
TIM2 Overflow
$FFEB
IF8
$FFEC
TIM2 Channel 1
$FFED
IF7
$FFEE
TIM2 Channel 0
$FFEF
IF6
$FFF0
TIM1 Overflow
$FFF1
IF5
$FFF2
TIM1 Channel 1
$FFF3
IF4
$FFF4
TIM1 Channel 0
$FFF5
IF3
$FFF6
PLL
$FFF7
IF2
$FFF8
IRQ2
$FFF9
IF1
$FFFA
IRQ1
$FFFB
$FFFC
SWI
$FFFD
$FFFE
Reset
Highest
$FFFF
System Integration Module (SIM)
Exception Control
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
System Integration Module (SIM)
157
9.6.1.5 Interrupt Status Register 2
IF14IF7 -- Interrupt Flags 147
These flags indicate the presence of interrupt requests from the
sources shown in
Table 9-3
.
1 = Interrupt request present
0 = No interrupt request present
9.6.1.6 Interrupt Status Register 3
IF17IF15 -- Interrupt Flags 1715
These flags indicate the presence of an interrupt request from the
source shown in
Table 9-3
.
1 = Interrupt request present
0 = No interrupt request present
Address:
$FE05
Bit 7
6
5
4
3
2
1
Bit 0
Read:
IF14
IF13
IF12
IF11
IF10
IF9
IF8
IF7
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
R
= Reserved
Figure 9-13. Interrupt Status Register 2 (INT2)
Address:
$FE06
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
0
IF17
IF16
IF15
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
R
= Reserved
Figure 9-14. Interrupt Status Register 3 (INT3)
System Integration Module (SIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
158
System Integration Module (SIM)
MOTOROLA
9.6.2 Reset
All reset sources always have equal and highest priority and cannot be
arbitrated.
9.6.3 Break Interrupts
The break module can stop normal program flow at a software-
programmable break point by asserting its break interrupt output.
(See
Section 23. Break Module (BRK)
.) The SIM puts the CPU into the
break state by forcing it to the SWI vector location. Refer to the break
interrupt subsection of each module to see how each module is affected
by the break state.
9.6.4 Status Flag Protection in Break Mode
The SIM controls whether status flags contained in other modules can
be cleared during break mode. The user can select whether flags are
protected from being cleared by properly initializing the break clear flag
enable bit (BCFE) in the SIM break flag control register (SBFCR).
Protecting flags in break mode ensures that set flags will not be cleared
while in break mode. This protection allows registers to be freely read
and written during break mode without losing status flag information.
Setting the BCFE bit enables the clearing mechanisms. Once cleared in
break mode, a flag remains cleared even when break mode is exited.
Status flags with a 2-step clearing mechanism -- for example, a read of
one register followed by the read or write of another -- are protected,
even when the first step is accomplished prior to entering break mode.
Upon leaving break mode, execution of the second step will clear the flag
as normal.
System Integration Module (SIM)
Low-Power Modes
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
System Integration Module (SIM)
159
9.7 Low-Power Modes
Executing the WAIT or STOP instruction puts the MCU in a low power-
consumption mode for standby situations. The SIM holds the CPU in a
non-clocked state. The operation of each of these modes is described in
the following subsections. Both STOP and WAIT clear the interrupt mask
(I) in the condition code register, allowing interrupts to occur.
9.7.1 Wait Mode
In wait mode, the CPU clocks are inactive while the peripheral clocks
continue to run.
Figure 9-15
shows the timing for wait mode entry.
A module that is active during wait mode can wake up the CPU with an
interrupt if the interrupt is enabled. Stacking for the interrupt begins one
cycle after the WAIT instruction during which the interrupt occurred. In
wait mode, the CPU clocks are inactive. Refer to the wait mode
subsection of each module to see if the module is active or inactive in
wait mode. Some modules can be programmed to be active in wait
mode.
Wait mode also can be exited by a reset or break. A break interrupt
during wait mode sets the SIM break stop/wait bit, SBSW, in the SIM
break status register (SBSR). If the COP disable bit, COPD, in the mask
option register is logic 0, then the computer operating properly module
(COP) is enabled and remains active in wait mode.
Figure 9-15. Wait Mode Entry Timing
Figure 9-16
and
Figure 9-17
show the timing for WAIT recovery.
WAIT ADDR + 1
SAME
SAME
IAB
IDB
PREVIOUS DATA
NEXT OPCODE
SAME
WAIT ADDR
SAME
R/W
NOTE: Previous data can be operand data or the WAIT opcode, depending on the
last instruction.
System Integration Module (SIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
160
System Integration Module (SIM)
MOTOROLA
Figure 9-16. Wait Recovery from Interrupt or Break
Figure 9-17. Wait Recovery from Internal Reset
9.7.2 Stop Mode
In stop mode, the SIM counter is reset and the system clocks are
disabled. An interrupt request from a module can cause an exit from stop
mode. Stacking for interrupts begins after the selected stop recovery
time has elapsed. Reset or break also causes an exit from stop mode.
The SIM disables the clock generator module output (CGMOUT) in stop
mode, stopping the CPU and peripherals. Stop recovery time is
selectable using the SSREC bit in the configuration register 1
(CONFIG1). If SSREC is set, stop recovery is reduced from the normal
delay of 4096 ICLK cycles down to 32. This is ideal for applications using
canned oscillators that do not require long start-up times from stop
mode.
NOTE:
External crystal applications should use the full stop recovery time by
clearing the SSREC bit.
$6E0C
$6E0B
$00FF
$00FE
$00FD
$00FC
$A6
$A6
$01
$0B
$6E
$A6
IAB
IDB
EXITSTOPWAIT
NOTE: EXITSTOPWAIT = RST pin OR CPU interrupt OR break interrupt
IAB
IDB
RST
$A6
$A6
$6E0B
RST VCT H RST VCT L
$A6
ICLK
32
CYCLES
32
CYCLES
System Integration Module (SIM)
SIM Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
System Integration Module (SIM)
161
A break interrupt during stop mode sets the SIM break stop/wait bit
(SBSW) in the SIM break status register (SBSR).
The SIM counter is held in reset from the execution of the STOP
instruction until the beginning of stop recovery. It is then used to time the
recovery period.
Figure 9-18
shows stop mode entry timing.
NOTE:
To minimize stop current, all pins configured as inputs should be driven
to a logic 1 or logic 0.
Figure 9-18. Stop Mode Entry Timing
Figure 9-19. Stop Mode Recovery from Interrupt or Break
9.8 SIM Registers
The SIM has three memory-mapped registers:
SIM Break Status Register (SBSR) -- $FE00
SIM Reset Status Register (SRSR) -- $FE01
SIM Break Flag Control Register (SBFCR) -- $FE03
STOP ADDR + 1
SAME
SAME
IAB
IDB
PREVIOUS DATA
NEXT OPCODE
SAME
STOP ADDR
SAME
R/W
CPUSTOP
NOTE: Previous data can be operand data or the STOP opcode, depending on the last
instruction.
ICLK
INT/BREAK
IAB
STOP + 2
STOP + 2
SP
SP 1
SP 2
SP 3
STOP +1
STOP RECOVERY PERIOD
System Integration Module (SIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
162
System Integration Module (SIM)
MOTOROLA
9.8.1 SIM Break Status Register
The SIM break status register (SBSR) contains a flag to indicate that a
break caused an exit from stop mode or wait mode.
SBSW -- Break Wait Bit
This status bit is set when a break interrupt causes an exit from wait
mode or stop mode. Clear SBSW by writing a logic 0 to it. Reset clears
SBSW.
1 = Stop mode or wait mode was exited by break interrupt
0 = Stop mode or wait mode was not exited by break interrupt
SBSW can be read within the break interrupt routine. The user can
modify the return address on the stack by subtracting 1 from it. The
following code is an example.
Address:
$FE00
Bit 7
6
5
4
3
2
1
Bit 0
Read:
R
R
R
R
R
R
SBSW
R
Write:
Note
Reset:
0
Note: Writing a logic 0 clears SBSW.
R
= Reserved
Figure 9-20. SIM Break Status Register (SBSR)
This code works if the H register has been pushed onto the stack in the break
service routine software. This code should be executed at the end of the break
service routine software.
HIBYTE
EQU
LOBYTE
EQU
If not SBSW, do RTI
BRCLR
SBSW,SBSR, RETURN
;
;
See if wait mode or stop mode was exited by
break.
TST
LOBYTE,SP
;If RETURNLO is not zero,
BNE
DOLO
;then just decrement low byte.
DEC
HIBYTE,SP
;Else deal with high byte, too.
DOLO
DEC
LOBYTE,SP
;Point to WAIT/STOP opcode.
RETURN
PULH
RTI
;Restore H register.
System Integration Module (SIM)
SIM Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
System Integration Module (SIM)
163
9.8.2 SIM Reset Status Register
This register contains six flags that show the source of the last reset
provided all previous reset status bits have been cleared. Clear the SIM
reset status register by reading it. A power-on reset sets the POR bit and
clears all other bits in the register.
POR -- Power-On Reset Bit
1 = Last reset caused by POR circuit
0 = Read of SRSR
PIN -- External Reset Bit
1 = Last reset caused by external reset pin (RST)
0 = POR or read of SRSR
COP -- Computer Operating Properly Reset Bit
1 = Last reset caused by COP counter
0 = POR or read of SRSR
ILOP -- Illegal Opcode Reset Bit
1 = Last reset caused by an illegal opcode
0 = POR or read of SRSR
ILAD -- Illegal Address Reset Bit (opcode fetches only)
1 = Last reset caused by an opcode fetch from an illegal address
0 = POR or read of SRSR
LVI -- Low-Voltage Inhibit Reset Bit
1 = Last reset caused by the LVI circuit
0 = POR or read of SRSR
Address:
$FE01
Bit 7
6
5
4
3
2
1
Bit 0
Read:
POR
PIN
COP
ILOP
ILAD
0
LVI
0
Write:
Reset:
1
0
0
0
0
0
0
0
= Unimplemented
Figure 9-21. SIM Reset Status Register (SRSR)
System Integration Module (SIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
164
System Integration Module (SIM)
MOTOROLA
9.8.3 SIM Break Flag Control Register
The SIM break control register contains a bit that enables software to
clear status bits while the MCU is in a break state.
BCFE -- Break Clear Flag Enable Bit
This read/write bit enables software to clear status bits by accessing
status registers while the MCU is in a break state. To clear status bits
during the break state, the BCFE bit must be set.
1 = Status bits clearable during break
0 = Status bits not clearable during break
Address:
$FE03
Bit 7
6
5
4
3
2
1
Bit 0
Read:
BCFE
R
R
R
R
R
R
R
Write:
Reset:
0
R
= Reserved
Figure 9-22. SIM Break Flag Control Register (SBFCR)
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Monitor ROM (MON)
165
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 10. Monitor ROM (MON)
10.1 Contents
10.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
10.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
10.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
10.4.1
Entering Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
10.4.2
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172
10.4.3
Break Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172
10.4.4
Baud Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
10.4.5
Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
10.5
Security. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
10.2 Introduction
This section describes the monitor ROM (MON) and the monitor mode
entry methods. The monitor ROM allows complete testing of the MCU
through a single-wire interface with a host computer. Monitor mode entry
can be achieved without use of the higher test voltage, V
TST
, as long as
vector addresses $FFFE and $FFFF are blank, thus reducing the
hardware requirements for in-circuit programming.
Monitor ROM (MON)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
166
Monitor ROM (MON)
MOTOROLA
10.3 Features
Features of the monitor ROM include:
Normal user-mode pin functionality
One pin dedicated to serial communication between monitor ROM
and host computer
Standard mark/space non-return-to-zero (NRZ) communication
with host computer
Execution of code in RAM or FLASH
FLASH memory security feature
1
FLASH memory programming interface
Enhanced PLL (phase-locked loop) option to allow use of external
32.768-kHz crystal to generate internal frequency of 2.4576 MHz
368 bytes monitor ROM code size ($FE10 to $FF7F)
Monitor mode entry without high voltage, V
TST
, if reset vector is
blank ($FFFE and $FFFF contain $FF)
Standard monitor mode entry if high voltage, V
TST
, is applied to
IRQ1
10.4 Functional Description
The monitor ROM receives and executes commands from a host
computer.
Figure 10-1
shows an example circuit used to enter monitor
mode and communicate with a host computer via a standard RS-232
interface.
Simple monitor commands can access any memory address. In monitor
mode, the MCU can execute code downloaded into RAM by a host
computer while most MCU pins retain normal operating mode functions.
All communication between the host computer and the MCU is through
the PTA0 pin. A level-shifting and multiplexing interface is required
between PTA0 and the host computer. PTA0 is used in a wired-OR
configuration and requires a pullup resistor.
1. No security feature is absolutely secure. However, Motorola's strategy is to make reading or
copying the FLASH difficult for unauthorized users.
Monitor ROM (MON)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Monitor ROM (MON)
167
Figure 10-1. Monitor Mode Circuit
+
+
+
MC145407
MC74HC125
RST
IRQ1
CGMXFC
OSC1
OSC2
V
SS
V
DD
PTA0
V
DD
10 k
0.1
F
10 k
6
5
2
4
3
1
DB-25
2
3
7
20
18
17
19
16
15
V
DD
V
DD
V
DD
10
F
10
F
10
F
10
F
1
2
4
7
14
3
0.1
F
PTC1
V
DD
B
A
(SEE NOTE 1)
5
6
+
V
DD
PTA1
PTA2
68HC908SR12
$FFFF
$FFFE
RESET VECTORS
V
SSA
V
SSAM
V
DDA
D
C
C
C
D
D
630 pF
630 pF
32.768 kHz XTAL
10
M
SW2
SW1
SW4
SW3
(SEE NOTE 2)
(SEE NOTES 2
(SEE NOTE 2)
(SEE NOTE 3)
Notes:
1.
For monitor mode entry when SW2 at position C (IRQ1 = V
TST
):
SW1: Position A -- Bus clock = CGMXCLK
4
SW1: Position B -- Bus clock = CGMXCLK
2
2.
SW2, SW3, and SW4: Position C -- Enter monitor mode using off-chip oscillator only.
SW2, SW3, and SW4: Position D -- Enter monitor mode using 32.768kHz XTAL and internal PLL.
3.
See
Table 24-5
for IRQ1 voltage level requirements.
4.
See
Table 10-1
for other monitor mode entry configurations.
10 k
0.0
1
F
0.033
F
V
TST
330 k
AND 3)
V
REFL
V
REFH
4.9152MHz/9.8304MHz
Monitor ROM (MON)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
168
Monitor ROM (MON)
MOTOROLA
The monitor code allows enabling the PLL to generate the internal clock,
provided the reset vector is blank ($FF), when the device is being
clocked by a low-frequency crystal. This entry method, which is enabled
when IRQ1 is held low out of reset, is intended to support serial
communication/programming at 9600 baud in monitor mode by stepping
up the external frequency (assumed to be 32.768 kHz) by a fixed amount
to generate the desired internal frequency (2.4576 MHz).
If the reset vector is not blank (not $FF), the frequency stepping feature
is not supported, because IRQ1 cannot be held low for monitor mode
entry. With a non-blank reset vector, entry into monitor mode requires
V
TST
on IRQ1.
10.4.1 Entering Monitor Mode
Table 10-1
shows the pin conditions for entering monitor mode. As
specified in the table, monitor mode may be entered after a POR and will
allow communication at 9600 baud provided one of the following sets of
conditions is met:
1. If $FFFE and $FFFF do not contain $FF (programmed state):
The external clock is 4.9152 MHz with PTC1 low or
9.8304 MHz with PTC1 high
IRQ1 = V
TST
(PLL off)
2. If $FFFE and $FFFF both contain $FF (erased state):
The external clock is 9.8304 MHz
IRQ1 = V
DD
(this can be implemented through the internal
IRQ1 pullup; PLL off)
3. If $FFFE and $FFFF both contain $FF (erased state):
The external clock is 32.768 kHz (crystal)
IRQ1 = V
SS
(this setting initiates the PLL to boost the external
32.768 kHz to an internal bus frequency of 2.4576 MHz)
MC6
8
HC9
08S
R12
MC6
8
HC08
S
R1
2
--
Rev
.
4.0
T
ech
n
i
c
a
l
Da
ta
MO
T
O
RO
LA
Mo
nit
o
r
RO
M (
M
O
N
)
1
6
9
Mo
nit
o
r
RO
M (
M
O
N
)
F
u
n
c
ti
on
al Des
c
r
i
ptio
n
Table 10-1. Monitor Mode Signal Requirements and Options
IRQ1
RST
Address
$FFFE/
$FFFF
PTA2
PTA1
PTA0
(1)
PTC1
External
Clock
Bus
Frequency
PLL
COP
Baud
Rate
Comment
X
GND
X
X
X
X
X
X
0
X
Disabled
0
No operation until
reset goes high
V
TST
V
DD
or
V
TST
X
0
1
1
0
4.9152
MHz
(2)
2.4576
MHz
OFF
Disabled
9600
PTA1 and PTA2
voltages only
required if
IRQ1 = V
TST
;
PTC1 determines
frequency divider
V
TST
V
DD
or
V
TST
X
0
1
1
1
9.8304
MHz
(2)
2.4576
MHz
OFF
Disabled
9600
PTA1 and PTA2
voltages only
required if
IRQ1 = V
TST
;
PTC1 determines
frequency divider
V
DD
V
DD
Blank
"$FFFF"
X
X
1
X
9.8304
MHz
(3)
2.4576
MHz
OFF
Disabled
9600
External frequency
always divided by 4
GND
V
DD
Blank
"$FFFF"
X
X
1
X
32.768
kHz
(3)
2.4576
MHz
ON
Disabled
9600
PLL enabled
(BCS set)
in monitor code
V
DD
or
GND
V
TST
Blank
"$FFFF"
X
X
X
X
X
--
OFF
Enabled
--
Enters user
mode -- will
encounter an illegal
address reset
V
DD
or
GND
V
DD
or
V
TST
Not Blank
X
X
X
X
X
--
OFF
Enabled
--
Enters user mode
Notes:
1. PTA0 = 1 if serial communication; PTA0 = 0 if parallel communication (factory use only)
2. When IRQ1 = V
TST
, external clock must be derived by a
4.9152MHz or 9.8304 MHz off-chip oscillator.
3. External clock is derived by a crystal or an off-chip oscillator.
Monitor ROM (MON)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
170
Monitor ROM (MON)
MOTOROLA
If V
TST
is applied to IRQ1 and PTC1 is low upon monitor mode entry
(above condition set 1), the bus frequency is a divide-by-two of the input
clock. If PTC1 is high with V
TST
applied to IRQ1 upon monitor mode
entry, the bus frequency will be a divide-by-four of the input clock.
Holding the PTC1 pin low when entering monitor mode causes a bypass
of a divide-by-two stage at the oscillator only if V
TST
is applied to IRQ1.
In this event, the CGMOUT frequency is equal to the CGMXCLK
frequency, and the OSC1 input directly generates internal bus clocks. In
this case, the OSC1 signal must have a 50% duty cycle at maximum bus
frequency.
If entering monitor mode without high voltage on IRQ1 (above condition
set 2 or 3, where applied voltage is either V
DD
or V
SS
), then all port A pin
requirements and conditions, including the PTC1 frequency divisor
selection, are not in effect. This is to reduce circuit requirements when
performing in-circuit programming.
NOTE:
If the reset vector is blank and monitor mode is entered, the chip will see
an additional reset cycle after the initial POR reset. Once the part has
been programmed, the traditional method of applying a voltage, V
TST
, to
IRQ1 must be used to enter monitor mode.
The COP module is disabled in monitor mode based on these
conditions:
If monitor mode was entered as a result of the reset vector being
blank (above condition set 2 or 3), the COP is always disabled
regardless of the state of IRQ1 or RST.
If monitor mode was entered with V
TST
on IRQ1 (condition set 1),
then the COP is disabled as long as V
TST
is applied to either IRQ1
or RST.
The second condition states that as long as V
TST
is maintained on the
IRQ1 pin after entering monitor mode, or if V
TST
is applied to RST after
the initial reset to get into monitor mode (when V
TST
was applied to
IRQ1), then the COP will be disabled. In the latter situation, after V
TST
is
applied to the RST pin, V
TST
can be removed from the IRQ1 pin in the
interest of freeing the IRQ1 for normal functionality in monitor mode.
Monitor ROM (MON)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Monitor ROM (MON)
171
Figure 10-2
shows a simplified diagram of the monitor mode entry when
the reset vector is blank and just 1 x V
DD
voltage is applied to the IRQ1
pin. An external oscillator of 9.8304 MHz is required for a baud rate of
9600, as the internal bus frequency is automatically set to the external
frequency divided by four.
Figure 10-2. Low-Voltage Monitor Mode Entry Flowchart
Enter monitor mode with pin configuration shown in
Figure 10-1
by
pulling RST low and then high. The rising edge of RST latches monitor
mode. Once monitor mode is latched, the values on the specified pins
can change.
Once out of reset, the MCU waits for the host to send eight security
bytes. (See
10.5 Security
.) After the security bytes, the MCU sends a
break signal (10 consecutive logic 0s) to the host, indicating that it is
ready to receive a command.
In monitor mode, the MCU uses different vectors for reset, SWI
(software interrupt), and break interrupt than those for user mode. The
alternate vectors are in the $FE page instead of the $FF page and allow
code execution from the internal monitor firmware instead of user code.
IS VECTOR
BLANK?
POR
TRIGGERED?
NORMAL USER
MODE
MONITOR MODE
EXECUTE
MONITOR
CODE
NO
NO
YES
YES
POR RESET
Monitor ROM (MON)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
172
Monitor ROM (MON)
MOTOROLA
NOTE:
Exiting monitor mode after it has been initiated by having a blank reset
vector requires a power-on reset (POR). Pulling RST low will not exit
monitor mode in this situation.
Table 10-2
summarizes the differences between user mode and monitor
mode.
10.4.2 Data Format
Communication with the monitor ROM is in standard non-return-to-zero
(NRZ) mark/space data format. Transmit and receive baud rates must
be identical.
Figure 10-3. Monitor Data Format
10.4.3 Break Signal
A start bit (logic 0) followed by nine logic 0 bits is a break signal. When
the monitor receives a break signal, it drives the PTA0 pin high for the
duration of two bits and then echoes back the break signal.
Figure 10-4. Break Transaction
Table 10-2. Mode Differences
Modes
Functions
Reset
Vector
High
Reset
Vector
Low
Break
Vector
High
Break
Vector
Low
SWI
Vector
High
SWI
Vector
Low
User
$FFFE
$FFFF
$FFFC
$FFFD
$FFFC
$FFFD
Monitor
$FEFE
$FEFF
$FEFC
$FEFD
$FEFC
$FEFD
BIT 5
START
BIT
BIT 0
BIT 1
NEXT
STOP
BIT
START
BIT
BIT 2
BIT 3
BIT 4
BIT 6
BIT 7
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
MISSING STOP BIT
2-STOP BIT DELAY BEFORE ZERO ECHO
Monitor ROM (MON)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Monitor ROM (MON)
173
10.4.4 Baud Rate
The communication baud rate is controlled by the crystal frequency and
the state of the PTC1 pin (when IRQ1 is set to V
TST
) upon entry into
monitor mode. When PTC1 is high, the divide by ratio is 1024. If the
PTC1 pin is at logic 0 upon entry into monitor mode, the divide by ratio
is 512.
If monitor mode was entered with V
DD
on IRQ1, then the divide by ratio
is set at 1024, regardless of PTC1. If monitor mode was entered with V
SS
on IRQ, then the internal PLL steps up the external frequency, presumed
to be 32.768 kHz, to 2.4576 MHz. These latter two conditions for monitor
mode entry require that the reset vector is blank.
Table 10-3
lists external frequencies required to achieve a standard
baud rate of 9600 BPS. Other standard baud rates can be accomplished
using proportionally higher or lower frequency generators. If using a
crystal as the clock source, be aware of the upper frequency limit that the
internal clock module can handle. See
24.6 5.0V DC Electrical
Characteristics
and
24.8 5.0V Control Timing
for this limit.
10.4.5 Commands
The monitor ROM firmware uses these commands:
READ (read memory)
WRITE (write memory)
IREAD (indexed read)
Table 10-3. Monitor Baud Rate Selection
External
Frequency
IRQ1
PTC1
Internal
Frequency
Baud Rate
(BPS)
4.9152 MHz
V
TST
0
2.4576 MHz
9600
9.8304 MHz
V
TST
1
2.4576 MHz
9600
9.8304 MHz
V
DD
X
2.4576 MHz
9600
32.768 kHz
V
SS
X
2.4576 MHz
9600
Monitor ROM (MON)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
174
Monitor ROM (MON)
MOTOROLA
IWRITE (indexed write)
READSP (read stack pointer)
RUN (run user program)
The monitor ROM firmware echoes each received byte back to the PTA0
pin for error checking. An 11-bit delay at the end of each command
allows the host to send a break character to cancel the command. A
delay of two bit times occurs before each echo and before READ,
IREAD, or READSP data is returned. The data returned by a read
command appears after the echo of the last byte of the command.
NOTE:
Wait one bit time after each echo before sending the next byte.
Figure 10-5. Read Transaction
Figure 10-6. Write Transaction
READ
READ
ECHO
FROM
HOST
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
DATA
RETURN
1
3, 2
1
1
4
4
Notes:
2 = Data return delay, 2 bit times
3 = Cancel command delay, 11 bit times
4 = Wait 1 bit time before sending next byte.
4
4
1 = Echo delay, 2 bit times
WRITE
WRITE
ECHO
FROM
HOST
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
DATA
DATA
Notes:
2 = Cancel command delay, 11 bit times
3 = Wait 1 bit time before sending next byte.
1
1
3
1
1
3
3
3
2, 3
1 = Echo delay, 2 bit times
Monitor ROM (MON)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Monitor ROM (MON)
175
A brief description of each monitor mode command is given in
Table 10-4
through
Table 10-9
.
Table 10-4. READ (Read Memory) Command
Description
Read byte from memory
Operand
2-byte address in high-byte:low-byte order
Data
Returned
Returns contents of specified address
Opcode
$4A
Command Sequence
Table 10-5. WRITE (Write Memory) Command
Description
Write byte to memory
Operand
2-byte address in high-byte:low-byte order; low byte followed by
data byte
Data
Returned
None
Opcode
$49
Command Sequence
READ
READ
ECHO
SENT TO
MONITOR
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
DATA
RETURN
ADDRESS
LOW
WRITE
WRITE
ECHO
FROM
HOST
ADDRESS
HIGH
ADDRESS
HIGH
ADDRESS
LOW
ADDRESS
LOW
DATA
DATA
Monitor ROM (MON)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
176
Monitor ROM (MON)
MOTOROLA
Table 10-6. IREAD (Indexed Read) Command
Description
Read next 2 bytes in memory from last address accessed
Operand
2-byte address in high byte:low byte order
Data
Returned
Returns contents of next two addresses
Opcode
$1A
Command Sequence
Table 10-7. IWRITE (Indexed Write) Command
Description
Write to last address accessed + 1
Operand
Single data byte
Data
Returned
None
Opcode
$19
Command Sequence
IREAD
IREAD
ECHO
FROM
HOST
DATA
RETURN
DATA
IWRITE
IWRITE
ECHO
FROM
HOST
DATA
DATA
Monitor ROM (MON)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Monitor ROM (MON)
177
A sequence of IREAD or IWRITE commands can access a block of
memory sequentially over the full 64k-byte memory map.
Table 10-8. READSP (Read Stack Pointer) Command
Description
Reads stack pointer
Operand
None
Data
Returned
Returns incremented stack pointer value (SP + 1) in high-byte:low-
byte order
Opcode
$0C
Command Sequence
Table 10-9. RUN (Run User Program) Command
Description
Executes PULH and RTI instructions
Operand
None
Data
Returned
None
Opcode
$28
Command Sequence
READSP
READSP
ECHO
FROM
HOST
SP
RETURN
SP
HIGH
LOW
RUN
RUN
ECHO
FROM
HOST
Monitor ROM (MON)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
178
Monitor ROM (MON)
MOTOROLA
The MCU executes the SWI and PSHH instructions when it enters
monitor mode. The RUN command tells the MCU to execute the PULH
and RTI instructions. Before sending the RUN command, the host can
modify the stacked CPU registers to prepare to run the host program.
The READSP command returns the incremented stack pointer value,
SP + 1. The high and low bytes of the program counter are at addresses
SP + 5 and SP + 6.
Figure 10-7. Stack Pointer at Monitor Mode Entry
10.5 Security
A security feature discourages unauthorized reading of FLASH locations
while in monitor mode. The host can bypass the security feature at
monitor mode entry by sending eight security bytes that match the bytes
at locations $FFF6$FFFD. Locations $FFF6$FFFD contain user-
defined data.
NOTE:
Do not leave locations $FFF6$FFFD blank. For security reasons,
program locations $FFF6$FFFD even if they are not used for vectors.
During monitor mode entry, the MCU waits after the power-on reset for
the host to send the eight security bytes on pin PTA0. If the received
bytes match those at locations $FFF6$FFFD, the host bypasses the
security feature and can read all FLASH locations and execute code
from FLASH. Security remains bypassed until a power-on reset occurs.
If the reset was not a power-on reset, security remains bypassed and
security code entry is not required. (See
Figure 10-8
.)
CONDITION CODE REGISTER
ACCUMULATOR
LOW BYTE OF INDEX REGISTER
HIGH BYTE OF PROGRAM COUNTER
LOW BYTE OF PROGRAM COUNTER
SP + 1
SP + 2
SP + 3
SP + 4
SP + 5
SP
SP + 6
HIGH BYTE OF INDEX REGISTER
SP + 7
Monitor ROM (MON)
Security
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Monitor ROM (MON)
179
Figure 10-8. Monitor Mode Entry Timing
Upon power-on reset, if the received bytes of the security code do not
match the data at locations $FFF6$FFFD, the host fails to bypass the
security feature. The MCU remains in monitor mode, but reading a
FLASH location returns an invalid value and trying to execute code from
FLASH causes an illegal address reset. After receiving the eight security
bytes from the host, the MCU transmits a break character, signifying that
it is ready to receive a command.
NOTE:
The MCU does not transmit a break character until after the host sends
the eight security bits.
To determine whether the security code entered is correct, check to see
if bit 6 of RAM address $40 is set. If it is, then the correct security code
has been entered and FLASH can be accessed.
If the security sequence fails, the device should be reset by a power-on
reset and brought up in monitor mode to attempt another entry. After
failing the security sequence, the FLASH module can also be mass
erased by executing an erase routine that was downloaded into internal
RAM. The mass erase operation clears the security code locations so
that all eight security bytes become $FF (blank).
BY
T
E
1
B
Y
TE
1
E
CHO
BY
T
E
2
B
Y
TE
2
E
CHO
BY
T
E
8
BY
TE
8
EC
H
O
COMM
A
N
D
COMM
A
ND E
CHO
PTA0
RST
V
DD
4096 + 32 ICLK CYCLES
256 BUS CYCLES (MINIMUM)
1
4
1
1
2
1
BR
E
A
K
NOTES:
2 = Data return delay, 2 bit times.
4 = Wait 1 bit time before sending next byte.
4
FROM HOST
FROM MCU
1 = Echo delay, 2 bit times.
Monitor ROM (MON)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
180
Monitor ROM (MON)
MOTOROLA
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timer Interface Module (TIM)
181
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 11. Timer Interface Module (TIM)
11.1 Contents
11.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
11.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
11.4
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
11.5
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
11.5.1
TIM Counter Prescaler . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
11.5.2
Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
11.5.3
Output Compare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
11.5.3.1
Unbuffered Output Compare . . . . . . . . . . . . . . . . . . . . . 188
11.5.3.2
Buffered Output Compare . . . . . . . . . . . . . . . . . . . . . . . 189
11.5.4
Pulse Width Modulation (PWM) . . . . . . . . . . . . . . . . . . . . . 189
11.5.4.1
Unbuffered PWM Signal Generation . . . . . . . . . . . . . . . 190
11.5.4.2
Buffered PWM Signal Generation . . . . . . . . . . . . . . . . . 191
11.5.4.3
PWM Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
11.6
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
11.7
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .193
11.7.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
11.7.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
11.8
TIM During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . 194
11.9
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
11.10 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
11.10.1 TIM Status and Control Register . . . . . . . . . . . . . . . . . . . . 196
11.10.2 TIM Counter Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198
11.10.3 TIM Counter Modulo Registers . . . . . . . . . . . . . . . . . . . . . 199
11.10.4 TIM Channel Status and Control Registers . . . . . . . . . . . .200
11.10.5 TIM Channel Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Timer Interface Module (TIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
182
Timer Interface Module (TIM)
MOTOROLA
11.2 Introduction
This section describes the timer interface (TIM) module. The TIM is a
two-channel timer that provides a timing reference with input capture,
output compare, and pulse-width-modulation functions.
Figure 11-1
is a
block diagram of the TIM.
This particular MCU has two timer interface modules which are denoted
as TIM1 and TIM2.
11.3 Features
Features of the TIM include:
Two input capture/output compare channels:
Rising-edge, falling-edge, or any-edge input capture trigger
Set, clear, or toggle output compare action
Buffered and unbuffered pulse-width-modulation (PWM) signal
generation
Programmable TIM clock input with 7-frequency internal bus clock
prescaler selection
Free-running or modulo up-count operation
Toggle any channel pin on overflow
TIM counter stop and reset bits
Timer Interface Module (TIM)
Pin Name Conventions
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timer Interface Module (TIM)
183
11.4 Pin Name Conventions
The text that follows describes both timers, TIM1 and TIM2. The TIM
input/output (I/O) pin names are T[1,2]CH0 (timer channel 0) and
T[1,2]CH1 (timer channel 1), where "1" is used to indicate TIM1 and "2"
is used to indicate TIM2. The two TIMs share four I/O pins with four I/O
port pins. The full names of the TIM I/O pins are listed in
Table 11-1
.
The generic pin names appear in the text that follows.
NOTE:
References to either timer 1 or timer 2 may be made in the following text
by omitting the timer number. For example, TCH0 may refer generically
to T1CH0 and T2CH0, and TCH1 may refer to T1CH1 and T2CH1.
11.5 Functional Description
Figure 11-1
shows the structure of the TIM. The central component of
the TIM is the 16-bit TIM counter that can operate as a free-running
counter or a modulo up-counter. The TIM counter provides the timing
reference for the input capture and output compare functions. The TIM
counter modulo registers, TMODH:TMODL, control the modulo value of
the TIM counter. Software can read the TIM counter value at any time
without affecting the counting sequence.
The two TIM channels (per timer) are programmable independently as
input capture or output compare channels.
Table 11-1. Pin Name Conventions
TIM Generic Pin Names:
T[1,2]CH0
T[1,2]CH1
Full TIM
Pin Names:
TIM1
PTA6/T1CH0
PTA7/T1CH1
TIM2
PTB4/T2CH0
PTB5/T2CH1
Timer Interface Module (TIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
184
Timer Interface Module (TIM)
MOTOROLA
Figure 11-1. TIM Block Diagram
Figure 11-2
summarizes the timer registers.
NOTE:
References to either timer 1 or timer 2 may be made in the following text
by omitting the timer number. For example, TSC may generically refer to
both T1SC and T2SC.
PRESCALER
PRESCALER SELECT
INTERNAL
16-BIT COMPARATOR
PS2
PS1
PS0
16-BIT COMPARATOR
16-BIT LATCH
TCH0H:TCH0L
MS0A
ELS0B
ELS0A
TOF
TOIE
16-BIT COMPARATOR
16-BIT LATCH
TCH1H:TCH1L
CHANNEL 0
CHANNEL 1
TMODH:TMODL
TRST
TSTOP
TOV0
CH0IE
CH0F
ELS1B
ELS1A
TOV1
CH1IE
CH1MAX
CH1F
CH0MAX
MS0B
16-BIT COUNTER
I
N
T
E
RN
AL
BU
S
BUS CLOCK
MS1A
T[1,2]CH0
T[1,2]CH1
INTERRUPT
LOGIC
PORT
LOGIC
INTERRUPT
LOGIC
INTERRUPT
LOGIC
PORT
LOGIC
Timer Interface Module (TIM)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timer Interface Module (TIM)
185
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0020
Timer 1 Status and Control
Register (T1SC)
Read:
TOF
TOIE
TSTOP
0
0
PS2
PS1
PS0
Write:
0
TRST
Reset:
0
0
1
0
0
0
0
0
$0021
Timer 1 Counter Register
High (T1CNTH)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
0
0
0
0
0
0
0
0
$0022
Timer 1 Counter Register
Low (T1CNTL)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
0
0
0
0
0
0
0
0
$0023
Timer 1 Counter Modulo
Register High (T1MODH)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
1
1
1
1
1
1
1
1
$0024
Timer 1 Counter Modulo
Register Low (T1MODL)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
1
1
1
1
1
1
1
1
$0025
Timer 1 Channel 0 Status
and Control Register
(T1SC0)
Read:
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
TOV0
CH0MAX
Write:
0
Reset:
0
0
0
0
0
0
0
0
$0026
Timer 1 Channel 0
Register High (T1CH0H)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
Indeterminate after reset
$0027
Timer 1 Channel 0
Register Low (T1CH0L)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
Indeterminate after reset
$0028
Timer 1 Channel 1 Status
and Control Register
(T1SC1)
Read:
CH1F
CH1IE
0
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
Write:
0
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 11-2. TIM I/O Register Summary (Sheet 1 of 3)
Timer Interface Module (TIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
186
Timer Interface Module (TIM)
MOTOROLA
$0029
Timer 1 Channel 1
Register High (T1CH1H)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
Indeterminate after reset
$002A
Timer 1 Channel 1
Register Low (T1CH1L)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
Indeterminate after reset
$002B
Timer 2 Status and Control
Register (T2SC)
Read:
TOF
TOIE
TSTOP
0
0
PS2
PS1
PS0
Write:
0
TRST
Reset:
0
0
1
0
0
0
0
0
$002C
Timer 2 Counter Register
High (T2CNTH)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
0
0
0
0
0
0
0
0
$002D
Timer 2 Counter Register
Low (T2CNTL)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
0
0
0
0
0
0
0
0
$002E
Timer 2 Counter Modulo
Register High (T2MODH)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
1
1
1
1
1
1
1
1
$002F
Timer 2 Counter Modulo
Register Low (T2MODL)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
1
1
1
1
1
1
1
1
$0030
Timer 2 Channel 0 Status
and Control Register
(T2SC0)
Read:
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
TOV0
CH0MAX
Write:
0
Reset:
0
0
0
0
0
0
0
0
$0031
Timer 2 Channel 0
Register High (T2CH0H)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
Indeterminate after reset
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
= Unimplemented
Figure 11-2. TIM I/O Register Summary (Sheet 2 of 3)
Timer Interface Module (TIM)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timer Interface Module (TIM)
187
11.5.1 TIM Counter Prescaler
The TIM clock source can be one of the seven prescaler outputs. The
prescaler generates seven clock rates from the internal bus clock. The
prescaler select bits, PS[2:0], in the TIM status and control register
select the TIM clock source.
11.5.2 Input Capture
With the input capture function, the TIM can capture the time at which an
external event occurs. When an active edge occurs on the pin of an input
capture channel, the TIM latches the contents of the TIM counter into the
TIM channel registers, TCHxH:TCHxL. The polarity of the active edge is
programmable. Input captures can generate TIM CPU interrupt
requests.
$0032
Timer 2 Channel 0
Register Low (T2CH0L)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
Indeterminate after reset
$0033
Timer 2 Channel 1 Status
and Control Register
(T2SC1)
Read:
CH1F
CH1IE
0
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
Write:
0
Reset:
0
0
0
0
0
0
0
0
$0034
Timer 2 Channel 1
Register High (T2CH1H)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
Indeterminate after reset
$0035
Timer 2 Channel 1
Register Low (T2CH1L)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
Indeterminate after reset
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
= Unimplemented
Figure 11-2. TIM I/O Register Summary (Sheet 3 of 3)
Timer Interface Module (TIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
188
Timer Interface Module (TIM)
MOTOROLA
11.5.3 Output Compare
With the output compare function, the TIM can generate a periodic pulse
with a programmable polarity, duration, and frequency. When the
counter reaches the value in the registers of an output compare channel,
the TIM can set, clear, or toggle the channel pin. Output compares can
generate TIM CPU interrupt requests.
11.5.3.1 Unbuffered Output Compare
Any output compare channel can generate unbuffered output compare
pulses as described in
11.5.3 Output Compare
. The pulses are
unbuffered because changing the output compare value requires writing
the new value over the old value currently in the TIM channel registers.
An unsynchronized write to the TIM channel registers to change an
output compare value could cause incorrect operation for up to two
counter overflow periods. For example, writing a new value before the
counter reaches the old value but after the counter reaches the new
value prevents any compare during that counter overflow period. Also,
using a TIM overflow interrupt routine to write a new, smaller output
compare value may cause the compare to be missed. The TIM may pass
the new value before it is written.
Use the following methods to synchronize unbuffered changes in the
output compare value on channel x:
When changing to a smaller value, enable channel x output
compare interrupts and write the new value in the output compare
interrupt routine. The output compare interrupt occurs at the end
of the current output compare pulse. The interrupt routine has until
the end of the counter overflow period to write the new value.
When changing to a larger output compare value, enable TIM
overflow interrupts and write the new value in the TIM overflow
interrupt routine. The TIM overflow interrupt occurs at the end of
the current counter overflow period. Writing a larger value in an
output compare interrupt routine (at the end of the current pulse)
could cause two output compares to occur in the same counter
overflow period.
Timer Interface Module (TIM)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timer Interface Module (TIM)
189
11.5.3.2 Buffered Output Compare
Channels 0 and 1 can be linked to form a buffered output compare
channel whose output appears on the TCH0 pin. The TIM channel
registers of the linked pair alternately control the output.
Setting the MS0B bit in TIM channel 0 status and control register (TSC0)
links channel 0 and channel 1. The output compare value in the TIM
channel 0 registers initially controls the output on the TCH0 pin. Writing
to the TIM channel 1 registers enables the TIM channel 1 registers to
synchronously control the output after the TIM overflows. At each
subsequent overflow, the TIM channel registers (0 or 1) that control the
output are the ones written to last. TSC0 controls and monitors the
buffered output compare function, and TIM channel 1 status and control
register (TSC1) is unused. While the MS0B bit is set, the channel 1 pin,
TCH1, is available as a general-purpose I/O pin.
NOTE:
In buffered output compare operation, do not write new output compare
values to the currently active channel registers. User software should
track the currently active channel to prevent writing a new value to the
active channel. Writing to the active channel registers is the same as
generating unbuffered output compares.
11.5.4 Pulse Width Modulation (PWM)
By using the toggle-on-overflow feature with an output compare channel,
the TIM can generate a PWM signal. The value in the TIM counter
modulo registers determines the period of the PWM signal. The channel
pin toggles when the counter reaches the value in the TIM counter
modulo registers. The time between overflows is the period of the PWM
signal.
As
Figure 11-3
shows, the output compare value in the TIM channel
registers determines the pulse width of the PWM signal. The time
between overflow and output compare is the pulse width. Program the
TIM to clear the channel pin on output compare if the state of the PWM
pulse is logic 1. Program the TIM to set the pin if the state of the PWM
pulse is logic 0.
Timer Interface Module (TIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
190
Timer Interface Module (TIM)
MOTOROLA
The value in the TIM counter modulo registers and the selected
prescaler output determines the frequency of the PWM output. The
frequency of an 8-bit PWM signal is variable in 256 increments. Writing
$00FF (255) to the TIM counter modulo registers produces a PWM
period of 256 times the internal bus clock period if the prescaler select
value is $000. See
11.10.1 TIM Status and Control Register
.
Figure 11-3. PWM Period and Pulse Width
The value in the TIM channel registers determines the pulse width of the
PWM output. The pulse width of an 8-bit PWM signal is variable in 256
increments. Writing $0080 (128) to the TIM channel registers produces
a duty cycle of 128/256 or 50%.
11.5.4.1 Unbuffered PWM Signal Generation
Any output compare channel can generate unbuffered PWM pulses as
described in
11.5.4 Pulse Width Modulation (PWM)
. The pulses are
unbuffered because changing the pulse width requires writing the new
pulse width value over the old value currently in the TIM channel
registers.
An unsynchronized write to the TIM channel registers to change a pulse
width value could cause incorrect operation for up to two PWM periods.
For example, writing a new value before the counter reaches the old
value but after the counter reaches the new value prevents any compare
during that PWM period. Also, using a TIM overflow interrupt routine to
write a new, smaller pulse width value may cause the compare to be
missed. The TIM may pass the new value before it is written.
TCHx
PERIOD
PULSE
WIDTH
OVERFLOW
OVERFLOW
OVERFLOW
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
Timer Interface Module (TIM)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timer Interface Module (TIM)
191
Use the following methods to synchronize unbuffered changes in the
PWM pulse width on channel x:
When changing to a shorter pulse width, enable channel x output
compare interrupts and write the new value in the output compare
interrupt routine. The output compare interrupt occurs at the end
of the current pulse. The interrupt routine has until the end of the
PWM period to write the new value.
When changing to a longer pulse width, enable TIM overflow
interrupts and write the new value in the TIM overflow interrupt
routine. The TIM overflow interrupt occurs at the end of the current
PWM period. Writing a larger value in an output compare interrupt
routine (at the end of the current pulse) could cause two output
compares to occur in the same PWM period.
NOTE:
In PWM signal generation, do not program the PWM channel to toggle
on output compare. Toggling on output compare prevents reliable 0%
duty cycle generation and removes the ability of the channel to self-
correct in the event of software error or noise. Toggling on output
compare also can cause incorrect PWM signal generation when
changing the PWM pulse width to a new, much larger value.
11.5.4.2 Buffered PWM Signal Generation
Channels 0 and 1 can be linked to form a buffered PWM channel whose
output appears on the TCH0 pin. The TIM channel registers of the linked
pair alternately control the pulse width of the output.
Setting the MS0B bit in TIM channel 0 status and control register (TSC0)
links channel 0 and channel 1. The TIM channel 0 registers initially
control the pulse width on the TCH0 pin. Writing to the TIM channel 1
registers enables the TIM channel 1 registers to synchronously control
the pulse width at the beginning of the next PWM period. At each
subsequent overflow, the TIM channel registers (0 or 1) that control the
pulse width are the ones written to last. TSC0 controls and monitors the
buffered PWM function, and TIM channel 1 status and control register
(TSC1) is unused. While the MS0B bit is set, the channel 1 pin, TCH1,
is available as a general-purpose I/O pin.
Timer Interface Module (TIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
192
Timer Interface Module (TIM)
MOTOROLA
NOTE:
In buffered PWM signal generation, do not write new pulse width values
to the currently active channel registers. User software should track the
currently active channel to prevent writing a new value to the active
channel. Writing to the active channel registers is the same as
generating unbuffered PWM signals.
11.5.4.3 PWM Initialization
To ensure correct operation when generating unbuffered or buffered
PWM signals, use the following initialization procedure:
1. In the TIM status and control register (TSC):
a. Stop the TIM counter by setting the TIM stop bit, TSTOP.
b. Reset the TIM counter and prescaler by setting the TIM reset
bit, TRST.
2. In the TIM counter modulo registers (TMODH:TMODL), write the
value for the required PWM period.
3. In the TIM channel x registers (TCHxH:TCHxL), write the value for
the required pulse width.
4. In TIM channel x status and control register (TSCx):
a. Write 0:1 (for unbuffered output compare or PWM signals) or
1:0 (for buffered output compare or PWM signals) to the
mode select bits, MSxB:MSxA. (See
Table 11-3
.)
b. Write 1 to the toggle-on-overflow bit, TOVx.
c. Write 1:0 (to clear output on compare) or 1:1 (to set output on
compare) to the edge/level select bits, ELSxB:ELSxA. The
output action on compare must force the output to the
complement of the pulse width level. (See
Table 11-3
.)
NOTE:
In PWM signal generation, do not program the PWM channel to toggle
on output compare. Toggling on output compare prevents reliable 0%
duty cycle generation and removes the ability of the channel to self-
correct in the event of software error or noise. Toggling on output
compare can also cause incorrect PWM signal generation when
changing the PWM pulse width to a new, much larger value.
5. In the TIM status control register (TSC), clear the TIM stop bit,
TSTOP.
Timer Interface Module (TIM)
Interrupts
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timer Interface Module (TIM)
193
Setting MS0B links channels 0 and 1 and configures them for buffered
PWM operation. The TIM channel 0 registers (TCH0H:TCH0L) initially
control the buffered PWM output. TIM status control register 0 (TSCR0)
controls and monitors the PWM signal from the linked channels.
Clearing the toggle-on-overflow bit, TOVx, inhibits output toggles on TIM
overflows. Subsequent output compares try to force the output to a state
it is already in and have no effect. The result is a 0% duty cycle output.
Setting the channel x maximum duty cycle bit (CHxMAX) and setting the
TOVx bit generates a 100% duty cycle output. (See
11.10.4 TIM
Channel Status and Control Registers
.)
11.6 Interrupts
The following TIM sources can generate interrupt requests:
TIM overflow flag (TOF) -- The TOF bit is set when the TIM
counter reaches the modulo value programmed in the TIM counter
modulo registers. The TIM overflow interrupt enable bit, TOIE,
enables TIM overflow CPU interrupt requests. TOF and TOIE are
in the TIM status and control register.
TIM channel flags (CH1F:CH0F) -- The CHxF bit is set when an
input capture or output compare occurs on channel x. Channel x
TIM CPU interrupt requests are controlled by the channel x
interrupt enable bit, CHxIE. Channel x TIM CPU interrupt requests
are enabled when CHxIE = 1. CHxF and CHxIE are in the TIM
channel x status and control register.
11.7 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
Timer Interface Module (TIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
194
Timer Interface Module (TIM)
MOTOROLA
11.7.1 Wait Mode
The TIM remains active after the execution of a WAIT instruction. In wait
mode, the TIM registers are not accessible by the CPU. Any enabled
CPU interrupt request from the TIM can bring the MCU out of wait mode.
If TIM functions are not required during wait mode, reduce power
consumption by stopping the TIM before executing the WAIT instruction.
11.7.2 Stop Mode
The TIM is inactive after the execution of a STOP instruction. The STOP
instruction does not affect register conditions or the state of the TIM
counter. TIM operation resumes when the MCU exits stop mode after an
external interrupt.
11.8 TIM During Break Interrupts
A break interrupt stops the TIM counter.
The system integration module (SIM) controls whether status bits in
other modules can be cleared during the break state. The BCFE bit in
the SIM break flag control register (SBFCR) enables software to clear
status bits during the break state. (See
9.8.3 SIM Break Flag Control
Register
.)
To allow software to clear status bits during a break interrupt, write a
logic 1 to the BCFE bit. If a status bit is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect status bits during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), software can read and write
I/O registers during the break state without affecting status bits. Some
status bits have a 2-step read/write clearing procedure. If software does
the first step on such a bit before the break, the bit cannot change during
the break state as long as BCFE is at logic 0. After the break, doing the
second step clears the status bit.
Timer Interface Module (TIM)
I/O Signals
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timer Interface Module (TIM)
195
11.9 I/O Signals
Port A and port B each shares two of its pins with the TIM. The four TIM
channel I/O pins are T1CH0, T1CH1, T2CH0, and T2CH1 as described
in
11.4 Pin Name Conventions
.
Each channel I/O pin is programmable independently as an input
capture pin or an output compare pin. T1CH0 and T2CH0 can be
configured as buffered output compare or buffered PWM pins.
11.10 I/O Registers
NOTE:
References to either timer 1 or timer 2 may be made in the following text
by omitting the timer number. For example, TSC may generically refer to
both T1SC AND T2SC.
These I/O registers control and monitor operation of the TIM:
TIM status and control register (TSC)
TIM counter registers (TCNTH:TCNTL)
TIM counter modulo registers (TMODH:TMODL)
TIM channel status and control registers (TSC0, TSC1)
TIM channel registers (TCH0H:TCH0L, TCH1H:TCH1L)
Timer Interface Module (TIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
196
Timer Interface Module (TIM)
MOTOROLA
11.10.1 TIM Status and Control Register
The TIM status and control register (TSC):
Enables TIM overflow interrupts
Flags TIM overflows
Stops the TIM counter
Resets the TIM counter
Prescales the TIM counter clock
TOF -- TIM Overflow Flag Bit
This read/write flag is set when the TIM counter reaches the modulo
value programmed in the TIM counter modulo registers. Clear TOF by
reading the TIM status and control register when TOF is set and then
writing a logic 0 to TOF. If another TIM overflow occurs before the
clearing sequence is complete, then writing logic 0 to TOF has no
effect. Therefore, a TOF interrupt request cannot be lost due to
inadvertent clearing of TOF. Reset clears the TOF bit. Writing a logic
1 to TOF has no effect.
1 = TIM counter has reached modulo value
0 = TIM counter has not reached modulo value
TOIE -- TIM Overflow Interrupt Enable Bit
This read/write bit enables TIM overflow interrupts when the TOF bit
becomes set. Reset clears the TOIE bit.
1 = TIM overflow interrupts enabled
0 = TIM overflow interrupts disabled
Address: T1SC, $0020 and T2SC, $002B
Bit 7
6
5
4
3
2
1
Bit 0
Read:
TOF
TOIE
TSTOP
0
0
PS2
PS1
PS0
Write:
0
TRST
Reset:
0
0
1
0
0
0
0
0
= Unimplemented
Figure 11-4. TIM Status and Control Register (TSC)
Timer Interface Module (TIM)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timer Interface Module (TIM)
197
TSTOP -- TIM Stop Bit
This read/write bit stops the TIM counter. Counting resumes when
TSTOP is cleared. Reset sets the TSTOP bit, stopping the TIM
counter until software clears the TSTOP bit.
1 = TIM counter stopped
0 = TIM counter active
NOTE:
Do not set the TSTOP bit before entering wait mode if the TIM is required
to exit wait mode.
TRST -- TIM Reset Bit
Setting this write-only bit resets the TIM counter and the TIM
prescaler. Setting TRST has no effect on any other registers.
Counting resumes from $0000. TRST is cleared automatically after
the TIM counter is reset and always reads as logic 0. Reset clears the
TRST bit.
1 = Prescaler and TIM counter cleared
0 = No effect
NOTE:
Setting the TSTOP and TRST bits simultaneously stops the TIM counter
at a value of $0000.
PS[2:0] -- Prescaler Select Bits
These read/write bits select one of the seven prescaler outputs as the
input to the TIM counter as
Table 11-2
shows. Reset clears the
PS[2:0] bits.
Table 11-2. Prescaler Selection
PS2
PS1
PS0
TIM Clock Source
0
0
0
Internal bus clock
1
0
0
1
Internal bus clock
2
0
1
0
Internal bus clock
4
0
1
1
Internal bus clock
8
1
0
0
Internal bus clock
16
1
0
1
Internal bus clock
32
1
1
0
Internal bus clock
64
1
1
1
Not available
Timer Interface Module (TIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
198
Timer Interface Module (TIM)
MOTOROLA
11.10.2 TIM Counter Registers
The two read-only TIM counter registers contain the high and low bytes
of the value in the TIM counter. Reading the high byte (TCNTH) latches
the contents of the low byte (TCNTL) into a buffer. Subsequent reads of
TCNTH do not affect the latched TCNTL value until TCNTL is read.
Reset clears the TIM counter registers. Setting the TIM reset bit (TRST)
also clears the TIM counter registers.
NOTE:
If you read TCNTH during a break interrupt, be sure to unlatch TCNTL
by reading TCNTL before exiting the break interrupt. Otherwise, TCNTL
retains the value latched during the break.
Address: T1CNTH, $0021 and T2CNTH, $002C
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 11-5. TIM Counter Registers High (TCNTH)
Address: T1CNTL, $0022 and T2CNTL, $002D
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 11-6. TIM Counter Registers Low (TCNTL)
Timer Interface Module (TIM)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timer Interface Module (TIM)
199
11.10.3 TIM Counter Modulo Registers
The read/write TIM modulo registers contain the modulo value for the
TIM counter. When the TIM counter reaches the modulo value, the
overflow flag (TOF) becomes set, and the TIM counter resumes counting
from $0000 at the next timer clock. Writing to the high byte (TMODH)
inhibits the TOF bit and overflow interrupts until the low byte (TMODL) is
written. Reset sets the TIM counter modulo registers.
NOTE:
Reset the TIM counter before writing to the TIM counter modulo registers.
Address: T1MODH, $0023 and T2MODH, $002E
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
1
1
1
1
1
1
1
1
Figure 11-7. TIM Counter Modulo Register High (TMODH)
Address: T1MODL, $0024 and T2MODL, $002F
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
1
1
1
1
1
1
1
1
Figure 11-8. TIM Counter Modulo Register Low (TMODL)
Timer Interface Module (TIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
200
Timer Interface Module (TIM)
MOTOROLA
11.10.4 TIM Channel Status and Control Registers
Each of the TIM channel status and control registers:
Flags input captures and output compares
Enables input capture and output compare interrupts
Selects input capture, output compare, or PWM operation
Selects high, low, or toggling output on output compare
Selects rising edge, falling edge, or any edge as the active input
capture trigger
Selects output toggling on TIM overflow
Selects 0% and 100% PWM duty cycle
Selects buffered or unbuffered output compare/PWM operation
Address: T1SC0, $0025 and T2SC0, $0030
Bit 7
6
5
4
3
2
1
Bit 0
Read:
CH0F
CH0IE
MS0B
MS0A
ELS0B
ELS0A
TOV0
CH0MAX
Write:
0
Reset:
0
0
0
0
0
0
0
0
Figure 11-9. TIM Channel 0 Status and Control Register (TSC0)
Address: T1SC1, $0028 and T2SC1, $0033
Bit 7
6
5
4
3
2
1
Bit 0
Read:
CH1F
CH1IE
0
MS1A
ELS1B
ELS1A
TOV1
CH1MAX
Write:
0
Reset:
0
0
0
0
0
0
0
0
Figure 11-10. TIM Channel 1 Status and Control Register (TSC1)
Timer Interface Module (TIM)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timer Interface Module (TIM)
201
CHxF -- Channel x Flag Bit
When channel x is an input capture channel, this read/write bit is set
when an active edge occurs on the channel x pin. When channel x is
an output compare channel, CHxF is set when the value in the TIM
counter registers matches the value in the TIM channel x registers.
When TIM CPU interrupt requests are enabled (CHxIE = 1), clear
CHxF by reading TIM channel x status and control register with CHxF
set and then writing a logic 0 to CHxF. If another interrupt request
occurs before the clearing sequence is complete, then writing logic 0
to CHxF has no effect. Therefore, an interrupt request cannot be lost
due to inadvertent clearing of CHxF.
Reset clears the CHxF bit. Writing a logic 1 to CHxF has no effect.
1 = Input capture or output compare on channel x
0 = No input capture or output compare on channel x
CHxIE -- Channel x Interrupt Enable Bit
This read/write bit enables TIM CPU interrupt service requests on
channel x.
Reset clears the CHxIE bit.
1 = Channel x CPU interrupt requests enabled
0 = Channel x CPU interrupt requests disabled
MSxB -- Mode Select Bit B
This read/write bit selects buffered output compare/PWM operation.
MSxB exists only in the TIM1 channel 0 and TIM2 channel 0 status
and control registers.
Setting MS0B disables the channel 1 status and control register and
reverts TCH1 to general-purpose I/O.
Reset clears the MSxB bit.
1 = Buffered output compare/PWM operation enabled
0 = Buffered output compare/PWM operation disabled
MSxA -- Mode Select Bit A
When ELSxB:ELSxA
0:0, this read/write bit selects either input
capture operation or unbuffered output compare/PWM operation.
See
Table 11-3
.
1 = Unbuffered output compare/PWM operation
0 = Input capture operation
Timer Interface Module (TIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
202
Timer Interface Module (TIM)
MOTOROLA
When ELSxB:ELSxA = 0:0, this read/write bit selects the initial output
level of the TCHx pin. See
Table 11-3
. Reset clears the MSxA bit.
1 = Initial output level low
0 = Initial output level high
NOTE:
Before changing a channel function by writing to the MSxB or MSxA bit,
set the TSTOP and TRST bits in the TIM status and control register
(TSC).
ELSxB and ELSxA -- Edge/Level Select Bits
When channel x is an input capture channel, these read/write bits
control the active edge-sensing logic on channel x.
When channel x is an output compare channel, ELSxB and ELSxA
control the channel x output behavior when an output compare
occurs.
When ELSxB and ELSxA are both clear, channel x is not connected
to an I/O port, and pin TCHx is available as a general-purpose I/O pin.
Table 11-3
shows how ELSxB and ELSxA work. Reset clears the
ELSxB and ELSxA bits.
Table 11-3. Mode, Edge, and Level Selection
MSxB:MSxA
ELSxB:ELSxA
Mode
Configuration
X0
00
Output preset
Pin under port control;
initial output level high
X1
00
Pin under port control;
initial output level low
00
01
Input capture
Capture on rising edge only
00
10
Capture on falling edge only
00
11
Capture on rising or
falling edge
01
01
Output
compare or
PWM
Toggle output on compare
01
10
Clear output on compare
01
11
Set output on compare
1X
01
Buffered
output
compare or
buffered PWM
Toggle output on compare
1X
10
Clear output on compare
1X
11
Set output on compare
Timer Interface Module (TIM)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timer Interface Module (TIM)
203
NOTE:
Before enabling a TIM channel register for input capture operation, make
sure that the TCHx pin is stable for at least two bus clocks.
TOVx -- Toggle On Overflow Bit
When channel x is an output compare channel, this read/write bit
controls the behavior of the channel x output when the TIM counter
overflows. When channel x is an input capture channel, TOVx has no
effect.
Reset clears the TOVx bit.
1 = Channel x pin toggles on TIM counter overflow
0 = Channel x pin does not toggle on TIM counter overflow
NOTE:
When TOVx is set, a TIM counter overflow takes precedence over a
channel x output compare if both occur at the same time.
CHxMAX -- Channel x Maximum Duty Cycle Bit
When the TOVx bit is at logic 1, setting the CHxMAX bit forces the
duty cycle of buffered and unbuffered PWM signals to 100%. As
Figure 11-11
shows, the CHxMAX bit takes effect in the cycle after it
is set or cleared. The output stays at the 100% duty cycle level until
the cycle after CHxMAX is cleared.
Figure 11-11. CHxMAX Latency
11.10.5 TIM Channel Registers
These read/write registers contain the captured TIM counter value of the
input capture function or the output compare value of the output
compare function. The state of the TIM channel registers after reset is
unknown.
OUTPUT
OVERFLOW
TCHx
PERIOD
CHxMAX
OVERFLOW
OVERFLOW
OVERFLOW
OVERFLOW
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
Timer Interface Module (TIM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
204
Timer Interface Module (TIM)
MOTOROLA
In input capture mode (MSxB:MSxA = 0:0), reading the high byte of the
TIM channel x registers (TCHxH) inhibits input captures until the low
byte (TCHxL) is read.
In output compare mode (MSxB:MSxA
0:0), writing to the high byte of
the TIM channel x registers (TCHxH) inhibits output compares until the
low byte (TCHxL) is written.
Address: T1CH0H, $0026 and T2CH0H, $0031
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
Indeterminate after reset
Figure 11-12. TIM Channel 0 Register High (TCH0H)
Address: T1CH0L, $0027 and T2CH0L $0032
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
Indeterminate after reset
Figure 11-13. TIM Channel 0 Register Low (TCH0L)
Address: T1CH1H, $0029 and T2CH1H, $0034
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
Indeterminate after reset
Figure 11-14. TIM Channel 1 Register High (TCH1H)
Address: T1CH1L, $002A and T2CH1L, $0035
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
Indeterminate after reset
Figure 11-15. TIM Channel 1 Register Low (TCH1L)
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timebase Module (TBM)
205
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 12. Timebase Module (TBM)
12.1 Contents
12.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
12.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
12.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
12.5
Timebase Register Description. . . . . . . . . . . . . . . . . . . . . . . . 207
12.6
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
12.7
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .209
12.7.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
12.7.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
12.2 Introduction
This section describes the timebase module (TBM). The TBM will
generate periodic interrupts at user selectable rates using a counter
clocked by the selected OSCCLK clock from the oscillator module. This
TBM version uses 18 divider stages, eight of which are user selectable.
12.3 Features
Features of the TBM module include:
Software programmable 8s, 4s, 2s, 1s, 2ms, 1ms, 0.5ms, and
0.25ms periodic interrupt using 32.768-kHz OSCCLK clock
User selectable oscillator clock source enable during stop mode to
allow periodic wake-up from stop
Timebase Module (TBM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
206
Timebase Module (TBM)
MOTOROLA
12.4 Functional Description
This module can generate a periodic interrupt by dividing the oscillator
clock frequency, OSCCLK. The counter is initialized to all 0s when
TBON bit is cleared. The counter, shown in
Figure 12-1
, starts counting
when the TBON bit is set. When the counter overflows at the tap
selected by TBR2:TBR0, the TBIF bit gets set. If the TBIE bit is set, an
interrupt request is sent to the CPU. The TBIF flag is cleared by writing
a 1 to the TACK bit. The first time the TBIF flag is set after enabling the
timebase module, the interrupt is generated at approximately half of the
overflow period. Subsequent events occur at the exact period.
The reference clock OSCCLK is derived from the oscillator module, see
7.3.2 TBM Reference Clock Selection
.
Figure 12-1. Timebase Block Diagram
(See
Section 7. Oscillator (OSC)
.)
2
SEL
0 0 0
0 0 1
0 1 0
0 1 1
TBIF
TB
R1
TB
R
0
TBIE
TBON
R
TA
CK
TB
R2
1 0 0
1 0 1
1 1 0
1 1 1
OSCCLK
2
2
2
2
2
2
2
2
2
2
2
2
2
8
16
32
64
2048
32768
65536
131072
TBMINT
2
2
2
2
262144
From OSC module
Timebase Module (TBM)
Timebase Register Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timebase Module (TBM)
207
12.5 Timebase Register Description
The timebase has one register, the TBCR, which is used to enable the
timebase interrupts and set the rate.
TBIF -- Timebase Interrupt Flag
This read-only flag bit is set when the timebase counter has rolled
over.
1 = Timebase interrupt pending
0 = Timebase interrupt not pending
TBR2TBR0 -- Timebase Rate Selection
These read/write bits are used to select the rate of timebase interrupts
as shown in
Table 12-1
.
Address:
$0046
Bit 7
6
5
4
3
2
1
Bit 0
Read:
TBIF
TBR2
TBR1
TBR0
0
TBIE
TBON
R
Write:
TACK
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 12-2. Timebase Control Register (TBCR)
Table 12-1. Timebase Rate Selection for OSCCLK = 32.768 kHz
TBR2
TBR1
TBR0
Divider
Timebase Interrupt Rate
Hz
ms
0
0
0
262144
0.125
8000
0
0
1
131072
0.25
4000
0
1
0
65536
0.5
2000
0
1
1
32768
1
1000
1
0
0
64
512
~2
1
0
1
32
1024
~1
1
1
0
16
2048
~0.5
1
1
1
8
4096
~0.24
Timebase Module (TBM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
208
Timebase Module (TBM)
MOTOROLA
NOTE:
Do not change TBR2TBR0 bits while the timebase is enabled
(TBON = 1).
TACK -- Timebase ACKnowledge
The TACK bit is a write-only bit and always reads as 0. Writing a logic
1 to this bit clears TBIF, the timebase interrupt flag bit. Writing a logic
0 to this bit has no effect.
1 = Clear timebase interrupt flag
0 = No effect
TBIE -- Timebase Interrupt Enabled
This read/write bit enables the timebase interrupt when the TBIF bit
becomes set. Reset clears the TBIE bit.
1 = Timebase interrupt enabled
0 = Timebase interrupt disabled
TBON -- Timebase Enabled
This read/write bit enables the timebase. Timebase may be turned off
to reduce power consumption when its function is not necessary. The
counter can be initialized by clearing and then setting this bit. Reset
clears the TBON bit.
1 = Timebase enabled
0 = Timebase disabled and the counter initialized to 0s
12.6 Interrupts
The timebase module can interrupt the CPU on a regular basis with a
rate defined by TBR2TBR0. When the timebase counter chain rolls
over, the TBIF flag is set. If the TBIE bit is set, enabling the timebase
interrupt, the counter chain overflow will generate a CPU interrupt
request. The interrupt vector is defined in
Table 2-1 . Vector
Addresses
.
Interrupts must be acknowledged by writing a logic 1 to the TACK bit.
Timebase Module (TBM)
Low-Power Modes
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Timebase Module (TBM)
209
12.7 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
12.7.1 Wait Mode
The timebase module remains active after execution of the WAIT
instruction. In wait mode, the timebase register is not accessible by the
CPU.
If the timebase functions are not required during wait mode, reduce the
power consumption by stopping the timebase before enabling the WAIT
instruction.
12.7.2 Stop Mode
The timebase module may remain active after execution of the STOP
instruction if the oscillator has been enabled to operate during stop mode
through the stop mode oscillator enable bit (STOP_ICLKEN,
STOP_RCLKEN, or STOP_XCLKEN) for the selected oscillator in the
CONFIG2 register. The timebase module can be used in this mode to
generate a periodic walk-up from stop mode.
If the oscillator has not been enabled to operate in stop mode, the
timebase module will not be active during STOP mode. In stop mode the
timebase register is not accessible by the CPU.
If the timebase functions are not required during stop mode, reduce the
power consumption by stopping the timebase before enabling the STOP
instruction.
Timebase Module (TBM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
210
Timebase Module (TBM)
MOTOROLA
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Pulse Width Modulator (PWM)
211
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 13. Pulse Width Modulator (PWM)
13.1 Contents
13.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
13.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
13.4
PWM Period and Resolution. . . . . . . . . . . . . . . . . . . . . . . . . . 214
13.5
PWM Automatic Phase Control . . . . . . . . . . . . . . . . . . . . . . . 215
13.6
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .216
13.7
Wait Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
13.8
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
13.9
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
13.10 I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
13.10.1 PWM Control Register (PWMCR) . . . . . . . . . . . . . . . . . . .217
13.10.2 PWM Clock Control Register (PWMCCR) . . . . . . . . . . . . . 218
13.10.3 PWM Data Registers (PWMDR0PWMDR2) . . . . . . . . . . 219
13.10.4 PWM Phase Control Register . . . . . . . . . . . . . . . . . . . . . . 220
13.2 Introduction
This section describes the pulse width modulator (PWM) module. The
PWM module provides three 8-bit PWM output channels, with an
independent 8-bit counter for each channel. The PWM period is equal to
seconds, where P
CLK
is the PWM counter clock.
For a 32MHz PWM counter clock, the PWM period is 8
s (a PWM
frequency of 125kHz). The automatic phase control feature allows
phase delays between the channels.
Figure 13-2
shows the structure of the PWM module.
256
1
P
CLK
---------------
Pulse Width Modulator (PWM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
212
Pulse Width Modulator (PWM)
MOTOROLA
NOTE:
The CGM's PLL must be running (enabled by setting PLLON bit in the
PLL control register) if the CGMVCLK is selected for the PWM module
input clock. (See
Section 8. Clock Generator Module (CGM)
.)
13.3 Features
Features of the PWM include the following:
Three independent PWM channels with independent counters
PWM input clock select
PWM input clock prescaler
Automatic phase control
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0051
PWM Control Register
(PWMCR)
Read:
PWMEN2 PWMEN1 PWMEN0
0
0
PCH2
PCH1
PCH0
Write:
Reset:
0
0
0
0
0
0
0
0
$0052
PWM Clock Control
Register
(PWMCCR)
Read:
PCLKSEL
0
0
0
0
0
PCLK1
PCLK0
Write:
Reset:
0
0
0
0
0
0
0
0
$0053
PWM Data Register 0
(PWMDR0)
Read:
0PWMD7 0PWMD6 0PWMD5 0PWMD4 0PWMD3 0PWMD2 0PWMD1 0PWMD0
Write:
Reset:
0
0
0
0
0
0
0
0
$0054
PWM Data Register 1
(PWMDR1)
Read:
1PWMD7 1PWMD6 1PWMD5 1PWMD4 1PWMD3 1PWMD2 1PWMD1 1PWMD0
Write:
Reset:
0
0
0
0
0
0
0
0
$0055
PWM Data Register 2
(PWMDR2)
Read:
2PWMD7 2PWMD6 2PWMD5 2PWMD4 2PWMD3 2PWMD2 2PWMD1 2PWMD0
Write:
Reset:
0
0
0
0
0
0
0
0
$0056
PWM Phase Control
Register
(PWMPCR)
Read:
PHEN
PHD6
PHD5
PHD4
PHD3
PHD2
PHD1
PHD0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 13-1. PWM I/O Register Summary
Pulse Width Modulator (PWM)
Features
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Pulse Width Modulator (PWM)
213
Figure 13-2. PWM Block Diagram
ZERO
DETECTOR
INTERNAL BUS
8-BIT PWM
DATA REGISTER
8-BIT
DATA REGISTER
BUFFER
COMPARATOR
8-BIT COUNTER
S
R
LATCH
CHANNEL 0
TO
CHANNEL 1
TO
CHANNEL 2
PWMR0
Q
8-BIT COUNTER
8-BIT COUNTER
2
2
2
MUX
PCLK0
PCLK1
PCLKSEL
CGMOUT
CGMVCLK
A
B
1
S
P
CLK
PWM0
WHEN PCLKSEL= 0,
PWMCLK=CGMOUT.
PWMCLK
B
1
A
S
PWM1
PTC1/PWM1
PIN
CDOEN
PCH0
A
B
1
S
B
1
A
S
CDIF
PTC0/PWM0/CD
PIN
TO/FROM
CONFIG2
FROM
ANALOG
MODULE
PWMCR
PWMCCR
PWMCR
PCH1
PWMCR
TO/FROM
PTC1
PTC0
LOGIC
LOGIC
CHANNEL 1 OUTPUT LOGIC
B
1
A
S
PWM2
PTC2/PWM2
PIN
PCH2
PWMCR
TO/FROM
PTC2
LOGIC
CHANNEL 2 OUTPUT LOGIC
CHANNEL 0 OUTPUT LOGIC
A IS SELECTED
WHEN S= 0
A IS SELECTED
WHEN S= 0
A IS SELECTED
WHEN S=0
FROM CGM
IF CGMVCLK IS SELECTED,
CGM'S PLL MUST BE RUNNING.
Pulse Width Modulator (PWM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
214
Pulse Width Modulator (PWM)
MOTOROLA
13.4 PWM Period and Resolution
The PWM period is equal to
, resolution is
, where
P
CLK
is the PWM counter clock. The value in the PWM data register
(PWMDR) defines the period where the PWM output is high, the low
period is equal to 256 minus that value. Each PWM channel has its own
counter and I/O control bits so it can be turned on and off independently.
Figure 13-3
shows the PWM output waveforms for a channel with
different values in the PWM data register.
Figure 13-3. PWM Output Waveforms
256
1
P
CLK
---------------
1
P
C LK
---------------
PWMDR = 256
PWM PERIOD = 256
T
128
T
128
T
T
T
255
T
255
T
PWMDR = 1
PWMDR = 255
PWMDR = 128
T =
1
P
CLK
NOTE:
Pulse Width Modulator (PWM)
PWM Automatic Phase Control
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Pulse Width Modulator (PWM)
215
13.5 PWM Automatic Phase Control
The automatic phase control function allows precise phase difference
between the PWM output signals.
Figure 13-4
shows the phase delays between the PWM output signals.
Figure 13-4. PWM Automatic Phase Control
Use the following steps to generate phase difference on PWM channels:
1. Clear PWM enable bits, PWMEN[0:2], to logic 0.
2. Write delay value in PHD[0:6].
3. Set PWM automatic phase control enable bit, PHEN, to logic 1.
4. Set the PWM channel enable bits, PCH[0:2], to logic 1.
5. Set the PWM enable bits, PWMEN[0:2], to logic 1, to enable the
PWM counters.
When phase control is enabled, the PWM2 counter will start counting
immediately, but the PWM1 and PWM0 counters will be held at zero.
After the PWM2 counter reaches the phase value, PH[0:6], the PWM1
counter is released and starts counting. Finally, when the PMW1 counter
reaches the phase value, PH[0:6], PWM0 is released and starts
counting. It is possible to change the value of PH[0:6] after the PWM1
counter has started and before the start of the PWM0 counter. This way,
difference phases can be set between PWM2 and PWM1; PWM1 and
PWM0.
PWM2
PWM1
PWM0
PHASE VALUE 1
PHASE VALUE 2
256
T
256
T
256
T
256
T
Pulse Width Modulator (PWM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
216
Pulse Width Modulator (PWM)
MOTOROLA
The PH[0:6] value is used once to determine the start-up time of the
different PWM counters. After that, all PWM counters become free
running counters and the phase between the counters will remain
unchanged. Changing the value of PH[0:6] after all PWM counters are
running has no effect. The counters must first be disabled by clearing the
PWM enable bits, PWMEN[0:2], to logic 0, before a new phase value is
effective.
Automatic phase control is only available with two (PWM2PWM1) or
three (PWM2PWM0) PWM channels.
13.6 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
13.7 Wait Mode
The PWM module remains active after the execution of a WAIT
instruction. In wait mode, the PWM registers are not accessible by the
CPU.
If PWM functions are not required during wait mode, reduce power
consumption by disabling the PWM before executing the WAIT
instruction.
13.8 Stop Mode
The PWM is inactive after the execution of a STOP instruction. The
STOP instruction does not affect register conditions or the state of the
PWM counters and outputs. PWM operation resumes when the MCU
exits stop mode after an external interrupt.
Pulse Width Modulator (PWM)
I/O Signals
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Pulse Width Modulator (PWM)
217
13.9 I/O Signals
The PWM module has three output pins shared with port C:
PTC0/PWM0/CD, PWM1/PTC1, and PTC2/PWM2. PTC0 is also shared
with current flow detect output, CD, of the analog module, see (see 18.5
Port C).
13.10 I/O Registers
These I/O registers control PWM operation:
PWM control register (PWMCR)
PWM clock control register (PWMCCR)
PWM phase control register (PWMPCR)
Three PWM data registers (PWMDR0PWMDR2)
13.10.1 PWM Control Register (PWMCR)
The PWM control register (PWMCR) enables/disables the independent
PWM counters and port pins used for the PWM channels.
PWMEN2PWMEN0 -- PWM Enable Bits
Writing a 0 to the PWMENx bit clears the corresponding PWM counter
and force the PWM channel x output to 0. Reset clears these bits.
1 = PWM channel x enabled
0 = PWM channel x is disabled; PWM counter cleared to zero and
PWM channel x output forced to zero
Address:
$0051
Read:
PWMEN2 PWMEN1 PWMEN0
0
0
PCH2
PCH1
PCH0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 13-5. PWM Control Register (PWMCR)
Pulse Width Modulator (PWM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
218
Pulse Width Modulator (PWM)
MOTOROLA
PCH2PCH0 -- PWM Channel Enable Bits
Setting a bit will enable the corresponding port pin to be a PWM
output pin. When a bit is set, the DDR bit has no effect on the port
function.
1 = Port pin is enabled for PWM output
0 = Port pin is standard I/O pin
Exception for PTC0/PWM0/CD control:
13.10.2 PWM Clock Control Register (PWMCCR)
The PWM clock control register (PWMCCR) selects and defines the
clock to the PWM counter, P
CLK
.
PCLKSEL
-- PWM Input Clock Select Bit
This bit selects either the CGMOUT or CGMVCLK clock as the input
clock to the PWM counters. Reset clears this bit.
1 = Select CGMVCLK as PWM input clock
0 = Select CGMOUT (CPU bus clock) as PWM input clock
Table 13-1. PTC0 Pin Configuration
Pin
CDOEN Bit
($001D)
PCH0 Bit
($0051)
Pin function
PTC0/PWM0/CD
0
0
PTC0
0
1
PWM0
1
X
CD
Address:
$0052
Read:
PCLKSEL
0
0
0
0
0
PCLK1
PCLK0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 13-6. PWM Clock Control Register (PWMCCR)
Pulse Width Modulator (PWM)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Pulse Width Modulator (PWM)
219
PCLK1PCLK0 -- PWM Clock Prescaler Bits
These two bits select the divide ratio used to divide the PWM input
clock.
Table 13-2
shows the available clock divisions.
13.10.3 PWM Data Registers (PWMDR0PWMDR2)
The three PWM data registers (PWMDR0PWMDR2) defines the high
period for corresponding PWM channels.
Table 13-2. PWM Counter Clock Prescaler Selection
PCLK1
PCLK0
PWM Clock, P
CLK
0
0
Source clock
1
0
1
Source clock
2
1
0
Source clock
4
1
1
Source clock
8
Address:
$0053
Read:
0PWMD7 0PWMD6 0PWMD5 0PWMD4 0PWMD3 0PWMD2 0PWMD1 0PWMD0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 13-7. PWM Data Register 0 (PWMDR0)
Address:
$0054
Read:
1PWMD7 1PWMD6 1PWMD5 1PWMD4 1PWMD3 1PWMD2 1PWMD1 1PWMD0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 13-8. PWM Data Register 1 (PWMDR1)
Address:
$0055
Read:
2PWMD7 2PWMD6 2PWMD5 2PWMD4 2PWMD3 2PWMD2 2PWMD1 2PWMD0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 13-9. PWM Data Register 2 (PWMDR2)
Pulse Width Modulator (PWM)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
220
Pulse Width Modulator (PWM)
MOTOROLA
The value of each PWM data register is continuously compared with the
content of a PWM counter to determine the state of each PWM channel
output pin.
A value of $00 loaded into these register results in a continuously low
output on the corresponding PWM output pin. A value of $80 results in a
50% duty cycle output and so on. The maximum value, $FF correspond
to an output which is a "1" for 255/256 of the PWM cycle.
A new value written to the PWM data register will not be effective until
the end of the current PWM period. Upon the end of the current PWM
period, the contain of the PWM data register is loaded into the PWM data
buffer, the value of the PWM data buffer controls the PWM output.
13.10.4 PWM Phase Control Register
The PWM phase control register (PWMPCR) enables the automatic
phase control and sets the phase values between the PWM channels.
PHEN
-- PWM Automatic Phase Control Enable Bit
Setting this bit to 1 will enable the automatic phase control function.
Reset clears this bit.
1 = Automatic phase control enabled
0 = Automatic phase control disabled
PHD6PHD0 -- PWM Phase Value Bits
This 7-bit phase value is used to determined the start-up time of the
different PWM counters when PHEN bit is set. Reset clears these bits.
Address:
$0056
Read:
PHEN
PHD6
PHD5
PHD4
PHD3
PHD2
PHD1
PHD0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 13-10. PWM Phase Control Register (PWMPCR)
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog Module
221
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 14. Analog Module
14.1 Contents
14.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
14.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
14.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
14.4.1
On-Chip Temperature Sensor . . . . . . . . . . . . . . . . . . . . . . 223
14.4.2
Two-Stage Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
14.4.3
Amplifier Response Time . . . . . . . . . . . . . . . . . . . . . . . . . . 224
14.4.4
Current Flow Detection Amplifier . . . . . . . . . . . . . . . . . . . . 225
14.4.5
Current Flow Detect Output . . . . . . . . . . . . . . . . . . . . . . . . 225
14.5
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
14.6
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .225
14.6.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
14.6.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
14.7
Analog Module I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . 226
14.7.1
Analog Module Control Register (AMCR) . . . . . . . . . . . . . 226
14.7.2
Analog Module Gain Control Register (AMGCR) . . . . . . . .227
14.7.3
Analog Module Status and Control Register (AMSCR) . . . 228
14.2 Introduction
This section describes the analog module. The analog module is
designed to be use in conjunction with the analog-to-digital converter
module for monitoring temperature, charge and discharge currents in
smart battery applications.
NOTE:
The analog module uses clock signals from the CGM's PLL, therefore
the PLL must be running -- PLLON bit in the PLL control register must
be set. (See
Section 8. Clock Generator Module (CGM)
.)
Analog Module
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
222
Analog Module
MOTOROLA
14.3 Features
The features of the analog module include the following:
Temperature sensor
Current flow detection amplifier
Two-stage amplifier
Figure 14-1. Analog Module Block Diagram
0.01
R
SENSE
I
SENSE
OPOUT
EXTERNAL
BATT +
BATT
THERMISTOR
IN0
IN1
IN2
IN3
TS
OUT
OPIN2/
ATD1
OPIN1/
ATD0
V
SSAM
2-STAGE
AMP
CLOCK
DIVIDER
ADCICLK
+
INTERNAL
REFERENCE
ANALOG MODULE
INTERRUPT REQUEST
D
Q
R
V
DD
+
V
DET
9mV
PTC0
LOGIC
PTC0/
PWM0/
CD
FROM CONFIG2
CGMXCLK
GAINA[3:0]
GAINB[3:0]
DO[2:0]
OPIF
CDIF
V
SSA
INTERNAL
TEMPERATURE
SENSOR
ATD1
TO ADC
TO ADC
BATT +
BATT
TO IRQ
LOGIC
DOF
OPIFR
AMIEN
CDIFR
CDOEN
OPCH[1:0]
AMCDIV[1:0]
CDIF
OPIF
ATD0
FROM ADC
ANALOG MODULE
AMCLK
CGMVCLK
FROM CGM
Analog Module
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog Module
223
14.4 Functional Description
Figure 14-1
shows the block diagram of the analog module. The central
component of the analog module is the two-stage gain amplifier used for
amplifying the small signals on the analog input pins, OPIN1 and OPIN2.
These two signals feed into a multiplexer together with the signal from
the internal temperature sensor and a reference input. The selected
signal is then fed into the two-stage gain amplifier before going into the
analog-to-digital converter (ADC) as OPOUT. The OPIN1 and OPIN2
pins can also feed directly into the ADC as channels ATD0 and ATD1
respectively, without any amplification.
14.4.1 On-Chip Temperature Sensor
The on-chip temperature sensor is designed to measure temperatures
from 20
C to 70
C. The output of the internal temperature sensor
TSOUT is amplified by the two-stage amplifier. The amplified
temperature sensor signal is routed to the analog-to-digital converter for
analog-to-digital conversion (see
Figure 14-1
).
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$000E
Analog Module Control
Register
(AMCR)
Read:
PWR1
PWR0
OPCH1
OPCH0
AMIEN
DO2
DO1
DO0
Write:
Reset:
0
0
0
0
0
0
0
0
$000F
Analog Module Gain
Control Register
(AMGCR)
Read:
GAINB3
GAINB2
GAINB1
GAINB0
GAINA3
GAINA2
GAINA1
GAINA0
Write:
Reset:
0
0
0
0
0
0
0
0
$0010
Analog Module Status and
Control Register
(AMSCR)
Read:
AMCDIV1 AMCDIV0
0
OPIF
0
DOF
0
CDIF
Write:
OPIFR
CDIFR
Reset:
0
0
U
0
0
0
U
0
= Unimplemented
U = Unaffected
Figure 14-2. Analog Module I/O Register Summary
Analog Module
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
224
Analog Module
MOTOROLA
14.4.2 Two-Stage Amplifier
The two-stage amplifier is used to amplify small input signals from the
on-chip temperature sensor or external voltage sources such as external
thermistor and current sensing resistor, for temperature and current
monitoring. The amplified signal, OPOUT, is fed to the ADC module for
analog-to-digital conversion. The gain of the two-stage amplifier is
defined by the GAINAx and GAINBx bits in the analog module gain
control register (AMGCR) (see
Figure 14-1
).
14.4.3 Amplifier Response Time
The two-stage amplifier requires the input signal to be stable for
sampling. This signal hold-time varies with gain setting for stage-1 of the
two-stage amplifier, and is determined by the formula:
10 + [(Gain of stage-1 amplifier 1)
2] AMCLK cycles
The AMCLK clock is the analog amplifier clock, which is divided from the
ADC clock, ADCICLK.
The time for the two-stage amplifier to amplify the input signal to the
desired output is dependent on the gain setting in both stages of the two-
stage amplifier. The amplifier response time is determined by the
formula:
70 + (8
Gain of stage-1) + (6
Gain of stage-2) AMCLK cycles
This amplifier response time should be added to the ADC conversion
time to obtain the total time for the small-signal conversion.
Therefore, conversion time for OPINx signals, with amplification is:
Amplifier response time + ADC conversion time
Analog Module
Interrupts
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog Module
225
14.4.4 Current Flow Detection Amplifier
The current flow detection amplifier is used to detect charge and
discharge current flowing through an external sensing resistor, R
SENSE
.
The current flow detection flag CDIF is set when the voltage at OPIN1
exceeds 9mV (typical) (0.9 ampere when R
SENSE
= 0.01
). When set,
CDIF can generate an interrupt request to the CPU when the analog
module interrupt enable bit AMIEN is set (see
Figure 14-1
).
14.4.5 Current Flow Detect Output
The current detect flag, CDIF, can be configured for direct control to
other external circuitry. When the CDOEN bit in CONFIG2 is set, the
status of CDIF is reflected on the PTC0/PWM0/CD pin. (See
5.5
Configuration Register 2 (CONFIG2)
and
18.5 Port C
.)
14.5 Interrupts
When the AMIEN bit is set, the analog module is capable of generating
CPU interrupt requests. The interrupt vector is defined in
Table 2-1 .
Vector Addresses
.
14.6 Low-Power Modes
The STOP and WAIT instructions put the MCU in low power-
consumption standby modes.
14.6.1 Wait Mode
In wait mode the analog module if enabled, continues to operate and
may generate an interrupt to trigger the MCU out of wait mode.
14.6.2 Stop Mode
In stop mode, the temperature sensor and the two-stage amplifier are
disabled, but the current flow detection amplifier (when enabled)
continues to operate if the oscillator is enabled in stop mode. When
AMIEN is set, CDIF can be used to wake-up the MCU from the stop
mode.
Analog Module
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
226
Analog Module
MOTOROLA
14.7 Analog Module I/O Registers
Three registers control and monitor the operation of the analog module:
Analog module control register (AMCR) -- $000E
Analog module gain control register (AMGCR) -- $000F
Analog module status and control register (AMSCR) -- $0010
14.7.1 Analog Module Control Register (AMCR)
The analog module control register (AMCR):
Powers on and off analog sub-modules
Selects the input signal to the two-stage amplifier
Enables analog module interrupt requests
Offset adjustment for calibration
PWR1PWR0 -- Analog Module Power Control Bits
These read/write bits power on/off the different functions within the
analog module. Reset clears the PWR1 and PWR0 bits.
Address:
$000E
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PWR1
PWR0
OPCH1
OPCH0
AMIEN
DO2
DO1
DO0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 14-3. Analog Module Control Register (AMCR)
Table 14-1. Analog Module Power Control
PWR1
PWR0
Current Detect
Module
Temperature
Sensor
Two-Stage
Amplifier
0
0
Off
Off
Off
0
1
On
Off
Off
1
0
Off
Off
On
1
1
On
On
On
Analog Module
Analog Module I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog Module
227
OPCH1OPCH0 -- Amplifier Channel Select Control Bits
These read/write bits select the input source to be amplified by the
two-stage amplifier. Reset clears the OPCH1 and OPCH0 bits.
AMIEN -- Analog Module Interrupt Enable
Setting this bit will enable the CDIF and OPIF flags to generate an
CPU interrupt requests. Reset clears the AMIEN bit.
1 = Analog module CPU interrupt requests enabled
0 = Analog module CPU interrupt requests disabled
DO[2:0] -- DC Offset Control Bits
Set these bits to zero for optimum analog module performance.
14.7.2 Analog Module Gain Control Register (AMGCR)
The analog module gain control register (AMGCR) selects the two gains
for the two-stage amplifier.
Table 14-2. Amplifier Channel Select Control bits
OPCH1
OPCH0
Input Source
Comments
0
0
V
SSAM
External negative reference
0
1
OPIN1/ATD0
External pin
1
0
OPIN2/ATD1
External pin
1
1
TSOUT (internal)
Internal temperature sensor
Address:
$000F
Bit 7
6
5
4
3
2
1
Bit 0
Read:
GAINB3
GAINB2
GAINB1
GAINB0
GAINA3
GAINA2
GAINA1
GAINA0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 14-4. Analog Module Gain Control Register (AMGCR)
Analog Module
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
228
Analog Module
MOTOROLA
GAINB[3:0] -- Analog Module 2nd-stage Gain Control Bits
These read/write bits define the 2nd-stage gain of the two-stage
amplifier. The overall gain of the amplifier equals the 1st-stage gain
multiplied by the 2nd-stage gain. Reset clears the GAINB[3:0] bits.
GAINA[3:0] -- Analog Module 1st-stage Gain Control Bits
These read/write bits define the 1st-stage gain of the two-stage
amplifier. The overall gain of the amplifier equals the 1st-stage gain
multiplied by the 2nd-stage gain. Reset clears the GAINA[3:0] bits.
14.7.3 Analog Module Status and Control Register (AMSCR)
The analog module status and control register (AMSCR):
Selects input clock divider value
Monitors and clears the amplifier ready interrupt flag
Monitors DC offset flag
Monitors and clears the current detect interrupt flag
Table 14-3. Analog Module Gain Values
GAINx3
GAINx2
GAINx1
GAINx0
Amplifier Gain
0
0
0
0
1
0
0
0
1
2
0
0
1
0
3
0
0
1
1
4
0
1
0
0
5
0
1
0
1
6
0
1
1
0
7
0
1
1
1
8
1
0
0
0
9
1
0
0
1
10
1
0
1
0
11
1
0
1
1
12
1
1
0
0
13
1
1
0
1
14
1
1
1
0
15
1
1
1
1
16
Analog Module
Analog Module I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog Module
229
AMCDIV[1:0] -- Analog Module Clock Divider Control Bits
These read/write bits select the analog module input clock divider
value. The ADC clock, ADICLK, is divided by this value to obtain the
AMCLK. Reset clears the AMCDIV[1:0] bits.
Set AMCDIV1 and AMCDIV0 bits to zero for optimum analog module
performance.
OPIFR -- Amplifier Ready Interrupt Flag Reset
Writing a logic 1 to this write-only bit clears the OPIF bit. OPIFR
always reads as a logic 0. Reset does not affect OPIFR.
1 = Clear OPIF bit
0 = No affect on OPIF bit
OPIF -- Amplifier Ready Interrupt Flag
This read-only bit is set when the output of the two-stage amplifier is
ready. A CPU interrupt request will be generated if the AMIEN bit is
also set. Reset clears OPIF bit.
1 = Two-stage amplifier output is ready
0 = Two-stage amplifier output is not ready
Address:
$0010
Bit 7
6
5
4
3
2
1
Bit 0
Read:
AMCDIV1 AMCDIV0
0
OPIF
0
DOF
0
CDIF
Write:
OPIFR
CDIFR
Reset:
0
0
U
0
0
0
U
0
= Unimplemented
U = Unaffected
Figure 14-5. Analog Module Status and Control Register (AMSCR)
Table 14-4. Analog Module Clock Divider Select
AMCDIV1
AMCDIV0
Divider Value
0
0
2
0
1
4
1
0
8
1
1
16
Analog Module
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
230
Analog Module
MOTOROLA
DOF -- DC Offset Flag
This is a reserved bit.
CDIFR -- Current Detect Interrupt Flag Reset
Writing a logic 1 to this write-only bit clears the CDIF bit. CDIFR
always reads as a logic 0. Reset does not affect CDIFR.
1 = Clear CDIF bit
0 = No affect on CDIF bit
CDIF -- Current Detect Interrupt Flag
This read-only bit is set when the voltage developed across the sense
resistor, R
SENSE
is equal to or greater than V
DET
(the current sense
amplifier comparator trip voltage, typically 9mV). CDIF generates an
CPU interrupt request if AMIEN bit is also set. The CDIF bit is cleared
by writing a logic 1 to the CDIFR bit. Reset clears CDIF bit.
1 = Current detect interrupt has occurred
0 = No current detect interrupt since CDIF last cleared
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog-to-Digital Converter (ADC)
231
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 15. Analog-to-Digital Converter (ADC)
15.1 Contents
15.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
15.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232
15.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
15.4.1
ADC Port I/O Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
15.4.2
Voltage Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
15.4.3
Conversion Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
15.4.4
Continuous Conversion . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
15.4.5
Auto-scan Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
15.4.6
Result Justification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
15.4.7
Data Register Interlocking . . . . . . . . . . . . . . . . . . . . . . . . . 239
15.4.8
Monotonicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .239
15.5
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
15.6
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .239
15.6.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
15.6.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
15.7
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
15.7.1
ADC Voltage In (V
ADIN
) . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
15.7.2
ADC Analog Power Pin (V
DDA
) . . . . . . . . . . . . . . . . . . . . . 240
15.7.3
ADC Analog Ground Pin (V
SSA
) . . . . . . . . . . . . . . . . . . . . . 240
15.7.4
ADC Voltage Reference High Pin (V
REFH
). . . . . . . . . . . . . 241
15.7.5
ADC Voltage Reference Low Pin (V
REFL
) . . . . . . . . . . . . . 241
15.8
I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
15.8.1
ADC Status and Control Register. . . . . . . . . . . . . . . . . . . . 242
15.8.2
ADC Clock Control Register. . . . . . . . . . . . . . . . . . . . . . . . 244
15.8.3
ADC Data Register 0 (ADRH0 and ADRL0). . . . . . . . . . . . 246
15.8.4
ADC Auto-Scan Mode Data Registers (ADRL1ADRL3). . 248
15.8.5
ADC Auto-Scan Control Register (ADASCR). . . . . . . . . . . 248
Analog-to-Digital Converter (ADC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
232
Analog-to-Digital Converter (ADC)
MOTOROLA
15.2 Introduction
This section describes the analog-to-digital converter (ADC). The ADC
is a 14-channel 10-bit linear successive approximation ADC.
15.3 Features
Features of the ADC module include:
Fourteen channels with multiplexed input
High impedance buffered input
Linear successive approximation with monotonicity
10-bit resolution
Single or continuous conversion
Auto-scan conversion on four channels
Conversion complete flag or conversion complete interrupt
Selectable ADC clock
Conversion result justification
8-bit truncated mode
Right justified mode
Left justified mode
Left justified sign mode
Analog-to-Digital Converter (ADC)
Features
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog-to-Digital Converter (ADC)
233
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0057
ADC Status and Control
Register
(ADSCR)
Read:
COCO
AIEN
ADCO
ADCH4
ADCH3
ADCH2
ADCH1
ADCH0
Write:
Reset:
0
0
0
1
1
1
1
1
$0058
ADC Clock Control
Register
(ADICLK)
Read:
ADIV2
ADIV1
ADIV0
ADICLK
MODE1
MODE0
0
0
Write:
R
Reset:
0
0
0
0
0
1
0
0
$0059
ADC Data Register High 0
(ADRH0)
Read:
ADx
ADx
ADx
ADx
ADx
ADx
ADx
ADx
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005A
ADC Data Register Low 0
(ADRL0)
Read:
ADx
ADx
ADx
ADx
ADx
ADx
ADx
ADx
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005B
ADC Data Register Low 1
(ADRL1)
Read:
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005C
ADC Data Register Low 2
(ADRL3)
Read:
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005D
ADC Data Register Low 3
(ADRL3)
Read:
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005E
ADC Auto-scan Control
Register
(ADASCR)
Read:
0
0
0
0
0
AUTO1
AUTO0
ASCAN
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 15-1. ADC I/O Register Summary
Analog-to-Digital Converter (ADC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
234
Analog-to-Digital Converter (ADC)
MOTOROLA
15.4 Functional Description
The ADC provides thirteen pins for sampling external sources at pins
PTA0/ATD2PTA5/ATD7, PTC3/ATD8PTC7/ATD12, and
OPIN1OPIN2; one internal source from the analog module. An analog
multiplexer allows the single ADC converter to select one of fourteen
ADC channels as ADC voltage in (V
ADIN
). V
ADIN
is converted by the
successive approximation register-based analog-to-digital converter.
When the conversion is completed, ADC places the result in the ADC
data register, high and low byte (ADRH0 and ADRL0), and sets a flag or
generates an interrupt.
An additional three ADC data registers (ADRL1ADRL3) are available to
store the individual converted data for ADC channels ATD1ATD3 when
the auto-scan mode is enabled. Data from channel ATD0 is stored in
ADRL0 in the auto-scan mode.
Figure 15-2
shows the structure of the ADC module.
15.4.1 ADC Port I/O Pins
PTA0PTA5 and PTC3PTC7 are general-purpose I/O pins that are
shared with the ADC channels, OPIN1 and OPIN2 are two analog inputs
that are always connected to the ADC channel select multiplexer. The
channel select bits, ADCH[4:0], define which ADC channel/port pin will
be used as the input signal. The ADC overrides the port I/O logic by
forcing that pin as input to the ADC. The remaining ADC channels/port
pins are controlled by the port I/O logic and can be used as general-
purpose I/O pins. Writes to the port data register or data direction
register will not have any affect on the port pin that is selected by the
ADC. Read of a port pin which is in use by the ADC will return the pin
condition if the corresponding DDR bit is at logic 0. If the DDR bit is at
logic 1, the value in the port data latch is read.
Analog-to-Digital Converter (ADC)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog-to-Digital Converter (ADC)
235
15.4.2 Voltage Conversion
When the input voltage to the ADC equals V
REFH
, the ADC converts the
signal to $3FF (full scale). If the input voltage equals V
REFL
, the ADC
converts it to $000. Input voltages between V
REFH
and V
REFL
is a
straight-line linear conversion. All other input voltages will result in $3FF
if greater than V
REFH
and $000 if less than V
REFL
.
NOTE:
Input voltage should not exceed the analog supply voltages.
Figure 15-2. ADC Block Diagram
ADC DATA REGISTERS
INTERNAL
DATA BUS
READ DDRAx/DDRCx
WRITE DDRAx/DDRCx
RESET
WRITE PTAx/PTCx
READ PTAx/PTCx
PTAx/PTCx
DDRAx/DDRCx
PTAx/PTCx
INTERRUPT
LOGIC
CHANNEL
SELECT
ADC
CLOCK
GENERATOR
CONVERSION
COMPLETE
ADC
(V
ADIN
)
ADCICLK
CGMXCLK
BUS CLOCK
ASCAN
DISABLE
DISABLE
(11 CHANNELS)
ADIV[2:0]
ADICLK
VOLTAGE IN
OPIN1
OPIN2
OPOUT
V
REFL
V
REFH
FROM
ANALOG MODULE
ADCH[4:0]
ATD2ATD12
MUX
2-BIT UP-COUNTER
COCO
AIEN
ADRH0
ADRL1
ADRL0
ADRL2
ADRL3
AUTO[1:0]
Analog-to-Digital Converter (ADC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
236
Analog-to-Digital Converter (ADC)
MOTOROLA
15.4.3 Conversion Time
Conversion starts after a write to the ADSCR. One conversion will take
between 16 and 17 ADC clock cycles, therefore:
The ADC conversion time is determined by the clock source chosen and
the divide ratio selected. The clock source is either the bus clock or
CGMXCLK and is selectable by the ADICLK bit located in the ADC clock
register. The divide ratio is selected by the ADIV[2:0] bits.
For example, if a 4MHz CGMXCLK is selected as the ADC input clock
source, with a divide-by-four prescale, and the bus speed is set at 2MHz:
NOTE:
The ADC frequency must be between f
ADIC
minimum and f
ADIC
maximum to meet ADC specifications. (See
24.12 5.0V ADC Electrical
Characteristics
.)
Since an ADC cycle may comprised of several bus cycles (two in the
previous example) and the start of a conversion is initiated by a bus cycle
write to the ADSCR, from zero to two additional bus cycles may occur
before the start of the initial ADC cycle. This results in a fractional ADC
cycle and is represented as the 17th cycle.
NOTE:
When OPOUT is selected as the ADC input, V
ADIN
, the conversion time
is the accumulation of the op-amp settling time and the normal ADC
conversion time. After writing to the ADSCR to initiate a conversion
cycle, the ADC module sends a signal to the analog module for a
OPOUT output. A signal will be sent back to the ADC by the analog
module to indicate that OPOUT signal is ready for sampling. Upon
receiving this signal, the ADC module starts its normal conversion cycle.
(See
24.12 5.0V ADC Electrical Characteristics
.)
16 to17 ADC cycles
Conversion time =
ADC frequency
Number of bus cycles = conversion time
bus frequency
16 to17 ADC cycles
Conversion time =
4MHz
4
Number of bus cycles = 16
s
2MHz = 32 to 34 cycles
= 16 to 17
s
Analog-to-Digital Converter (ADC)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog-to-Digital Converter (ADC)
237
15.4.4 Continuous Conversion
In the continuous conversion mode, the ADC continuously converts the
selected channel, filling the ADC data register with new data after each
conversion. Data from the previous conversion will be overwritten
whether that data has been read or not. Conversions will continue until
the ADCO bit is cleared. The COCO bit is set after each conversion and
can be cleared by writing to the ADC status and control register or
reading of the ADRL0 data register.
15.4.5 Auto-scan Mode
In auto-scan mode, the ADC input channel is selected by the value of the
2-bit up-counter, instead of the channel select bits, ADCH[4:0]. The
value of the counter also defines the data register ADRLx to be used to
store the conversion result. When ASCAN bit is set, a write to ADC
status and control register (ADSCR) will reset the auto-scan up-counter
and ADC conversion will start on the channel 0 up to the channel number
defined by the integer value of AUTO[1:0]. After a channel conversion is
completed, data is stored in ADRLx and the COCO-bit will be set. The
counter value will be incremented by 1 and a new conversion will start.
This process will continue until the counter value reaches the value of
AUTO[1:0]. When this happens, it indicates that the current channel is
the last channel to be converted. Upon the completion on the last
channel, the counter value will not be incremented and no further
conversion will be performed. To start another auto-scan cycle, a write
to ADSCR must be performed.
NOTE:
The system only provides 8-bit data storage in auto-scan code, user
must clear MODE[1:0] bits to select 8-bit truncation mode before
entering auto-scan mode.
It is recommended that user should disable the auto-scan function
before switching channel and also before entering STOP mode!
Analog-to-Digital Converter (ADC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
238
Analog-to-Digital Converter (ADC)
MOTOROLA
15.4.6 Result Justification
The conversion result may be formatted in four different ways.
Left justified
Right justified
Left justified sign data mode
8-bit truncation
All four of these modes are controlled using MODE0 and MODE1 bits
located in the ADC clock control register (ADICLK).
Left justification will place the eight most significant bits (MSB) in the
corresponding ADC data register high (ADRH). This may be useful if the
result is to be treated as an 8-bit result where the least significant two
bits, located in the ADC data register low (ADRL) can be ignored.
However, you must read ADRL after ADRH or else the interlocking will
prevent all new conversions from being stored.
Right justification will place only the two MSBs in the corresponding ADC
data register high (ADRH) and the eight LSB bits in ADC data register
low (ADRL). This mode of operation typically is used when a 10-bit
unsigned result is desired.
Left justified sign data mode is similar to left justified mode with one
exception. The MSB of the 10-bit result, AD9 located in ADRH is
complemented. This mode of operation is useful when a result,
represented as a signed magnitude from mid-scale, is needed.
Finally, 8-bit truncation mode will place the eight MSBs in ADC data
register low (ADRL). The two LSBs are dropped. This mode of operation
is used when compatibility with 8-bit ADC designs are required. No
interlocking between ADRH and ADRL is present.
Analog-to-Digital Converter (ADC)
Interrupts
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog-to-Digital Converter (ADC)
239
15.4.7 Data Register Interlocking
Reading ADRH in any 10-bit mode latches the contents of ADRL until
ADRL is read. Until ADRL is read all subsequent ADC results will be lost.
This register interlocking can also be reset by a write to the ADC status
and control register, or ADC clock control register. A power-on reset or
reset will also clear the interlocking. Note that an external conversion
request will not reset the lock.
15.4.8 Monotonicity
The conversion process is monotonic and has no missing codes.
15.5 Interrupts
When the AIEN bit is set, the ADC module is capable of generating a
CPU interrupt after each ADC conversion or after an auto-scan
conversion cycle. A CPU interrupt is generated if the COCO bit is at
logic 0. The COCO bit is not used as a conversion complete flag when
interrupts are enabled. The interrupt vector is defined in
Table 2-1 .
Vector Addresses
.
15.6 Low-Power Modes
The STOP and WAIT instructions put the MCU in low power-
consumption standby modes.
15.6.1 Wait Mode
The ADC continues normal operation in wait mode. Any enabled CPU
interrupt request from the ADC can bring the MCU out of wait mode. If
the ADC is not required to bring the MCU out of wait mode, power down
the ADC by setting the ADCH[4:0] bits to logic 1's before executing the
WAIT instruction.
Analog-to-Digital Converter (ADC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
240
Analog-to-Digital Converter (ADC)
MOTOROLA
15.6.2 Stop Mode
The ADC module is inactive after the execution of a STOP instruction.
Any pending conversion is aborted. ADC conversions resume when the
MCU exits stop mode. Allow one conversion cycle to stabilize the analog
circuitry before attempting a new ADC conversion after exiting stop
mode.
15.7 I/O Signals
The ADC module has fourteen channels, eleven channels are shared
with port A and port C I/O pins; two channels are analog pins, OPIN1 and
OPIN2, that are shared with the analog module; and one channel,
OPOUT, from the analog module.
15.7.1 ADC Voltage In (V
ADIN
)
V
ADIN
is the input voltage signal from one of the fourteen channels to the
ADC module.
15.7.2 ADC Analog Power Pin (V
DDA
)
The ADC analog portion uses V
DDA
as its power pin. Connect the V
DDA
pin to the same voltage potential as V
DD
. External filtering may be
necessary to ensure clean V
DDA
for good results.
NOTE:
Route V
DDA
carefully for maximum noise immunity and place bypass
capacitors as close as possible to the package.
15.7.3 ADC Analog Ground Pin (V
SSA
)
The ADC analog portion uses V
SSA
as its ground pin. Connect the V
SSA
pin to the same voltage potential as V
SS
.
Analog-to-Digital Converter (ADC)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog-to-Digital Converter (ADC)
241
15.7.4 ADC Voltage Reference High Pin (V
REFH
)
V
REFH
is the power supply for setting the reference voltage V
REFH
.
Connect the V
REFH
pin to the same voltage potential as V
DDA
. There will
be a finite current associated with V
REFH
(see
Section 24. Electrical
Specifications
).
NOTE:
Route V
REFH
carefully for maximum noise immunity and place bypass
capacitors as close as possible to the package.
15.7.5 ADC Voltage Reference Low Pin (V
REFL
)
V
REFL
is the lower reference supply for the ADC. Connect the V
REFL
pin
to the same voltage potential as V
SSA
. There will be a finite current
associated with V
REFL
(see
Section 24. Electrical Specifications
).
15.8 I/O Registers
These I/O registers control and monitor ADC operation:
ADC status and control register (ADSCR) -- $0057
ADC clock control register (ADICLK) -- $0058
ADC data register high 0 (ADRH0) -- $0059
ADC data register low 0 (ADRL0) -- $005A
ADC data register low 1 (ADRL1) -- $005B
ADC data register low 2 (ADRL2) -- $005C
ADC data register low 3 (ADRL3) -- $005D
ADC auto-scan control register (ADASCR) -- $005E
Analog-to-Digital Converter (ADC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
242
Analog-to-Digital Converter (ADC)
MOTOROLA
15.8.1 ADC Status and Control Register
Function of the ADC status and control register is described here.
COCO -- Conversions Complete Bit
When the AIEN bit is a logic 0, the COCO is a read-only bit which is
set each time a conversion is completed. This bit is cleared whenever
the ADSCR is written, or whenever the ADC clock control register is
written, or whenever the ADC data register low, ADRLx, is read.
If the AIEN bit is logic 1, the COCO bit always read as logic 0. ADC
interrupt will be generated at the end if an ADC conversion. Reset
clears the COCO bit.
1 = Conversion completed (AIEN = 0)
0 = Conversion not completed (AIEN = 0)/CPU interrupt (AIEN=1)
AIEN -- ADC Interrupt Enable Bit
When this bit is set, an interrupt is generated at the end of an ADC
conversion. The interrupt signal is cleared when the data register,
ADR0, is read or the ADSCR is written. Reset clears the AIEN bit.
1 = ADC interrupt enabled
0 = ADC interrupt disabled
ADCO -- ADC Continuous Conversion Bit
When set, the ADC will convert samples continuously and update the
ADC data register at the end of each conversion. Only one conversion
is allowed when this bit is cleared. Reset clears the ADCO bit.
1 = Continuous ADC conversion
0 = One ADC conversion
This bit should not be set when auto-scan mode is enabled; i.e. when
ASCAN=1.
Address:
$0057
Read:
COCO
AIEN
ADCO
ADCH4
ADCH3
ADCH2
ADCH1
ADCH0
Write:
Reset:
0
0
0
1
1
1
1
1
= Unimplemented
Figure 15-3. ADC Status and Control Register (ADSCR)
Analog-to-Digital Converter (ADC)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog-to-Digital Converter (ADC)
243
ADCH[4:0] -- ADC Channel Select Bits
ADCH[4:0] form a 5-bit field which is used to select one of the ADC
channels when not in auto-scan mode. The five channel select bits
are detailed in
Table 15-1
.
NOTE:
Care should be taken when using a port pin as both an analog and a
digital input simultaneously to prevent switching noise from corrupting
the analog signal.
NOTE:
Recovery from the disabled state requires one conversion cycle to
stabilize.
Table 15-1. MUX Channel Select
ADCH4
ADCH3
ADCH2
ADCH1
ADCH0
ADC Channel
Input Select
0
0
0
0
0
ATD0
OPIN1
0
0
0
0
1
ATD1
OPIN2
0
0
0
1
0
ATD2
PTA0
0
0
0
1
1
ATD3
PTA1
0
0
1
0
0
ATD4
PTA2
0
0
1
0
1
ATD5
PTA3
0
0
1
1
0
ATD6
PTA4
0
0
1
1
1
ATD7
PTA5
0
1
0
0
0
ATD8
PTC3
0
1
0
0
1
ATD9
PTC4
0
1
0
1
0
ATD10
PTC5
0
1
0
1
1
ATD11
PTC6
0
1
1
0
0
ATD12
PTC7
0
1
1
0
1
ATD13
OPOUT
0
1
0
0
0
ATD14
ATD28
Reserved
1
1
1
0
0
1
1
1
0
1
ATD29
V
REFH
(see Note 2)
1
1
1
1
0
ATD30
V
REFL
(see Note 2)
1
1
1
1
1
ADC powered-off
--
NOTES:
1. If any unused channels are selected, the resulting ADC conversion will be unknown.
2. The voltage levels supplied from internal reference nodes as specified in the table are used to verify the operation of
the ADC converter both in production test and for user applications.
Analog-to-Digital Converter (ADC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
244
Analog-to-Digital Converter (ADC)
MOTOROLA
15.8.2 ADC Clock Control Register
The ADC clock control register (ADICLK) selects the clock frequency for
the ADC.
ADIV[2:0] -- ADC Clock Prescaler Bits
ADIV2, ADIV1, and ADIV0 form a 3-bit field which selects the divide
ratio used by the ADC to generate the internal ADC clock.
Table 15-2
shows the available clock configurations. The ADC clock
should be set to between 500kHz and 2MHz.
ADICLK -- ADC Input Clock Select Bit
ADICLK selects either bus clock or CGMXCLK as the input clock
source to generate the internal ADC clock. Reset selects CGMXCLK
as the ADC clock source.
Address:
$0058
Read:
ADIV2
ADIV1
ADIV0
ADICLK
MODE1
MODE0
0
0
Write:
R
Reset:
0
0
0
0
0
1
0
0
= Unimplemented
R
= Reserved
Figure 15-4. ADC Clock Control Register (ADICLK)
Table 15-2. ADC Clock Divide Ratio
ADIV2
ADIV1
ADIV0
ADC Clock Rate
0
0
0
ADC input clock
1
0
0
1
ADC input clock
2
0
1
0
ADC input clock
4
0
1
1
ADC input clock
8
1
X
X
ADC input clock
16
X = don't care
Analog-to-Digital Converter (ADC)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog-to-Digital Converter (ADC)
245
If the external clock (CGMXCLK) is equal to or greater than 1MHz,
CGMXCLK can be used as the clock source for the ADC. If
CGMXCLK is less than 1MHz, use the PLL-generated bus clock as
the clock source. As long as the internal ADC clock is at f
ADIC
, correct
operation can be guaranteed.
1 = Internal bus clock
0 = External clock, CGMXCLK
MODE1 and MODE0 -- Modes of Result Justification
MODE1 and MODE0 selects between four modes of operation. The
manner in which the ADC conversion results will be placed in the ADC
data registers is controlled by these modes of operation. Reset
returns right-justified mode.
Table 15-3. ADC Mode Select
MODE1
MODE0
ADC Clock Rate
0
0
8-bit truncated mode
0
1
Right justified mode
1
0
Left justified mode
1
1
Left justified sign data mode
CGMXCLK or bus frequency
f
ADIC
=
ADIV[2:0]
Analog-to-Digital Converter (ADC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
246
Analog-to-Digital Converter (ADC)
MOTOROLA
15.8.3 ADC Data Register 0 (ADRH0 and ADRL0)
The ADC data register 0 consist of a pair of 8-bit registers: high byte
(ADRH0), and low byte (ADRL0). This pair form a 16-bit register to store
the 10-bit ADC result for the selected ADC result justification mode.
In 8-bit truncated mode, the ADRL0 holds the eight most significant bits
(MSBs) of the 10-bit result. The ADRL0 is updated each time an ADC
conversion completes. In 8-bit truncated mode, ADRL0 contains no
interlocking with ADRH0. (See
Figure 15-5 . ADRH0 and ADRL0 in 8-
Bit Truncated Mode
.)
In right justified mode the ADRH0 holds the two MSBs, and the ADRL0
holds the eight least significant bits (LSBs), of the 10-bit result. ADRH0
and ADRL0 are updated each time a single channel ADC conversion
completes. Reading ADRH0 latches the contents of ADRL0. Until
ADRL0 is read all subsequent ADC results will be lost.
(See
Figure 15-6 . ADRH0 and ADRL0 in Right Justified Mode
.)
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0059
ADC Data Register High 0
(ADRH0)
Read:
0
0
0
0
0
0
0
0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005A
ADC Data Register Low 0
(ADRL0)
Read:
AD9
AD8
AD7
AD6
AD5
AD4
AD3
AD2
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
Figure 15-5. ADRH0 and ADRL0 in 8-Bit Truncated Mode
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0059
ADC Data Register High 0
(ADRH0)
Read:
0
0
0
0
0
0
AD9
AD8
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005A
ADC Data Register Low 0
(ADRL0)
Read:
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
Figure 15-6. ADRH0 and ADRL0 in Right Justified Mode
Analog-to-Digital Converter (ADC)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog-to-Digital Converter (ADC)
247
In left justified mode the ADRH0 holds the eight most significant bits
(MSBs), and the ADRL0 holds the two least significant bits (LSBs), of the
10-bit result. The ADRH0 and ADRL0 are updated each time a single
channel ADC conversion completes. Reading ADRH0 latches the
contents of ADRL0. Until ADRL0 is read all subsequent ADC results will
be lost. (See
Figure 15-7 . ADRH0 and ADRL0 in Left Justified Mode
.)
In left justified sign mode the ADRH0 holds the eight MSBs with the MSB
complemented, and the ADRL0 holds the two least significant bits
(LSBs), of the 10-bit result. The ADRH0 and ADRL0 are updated each
time a single channel ADC conversion completes. Reading ADRH0
latches the contents of ADRL0. Until ADRL0 is read all subsequent ADC
results will be lost. (See
Figure 15-8 . ADRH0 and ADRL0 in Left
Justified Sign Data Mode
.)
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0059
ADC Data Register High 0
(ADRH0)
Read:
AD9
AD8
AD7
AD6
AD5
AD4
AD3
AD2
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005A
ADC Data Register Low 0
(ADRL0)
Read:
AD1
AD0
0
0
0
0
0
0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
Figure 15-7. ADRH0 and ADRL0 in Left Justified Mode
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0059
ADC Data Register High 0
(ADRH0)
Read:
AD9
AD8
AD7
AD6
AD5
AD4
AD3
AD2
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
$005A
ADC Data Register Low 0
(ADRL0)
Read:
AD1
AD0
0
0
0
0
0
0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
Figure 15-8. ADRH0 and ADRL0 in Left Justified Sign Data Mode
Analog-to-Digital Converter (ADC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
248
Analog-to-Digital Converter (ADC)
MOTOROLA
15.8.4 ADC Auto-Scan Mode Data Registers (ADRL1ADRL3)
The ADC data registers 1 to 3 (ADRL1ADRL3), are 8-bit registers for
conversion results in 8-bit truncated mode, for channels ATD1 to ATD3,
when the ADC is operating in auto-scan mode (MODE[1:0] = 00).
15.8.5 ADC Auto-Scan Control Register (ADASCR)
The ADC auto-scan control register (ADASCR) enables and controls the
ADC auto-scan function.
AUTO[1:0] -- Auto-scan Mode Channel Select Bits
AUTO1 and AUTO0 form a 2-bit field which is used to define the
number of auto-scan channels used when in auto-scan mode.
Reset clears these bits.
Address: ADRL1, $005B; ADRL2, $005C; and ADRL3, $005D
Read:
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
Write:
R
R
R
R
R
R
R
R
Reset:
0
0
0
0
0
0
0
0
R
= Reserved
Figure 15-9. ADC Data Register Low 1 to 3 (ADRL1ADRL3)
Address:
$005E
Read:
0
0
0
0
0
AUTO1
AUTO0
ASCAN
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 15-10. ADC Scan Control Register (ADASCR)
Table 15-4. Auto-scan Mode Channel Select
AUTO1
AUTO0
ADC Clock Rate
0
0
ATD0 only
0
1
ATD0 to ATD1
1
0
ATD0 to ATD2
1
1
ATD0 to ATD3
Analog-to-Digital Converter (ADC)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Analog-to-Digital Converter (ADC)
249
ASCAN -- Auto-scan Mode Enable Bit
This bit enable/disable the Auto-scan mode. Reset clears this bit.
1 = Auto-scan mode is enabled
0 = Auto-scan mode is disabled
Auto-scan mode should not be enabled when ADC continuous
conversion is enabled; i.e. when ADCO=1.
Analog-to-Digital Converter (ADC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
250
Analog-to-Digital Converter (ADC)
MOTOROLA
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
251
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 16. Serial Communications Interface (SCI)
16.1 Contents
16.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
16.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
16.4
Pin Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
16.5
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
16.5.1
Data Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .257
16.5.2
Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
16.5.2.1
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
16.5.2.2
Character Transmission . . . . . . . . . . . . . . . . . . . . . . . . . 259
16.5.2.3
Break Characters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
16.5.2.4
Idle Characters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260
16.5.2.5
Inversion of Transmitted Output. . . . . . . . . . . . . . . . . . . 261
16.5.2.6
Transmitter Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . 261
16.5.3
Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
16.5.3.1
Character Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
16.5.3.2
Character Reception . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
16.5.3.3
Data Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264
16.5.3.4
Framing Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
16.5.3.5
Baud Rate Tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
16.5.3.6
Receiver Wakeup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
16.5.3.7
Receiver Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . .270
16.5.3.8
Error Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
16.6
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .271
16.6.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
16.6.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271
16.7
SCI During Break Module Interrupts. . . . . . . . . . . . . . . . . . . . 272
16.8
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
16.8.1
TxD (Transmit Data). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
252
Serial Communications Interface (SCI)
MOTOROLA
16.8.2
RxD (Receive Data) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
16.9
I/O Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
16.9.1
SCI Control Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273
16.9.2
SCI Control Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
16.9.3
SCI Control Register 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 279
16.9.4
SCI Status Register 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .282
16.9.5
SCI Status Register 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .286
16.9.6
SCI Data Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287
16.9.7
SCI Baud Rate Register . . . . . . . . . . . . . . . . . . . . . . . . . . . 288
16.2 Introduction
This section describes the serial communications interface (SCI)
module, which allows high-speed asynchronous communications with
peripheral devices and other MCUs.
NOTE:
When the SCI is enabled, the TxD pin is an open-drain output and
requires a pullup resistor to be connected for proper SCI operation.
NOTE:
References to DMA (direct-memory access) and associated functions
are only valid if the MCU has a DMA module. This MCU does not have
the DMA function. Any DMA-related register bits should be left in their
reset state for normal MCU operation.
16.3 Features
Features of the SCI module include the following:
Full-duplex operation
Standard mark/space non-return-to-zero (NRZ) format
32 programmable baud rates
Programmable 8-bit or 9-bit character length
Separately enabled transmitter and receiver
Separate receiver and transmitter CPU interrupt requests
Programmable transmitter output polarity
Serial Communications Interface (SCI)
Features
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
253
Two receiver wakeup methods:
Idle line wakeup
Address mark wakeup
Interrupt-driven operation with eight interrupt flags:
Transmitter empty
Transmission complete
Receiver full
Idle receiver input
Receiver overrun
Noise error
Framing error
Parity error
Receiver framing error detection
Hardware parity checking
1/16 bit-time noise detection
Configuration register bit, SCIBDSRC, to allow selection of baud
rate clock source
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
254
Serial Communications Interface (SCI)
MOTOROLA
16.4 Pin Name Conventions
The generic names of the SCI I/O pins are:
RxD (receive data)
TxD (transmit data)
SCI I/O (input/output) lines are implemented by sharing parallel I/O port
pins. The full name of an SCI input or output reflects the name of the
shared port pin.
Table 16-1
shows the full names and the generic names
of the SCI I/O pins. The generic pin names appear in the text of this
section.
NOTE:
When the SCI is enabled, the TxD pin is an open-drain output and
requires a pullup resistor to be connected for proper SCI operation.
16.5 Functional Description
Figure 16-1
shows the structure of the SCI module. The SCI allows full-
duplex, asynchronous, NRZ serial communication among the MCU and
remote devices, including other MCUs. The transmitter and receiver of
the SCI operate independently, although they use the same baud rate
generator. During normal operation, the CPU monitors the status of the
SCI, writes the data to be transmitted, and processes received data.
The baud rate clock source for the SCI can be selected via the
configuration bit, SCIBDSRC, of the CONFIG2 register ($001D). Source
selection values are shown in
Figure 16-1
.
Table 16-1. Pin Name Conventions
Generic Pin Names:
RxD
TxD
Full Pin Names:
PTB3/SCL1/RxD
PTB2/SDA1/TxD
Serial Communications Interface (SCI)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
255
Figure 16-1. SCI Module Block Diagram
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
SCTIE
TCIE
SCRIE
ILIE
TE
RE
RWU
SBK
R8
T8
DMATE
ORIE
FEIE
PEIE
BKF
RPF
SCI DATA
RECEIVE
SHIFT REGISTER
SCI DATA
REGISTER
TRANSMIT
SHIFT REGISTER
NEIE
M
WAKE
ILTY
FLAG
CONTROL
TRANSMIT
CONTROL
RECEIVE
CONTROL
DATA SELECTION
CONTROL
WAKEUP
PTY
PEN
REGISTER
DM
A
IN
TE
RR
UPT
CO
NT
RO
L
T
R
AN
SM
ITT
E
R
IN
TE
RR
UPT
CO
NT
RO
L
RE
CE
IVE
R
IN
TE
RR
UPT
CO
NT
RO
L
ER
RO
R
IN
TE
RR
UPT
CO
NT
RO
L
CONTROL
DMARE
ENSCI
LOOPS
ENSCI
INTERNAL BUS
TXINV
LOOPS
4
16
PRE-
SCALER
BAUD
DIVIDER
CGMXCLK
IT12
A
B
SL
X
SCIBDSRC
FROM
SL = 0 => X = A
SL = 1 => X = B
CONFIG
RxD
TxD
CGMXCLK is from CGM module
IT12 = f
BUS
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
256
Serial Communications Interface (SCI)
MOTOROLA
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0013
SCI Control Register 1
(SCC1)
Read:
LOOPS
ENSCI
TXINV
M
WAKE
ILTY
PEN
PTY
Write:
Reset:
0
0
0
0
0
0
0
0
$0014
SCI Control Register 2
(SCC2)
Read:
SCTIE
TCIE
SCRIE
ILIE
TE
RE
RWU
SBK
Write:
Reset:
0
0
0
0
0
0
0
0
$0015
SCI Control Register 3
(SCC3)
Read:
R8
T8
DMARE
DMATE
ORIE
NEIE
FEIE
PEIE
Write:
Reset:
U
U
0
0
0
0
0
0
$0016
SCI Status Register 1
(SCS1)
Read:
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
Write:
Reset:
1
1
0
0
0
0
0
0
$0017
SCI Status Register 2
(SCS2)
Read:
BKF
RPF
Write:
Reset:
0
0
0
0
0
0
0
0
$0018
SCI Data Register
(SCDR)
Read:
R7
R6
R5
R4
R3
R2
R1
R0
Write:
T7
T6
T5
T4
T3
T2
T1
T0
Reset:
Unaffected by reset
$0019
SCI Baud Rate Register
(SCBR)
Read:
0
0
SCP1
SCP0
R
SCR2
SCR1
SCR0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
R = Reserved
U = Unaffected
Figure 16-2. SCI I/O Register Summary
Serial Communications Interface (SCI)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
257
16.5.1 Data Format
The SCI uses the standard non-return-to-zero mark/space data format
illustrated in
Figure 16-3
.
Figure 16-3. SCI Data Formats
16.5.2 Transmitter
Figure 16-4
shows the structure of the SCI transmitter.
The baud rate clock source for the SCI can be selected via the
configuration bit, SCIBDSRC. Source selection values are shown in
Figure 16-4
.
BIT 5
START
BIT
BIT 0
BIT 1
NEXT
STOP
BIT
START
BIT
8-BIT DATA FORMAT
BIT M IN SCC1 CLEAR
START
BIT
BIT 0
NEXT
STOP
BIT
START
BIT
9-BIT DATA FORMAT
BIT M IN SCC1 SET
BIT 1
BIT 2
BIT 3
BIT 4
BIT 5
BIT 6
BIT 7
BIT 8
BIT 2
BIT 3
BIT 4
BIT 6
BIT 7
PARITY
BIT
PARITY
BIT
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
258
Serial Communications Interface (SCI)
MOTOROLA
Figure 16-4. SCI Transmitter
DMATE
SCTE
PEN
PTY
H
8
7
6
5
4
3
2
1
0
L
11-BIT
TRANSMIT
ST
OP
ST
AR
T
T8
DMATE
SCTE
SCTIE
TCIE
SBK
TC
PARITY
GENERATION
MS
B
SCI DATA REGISTER
LO
AD
FR
OM
SC
DR
SH
IFT
EN
AB
LE
PR
EA
MB
LE
AL
L 1
s
BRE
A
K
A
LL 0s
TRANSMITTER
CONTROL LOGIC
SHIFT REGISTER
DMATE
TC
SCTIE
TCIE
SCTE
T
R
A
N
S
M
I
T
T
E
R
C
P
U
INTER
RUPT REQ
U
EST
T
R
A
N
SM
IT
T
E
R
DM
A SE
R
V
I
C
E
RE
QU
E
S
T
M
ENSCI
LOOPS
TE
TXINV
INTERNAL BUS
4
PRE-
SCALER
SCP1
SCP0
SCR2
SCR1
SCR0
BAUD
DIVIDER
16
SCTIE
CGMXCLK
IT12
A
B
SL
X
SL = 0 => X = A
SL = 1 => X = B
SCIBDSRC
FROM
CONFIG2
TxD
Serial Communications Interface (SCI)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
259
16.5.2.1 Character Length
The transmitter can accommodate either 8-bit or 9-bit data. The state of
the M bit in SCI control register 1 (SCC1) determines character length.
When transmitting 9-bit data, bit T8 in SCI control register 3 (SCC3) is
the ninth bit (bit 8).
16.5.2.2 Character Transmission
During an SCI transmission, the transmit shift register shifts a character
out to the TxD pin. The SCI data register (SCDR) is the write-only buffer
between the internal data bus and the transmit shift register. To initiate
an SCI transmission:
1. Enable the SCI by writing a logic 1 to the enable SCI bit (ENSCI)
in SCI control register 1 (SCC1).
2. Enable the transmitter by writing a logic 1 to the transmitter enable
bit (TE) in SCI control register 2 (SCC2).
3. Clear the SCI transmitter empty bit by first reading SCI status
register 1 (SCS1) and then writing to the SCDR.
4. Repeat step 3 for each subsequent transmission.
At the start of a transmission, transmitter control logic automatically
loads the transmit shift register with a preamble of logic 1s. After the
preamble shifts out, control logic transfers the SCDR data into the
transmit shift register. A logic 0 start bit automatically goes into the least
significant bit position of the transmit shift register. A logic 1 stop bit goes
into the most significant bit position.
The SCI transmitter empty bit, SCTE, in SCS1 becomes set when the
SCDR transfers a byte to the transmit shift register. The SCTE bit
indicates that the SCDR can accept new data from the internal data bus.
If the SCI transmit interrupt enable bit, SCTIE, in SCC2 is also set, the
SCTE bit generates a transmitter CPU interrupt request.
When the transmit shift register is not transmitting a character, the TxD
pin goes to the idle condition, logic 1. If at any time software clears the
ENSCI bit in SCI control register 1 (SCC1), the transmitter and receiver
relinquish control of the port pin.
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
260
Serial Communications Interface (SCI)
MOTOROLA
16.5.2.3 Break Characters
Writing a logic 1 to the send break bit, SBK, in SCC2 loads the transmit
shift register with a break character. A break character contains all logic
0s and has no start, stop, or parity bit. Break character length depends
on the M bit in SCC1. As long as SBK is at logic 1, transmitter logic
continuously loads break characters into the transmit shift register. After
software clears the SBK bit, the shift register finishes transmitting the
last break character and then transmits at least one logic 1. The
automatic logic 1 at the end of a break character guarantees the
recognition of the start bit of the next character.
The SCI recognizes a break character when a start bit is followed by
eight or nine logic 0 data bits and a logic 0 where the stop bit should be.
Receiving a break character has these effects on SCI registers:
Sets the framing error bit (FE) in SCS1
Sets the SCI receiver full bit (SCRF) in SCS1
Clears the SCI data register (SCDR)
Clears the R8 bit in SCC3
Sets the break flag bit (BKF) in SCS2
May set the overrun (OR), noise flag (NF), parity error (PE), or
reception in progress flag (RPF) bits
16.5.2.4 Idle Characters
An idle character contains all logic 1s and has no start, stop, or parity bit.
Idle character length depends on the M bit in SCC1. The preamble is a
synchronizing idle character that begins every transmission.
If the TE bit is cleared during a transmission, the TxD pin becomes idle
after completion of the transmission in progress. Clearing and then
setting the TE bit during a transmission queues an idle character to be
sent after the character currently being transmitted.
Serial Communications Interface (SCI)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
261
NOTE:
When queueing an idle character, return the TE bit to logic 1 before the
stop bit of the current character shifts out to the TxD pin. Setting TE after
the stop bit appears on TxD causes data previously written to the SCDR
to be lost.
Toggle the TE bit for a queued idle character when the SCTE bit
becomes set and just before writing the next byte to the SCDR.
16.5.2.5 Inversion of Transmitted Output
The transmit inversion bit (TXINV) in SCI control register 1 (SCC1)
reverses the polarity of transmitted data. All transmitted values, including
idle, break, start, and stop bits, are inverted when TXINV is at logic 1.
(See
16.9.1 SCI Control Register 1
.)
16.5.2.6 Transmitter Interrupts
These conditions can generate CPU interrupt requests from the SCI
transmitter:
SCI transmitter empty (SCTE) -- The SCTE bit in SCS1 indicates
that the SCDR has transferred a character to the transmit shift
register. SCTE can generate a transmitter CPU interrupt request.
Setting the SCI transmit interrupt enable bit, SCTIE, in SCC2
enables the SCTE bit to generate transmitter CPU interrupt
requests.
Transmission complete (TC) -- The TC bit in SCS1 indicates that
the transmit shift register and the SCDR are empty and that no
break or idle character has been generated. The transmission
complete interrupt enable bit, TCIE, in SCC2 enables the TC bit to
generate transmitter CPU interrupt requests.
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
262
Serial Communications Interface (SCI)
MOTOROLA
16.5.3 Receiver
Figure 16-5
shows the structure of the SCI receiver.
16.5.3.1 Character Length
The receiver can accommodate either 8-bit or 9-bit data. The state of the
M bit in SCI control register 1 (SCC1) determines character length.
When receiving 9-bit data, bit R8 in SCI control register 2 (SCC2) is the
ninth bit (bit 8). When receiving 8-bit data, bit R8 is a copy of the eighth
bit (bit 7).
16.5.3.2 Character Reception
During an SCI reception, the receive shift register shifts characters in
from the RxD
pin. The SCI data register (SCDR) is the read-only buffer
between the internal data bus and the receive shift register.
After a complete character shifts into the receive shift register, the data
portion of the character transfers to the SCDR. The SCI receiver full bit,
SCRF, in SCI status register 1 (SCS1) becomes set, indicating that the
received byte can be read. If the SCI receive interrupt enable bit, SCRIE,
in SCC2 is also set, the SCRF bit generates a receiver CPU interrupt
request.
Serial Communications Interface (SCI)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
263
Figure 16-5. SCI Receiver Block Diagram
AL
L 1
s
ALL 0s
M
WAKE
ILTY
PEN
PTY
BKF
RPF
H
8
7
6
5
4
3
2
1
0
L
11-BIT
RECEIVE SHIFT REGISTER
ST
OP
ST
AR
T
DATA
RECOVERY
DMARE
SCRF
OR
ORIE
NF
NEIE
FE
FEIE
PE
PEIE
DMARE
SCRIE
SCRF
ILIE
IDLE
WAKEUP
LOGIC
PARITY
CHECKING
MS
B
E
R
R
O
R
C
P
U
INTERRUP
T R
E
Q
U
E
S
T
DM
A SER
VIC
E
REQ
U
E
S
T
CP
U I
N
TE
RR
UP
T
R
E
Q
U
E
S
T
SCI DATA REGISTER
R8
DMARE
ORIE
NEIE
FEIE
PEIE
SCRIE
ILIE
RWU
SCRF
IDLE
OR
NF
FE
PE
INTERNAL BUS
PRE-
SCALER
BAUD
DIVIDER
4
16
SCP1
SCP0
SCR2
SCR1
SCR0
SCRIE
DMARE
CGMXCLK
IT12
A
B
SL
X
SCIBDSRC
FROM
SL = 0 => X = A
SL = 1 => X = B
CONFIG2
RxD
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
264
Serial Communications Interface (SCI)
MOTOROLA
16.5.3.3 Data Sampling
The receiver samples the RxD pin at the RT clock rate. The RT clock is
an internal signal with a frequency 16 times the baud rate. To adjust for
baud rate mismatch, the RT clock is resynchronized at the following
times (see
Figure 16-6
):
After every start bit
After the receiver detects a data bit change from logic 1 to logic 0
(after the majority of data bit samples at RT8, RT9, and RT10
returns a valid logic 1 and the majority of the next RT8, RT9, and
RT10 samples returns a valid logic 0)
To locate the start bit, data recovery logic does an asynchronous search
for a logic 0 preceded by three logic 1s. When the falling edge of a
possible start bit occurs, the RT clock begins to count to 16.
Figure 16-6. Receiver Data Sampling
RT CLOCK
RESET
RT1
RT1
RT1
RT1
RT1
RT1
RT1
RT1
RT1
RT2
RT3
RT4
RT5
RT8
RT7
RT6
RT11
RT10
RT9
RT15
RT14
RT13
RT12
RT16
RT1
RT2
RT3
RT4
START BIT
QUALIFICATION
START BIT
VERIFICATION
DATA
SAMPLING
SAMPLES
RT
CLOCK
RT CLOCK
STATE
START BIT
LSB
RxD
Serial Communications Interface (SCI)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
265
To verify the start bit and to detect noise, data recovery logic takes
samples at RT3, RT5, and RT7.
Table 16-2
summarizes the results of
the start bit verification samples.
Start bit verification is not successful if any two of the three verification
samples are logic 1s. If start bit verification is not successful, the RT
clock is reset and a new search for a start bit begins.
To determine the value of a data bit and to detect noise, recovery logic
takes samples at RT8, RT9, and RT10.
Table 16-3
summarizes the
results of the data bit samples.
Table 16-2. Start Bit Verification
RT3, RT5, and RT7
Samples
Start Bit
Verification
Noise Flag
000
Yes
0
001
Yes
1
010
Yes
1
011
No
0
100
Yes
1
101
No
0
110
No
0
111
No
0
Table 16-3. Data Bit Recovery
RT8, RT9, and RT10
Samples
Data Bit
Determination
Noise Flag
000
0
0
001
0
1
010
0
1
011
1
1
100
0
1
101
1
1
110
1
1
111
1
0
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
266
Serial Communications Interface (SCI)
MOTOROLA
NOTE:
The RT8, RT9, and RT10 samples do not affect start bit verification. If
any or all of the RT8, RT9, and RT10 start bit samples are logic 1s
following a successful start bit verification, the noise flag (NF) is set and
the receiver assumes that the bit is a start bit.
To verify a stop bit and to detect noise, recovery logic takes samples at
RT8, RT9, and RT10.
Table 16-4
summarizes the results of the stop bit
samples.
16.5.3.4 Framing Errors
If the data recovery logic does not detect a logic 1 where the stop bit
should be in an incoming character, it sets the framing error bit, FE, in
SCS1. A break character also sets the FE bit because a break character
has no stop bit. The FE bit is set at the same time that the SCRF bit is
set.
16.5.3.5 Baud Rate Tolerance
A transmitting device may be operating at a baud rate below or above
the receiver baud rate. Accumulated bit time misalignment can cause
one of the three stop bit data samples to fall outside the actual stop bit.
Then a noise error occurs. If more than one of the samples is outside the
stop bit, a framing error occurs. In most applications, the baud rate
Table 16-4. Stop Bit Recovery
RT8, RT9, and RT10
Samples
Framing
Error Flag
Noise Flag
000
1
0
001
1
1
010
1
1
011
0
1
100
1
1
101
0
1
110
0
1
111
0
0
Serial Communications Interface (SCI)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
267
tolerance is much more than the degree of misalignment that is likely to
occur.
As the receiver samples an incoming character, it resynchronizes the RT
clock on any valid falling edge within the character. Resynchronization
within characters corrects misalignments between transmitter bit times
and receiver bit times.
Slow Data Tolerance
Figure 16-7
shows how much a slow received character can be
misaligned without causing a noise error or a framing error. The slow
stop bit begins at RT8 instead of RT1 but arrives in time for the stop bit
data samples at RT8, RT9, and RT10.
Figure 16-7. Slow Data
For an 8-bit character, data sampling of the stop bit takes the receiver
9 bit times
16 RT cycles + 10 RT cycles = 154 RT cycles.
With the misaligned character shown in
Figure 16-7
, the receiver counts
154 RT cycles at the point when the count of the transmitting device is
9 bit times
16 RT cycles + 3 RT cycles = 147 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a slow 8-bit character with no errors is
For a 9-bit character, data sampling of the stop bit takes the receiver
10 bit times
16 RT cycles + 10 RT cycles = 170 RT cycles.
MSB
STOP
RT
1
RT
2
RT
3
RT
4
RT
5
RT
6
RT
7
RT
8
RT
9
RT10
RT11
RT12
RT13
RT14
RT15
RT16
DATA
SAMPLES
RECEIVER
RT CLOCK
154
147
154
--------------------------
100
4.54%
=
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
268
Serial Communications Interface (SCI)
MOTOROLA
With the misaligned character shown in
Figure 16-7
, the receiver counts
170 RT cycles at the point when the count of the transmitting device is
10 bit times
16 RT cycles + 3 RT cycles = 163 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a slow 9-bit character with no errors is
Fast Data Tolerance
Figure 16-8
shows how much a fast received character can be
misaligned without causing a noise error or a framing error. The fast stop
bit ends at RT10 instead of RT16 but is still there for the stop bit data
samples at RT8, RT9, and RT10.
Figure 16-8. Fast Data
For an 8-bit character, data sampling of the stop bit takes the receiver
9 bit times
16 RT cycles + 10 RT cycles = 154 RT cycles.
With the misaligned character shown in
Figure 16-8
, the receiver counts
154 RT cycles at the point when the count of the transmitting device is
10 bit times
16 RT cycles = 160 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a fast 8-bit character with no errors is
170
163
170
--------------------------
100
4.12%
=
IDLE OR NEXT CHARACTER
STOP
RT1
RT2
RT3
RT4
RT5
RT6
RT7
RT8
RT9
RT
10
RT
11
RT
12
RT
13
RT
14
RT
15
RT
16
DATA
SAMPLES
RECEIVER
RT CLOCK
154
160
154
--------------------------
100
3.90%
=
Serial Communications Interface (SCI)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
269
For a 9-bit character, data sampling of the stop bit takes the receiver
10 bit times
16 RT cycles + 10 RT cycles = 170 RT cycles.
With the misaligned character shown in
Figure 16-8
, the receiver counts
170 RT cycles at the point when the count of the transmitting device is
11 bit times
16 RT cycles = 176 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a fast 9-bit character with no errors is
16.5.3.6 Receiver Wakeup
So that the MCU can ignore transmissions intended only for other
receivers in multiple-receiver systems, the receiver can be put into a
standby state. Setting the receiver wakeup bit, RWU, in SCC2 puts the
receiver into a standby state during which receiver interrupts are
disabled.
Depending on the state of the WAKE bit in SCC1, either of two
conditions on the RxD pin can bring the receiver out of the standby state:
Address mark -- An address mark is a logic 1 in the most
significant bit position of a received character. When the WAKE bit
is set, an address mark wakes the receiver from the standby state
by clearing the RWU bit. The address mark also sets the SCI
receiver full bit, SCRF. Software can then compare the character
containing the address mark to the user-defined address of the
receiver. If they are the same, the receiver remains awake and
processes the characters that follow. If they are not the same,
software can set the RWU bit and put the receiver back into the
standby state.
Idle input line condition -- When the WAKE bit is clear, an idle
character on the RxD pin wakes the receiver from the standby
state by clearing the RWU bit. The idle character that wakes the
receiver does not set the receiver idle bit, IDLE, or the SCI receiver
170
176
170
--------------------------
100
3.53%
=
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
270
Serial Communications Interface (SCI)
MOTOROLA
full bit, SCRF. The idle line type bit, ILTY, determines whether the
receiver begins counting logic 1s as idle character bits after the
start bit or after the stop bit.
NOTE:
With the WAKE bit clear, setting the RWU bit after the RxD pin has been
idle may cause the receiver to wake up immediately.
16.5.3.7 Receiver Interrupts
The following sources can generate CPU interrupt requests from the SCI
receiver:
SCI receiver full (SCRF) -- The SCRF bit in SCS1 indicates that
the receive shift register has transferred a character to the SCDR.
SCRF can generate a receiver CPU interrupt request. Setting the
SCI receive interrupt enable bit, SCRIE, in SCC2 enables the
SCRF bit to generate receiver CPU interrupts.
Idle input (IDLE) -- The IDLE bit in SCS1 indicates that 10 or 11
consecutive logic 1s shifted in from the RxD pin. The idle line
interrupt enable bit, ILIE, in SCC2 enables the IDLE bit to generate
CPU interrupt requests.
16.5.3.8 Error Interrupts
The following receiver error flags in SCS1 can generate CPU interrupt
requests:
Receiver overrun (OR) -- The OR bit indicates that the receive
shift register shifted in a new character before the previous
character was read from the SCDR. The previous character
remains in the SCDR, and the new character is lost. The overrun
interrupt enable bit, ORIE, in SCC3 enables OR to generate SCI
error CPU interrupt requests.
Noise flag (NF) -- The NF bit is set when the SCI detects noise on
incoming data or break characters, including start, data, and stop
bits. The noise error interrupt enable bit, NEIE, in SCC3 enables
NF to generate SCI error CPU interrupt requests.
Serial Communications Interface (SCI)
Low-Power Modes
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
271
Framing error (FE) -- The FE bit in SCS1 is set when a logic 0
occurs where the receiver expects a stop bit. The framing error
interrupt enable bit, FEIE, in SCC3 enables FE to generate SCI
error CPU interrupt requests.
Parity error (PE) -- The PE bit in SCS1 is set when the SCI
detects a parity error in incoming data. The parity error interrupt
enable bit, PEIE, in SCC3 enables PE to generate SCI error CPU
interrupt requests.
16.6 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
16.6.1 Wait Mode
The SCI module remains active after the execution of a WAIT
instruction. In wait mode, the SCI module registers are not accessible by
the CPU. Any enabled CPU interrupt request from the SCI module can
bring the MCU out of wait mode.
If SCI module functions are not required during wait mode, reduce power
consumption by disabling the module before executing the WAIT
instruction.
Refer to
9.7 Low-Power Modes
for information on exiting wait mode.
16.6.2 Stop Mode
The SCI module is inactive after the execution of a STOP instruction.
The STOP instruction does not affect SCI register states. SCI module
operation resumes after an external interrupt.
Because the internal clock is inactive during stop mode, entering stop
mode during an SCI transmission or reception results in invalid data.
Refer to
9.7 Low-Power Modes
for information on exiting stop mode.
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
272
Serial Communications Interface (SCI)
MOTOROLA
16.7 SCI During Break Module Interrupts
The system integration module (SIM) controls whether status bits in
other modules can be cleared during the break state. The BCFE bit in
the SIM break flag control register (SBFCR) enables software to clear
status bits during the break state.
To allow software to clear status bits during a break interrupt, write a
logic 1 to the BCFE bit. If a status bit is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect status bits during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), software can read and write
I/O registers during the break state without affecting status bits. Some
status bits have a 2-step read/write clearing procedure. If software does
the first step on such a bit before the break, the bit cannot change during
the break state as long as BCFE is at logic 0. After the break, doing the
second step clears the status bit.
16.8 I/O Signals
Port B shares two of its pins with the SCI module.
The two SCI I/O pins are:
PTB2/SDA1/TxD -- Transmit data
PTB3/SCL1/RxD -- Receive data
16.8.1 TxD (Transmit Data)
When the SCI is enabled (ENSCI=1), the PTB2/SDA1/TxD
pin becomes
the serial data output, TxD, from the SCI transmitter regardless of the
state of the DDRB2 bit in data direction register B (DDRB). The TxD pin
is an open-drain output and requires a pullup resistor to be connected for
proper SCI operation.
NOTE:
The PTB2/SDA1/TxD pin is an open-drain pin when configured as an
output. Therefore, when configured as a general purpose output pin
(PTB2), a pullup resistor must be connected to this pin.
Serial Communications Interface (SCI)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
273
16.8.2 RxD (Receive Data)
When the SCI is enabled (ENSCI=1), the PTB3/SCL1/RxD
pin becomes
the serial data input, RxD, to the SCI receiver regardless of the state of
the DDRB3 bit in data direction register B (DDRB).
NOTE:
The PTB3/SCL1/RxD pin is an open-drain pin when configured as an
output. Therefore, when configured as a general purpose output pin
(PTB3), a pullup resistor must be connected to this pin.
16.9 I/O Registers
These I/O registers control and monitor SCI operation:
SCI control register 1 (SCC1)
SCI control register 2 (SCC2)
SCI control register 3 (SCC3)
SCI status register 1 (SCS1)
SCI status register 2 (SCS2)
SCI data register (SCDR)
SCI baud rate register (SCBR)
16.9.1 SCI Control Register 1
SCI control register 1:
Enables loop mode operation
Enables the SCI
Controls output polarity
Controls character length
Controls SCI wakeup method
Controls idle character detection
Enables parity function
Controls parity type
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
274
Serial Communications Interface (SCI)
MOTOROLA
LOOPS -- Loop Mode Select Bit
This read/write bit enables loop mode operation. In loop mode the
RxD
pin is disconnected from the SCI, and the transmitter output goes
into the receiver input. Both the transmitter and the receiver must be
enabled to use loop mode. Reset clears the LOOPS bit.
1 = Loop mode enabled
0 = Normal operation enabled
ENSCI -- Enable SCI Bit
This read/write bit enables the SCI and the SCI baud rate generator.
Clearing ENSCI sets the SCTE and TC bits in SCI status register 1
and disables transmitter interrupts. Reset clears the ENSCI bit.
1 = SCI enabled
0 = SCI disabled
TXINV -- Transmit Inversion Bit
This read/write bit reverses the polarity of transmitted data. Reset
clears the TXINV bit.
1 = Transmitter output inverted
0 = Transmitter output not inverted
NOTE:
Setting the TXINV bit inverts all transmitted values, including idle, break,
start, and stop bits.
Address:
$0013
Bit 7
6
5
4
3
2
1
Bit 0
Read:
LOOPS
ENSCI
TXINV
M
WAKE
ILTY
PEN
PTY
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 16-9. SCI Control Register 1 (SCC1)
Serial Communications Interface (SCI)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
275
M -- Mode (Character Length) Bit
This read/write bit determines whether SCI characters are eight or
nine bits long. (See Table 16-5.) The ninth bit can serve as an extra
stop bit, as a receiver wakeup signal, or as a parity bit. Reset clears
the M bit.
1 = 9-bit SCI characters
0 = 8-bit SCI characters
WAKE -- Wakeup Condition Bit
This read/write bit determines which condition wakes up the SCI: a
logic 1 (address mark) in the most significant bit position of a received
character or an idle condition on the RxD pin. Reset clears the WAKE
bit.
1 = Address mark wakeup
0 = Idle line wakeup
ILTY -- Idle Line Type Bit
This read/write bit determines when the SCI starts counting logic 1s
as idle character bits. The counting begins either after the start bit or
after the stop bit. If the count begins after the start bit, then a string of
logic 1s preceding the stop bit may cause false recognition of an idle
character. Beginning the count after the stop bit avoids false idle
character recognition, but requires properly synchronized
transmissions. Reset clears the ILTY bit.
1 = Idle character bit count begins after stop bit
0 = Idle character bit count begins after start bit
PEN -- Parity Enable Bit
This read/write bit enables the SCI parity function. (See Table 16-5.)
When enabled, the parity function inserts a parity bit in the most
significant bit position. (See Figure 16-3.) Reset clears the PEN bit.
1 = Parity function enabled
0 = Parity function disabled
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
276
Serial Communications Interface (SCI)
MOTOROLA
PTY -- Parity Bit
This read/write bit determines whether the SCI generates and checks
for odd parity or even parity. (See Table 16-5.) Reset clears the PTY
bit.
1 = Odd parity
0 = Even parity
NOTE:
Changing the PTY bit in the middle of a transmission or reception can
generate a parity error.
16.9.2 SCI Control Register 2
SCI control register 2:
Enables the following CPU interrupt requests:
Enables the SCTE bit to generate transmitter CPU interrupt
requests
Enables the TC bit to generate transmitter CPU interrupt
requests
Enables the SCRF bit to generate receiver CPU interrupt
requests
Enables the IDLE bit to generate receiver CPU interrupt
requests
Table 16-5. Character Format Selection
Control Bits
Character Format
M
PEN and
PTY
Start
Bits
Data
Bits
Parity
Stop
Bits
Character
Length
0
0X
1
8
None
1
10 bits
1
0X
1
9
None
1
11 bits
0
10
1
7
Even
1
10 bits
0
11
1
7
Odd
1
10 bits
1
10
1
8
Even
1
11 bits
1
11
1
8
Odd
1
11 bits
Serial Communications Interface (SCI)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
277
Enables the transmitter
Enables the receiver
Enables SCI wakeup
Transmits SCI break characters
SCTIE -- SCI Transmit Interrupt Enable Bit
This read/write bit enables the SCTE bit to generate SCI transmitter
CPU interrupt requests. Reset clears the SCTIE bit.
1 = SCTE enabled to generate CPU interrupt
0 = SCTE not enabled to generate CPU interrupt
TCIE -- Transmission Complete Interrupt Enable Bit
This read/write bit enables the TC bit to generate SCI transmitter CPU
interrupt requests. Reset clears the TCIE bit.
1 = TC enabled to generate CPU interrupt requests
0 = TC not enabled to generate CPU interrupt requests
SCRIE -- SCI Receive Interrupt Enable Bit
This read/write bit enables the SCRF bit to generate SCI receiver
CPU interrupt requests. Reset clears the SCRIE bit.
1 = SCRF enabled to generate CPU interrupt
0 = SCRF not enabled to generate CPU interrupt
ILIE -- Idle Line Interrupt Enable Bit
This read/write bit enables the IDLE bit to generate SCI receiver CPU
interrupt requests. Reset clears the ILIE bit.
1 = IDLE enabled to generate CPU interrupt requests
0 = IDLE not enabled to generate CPU interrupt requests
Address:
$0014
Bit 7
6
5
4
3
2
1
Bit 0
Read:
SCTIE
TCIE
SCRIE
ILIE
TE
RE
RWU
SBK
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 16-10. SCI Control Register 2 (SCC2)
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
278
Serial Communications Interface (SCI)
MOTOROLA
TE -- Transmitter Enable Bit
Setting this read/write bit begins the transmission by sending a
preamble of 10 or 11 logic 1s from the transmit shift register to the
TxD
pin. If software clears the TE bit, the transmitter completes any
transmission in progress before the TxD returns to the idle condition
(logic 1). Clearing and then setting TE during a transmission queues
an idle character to be sent after the character currently being
transmitted. Reset clears the TE bit.
1 = Transmitter enabled
0 = Transmitter disabled
NOTE:
Writing to the TE bit is not allowed when the enable SCI bit (ENSCI) is
clear. ENSCI is in SCI control register 1.
RE -- Receiver Enable Bit
Setting this read/write bit enables the receiver. Clearing the RE bit
disables the receiver but does not affect receiver interrupt flag bits.
Reset clears the RE bit.
1 = Receiver enabled
0 = Receiver disabled
NOTE:
Writing to the RE bit is not allowed when the enable SCI bit (ENSCI) is
clear. ENSCI is in SCI control register 1.
RWU -- Receiver Wakeup Bit
This read/write bit puts the receiver in a standby state during which
receiver interrupts are disabled. The WAKE bit in SCC1 determines
whether an idle input or an address mark brings the receiver out of the
standby state and clears the RWU bit. Reset clears the RWU bit.
1 = Standby state
0 = Normal operation
Serial Communications Interface (SCI)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
279
SBK -- Send Break Bit
Setting and then clearing this read/write bit transmits a break
character followed by a logic 1. The logic 1 after the break character
guarantees recognition of a valid start bit. If SBK remains set, the
transmitter continuously transmits break characters with no logic 1s
between them. Reset clears the SBK bit.
1 = Transmit break characters
0 = No break characters being transmitted
NOTE:
Do not toggle the SBK bit immediately after setting the SCTE bit.
Toggling SBK before the preamble begins causes the SCI to send a
break character instead of a preamble.
16.9.3 SCI Control Register 3
SCI control register 3:
Stores the ninth SCI data bit received and the ninth SCI data bit to
be transmitted
Enables these interrupts:
Receiver overrun interrupts
Noise error interrupts
Framing error interrupts
Parity error interrupts
Address:
$0015
Bit 7
6
5
4
3
2
1
Bit 0
Read:
R8
T8
DMARE
DMATE
ORIE
NEIE
FEIE
PEIE
Write:
Reset:
U
U
0
0
0
0
0
0
= Unimplemented
U = Unaffected
Figure 16-11. SCI Control Register 3 (SCC3)
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
280
Serial Communications Interface (SCI)
MOTOROLA
R8 -- Received Bit 8
When the SCI is receiving 9-bit characters, R8 is the read-only ninth
bit (bit 8) of the received character. R8 is received at the same time
that the SCDR receives the other 8 bits.
When the SCI is receiving 8-bit characters, R8 is a copy of the eighth
bit (bit 7). Reset has no effect on the R8 bit.
T8 -- Transmitted Bit 8
When the SCI is transmitting 9-bit characters, T8 is the read/write
ninth bit (bit 8) of the transmitted character. T8 is loaded into the
transmit shift register at the same time that the SCDR is loaded into
the transmit shift register. Reset has no effect on the T8 bit.
DMARE -- DMA Receive Enable Bit
CAUTION:
The DMA module is not included on this MCU. Writing a logic 1 to
DMARE or DMATE may adversely affect MCU performance.
1 = DMA not enabled to service SCI receiver DMA service requests
generated by the SCRF bit (SCI receiver CPU interrupt
requests enabled)
0 = DMA not enabled to service SCI receiver DMA service requests
generated by the SCRF bit (SCI receiver CPU interrupt
requests enabled)
DMATE -- DMA Transfer Enable Bit
CAUTION:
The DMA module is not included on this MCU. Writing a logic 1 to
DMARE or DMATE may adversely affect MCU performance.
1 = SCTE DMA service requests enabled; SCTE CPU interrupt
requests disabled
0 = SCTE DMA service requests disabled; SCTE CPU interrupt
requests enabled
Serial Communications Interface (SCI)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
281
ORIE -- Receiver Overrun Interrupt Enable Bit
This read/write bit enables SCI error CPU interrupt requests
generated by the receiver overrun bit, OR.
1 = SCI error CPU interrupt requests from OR bit enabled
0 = SCI error CPU interrupt requests from OR bit disabled
NEIE -- Receiver Noise Error Interrupt Enable Bit
This read/write bit enables SCI error CPU interrupt requests
generated by the noise error bit, NE. Reset clears NEIE.
1 = SCI error CPU interrupt requests from NE bit enabled
0 = SCI error CPU interrupt requests from NE bit disabled
FEIE -- Receiver Framing Error Interrupt Enable Bit
This read/write bit enables SCI error CPU interrupt requests
generated by the framing error bit, FE. Reset clears FEIE.
1 = SCI error CPU interrupt requests from FE bit enabled
0 = SCI error CPU interrupt requests from FE bit disabled
PEIE -- Receiver Parity Error Interrupt Enable Bit
This read/write bit enables SCI receiver CPU interrupt
requests generated by the parity error bit, PE. (See
16.9.4 SCI Status
Register 1
.) Reset clears PEIE.
1 = SCI error CPU interrupt requests from PE bit enabled
0 = SCI error CPU interrupt requests from PE bit disabled
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
282
Serial Communications Interface (SCI)
MOTOROLA
16.9.4 SCI Status Register 1
SCI status register 1 (SCS1) contains flags to signal these conditions:
Transfer of SCDR data to transmit shift register complete
Transmission complete
Transfer of receive shift register data to SCDR complete
Receiver input idle
Receiver overrun
Noisy data
Framing error
Parity error
SCTE -- SCI Transmitter Empty Bit
This clearable, read-only bit is set when the SCDR transfers a
character to the transmit shift register. SCTE can generate an SCI
transmitter CPU interrupt request. When the SCTIE bit in SCC2 is set,
SCTE generates an SCI transmitter CPU interrupt request. In normal
operation, clear the SCTE bit by reading SCS1 with SCTE set and
then writing to SCDR. Reset sets the SCTE bit.
1 = SCDR data transferred to transmit shift register
0 = SCDR data not transferred to transmit shift register
Address:
$0016
Bit 7
6
5
4
3
2
1
Bit 0
Read:
SCTE
TC
SCRF
IDLE
OR
NF
FE
PE
Write:
Reset:
1
1
0
0
0
0
0
0
= Unimplemented
Figure 16-12. SCI Status Register 1 (SCS1)
Serial Communications Interface (SCI)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
283
TC -- Transmission Complete Bit
This read-only bit is set when the SCTE bit is set, and no data,
preamble, or break character is being transmitted. TC generates an
SCI transmitter CPU interrupt request if the TCIE bit in SCC2 is also
set. TC is automatically cleared when data, preamble or break is
queued and ready to be sent. There may be up to 1.5 transmitter
clocks of latency between queueing data, preamble, and break and
the transmission actually starting. Reset sets the TC bit.
1 = No transmission in progress
0 = Transmission in progress
SCRF -- SCI Receiver Full Bit
This clearable, read-only bit is set when the data in the receive shift
register transfers to the SCI data register. SCRF can generate an SCI
receiver CPU interrupt request. When the SCRIE bit in SCC2 is set,
SCRF generates a CPU interrupt request. In normal operation, clear
the SCRF bit by reading SCS1 with SCRF set and then reading the
SCDR. Reset clears SCRF.
1 = Received data available in SCDR
0 = Data not available in SCDR
IDLE -- Receiver Idle Bit
This clearable, read-only bit is set when 10 or 11 consecutive logic 1s
appear on the receiver input. IDLE generates an SCI error CPU
interrupt request if the ILIE bit in SCC2 is also set. Clear the IDLE bit
by reading SCS1 with IDLE set and then reading the SCDR. After the
receiver is enabled, it must receive a valid character that sets the
SCRF bit before an idle condition can set the IDLE bit. Also, after the
IDLE bit has been cleared, a valid character must again set the SCRF
bit before an idle condition can set the IDLE bit. Reset clears the IDLE
bit.
1 = Receiver input idle
0 = Receiver input active (or idle since the IDLE bit was cleared)
OR -- Receiver Overrun Bit
This clearable, read-only bit is set when software fails to read the
SCDR before the receive shift register receives the next character.
The OR bit generates an SCI error CPU interrupt request if the ORIE
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
284
Serial Communications Interface (SCI)
MOTOROLA
bit in SCC3 is also set. The data in the shift register is lost, but the data
already in the SCDR is not affected. Clear the OR bit by reading SCS1
with OR set and then reading the SCDR. Reset clears the OR bit.
1 = Receive shift register full and SCRF = 1
0 = No receiver overrun
Software latency may allow an overrun to occur between reads of
SCS1 and SCDR in the flag-clearing sequence.
Figure 16-13
shows
the normal flag-clearing sequence and an example of an overrun
caused by a delayed flag-clearing sequence. The delayed read of
SCDR does not clear the OR bit because OR was not set when SCS1
was read. Byte 2 caused the overrun and is lost. The next flag-
clearing sequence reads byte 3 in the SCDR instead of byte 2.
In applications that are subject to software latency or in which it is
important to know which byte is lost due to an overrun, the flag-
clearing routine can check the OR bit in a second read of SCS1 after
reading the data register.
NF -- Receiver Noise Flag Bit
This clearable, read-only bit is set when the SCI detects noise on the
RxD
pin. NF generates an NF CPU interrupt request if the NEIE bit in
SCC3 is also set. Clear the NF bit by reading SCS1 and then reading
the SCDR. Reset clears the NF bit.
1 = Noise detected
0 = No noise detected
FE -- Receiver Framing Error Bit
This clearable, read-only bit is set when a logic 0 is accepted as the
stop bit. FE generates an SCI error CPU interrupt request if the FEIE
bit in SCC3 also is set. Clear the FE bit by reading SCS1 with FE set
and then reading the SCDR. Reset clears the FE bit.
1 = Framing error detected
0 = No framing error detected
Serial Communications Interface (SCI)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
285
Figure 16-13. Flag Clearing Sequence
PE -- Receiver Parity Error Bit
This clearable, read-only bit is set when the SCI detects a parity error
in incoming data. PE generates a PE CPU interrupt request if the
PEIE bit in SCC3 is also set. Clear the PE bit by reading SCS1 with
PE set and then reading the SCDR. Reset clears the PE bit.
1 = Parity error detected
0 = No parity error detected
BYTE 1
NORMAL FLAG CLEARING SEQUENCE
READ SCS1
SCRF = 1
READ SCDR
BYTE 1
S
CRF =
1
S
CRF =
1
BYTE 2
BYTE 3
BYTE 4
OR = 0
READ SCS1
SCRF = 1
OR = 0
READ SCDR
BYTE 2
S
CRF =
0
READ SCS1
SCRF = 1
OR = 0
S
CRF
=
1
S
CRF
=
0
READ SCDR
BYTE 3
S
CRF =
0
BYTE 1
READ SCS1
SCRF = 1
READ SCDR
BYTE 1
S
CRF =
1
S
CRF =
1
BYTE 2
BYTE 3
BYTE 4
OR = 0
READ SCS1
SCRF = 1
OR = 1
READ SCDR
BYTE 3
DELAYED FLAG CLEARING SEQUENCE
OR =
1
S
CRF =
1
OR =
1
S
CRF =
0
OR =
1
S
CRF =
0
OR =
0
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
286
Serial Communications Interface (SCI)
MOTOROLA
16.9.5 SCI Status Register 2
SCI status register 2 contains flags to signal the following conditions:
Break character detected
Incoming data
BKF -- Break Flag Bit
This clearable, read-only bit is set when the SCI detects a break
character on the RxD pin. In SCS1, the FE and SCRF bits are also
set. In 9-bit character transmissions, the R8 bit in SCC3 is cleared.
BKF does not generate a CPU interrupt request. Clear BKF by
reading SCS2 with BKF set and then reading the SCDR. Once
cleared, BKF can become set again only after logic 1s again appear
on the RxD pin followed by another break character. Reset clears the
BKF bit.
1 = Break character detected
0 = No break character detected
RPF -- Reception in Progress Flag Bit
This read-only bit is set when the receiver detects a logic 0 during the
RT1 time period of the start bit search. RPF does not generate an
interrupt request. RPF is reset after the receiver detects false start bits
(usually from noise or a baud rate mismatch) or when the receiver
detects an idle character. Polling RPF before disabling the SCI
module or entering stop mode can show whether a reception is in
progress.
1 = Reception in progress
0 = No reception in progress
Address:
$0017
Bit 7
6
5
4
3
2
1
Bit 0
Read:
BKF
RPF
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 16-14. SCI Status Register 2 (SCS2)
Serial Communications Interface (SCI)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
287
16.9.6 SCI Data Register
The SCI data register (SCDR) is the buffer between the internal data bus
and the receive and transmit shift registers. Reset has no effect on data
in the SCI data register.
R7/T7R0/T0 -- Receive/Transmit Data Bits
Reading the SCI data register (SCDR) accesses the read-only
received data bits, R7:R0. Writing to the SCDR writes the data to be
transmitted, T7:T0. Reset has no effect on the SCDR.
NOTE:
Do not use read/modify/write instructions on the SCI data register.
Address:
$0018
Bit 7
6
5
4
3
2
1
Bit 0
Read:
R7
R6
R5
R4
R3
R2
R1
R0
Write:
T7
T6
T5
T4
T3
T2
T1
T0
Reset:
Unaffected by reset
Figure 16-15. SCI Data Register (SCDR)
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
288
Serial Communications Interface (SCI)
MOTOROLA
16.9.7 SCI Baud Rate Register
The baud rate register (SCBR) selects the baud rate for both the receiver
and the transmitter.
SCP1 and SCP0 -- SCI Baud Rate Prescaler Bits
These read/write bits select the baud rate prescaler divisor as shown
in
Table 16-6
. Reset clears SCP1 and SCP0.
SCR2SCR0 -- SCI Baud Rate Select Bits
These read/write bits select the SCI baud rate divisor as shown in
Table 16-7
. Reset clears SCR2SCR0.
Address:
$0019
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
SCP1
SCP0
R
SCR2
SCR1
SCR0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
R
= Reserved
Figure 16-16. SCI Baud Rate Register (SCBR)
Table 16-6. SCI Baud Rate Prescaling
SCP1 and SCP0
Prescaler Divisor (PD)
00
1
01
3
10
4
11
13
Serial Communications Interface (SCI)
I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Serial Communications Interface (SCI)
289
Use this formula to calculate the SCI baud rate:
where:
SCI clock source = f
BUS
or CGMXCLK
(selected by SCIBDSRC bit in CONFIG2 register)
PD = prescaler divisor
BD = baud rate divisor
Table 16-8
shows the SCI baud rates that can be generated with a
4.9152-MHz bus clock when f
BUS
is selected as SCI clock source.
Table 16-7. SCI Baud Rate Selection
SCR2, SCR1, and SCR0
Baud Rate Divisor (BD)
000
1
001
2
010
4
011
8
100
16
101
32
110
64
111
128
baud rate
SCI clock source
64
PD
BD
---------------------------------------------
=
Serial Communications Interface (SCI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
290
Serial Communications Interface (SCI)
MOTOROLA
Table 16-8. SCI Baud Rate Selection Examples
SCP1 and
SCP0
Prescaler
Divisor (PD)
SCR2, SCR1,
and SCR0
Baud Rate
Divisor (BD)
Baud Rate
(f
BUS
= 4.9152 MHz)
00
1
000
1
76,800
00
1
001
2
38,400
00
1
010
4
19,200
00
1
011
8
9600
00
1
100
16
4800
00
1
101
32
2400
00
1
110
64
1200
00
1
111
128
600
01
3
000
1
25,600
01
3
001
2
12,800
01
3
010
4
6400
01
3
011
8
3200
01
3
100
16
1600
01
3
101
32
800
01
3
110
64
400
01
3
111
128
200
10
4
000
1
19,200
10
4
001
2
9600
10
4
010
4
4800
10
4
011
8
2400
10
4
100
16
1200
10
4
101
32
600
10
4
110
64
300
10
4
111
128
150
11
13
000
1
5908
11
13
001
2
2954
11
13
010
4
1477
11
13
011
8
739
11
13
100
16
369
11
13
101
32
185
11
13
110
64
92
11
13
111
128
46
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
291
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 17. Multi-Master IIC Interface (MMIIC)
17.1 Contents
17.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292
17.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
17.4
I/O Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
17.5
Multi-Master IIC System Configuration . . . . . . . . . . . . . . . . . . 295
17.6
Multi-Master IIC Bus Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 295
17.6.1
START Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
17.6.2
Slave Address Transmission . . . . . . . . . . . . . . . . . . . . . . . 296
17.6.3
Data Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
17.6.4
Repeated START Signal . . . . . . . . . . . . . . . . . . . . . . . . . .297
17.6.5
STOP Signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .297
17.6.6
Arbitration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . .297
17.6.7
Clock Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
17.6.8
Handshaking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
17.6.9
Packet Error Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
17.7
MMIIC I/O Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299
17.7.1
MMIIC Address Register (MMADR) . . . . . . . . . . . . . . . . . . 299
17.7.2
MMIIC Control Register 1 (MMCR1) . . . . . . . . . . . . . . . . . 301
17.7.3
MMIIC Control Register 2 (MMCR2) . . . . . . . . . . . . . . . . . 303
17.7.4
MMIIC Status Register (MMSR). . . . . . . . . . . . . . . . . . . . . 305
17.7.5
MMIIC Data Transmit Register (MMDTR) . . . . . . . . . . . . . 307
17.7.6
MMIIC Data Receive Register (MMDRR). . . . . . . . . . . . . . 308
17.7.7
MMIIC CRC Data Register (MMCRCDR). . . . . . . . . . . . . . 309
17.7.8
MMIIC Frequency Divider Register (MMFDR) . . . . . . . . . . 310
17.8
Program Algorithm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
17.8.1
Data Sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312
17.9
SMBus Protocols with PEC and without PEC. . . . . . . . . . . . . 313
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
292
Multi-Master IIC Interface (MMIIC)
MOTOROLA
17.9.1
Quick Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
17.9.2
Send Byte. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
17.9.3
Receive Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
17.9.4
Write Byte/Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
17.9.5
Read Byte/Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
17.9.6
Process Call . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .315
17.9.7
Block Read/Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
17.10 SMBus Protocol Implementation . . . . . . . . . . . . . . . . . . . . . . 316
17.2 Introduction
The multi-master IIC (MMIIC) interface is a two wire, bidirectional serial
bus which provides a simple, efficient way for data exchange between
devices. The interface is designed for internal serial communication
between the MCU and other IIC devices. It has hardware generated
START and STOP signals; and byte by byte interrupt driven software
algorithm.
This bus is suitable for applications which need frequent
communications over a short distance between a number of devices. It
also provides a flexibility that allows additional devices to be connected
to the bus. The maximum data rate is 100k-bps, and the maximum
communication distance and number of devices that can be connected
is limited by a maximum bus capacitance of 400pF.
This MMIIC interface is also SMBus (System Management Bus) version
1.0 and 1.1 compatible, with hardware cyclic redundancy code (CRC)
generation, making it suitable for smart battery applications.
For connection flexibility, two channels are available:
Channel 0 -- SDA0 and SCL0
Channel 1 -- SDA1 and SCL1
The two channels are multiplexed; only one channel is active at any one
time.
Multi-Master IIC Interface (MMIIC)
Features
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
293
17.3 Features
Features of the MMIC module include:
Full SMBus version 1.0/1.1 compliance
Multi-master IIC bus standard
Software programmable for one of eight different serial clock
frequencies
Software controllable acknowledge bit generation
Interrupt driven byte by byte data transfer
Calling address identification interrupt
Arbitration loss detection and no-ACK awareness in master mode
and automatic mode switching from master to slave
Auto detection of R/W bit and switching of transmit or receive
mode accordingly
Detection of START, repeated START, and STOP signals
Auto generation of START and STOP condition in master mode
Repeated start generation
Master clock generator with eight selectable baud rates
Automatic recognition of the received acknowledge bit
Busy detection
Software enabled 8-bit CRC generation/decoding
17.4 I/O Pins
The MMIIC module uses four I/O pins, shared with standard port I/O
pins. The full name of the MMIIC I/O pins are listed in
Table 17-1
.
The
generic pin name appear in the text that follows.
The SDA0/SCL0 and SDA1/SCL1 pins are open-drain. When configured
as general purpose output pins (PTB0PTB3), pullup resistors must be
connected to these pins.
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
294
Multi-Master IIC Interface (MMIIC)
MOTOROLA
Table 17-1. Pin Name Conventions
MMIIC Generic Pin Names:
Full MCU Pin Names:
Pin Selected for MMIIC Function By:
SDA0
PTB0/SDA0
MMEN and SDASCL1 bits in MMCR1 ($0049)
SCL0
PTB1/SCL0
SDA1
PTB2/SDA1/TxD
ENSCI bit in SCC1 ($0013);
MMEN and SDASCL1 bits in MMCR1 ($0049)
SCL1
PTB3/SCL1/RxD
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0048
MMIIC Address Register
(MMADR)
Read:
MMAD7
MMAD6
MMAD5
MMAD4
MMAD3
MMAD2
MMAD1
MMEXTAD
Write:
Reset:
1
0
1
0
0
0
0
0
$0049
MMIIC Control Register 1
(MMCR1)
Read:
MMEN
MMIEN
0
0
MMTXAK REPSEN
MMCRCBYTE
SDASCL1
Write:
MMCLRBB
Reset:
0
0
0
0
0
0
0
0
$004A
MMIIC Control Register 2
(MMCR2)
Read: MMALIF MMNAKIF
MMBB
MMAST
MMRW
0
0
MMCRCEF
Write:
0
0
Reset:
0
0
0
0
0
0
0
Unaffected
$004B
MMIIC Status Register
(MMSR)
Read: MMRXIF
MMTXIF
MMATCH
MMSRW MMRXAK
MMCRCBF
MMTXBE MMRXBF
Write:
0
0
Reset:
0
0
0
0
1
0
1
0
$004C
MMIIC Data Transmit
Register
(MMDTR)
Read:
MMTD7
MMTD6
MMTD5
MMTD4
MMTD3
MMTD2
MMTD1
MMTD0
Write:
Reset:
0
0
0
0
0
0
0
0
$004D
MMIIC Data Receive
Register
(MDDRR)
Read: MMRD7
MMRD6
MMRD5
MMRD4
MMRD3
MMRD2
MMRD1
MMRD0
Write:
Reset:
0
0
0
0
0
0
0
0
$004E
MMIIC CRC Data Register
(MMCRDR)
Read:
MMCRCD7 MMCRCD6 MMCRCD5 MMCRCD4 MMCRCD3 MMCRCD2 MMCRCD1 MMCRCD0
Write:
Reset:
0
0
0
0
0
0
0
0
$004F
MMIIC Frequency Divider
Register
(MMFDR)
Read:
0
0
0
0
0
MMBR2
MMBR1
MMBR0
Write:
Reset:
0
0
0
0
0
1
0
0
= Unimplemented
Figure 17-1. MMIIC I/O Register Summary
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC System Configuration
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
295
17.5 Multi-Master IIC System Configuration
The multi-master IIC system uses a serial data line SDA and a serial
clock line SCL for data transfer. All devices connected to it must have
open collector (drain) outputs and the logical-AND function is performed
on both lines by two pull-up resistors.
17.6 Multi-Master IIC Bus Protocol
Normally a standard communication is composed of four parts:
1. START signal,
2. slave address transmission,
3. data transfer, and
4. STOP signal.
These are described briefly in the following sections and illustrated in
Figure 17-2
.
Figure 17-2. Multi-Master IIC Bus Transmission Signal Diagram
1
0
1
0
0
0
1
1
1
0
1
1
0
0
1
1
1
0
1
0
0
0
1
1
1
0
1
1
0
0
1
1
SCL
SDA
SCL
SDA
MSB
LSB
MSB
LSB
MSB
LSB
MSB
LSB
START
STOP
Repeated
START
STOP
9th clock pulse
9th clock pulse
ACK
No ACK
signal
signal
signal
signal
signal
ACK
No ACK
START
Data must be stable
when SCL is HIGH
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
296
Multi-Master IIC Interface (MMIIC)
MOTOROLA
17.6.1 START Signal
When the bus is free, (i.e. no master device is engaging the bus -- both
SCL and SDA lines are at logic high) a master may initiate
communication by sending a START signal. As shown in
Figure 17-2
, a
START signal is defined as a high to low transition of SDA while SCL is
high. This signal denotes the beginning of a new data transfer (each data
transfer may contain several bytes of data) and wakes up all slaves.
17.6.2 Slave Address Transmission
The first byte transferred immediately after the START signal is the slave
address transmitted by the master. This is a 7-bit calling address
followed by a R/W-bit. The R/W-bit dictates to the slave the desired
direction of the data transfer. A logic 0 indicates that the master wishes
to transmit data to the slave; a logic 1 indicates that the master wishes
to receive data from the slave.
Only the slave with a matched address will respond by sending back an
acknowledge bit by pulling SDA low on the 9th clock cycle.
(See
Figure 17-2
.)
17.6.3 Data Transfer
Once a successful slave addressing is achieved, the data transfer can
proceed byte by byte in the direction specified by the R/W-bit sent by the
calling master.
Each data byte is 8 bits. Data can be changed only when SCL is low and
must be held stable when SCL is high as shown in
Figure 17-2
. The
MSB is transmitted first and each byte has to be followed by an
acknowledge bit. This is signalled by the receiving device by pulling the
SDA low on the 9th clock cycle. Therefore, one complete data byte
transfer requires 9 clock cycles.
If the slave receiver does not acknowledge the master, the SDA line
should be left high by the slave. The master can then generate a STOP
signal to abort the data transfer or a START signal (repeated START) to
commence a new transfer.
Multi-Master IIC Interface (MMIIC)
Multi-Master IIC Bus Protocol
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
297
If the master receiver does not acknowledge the slave transmitter after
a byte has been transmitted, it means an "end of data" to the slave. The
slave should release the SDA line for the master to generate a STOP or
START signal.
17.6.4 Repeated START Signal
As shown in
Figure 17-2
, a repeated START signal is used to generate
START signal without first generating a STOP to terminate the
communication. This is used by the master to communicate with another
slave or with the same slave in a different mode (transmit/receive mode)
without releasing the bus.
17.6.5 STOP Signal
The master can terminate the communication by generating a STOP
signal to free the bus. However, the master may generate a START
signal followed by a calling command without first generating a STOP
signal. This is called repeat START. A STOP signal is defined as a low
to high transition of SDA while SCL is at logic high (see
Figure 17-2
).
17.6.6 Arbitration Procedure
The interface circuit is a multi-master system which allows more than
one master to be connected. If two or more masters try to control the bus
at the same time, a clock synchronization procedure determines the bus
clock. The clock low period is equal to the longest clock low period and
the clock high period is equal to the shortest one among the masters. A
data arbitration procedure determines the priority. A master will lose
arbitration if it transmits a logic 1 while another transmits a logic 0. The
losing master will immediately switch over to slave receive mode and
stops its data and clock outputs. The transition from master to slave will
not generate a STOP condition. Meanwhile a software bit will be set by
hardware to indicates loss of arbitration.
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
298
Multi-Master IIC Interface (MMIIC)
MOTOROLA
17.6.7 Clock Synchronization
Since wired-AND logic is performed on SCL line, a high to low transition
on the SCL line will affect the devices connected to the bus. The devices
start counting their low period once a device's clock has gone low, it will
hold the SCL line low until the clock high state is reached. However, the
change of low to high in this device clock may not change the state of the
SCL line if another device clock is still in its low period. Therefore the
synchronized clock SCL will be held low by the device which last
releases SCL to logic high. Devices with shorter low periods enter a high
wait state during this time. When all devices concerned have counted off
their low period, the synchronized SCL line will be released and go high,
and all devices will start counting their high periods. The first device to
complete its high period will again pull the SCL line low.
Figure 17-3
illustrates the clock synchronization waveforms.
Figure 17-3. Clock Synchronization
17.6.8 Handshaking
The clock synchronization mechanism can be used as a handshake in
data transfer. A slave device may hold the SCL low after completion of
one byte data transfer and will halt the bus clock, forcing the master
clock into a wait state until the slave releases the SCL line.
SCL1
SCL2
SCL
Internal counter reset
WAIT
Start counting high period
Multi-Master IIC Interface (MMIIC)
MMIIC I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
299
17.6.9 Packet Error Code
The packet error code (PEC) for the MMIIC interface is in the form a
cyclic redundancy code (CRC). The PEC is generated by hardware for
every transmitted and received byte of data. The transmission of the
generated PEC is controlled by user software.
The CRC data register, MMCRCDR, contains the generated PEC byte,
with three other bits in the MMIIC control registers and status register
monitoring and controlling the PEC byte.
17.7 MMIIC I/O Registers
These I/O registers control and monitor MMIIC operation:
MMIIC address register (MMADR) -- $0048
MMIIC control register 1 (MMCR1) -- $0049
MMIIC control register 2 (MMCR2) -- $004A
MMIIC status register (MMSR) -- $004B
MMIIC data transmit register (MMDTR) -- $004C
MMIIC data receive register (MMDRR) -- $004D
MMIIC CRC data register (MMCRCDR) -- $004E
MMIIC frequency divide register (MMFDR) -- $004F
17.7.1
MMIIC
Address Register (MMADR)
Address:
$0048
Bit 7
6
5
4
3
2
1
Bit 0
Read:
MMAD7
MMAD6
MMAD5
MMAD4
MMAD3
MMAD2
MMAD1
MMEXTAD
Write:
Reset:
1
0
1
0
0
0
0
0
Figure 17-4. MMIIC Address Register (MMADR)
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
300
Multi-Master IIC Interface (MMIIC)
MOTOROLA
MMAD[7:1] -- Multi-Master Address
These seven bits represent the MMIIC interface's own specific slave
address when in slave mode, and the calling address when in master
mode. Software must update MMAD[7:1] as the calling address while
entering master mode and restore its own slave address after master
mode is relinquished. This register is cleared as $A0 upon reset.
MMEXTAD -- Multi-Master Expanded Address
This bit is set to expand the address of the MMIIC in slave mode.
When set, the MMIIC will acknowledge the following addresses from
a calling master: $MMAD[7:1], 0000000, and 0001100.
Reset clears this bit.
1 = MMIIC responds to the following calling addresses:
$MMAD[7:1], 0000000, and 0001100.
0 = MMIIC responds to address $MMAD[7:1]
For example, when MMADR is configured as:
The MMIIC module will respond to the calling address:
or the general calling address:
or the calling address:
Note that bit-0 of the 8-bit calling address is the MMRW bit from the
calling master.
MMAD7 MMAD6 MMAD5 MMAD4 MMAD3 MMAD2 MMAD
1 MMEXTAD
1
1
0
1
0
1
0
1
Bit 7
6
5
4
3
2
Bit 1
1
1
0
1
0
1
0
0
0
0
0
0
0
0
Bit 7
6
5
4
3
2
Bit 1
0
0
0
1
1
0
0
Multi-Master IIC Interface (MMIIC)
MMIIC I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
301
17.7.2
MMIIC
Control Register 1 (MMCR1)
MMEN -- MMIIC Enable
This bit is set to enable the Multi-master IIC module. When
MMEN = 0, module is disabled and all flags will restore to its power-
on default states. Reset clears this bit.
1 = MMIIC module enabled
0 = MMIIC module disabled
MMIEN -- MMIIC Interrupt Enable
When this bit is set, the MMTXIF, MMRXIF, MMALIF, and MMNAKIF
flags are enabled to generate an interrupt request to the CPU. When
MMIEN is cleared, the these flags are prevented from generating an
interrupt request. Reset clears this bit.
1 = MMTXIF, MMRXIF, MMALIF, and/or MMNAKIF bit set will
generate interrupt request to CPU
0 = MMTXIF, MMRXIF, MMALIF, and/or MMNAKIF bit set will not
generate interrupt request to CPU
MMCLRBB -- MMIIC Clear Busy Flag
Writing a logic 1 to this write-only bit clears the MMBB flag.
MMCLRBB always reads as a logic 0. Reset clears this bit.
1 = Clear MMBB flag
0 = No affect on MMBB flag
Address:
$0049
Bit 7
6
5
4
3
2
1
Bit 0
Read:
MMEN
MMIEN
0
0
MMTXAK REPSEN
MMCRCBYTE
SDASCL1
Write:
MMCLRBB
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 17-5. MMIIC Control Register 1 (MMCR1)
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
302
Multi-Master IIC Interface (MMIIC)
MOTOROLA
MMTXAK -- MMIIC Transmit Acknowledge Enable
This bit is set to disable the MMIIC from sending out an acknowledge
signal to the bus at the 9th clock bit after receiving 8 data bits. When
MMTXAK is cleared, an acknowledge signal will be sent at the 9th
clock bit. Reset clears this bit.
1 = MMIIC does not send acknowledge signals at 9th clock bit
0 = MMIIC sends acknowledge signal at 9th clock bit
REPSEN -- Repeated Start Enable
This bit is set to enable repeated START signal to be generated when
in master mode transfer (MMAST = 1). The REPSEN bit is cleared by
hardware after the completion of repeated START signal or when the
MMAST bit is cleared. Reset clears this bit.
1 = Repeated START signal will be generated if MMAST bit is set
0 = No repeated START signal will be generated
MMCRCBYTE -- MMIIC CRC Byte
In receive mode, this bit is set by software to indicate that the next
receiving byte will be the packet error checking (PEC) data.
In master receive mode, after completion of CRC generation on the
received PEC data, an acknowledge signal is sent if MMTXAK = 0; no
acknowledge is sent If MMTXAK = 1.
In slave receive mode, no acknowledge signal is sent if a CRC error
is detected on the received PEC data. If no CRC error is detected, an
acknowledge signal is sent if MMTXAK = 0; no acknowledge is sent If
MMTXAK = 1.
Under normal operation, the user software should clear MMTXAK bit
before setting MMCRCBYTE bit to ensure that an acknowledge signal
is sent when no CRC error is detected.
The MMCRCBYTE bit should not be set in transmit mode. This bit is
cleared by the next START signal. Reset also clears this bit.
1 = Next receiving byte is the packet error checking (PEC) data
0 = Next receiving byte is not PEC data
Multi-Master IIC Interface (MMIIC)
MMIIC I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
303
SDASCL1 -- SDA and SCL I/O Pin Select
This bit selects either SDA0 and SCL0, or SDA1 and SCL1, for MMIIC
I/O pins when MMIIC module is enabled (MMEN = 1). If the SCI
module is enabled (ENSCI = 0), the SDA1 and SCL1 pins are not
available for MMIIC.
Reset clears SDASCL1 bit.
1 = MMIIC module uses SDA1 and SCL1 I/O pins
0 = MMIIC module uses SDA0 and SCL0 I/O pins
17.7.3
MMIIC
Control Register 2 (MMCR2)
MMALIF -- Arbitration Loss Interrupt Flag
This flag is set when software attempt to set MMAST but the MMBB
has been set by detecting the start condition on the lines or when the
MMIIC is transmitting a "1" to SDA line but detected a "0" from SDA
line in master mode -- an arbitration loss. This bit generates an
interrupt request to the CPU if the MMIEN bit in MMCR1 is set. This
bit is cleared by writing "0" to it or by reset.
1 = Lost arbitration in master mode
0 = No arbitration lost
MMNAKIF -- No AcKnowledge Interrupt Flag (Master Mode)
This flag is only set in master mode (MMAST = 1) when there is no
acknowledge bit detected after one data byte or calling address is
transferred. This flag also clears MMAST. MMNAKIF generates an
interrupt request to CPU if the MMIEN bit in MMCR1 is set. This bit is
cleared by writing "0" to it or by reset.
1 = No acknowledge bit detected
0 = Acknowledge bit detected
Address:
$004A
Bit 7
6
5
4
3
2
1
Bit 0
Read: MMALIF MMNAKIF
MMBB
MMAST
MMRW
0
0
MMCRCEF
Write:
0
0
Reset:
0
0
0
0
0
0
0
Unaffected
= Unimplemented
Figure 17-6. MMIIC Control Register 2 (MMCR2)
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
304
Multi-Master IIC Interface (MMIIC)
MOTOROLA
MMBB -- MMIIC Bus Busy Flag
This flag is set after a start condition is detected (bus busy), and is
cleared when a stop condition (bus idle) is detected or the MMIIC is
disabled. Reset clears this bit.
1 = Start condition detected
0 = Stop condition detected or MMIIC is disabled
MMAST -- MMIIC Master Control
This bit is set to initiate a master mode transfer. In master mode, the
module generates a start condition to the SDA and SCL lines,
followed by sending the calling address stored in MMADR.
When the MMAST bit is cleared by MMNAKIF set (no acknowledge)
or by software, the module generates the stop condition to the lines
after the current byte is transmitted.
If an arbitration loss occurs (MMALIF = 1), the module reverts to slave
mode by clearing MMAST, and releasing SDA and SCL lines
immediately.
This bit is cleared by writing "0" to it or by reset.
1 = Master mode operation
0 = Slave mode operation
MMRW -- MMIIC Master Read/Write
This bit is transmitted out as bit 0 of the calling address when the
module sets the MMAST bit to enter master mode. The MMRW bit
determines the transfer direction of the data bytes that follows. When
it is "1", the module is in master receive mode. When it is "0", the
module is in master transmit mode. Reset clears this bit.
1 = Master mode receive
0 = Master mode transmit
MMCRCEF -- MMIIC CRC Error Flag
This flag is set when a CRC error is detected, and cleared when no
CRC error is detected. The MMCRCEF is only meaningful after
receiving a PEC data. This flag is unaffected by reset.
1 = CRC error detected on PEC byte
0 = No CRC error detected on PEC byte
Multi-Master IIC Interface (MMIIC)
MMIIC I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
305
17.7.4 MMIIC Status Register (MMSR)
MMRXIF -- MMIIC Receive Interrupt Flag
This flag is set after the data receive register (MMDRR) is loaded with
a new received data. Once the MMDRR is loaded with received data,
no more received data can be loaded to the MMDRR register until the
CPU reads the data from the MMDRR to clear MMRXBF flag.
MMRXIF generates an interrupt request to CPU if the MMIEN bit in
MMCR is also set. This bit is cleared by writing "0" to it or by reset; or
when the MMEN = 0.
1 = New data in data receive register (MMDRR)
0 = No data received
MMTXIF -- MMIIC Transmit Interrupt Flag
This flag is set when data in the data transmit register (MMDTR) is
downloaded to the output circuit, and that new data can be written to
the MMDTR. MMTXIF generates an interrupt request to CPU if the
MMIEN bit in MMCR is also set. This bit is cleared by writing "0" to it
or when the MMEN = 0.
1 = Data transfer completed
0 = Data transfer in progress
MMATCH -- MMIIC Address Match Flag
This flag is set when the received data in the data receive register
(MMDRR) is a calling address which matches with the address or its
extended addresses (MMEXTAD = 1) specified in the address
register (MMADR). The MMATCH flag is set at the 9th clock of the
calling address and will be cleared on the 9th clock of the next
receiving data. Note: slave transmits do not clear MMATCH.
Address:
$004B
Bit 7
6
5
4
3
2
1
Bit 0
Read: MMRXIF
MMTXIF
MMATCH
MMSRW MMRXAK
MMCRCBF
MMTXBE MMRXBF
Write:
0
0
Reset:
0
0
0
0
1
0
1
0
= Unimplemented
Figure 17-7. MMIIC Status Register (MMSR)
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
306
Multi-Master IIC Interface (MMIIC)
MOTOROLA
1 = Received address matches MMADR
0 = Received address does not match
MMSRW -- MMIIC Slave Read/Write Select
This bit indicates the data direction when the module is in slave mode.
It is updated after the calling address is received from a master
device. MMSRW = 1 when the calling master is reading data from the
module (slave transmit mode). MMSRW = 0 when the master is
writing data to the module (receive mode).
1 = Slave mode transmit
0 = Slave mode receive
MMRXAK -- MMIIC Receive Acknowledge
When this bit is cleared, it indicates an acknowledge signal has been
received after the completion of eight data bits transmission on the
bus. When MMRXAK is set, it indicates no acknowledge signal has
been detected at the 9th clock; the module will release the SDA line
for the master to generate STOP or repeated START condition. Reset
sets this bit.
1 = No acknowledge signal received at 9th clock
0 = Acknowledge signal received at 9th clock
MMCRCBF -- CRC Data Buffer Full Flag
This flag is set when the CRC data register (MMCRCDR) is loaded
with a CRC byte for the current received or transmitted data.
In transmit mode, after a byte of data has been sent (MMTXIF = 1),
the MMCRCBF will be set when the CRC byte has been generated
and ready in the MMCRCDR. The content of the MMCRCDR should
be copied to the MMDTR for transmission.
In receive mode, the MMCRCBF is set when the CRC byte has been
generated and ready in MMCRCDR, for the current byte of received
data.
The MMCRCBF bit is cleared when the CRC data register is read.
Reset also clears this bit.
1 = Data ready in CRC data register (MMCRCDR)
0 = Data not ready in CRC data register (MMCRCDR)
Multi-Master IIC Interface (MMIIC)
MMIIC I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
307
MMTXBE -- MMIIC Transmit Buffer Empty
This flag indicates the status of the data transmit register (MMDTR).
When the CPU writes the data to the MMDTR, the MMTXBE flag will
be cleared. MMTXBE is set when MMDTR is emptied by a transfer of
its data to the output circuit. Reset sets this bit.
1 = Data transmit register empty
0 = Data transmit register full
MMRXBF -- MMIIC Receive Buffer Full
This flag indicates the status of the data receive register (MMDRR).
When the CPU reads the data from the MMDRR, the MMRXBF flag
will be cleared. MMRXBF is set when MMDRR is full by a transfer of
data from the input circuit to the MMDRR. Reset clears this bit.
1 = Data receive register full
0 = Data receive register empty
17.7.5
MMIIC
Data Transmit Register (MMDTR)
When the MMIIC module is enabled, MMEN = 1, data written into this
register depends on whether module is in master or slave mode.
In slave mode, the data in MMDTR will be transferred to the output circuit
when:
the module detects a matched calling address (MMATCH = 1),
with the calling master requesting data (MMSRW = 1); or
the previous data in the output circuit has be transmitted and the
receiving master returns an acknowledge bit, indicated by a
received acknowledge bit (MMRXAK = 0).
Address:
$004C
Bit 7
6
5
4
3
2
1
Bit 0
Read:
MMTD7
MMTD6
MMTD5
MMTD4
MMTD3
MMTD2
MMTD1
MMTD0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 17-8. MMIIC Data Transmit Register (MMDTR)
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
308
Multi-Master IIC Interface (MMIIC)
MOTOROLA
If the calling master does not return an acknowledge bit (MMRXAK = 1),
the module will release the SDA line for master to generate a STOP or
repeated START condition. The data in the MMDTR will not be
transferred to the output circuit until the next calling from a master. The
transmit buffer empty flag remains cleared (MMTXBE = 0).
In master mode, the data in MMDTR will be transferred to the output
circuit when:
the module receives an acknowledge bit (MMRXAK = 0), after
setting master transmit mode (MMRW = 0), and the calling
address has been transmitted; or
the previous data in the output circuit has be transmitted and the
receiving slave returns an acknowledge bit, indicated by a
received acknowledge bit (MMRXAK = 0).
If the slave does not return an acknowledge bit (MMRXAK = 1), the
master will generate a STOP or repeated START condition. The data in
the MMDTR will not be transferred to the output circuit. The transmit
buffer empty flag remains cleared (MMTXBE = 0).
The sequence of events for slave transmit and master transmit are
illustrated in
Figure 17-12
.
17.7.6 MMIIC Data Receive Register (MMDRR)
When the MMIIC module is enabled, MMEN = 1, data in this read-only
register depends on whether module is in master or slave mode.
In slave mode, the data in MMDRR is:
Address:
$004D
Bit 7
6
5
4
3
2
1
Bit 0
Read: MMRD7
MMRD6
MMRD5
MMRD4
MMRD3
MMRD2
MMRD1
MMRD0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 17-9. MMIIC Data Receive Register (MMDRR)
Multi-Master IIC Interface (MMIIC)
MMIIC I/O Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
309
the calling address from the master when the address match flag
is set (MMATCH = 1); or
the last data received when MMATCH = 0.
In master mode, the data in the MMDRR is:
the last data received.
When the MMDRR is read by the CPU, the receive buffer full flag is
cleared (MMRXBF = 0), and the next received data is loaded to the
MMDRR. Each time when new data is loaded to the MMDRR, the
MMRXIF interrupt flag is set, indicating that new data is available in
MMDRR.
The sequence of events for slave receive and master receive are
illustrated in
Figure 17-12
.
17.7.7 MMIIC CRC Data Register (MMCRCDR)
When the MMIIC module is enabled, MMEN = 1, and the CRC buffer full
flag is set (MMCRCBF = 1), data in this read-only register contains the
generated CRC byte for the last byte of received or transmitted data.
A CRC byte is generated for each received and transmitted data byte
and loaded to the CRC data register. The MMCRCBF bit will be set to
indicate the CRC byte is ready in the CRC data register.
Reading the CRC data register clears the MMCRCBF bit. If the CRC
data register is not read, the MMCRCBF bit will be cleared by hardware
before the next CRC byte is loaded.
Address:
$004E
Bit 7
6
5
4
3
2
1
Bit 0
Read:
MMCRCD7 MMCRCD6 MMCRCD5 MMCRCD4 MMCRCD3 MMCRCD2 MMCRCD1 MMCRCD0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 17-10. MMIIC CRC Data Register (MMCRCDR)
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
310
Multi-Master IIC Interface (MMIIC)
MOTOROLA
17.7.8 MMIIC Frequency Divider Register (MMFDR)
The three bits in the frequency divider register (MMFDR) selects the
divider to divide the bus clock to the desired baud rate for the MMIIC data
transfer.
Table 17-2
shows the divider values for MMBR[2:0].
NOTE:
The frequency of the MMIIC baud rate is only guaranteed for 100kHz to
10kHz. The divider is available for the flexibility on bus frequency
selection.
Address:
$004F
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
0
MMBR2
MMBR1
MMBR0
Write:
Reset:
0
0
0
0
0
1
0
0
= Unimplemented
Figure 17-11. MMIIC Frequency Divider Register (MMFDR)
Table 17-2. MMIIC Baud Rate Selection
MMBR2
MMBR1
MMBR0
Divider
MMIIC Baud Rates for Bus Clocks:
8MHz
4MHz
2MHz
1MHz
0
0
0
20
400kHz
200kHz
100kHz
50kHz
0
0
1
40
200kHz
100kHz
50kHz
25kHz
0
1
0
80
100kHz
50kHz
25kHz
12.5kHz
0
1
1
160
50kHz
25kHz
12.5kHz
6.25kHz
1
0
0
320
25kHz
12.5kHz
6.25kHz
3.125kHz
1
0
1
640
12.5kHz
6.25kHz
3.125kHz
1.5625kHz
1
1
0
1280
6.25kHz
3.125kHz
1.5625kHz
0.78125kHz
1
1
1
2560
3.125kHz
1.5625kHz
0.78125kHz
0.3906kHz
Multi-Master IIC Interface (MMIIC)
Program Algorithm
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
311
17.8
Program Algorithm
When the MMIIC module detects an arbitration loss in master mode, it
releases both SDA and SCL lines immediately. But if there are no further
STOP conditions detected, the module will hang up. Therefore, it is
recommended to have time-out software to recover from this condition.
The software can start the time-out counter by looking at the MMBB (bus
busy) flag and reset the counter on the completion of one byte
transmission. If a time-out has occurred, software can clear the MMEN
bit (disable MMIIC module) to release the bus, and hence clear the
MMBB flag. This is the only way to clear the MMBB flag by software if
the module hangs up due to a no STOP condition received. The MMIIC
can resume operation again by setting the MMEN bit.
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
312
Multi-Master IIC Interface (MMIIC)
MOTOROLA
17.8.1 Data Sequence
Figure 17-12. Data Transfer Sequences for Master/Slave Transmit/Receive Modes
START
Address
ACK
TX Data1
MMTXBE=0
MMRW=0
MMAST=1
MMTXIF=1
MMTXBE=1
MMNAKIF=1
MMAST=0
MMTXBE=1
(a) Master Transmit Mode
(b) Master Receive Mode
(c) Slave Transmit Mode
MMTXIF=1
MMTXBE=0
ACK
TX DataN
ACK
STOP
MMTXIF=1
MMTXBE=1
START
Address
ACK
RX Data1
MMRXBF=0
MMAST=1
MMTXBE=0
MMRXBF=1
MMRXIF=1
MMNAKIF=1
MMAST=0
MMRXIF=1
MMRXBF=1
ACK
RX DataN
NAK
STOP
1
START
Address
ACK
TX Data1
MMTXBE=1
MMRXBF=0
MMNAKIF=1
MMTXBE=0
MMTXBE=1
(d) Slave Receive Mode
MMTXIF=1
ACK
TX DataN
NAK
STOP
MMRXBF=1
MMRXIF=1
MMATCH=1
MMSRW=1
MMTXIF=1
MMTXBE=1
0
START
Address
ACK
RX Data1
MMRXBF=1
MMRXIF=1
MMRXIF=1
MMRXBF=1
ACK
RX DataN
ACK
STOP
MMTXBE=0
MMRXBF=0
MMRXBF=1
MMRXIF=1
MMATCH=1
MMSRW=0
Data1
MMDRR
DataN
MMDRR
Data1
MMDTR
Data2
MMDTR
DataN+2
MMDTR
Data1
MMDTR
Data2
MMDTR
Data3
MMDTR
DataN+2
MMDTR
(dummy data
MMDTR)
MMRW=1
Data1
MMDRR
DataN
MMDRR
0
1
Shaded data packets indicate transmissions by the MCU
Multi-Master IIC Interface (MMIIC)
SMBus Protocols with PEC and without PEC
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
313
17.9 SMBus Protocols with PEC and without PEC
Following is a description of the various MMIIC bus protocols with and
without a packet error code (PEC).
17.9.1 Quick Command
Figure 17-13. Quick Command
17.9.2 Send Byte
Figure 17-14. Send Byte
17.9.3 Receive Byte
Figure 17-15. Receive Byte
START
Slave Address
ACK
STOP
RW
Master to Slave
Slave to Master
Command Bit
Acknowledge
Stop Condition
Start Condition
1
7
1
1
1
START
Slave Address
ACK
W
Command Code
ACK
STOP
ACK
STOP
PEC
START
Slave Address
ACK
W
Command Code
ACK
(a) Send Byte Protocol
(b) Send Byte Protocol with PEC
START
Slave Address
ACK
R
Data Byte
NAK
STOP
NAK
STOP
PEC
START
Slave Address
ACK
R
Data Byte
ACK
(b) Receive Byte Protocol with PEC
(a) Receive Byte Protocol
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
314
Multi-Master IIC Interface (MMIIC)
MOTOROLA
17.9.4 Write Byte/Word
Figure 17-16. Write Byte/Word
17.9.5 Read Byte/Word
Figure 17-17. Read Byte/Word
ACK
Command Code
ACK
Data Byte Low
ACK
Data Byte High
ACK
STOP
ACK
Command Code
ACK
Data Byte
ACK
STOP
ACK
STOP
PEC
START
Slave Address
W
START
Slave Address
W
ACK
Command Code
ACK
Data Byte
ACK
START
Slave Address
W
(a) Write Byte Protocol
(b) Write Byte Protocol with PEC
(c) Write Word Protocol
ACK
Command Code
ACK
Data Byte Low
ACK
Data Byte High
ACK
ACK
STOP
PEC
START
Slave Address
W
(d) Write Word Protocol with PEC
STOP
ACK
Command Code
ACK
Data Byte Low
ACK
Data Byte High
PEC
Data Byte High
ACK
NAK
ACK
NAK
START
ACK
Command Code
ACK
Data Byte Low
ACK
ACK
START
STOP
START
Slave Address
W
START
Slave Address
W
Slave Address
R
Slave Address
R
(d) Read Word Protocol with PEC
(c) Read Word Protocol
(b) Read Byte Protocol with PEC
ACK
Command Code
ACK
Data Byte
NAK
ACK
Command Code
ACK
NAK
STOP
PEC
ACK
START
ACK
Data Byte
ACK
START
START
Slave Address
W
START
Slave Address
W
Slave Address
R
Slave Address
R
STOP
(a) Read Byte Protocol
Multi-Master IIC Interface (MMIIC)
SMBus Protocols with PEC and without PEC
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Multi-Master IIC Interface (MMIIC)
315
17.9.6 Process Call
Figure 17-18. Process Call
17.9.7 Block Read/Write
Figure 17-19. Block Read/Write
NAK
STOP
ACK
Command Code
Data Byte Low
ACK
ACK
Data Byte High
ACK
Data Byte Low
Data Byte High
ACK
NAK
ACK
STOP
PEC
START
Slave Address
W
START
Slave Address
R
ACK
Command Code
Data Byte Low
ACK
ACK
Data Byte High
ACK
Data Byte Low
Data Byte High
ACK
ACK
ACK
STOP
START
Slave Address
W
START
Slave Address
R
(b) Process Call with PEC
(a) Process Call
ACK
Command Code
ACK
Byte Count = N
ACK
Data Byte 1
ACK
Data Byte 2
ACK
Data Byte N
NAK
STOP
START
ACK
ACK
Command Code
ACK
Byte Count = N
ACK
Data Byte 1
ACK
Data Byte 2
ACK
Data Byte N
ACK
STOP
START
Slave Address
W
START
Slave Address
W
Slave Address
R
Data Byte 1
ACK
Command Code
ACK
Byte Count = N
ACK
ACK
Data Byte 2
ACK
Data Byte N
NAK
STOP
START
ACK
START
Slave Address
W
Slave Address
R
Data Byte 1
PEC
ACK
(d) Block Write with PEC
(c) Block Write
(b) Block Read with PEC
ACK
Command Code
ACK
Byte Count = N
ACK
Data Byte 1
ACK
Data Byte 2
ACK
Data Byte N
ACK
STOP
START
Slave Address
W
PEC
ACK
(a) Block Read
Multi-Master IIC Interface (MMIIC)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
316
Multi-Master IIC Interface (MMIIC)
MOTOROLA
17.10 SMBus Protocol Implementation
Figure 17-20. SMBus Protocol Implementation
START
Address
ACK
Command
ACK
0
START
ACK
STOP
RX Data1
ACK
NAK
RX DataN
Address
1
ACK
Prepare for Master mode
ACTION:
1. Load slave address to MMADR
2. Clear MMRW
3. Load command to MMDTR
4. Set MMAST
OPERATION:
Prepare for repeated START
FLAGS:
MMTXIF set
MMRXAK clear
OPERATION:
ACTION:
1. Set MMRW
2. Set REPSEN
3. Clear MMTXAK
4. Load dummy ($FF) to MMDTR
Get ready to receive data
FLAGS:
MMTXIF set
MMRXAK clear
OPERATION:
ACTION:
Load dummy ($FF) to MMDTR
Generate STOP
FLAGS:
MMRXIF set
OPERATION:
ACTION:
Read DataN from MMDRR
Read received data and prepare for STOP
FLAGS:
MMRXIF set
OPERATION:
ACTION:
1. Set MMTXAK
2. Read Data(N-1) from MMDRR
3. Clear MMAST
Read received data
FLAGS:
MMRXIF set
OPERATION:
ACTION:
Read Data1 from MMDRR
MASTER MODE
START
Address
ACK
Command
ACK
0
START
ACK
STOP
TX Data1
ACK
NAK
TX DataN
Address
1
ACK
Slave address match and
FLAGS:
MMRXIF set
MMATCH set
OPERATION:
ACTION:
1. Check MMSRW
2. Read Slave address
Read and decode received command
FLAGS:
MMRXIF set
MMATCH clear
OPERATION:
ACTION:
Load Data1 to MMDTR
Last data sent
FLAGS:
MMTXIF set
MMRXAK set
OPERATION:
ACTION:
Load dummy ($FF) to MMDTR
Last data is going to be sent
FLAGS:
MMTXIF set
OPERATION:
ACTION:
Load dummy ($FF) to MMDTR
Transmit data
FLAGS:
MMTXIF set
OPERATION:
ACTION:
Load Data3 to MMDTR
Prepare for Slave mode
ACTION:
1. Load slave address to MMADR
2. Clear MMTXAK
3. Clear MMAST
OPERATION:
MMSRW depends on 8th
Slave address match and
FLAGS:
MMRXIF set
MMATCH set
OPERATION:
ACTION:
Check MMSRW
MMSRW depends on 8th
MMRXAK clear
MMRXAK clear
Transmit data
FLAGS:
MMTXIF set
OPERATION:
ACTION:
Load Data2 to MMDTR
check for data direction
bit of calling address byte
get ready to transmit data
bit of calling address byte
SLAVE MODE
Shaded data packets indicate transmissions by the MCU
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Input/Output (I/O) Ports
317
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 18. Input/Output (I/O) Ports
18.1 Contents
18.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317
18.3
Port A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320
18.3.1
Port A Data Register (PTA) . . . . . . . . . . . . . . . . . . . . . . . . 320
18.3.2
Data Direction Register A (DDRA) . . . . . . . . . . . . . . . . . . . 321
18.3.3
Port A LED Control Register (LEDA) . . . . . . . . . . . . . . . . . 323
18.4
Port B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323
18.4.1
Port B Data Register (PTB) . . . . . . . . . . . . . . . . . . . . . . . . 324
18.4.2
Data Direction Register B (DDRB) . . . . . . . . . . . . . . . . . . . 325
18.5
Port C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
18.5.1
Port C Data Register (PTC) . . . . . . . . . . . . . . . . . . . . . . . . 327
18.5.2
Data Direction Register C (DDRC). . . . . . . . . . . . . . . . . . . 329
18.5.3
Port C LED Control Register (LEDC) . . . . . . . . . . . . . . . . . 330
18.6
Port D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
18.6.1
Port D Data Register (PTD) . . . . . . . . . . . . . . . . . . . . . . . . 331
18.6.2
Data Direction Register D (DDRD). . . . . . . . . . . . . . . . . . . 332
18.2 Introduction
Thirty-one (31) bidirectional input-output (I/O) pins form four parallel
ports. All I/O pins are programmable as inputs or outputs.
NOTE:
Connect any unused I/O pins to an appropriate logic level, either V
DD
or
V
SS
. Although the I/O ports do not require termination for proper
operation, termination reduces excess current consumption and the
possibility of electrostatic damage.
Input/Output (I/O) Ports
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
318
Input/Output (I/O) Ports
MOTOROLA
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$0000
Port A Data Register
(PTA)
Read:
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
Write:
Reset:
Unaffected by reset
$0001
Port B Data Register
(PTB)
Read:
0
PTB6
PTB5
PTB4
PTB3
PTB2
PTB1
PTB0
Write:
Reset:
Unaffected by reset
$0002
Port C Data Register
(PTC)
Read:
PTC7
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1
PTC0
Write:
Reset:
Unaffected by reset
$0003
Port D Data Register
(PTD)
Read:
PTD7
PTD6
PTD5
PTD4
PTD3
PTD2
PTD1
PTD0
Write:
Reset:
Unaffected by reset
$0004
Data Direction Register A
(DDRA)
Read:
DDRA7
DDRA6
DDRA5
DDRA4
DDRA3
DDRA2
DDRA1
DDRA0
Write:
Reset:
0
0
0
0
0
0
0
0
$0005
Data Direction Register B
(DDRB)
Read:
0
DDRB6
DDRB5
DDRB4
DDRB3
DDRB2
DDRB1
DDRB0
Write:
Reset:
0
0
0
0
0
0
0
0
$0006
Data Direction Register C
(DDRC)
Read:
DDRC7
DDRC6
DDRC5
DDRC4
DDRC3
DDRC2
DDRC1
DDRC0
Write:
Reset:
0
0
0
0
0
0
0
0
$0007
Data Direction Register D
(DDRD)
Read:
DDRD7
DDRD6
DDRD5
DDRD4
DDRD3
DDRD2
DDRD1
DDRD0
Write:
Reset:
0
0
0
0
0
0
0
0
$000C
Port-A LED Control
Register
(LEDA)
Read:
0
0
LEDA5
LEDA4
LEDA3
LEDA2
LEDA1
LEDA0
Write:
Reset:
0
0
0
0
0
0
0
0
$000D
Port-C LED Control
Register
(LEDC)
Read:
LEDC7
LEDC6
LEDC5
LEDC4
LEDC3
0
0
0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 18-1. I/O Port Register Summary
Input/Output (I/O) Ports
Introduction
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Input/Output (I/O) Ports
319
Table 18-1. Port Control Register Bits Summary
Port
Bit
DDR
Module Control
Pin
Module
Register
Control Bit
A
0
DDRA0
ADC
ADSCR ($0057)
ADCH[4:0]
PTA0/ATD2
1
DDRA1
PTA1/ATD3
2
DDRA2
PTA2/ATD4
3
DDRA3
PTA3/ATD5
4
DDRA4
PTA4/ATD6
5
DDRA5
PTA5/ATD7
6
DDRA6
TIM1
T1SC0 ($0025)
ELS0B:ELS0A
PTA6/T1CH0
7
DDRA7
T1SC1 ($0028)
ELS1B:ELS1A
PTA7/T1CH1
B
0
DDRB0
MBUS
MMCR1 ($0049)
MMEN
SDASCL1
PTB0/SDA0
(1)
1
DDRB1
PTB1/SCL0
(1)
2
DDRB2
SCI
SCC1 ($0013)
(2)
ENSCI
PTB2/SDA1/TxD
(1)
3
DDRB3
MBUS MMCR1
($0049)
MMEN
SDASCL1
PTB3/SCL1/RxD
(1)
4
DDRB4
TIM2
T2SC0 ($0030)
ELS0B:ELS0A
PTB4/T2CH0
5
DDRB5
T2SC1 ($0033)
ELS1B:ELS1A
PTB5/T2CH1
6
DDRB6
IRQ
--
--
PTB6/IRQ2
C
0
DDRC0
ANALOG
CONFIG2 ($001D)
(1)
CDOEN
PTC0/PWM0/CD
PWM
PWMCR ($0051)
PCH0
1
DDRC1
PCH1
PTC1/PWM1
2
DDRC2
PCH2
PTC2/PWM2
3
DDRC3
ADC
ADSCR ($0057)
ADCH[4:0]
PTC3/ATD8
4
DDRC4
PTC4/ATD9
5
DDRC5
PTC5/ATD10
6
DDRC6
PTC6/ATD11
7
DDRC7
PTC7/ATD12
D
0
DDRD0
KBI
KBIER ($001B)
KBIE0
PTD0/KBI0
1
DDRD1
KBIE1
PTD1/KBI1
2
DDRD2
KBIE2
PTD2/KBI2
3
DDRD3
KBIE3
PTD3/KBI3
4
DDRD4
KBIE4
PTD4/KBI4
5
DDRD5
KBIE5
PTD5/KBI5
6
DDRD6
KBIE6
PTD6/KBI6
7
DDRD7
KBIE7
PTD7/KBI7
Notes:
1. Pins are open-drain when configured as outputs. Pullup resistors must be connected when configured as outputs.
2. Register has the highest priority control on port pin.
Input/Output (I/O) Ports
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
320
Input/Output (I/O) Ports
MOTOROLA
18.3 Port A
Port A is an 8-bit special function port that shares six of its port pins with
the analog-to-digital converter (ADC) module and two of its port pins with
the timer interface module 1 (TIM1). See
Section 15. Analog-to-Digital
Converter (ADC)
and
Section 11. Timer Interface Module (TIM)
.
PTA5PTA0 pins can be configured for direct LED drive.
18.3.1 Port A Data Register (PTA)
The port A data register contains a data latch for each of the eight port A
pins.
PTA[7:0] -- Port A Data Bits
These read/write bits are software programmable. Data direction of
each port A pin is under the control of the corresponding bit in data
direction register A. Reset has no effect on port A data.
ATD[7:2] -- ADC channels 2 to 7
ATD[7:2] are pins used for the input channels to the analog-to-digital
converter module. The channel select bits, ADCH[4:0], in the ADC
status and control register define which port pin will be used as an
ADC input and overrides any control from the port I/O logic. See
Section 14. Analog Module
.
Address:
$0000
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PTA7
PTA6
PTA5
PTA4
PTA3
PTA2
PTA1
PTA0
Write:
Reset:
Unaffected by Reset
Alternative Function:
T1CH1
T1CH0
ATD7
ATD6
ATD5
ATD4
ATD3
ATD2
Additional Function:
LED drive LED drive LED drive LED drive LED drive LED drive
Figure 18-2. Port A Data Register (PTA)
Input/Output (I/O) Ports
Port A
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Input/Output (I/O) Ports
321
T1CH[1:0] -- Timer 1 Channel I/O Bits
The T1CH1 and T1CH0 pins are the TIM1 input capture/output
compare pins. The edge/level select bits, ELSxB:ELSxA, determine
whether the PTA7/T1CH1 and PTA6/T1CH0 pins are timer channel
I/O pins or general-purpose I/O pins. See
Section 11. Timer
Interface Module (TIM)
.
NOTE:
Care must be taken when reading port A while applying analog voltages
to ATD[7:2] pins. If the appropriate ADC channel is not enabled,
excessive current drain may occur if analog voltages are applied to the
PTAx/ATDx pin, while PTA is read as a digital input. Those ports not
selected as analog input channels are considered digital I/O ports.
LED drive -- Direct LED drive Pins
PTA5PTA0 pins can be configured for direct LED drive. See
18.3.3
Port A LED Control Register (LEDA)
.
18.3.2 Data Direction Register A (DDRA)
Data direction register A determines whether each port A pin is an input
or an output. Writing a logic 1 to a DDRA bit enables the output buffer for
the corresponding port A pin; a logic 0 disables the output buffer.
DDRA[7:0] -- Data Direction Register A Bits
These read/write bits control port A data direction. Reset clears
DDRA[7:0], configuring all port A pins as inputs.
1 = Corresponding port A pin configured as output
0 = Corresponding port A pin configured as input
Address:
$0004
Bit 7
6
5
4
3
2
1
Bit 0
Read:
DDRA7
DDRA6
DDRA5
DDRA4
DDRA3
DDRA2
DDRA1
DDRA0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 18-3. Data Direction Register A (DDRA)
Input/Output (I/O) Ports
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
322
Input/Output (I/O) Ports
MOTOROLA
NOTE:
Avoid glitches on port A pins by writing to the port A data register before
changing data direction register A bits from 0 to 1.
Figure 18-4
shows
the port A I/O logic.
Figure 18-4. Port A I/O Circuit
When DDRAx is a logic 1, reading address $0000 reads the PTAx data
latch. When DDRAx is a logic 0, reading address $0000 reads the
voltage level on the pin. The data latch can always be written, regardless
of the state of its data direction bit.
Table 18-2
summarizes the operation of the port A pins.
Table 18-2. Port A Pin Functions
DDRA
Bit
PTA Bit
I/O Pin Mode
Accesses to DDRA
Accesses to PTA
Read/Write
Read
Write
0
X
(1)
Notes:
1. X = don't care.
Input, Hi-Z
(2)
2. Hi-Z = high impedance.
DDRA[7:0]
Pin
PTA[7:0]
(3)
3. Writing affects data register, but does not affect input.
1
X
Output
DDRA[7:0]
PTA[7:0]
PTA[7:0]
READ DDRA ($0004)
WRITE DDRA ($0004)
RESET
WRITE PTA ($0000)
READ PTA ($0000)
PTAx
DDRAx
PTAx
I
N
T
E
RN
AL
DA
T
A
BU
S
Input/Output (I/O) Ports
Port B
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Input/Output (I/O) Ports
323
18.3.3 Port A LED Control Register (LEDA)
The port-A LED control register (LEDA) controls the direct LED drive
capability on PTA5PTA0 pins. Each bit is individually configurable and
requires that the data direction register, DDRD, bit be configured as an
output.
LEDA[5:0] -- Port A LED Drive Enable Bits
These read/write bits are software programmable to enable the direct
LED drive on an output port pin.
1 = Corresponding port A pin configured for direct LED drive
0 = Corresponding port A pin configured for standard drive
18.4 Port B
Port B is a 7-bit special function port that shares four of its port pins with
the multi-master IIC (MMIIC) interface module, two of its port pins with
the serial communications interface (SCI) module, two of its port pins
with the timer interface module 2 (TIM2), and one of its port pins with the
IRQ module. See
Section 17. Multi-Master IIC Interface (MMIIC)
,
Section 16. Serial Communications Interface (SCI)
,
Section 11.
Timer Interface Module (TIM)
, and
Section 19. External Interrupt
(IRQ)
.
NOTE:
PTB3PTB0 are open-drain pins when configured as outputs regardless
whether the pins are used as general purpose I/O pins, MMIIC pins, or
SCI pins. Therefore, when configured as general purpose output pins,
MMIIC pins, or SCI pins (the TxD pin), pullup resistors must be
connected to these pins.
Address:
$000C
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
LEDA5
LEDA4
LEDA3
LEDA2
LEDA1
LEDA0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 18-5. Port A LED Control Register (LEDA)
Input/Output (I/O) Ports
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
324
Input/Output (I/O) Ports
MOTOROLA
18.4.1 Port B Data Register (PTB)
The port B data register contains a data latch for each of the eight port B
pins.
PTB[6:0] -- Port B Data Bits
These read/write bits are software programmable. Data direction of
each port B pin is under the control of the corresponding bit in data
direction register B. Reset has no effect on port B data.
SDA0, SCL0, SDA1, SCL1 -- MMIIC Channels 1 and 2
SDAx and SCLx are the data and clock lines for the MMIIC module.
The multi-master enable bit, MMEN, and the MMIIC channel select
bit, SDASCL1, in the MMIIC control register 1 determine whether the
PTB0/SDA0, PTB1/SCL0, PTB2/SDA1/TxD, and PTB3/SCL1/RxD
pins are MMIIC I/O pins or general purpose I/O pins. See
Section 17.
Multi-Master IIC Interface (MMIIC)
.
TxD, RxD -- SCI Data I/O Pins
The TxD and RxD pins are the transmit data output and receive data
input for the SCI module. The enable SCI bit, ENSCI, in the SCI
control register 1 enables the PTB2/SDA1/TxD and PTB3/SCL1/RxD
pins as SCI TxD and RxD pins and overrides any control from the port
I/O or MMIIC logic. See
Section 16. Serial Communications
Interface (SCI)
.
Address:
$0001
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
PTB6
PTB5
PTB4
PTB3
PTB2
PTB1
PTB0
Write:
Reset:
Unaffected by reset
Alternative Functions:
IRQ2
T2CH1
T2CH0
RxD
TxD
SCL0
SDA0
SCL1
SDA1
These four pins are open-drain when configured as
output pins. Pullup resistors must be connected
when configured as outputs.
Figure 18-6. Port B Data Register (PTB)
Input/Output (I/O) Ports
Port B
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Input/Output (I/O) Ports
325
T2CH[1:0] -- Timer 2 Channel I/O Bits
The T2CH1 and T2CH0 pins are the TIM2 input capture/output
compare pins. The edge/level select bits, ELSxB:ELSxA, determine
whether the PTB5/T2CH1 and PTB4/T2CH0 pins are timer channel
I/O pins or general-purpose I/O pins.See
Section 11. Timer
Interface Module (TIM)
.
IRQ2 -- External Interrupt Pin 2
IRQ2 pin is the second external interrupt input to the IRQ module.
When PTB6/IRQ2 is configured as an input by the data direction bit
bit, DDRB6, the pin is both a standard port input pin and an external
interrupt pin. See
Section 19. External Interrupt (IRQ)
.
18.4.2 Data Direction Register B (DDRB)
Data direction register B determines whether each port B pin is an input
or an output. Writing a logic 1 to a DDRB bit enables the output buffer for
the corresponding port B pin; a logic 0 disables the output buffer.
Table 18-3. PTB2 and PTB3 Pin Configurations
Pin
ENSCI
Bit
($0013)
MMEN
Bit
($0049)
SDASCL1
Bit
($0049)
Pin function
PTB2/SDA1/TxD
PTB3/SCL1/RxD
0
0
X
PTB2, PTB3
0
1
0
PTB2, PTB3
0
1
1
SDA1, SCL1
1
X
X
TxD, RxD
Address:
$0005
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
DDRB6
DDRB5
DDRB4
DDRB3
DDRB2
DDRB1
DDRB0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 18-7. Data Direction Register B (DDRB)
Input/Output (I/O) Ports
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
326
Input/Output (I/O) Ports
MOTOROLA
DDRB[6:0] -- Data Direction Register B Bits
These read/write bits control port B data direction. Reset clears
DDRB[6:0], configuring all port B pins as inputs.
1 = Corresponding port B pin configured as output
0 = Corresponding port B pin configured as input
NOTE:
Avoid glitches on port B pins by writing to the port B data register before
changing data direction register B bits from 0 to 1.
Figure 18-8
shows
the port B I/O logic.
Figure 18-8. Port B I/O Circuit
When DDRBx is a logic 1, reading address $0001 reads the PTBx data
latch. When DDRBx is a logic 0, reading address $0001 reads the
voltage level on the pin. The data latch can always be written, regardless
of the state of its data direction bit.
Table 18-4
summarizes the operation of the port B pins.
Table 18-4. Port B Pin Functions
DDRB
Bit
PTB Bit
I/O Pin Mode
Accesses to DDRB
Accesses to PTB
Read/Write
Read
Write
0
X
(1)
Notes:
1. X = don't care.
Input, Hi-Z
(2)
2. Hi-Z = high impedance.
DDRB[6:0]
Pin
PTB[6:0]
(3)
3. Writing affects data register, but does not affect input.
1
X
Output
DDRB[6:0]
PTB[6:0]
PTB[6:0]
READ DDRB ($0005)
WRITE DDRB ($0005)
RESET
WRITE PTB ($0001)
READ PTB ($0001)
PTBx
#
DDRBx
PTBx
INT
E
RN
AL
DA
T
A
BU
S
# PTB3PTB0 are open-drain pins when configured as outputs.
Input/Output (I/O) Ports
Port C
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Input/Output (I/O) Ports
327
18.5 Port C
Port C is an 8-bit special function port that shares three of its port pins
with the pulse width modulator module, five of its port pins with the
analog-to-digital converter module, and one of its pins with the analog
module. See
Section 13. Pulse Width Modulator (PWM)
,
Section 15.
Analog-to-Digital Converter (ADC)
, and
Section 14. Analog Module
.
PTC7PTC3 pins can be configured for direct LED drive.
18.5.1 Port C Data Register (PTC)
The port C data register contains a data latch for each of the six port C
pins.
NOTE:
Bit 7 and bit 6 of PTC are not available in a 42-pin shrink dual in-line
package.
PTC[7:0] -- Port C Data Bits
These read/write bits are software programmable. Data direction of
each port C pin is under the control of the corresponding bit in data
direction register C. Reset has no effect on port C data.
Address:
$0002
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PTC7
PTC6
PTC5
PTC4
PTC3
PTC2
PTC1
PTC0
Write:
Reset:
Unaffected by reset
Alternative Function:
ATD12
ATD11
ATD10
ATD9
ATD8
PWM2
PWM1
PWM0
CD
Additional Function: LED drive LED drive LED drive LED drive LED drive
Figure 18-9. Port C Data Register (PTC)
Input/Output (I/O) Ports
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
328
Input/Output (I/O) Ports
MOTOROLA
PWM[2:0] -- PWM Channels 0 to 2
PWM[2:0] are pins used for the output channels from the pulse width
modulator (PWM) module. The PWM enables bit, PCH[2:0], in the
PWM control register define which port pin will be used as a PWM
output and overrides any control from the port I/O logic. The PWM0
function on PCT0/PWM0/CD pin can be overrided by the CD output
function. See
Section 13. Pulse Width Modulator (PWM)
.
ATD[12:8] -- ADC channels 8 to 12
ATD[12:8] are pins used for the input channels to the analog-to-digital
converter module. The channel select bits, ADCH[4:0], in the ADC
status and control register define which port pin will be used as an
ADC input and overrides any control from the port I/O logic. See
Section 15. Analog-to-Digital Converter (ADC)
.
NOTE:
Care must be taken when reading port C while applying analog voltages
to ATD[12:8] pins. If the appropriate ADC channel is not enabled,
excessive current drain may occur if analog voltages are applied to the
PTCx/ATDx pin, while PTC is read as a digital input. Those ports not
selected as analog input channels are considered digital I/O ports.
CD -- Current Detect Output Pin
The CD pin is used for the current detect output from the analog
module. The pin reflects the status of the current detect interrupt flag.
The current detect output enable bit, CDOEN, in the configuration
register 2 enables the PTC0/PWM0/CD pin as the CD output pin and
overrides any control from the port I/O or PWM logic. See
Section 14.
Analog Module
.
LED drive -- Direct LED drive Pins
PTC7PTC3 pins can be configured for direct LED drive. See
18.5.3
Port C LED Control Register (LEDC)
.
Table 18-5. PTC0 Pin Configuration
Pin
CDOEN Bit
($001D)
PCH0 Bit
($0051)
Pin function
PTC0/PWM0/CD
0
0
PTC0
0
1
PWM0
1
X
CD
Input/Output (I/O) Ports
Port C
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Input/Output (I/O) Ports
329
18.5.2 Data Direction Register C (DDRC)
Data direction register C determines whether each port C pin is an input
or an output. Writing a logic 1 to a DDRC bit enables the output buffer for
the corresponding port C pin; a logic 0 disables the output buffer.
DDRC[7:0] -- Data Direction Register C Bits
These read/write bits control port C data direction. Reset clears
DDRC[7:0], configuring all port C pins as inputs.
1 = Corresponding port C pin configured as output
0 = Corresponding port C pin configured as input
NOTE:
Avoid glitches on port C pins by writing to the port C data register before
changing data direction register C bits from 0 to 1.
Figure 18-11
shows
the port C I/O logic.
NOTE:
For those devices packaged in a 42-pin shrink dual in-line package,
PTC6 and PTC7 are not connected. DDRC6 and DDRC7 should be set
to a 1 to configure PTC6 and PTC7 as outputs.
Figure 18-11. Port C I/O Circuit
Address:
$0006
Bit 7
6
5
4
3
2
1
Bit 0
Read:
DDRC7
DDRC6
DDRC5
DDRC4
DDRC3
DDRC2
DDRC1
DDRC0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 18-10. Data Direction Register B (DDRB)
READ DDRC ($0006)
WRITE DDRC ($0006)
RESET
WRITE PTC ($0002)
READ PTC ($0002)
PTCx
DDRCx
PTCx
INT
E
R
N
AL
DA
T
A
BU
S
Input/Output (I/O) Ports
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
330
Input/Output (I/O) Ports
MOTOROLA
When DDRCx is a logic 1, reading address $0002 reads the PTCx data
latch. When DDRCx is a logic 0, reading address $0002 reads the
voltage level on the pin. The data latch can always be written, regardless
of the state of its data direction bit.
Table 18-6
summarizes the operation of the port C pins.
18.5.3 Port C LED Control Register (LEDC)
The port-C LED control register (LEDC) controls the direct LED drive
capability on PTC7PTC3 pins. Each bit is individually configurable and
requires that the data direction register, DDRD, bit be configured as an
output.
LEDC[7:3] -- Port C LED Drive Enable Bits
These read/write bits are software programmable to enable the direct
LED drive on an output port pin.
1 = Corresponding port C pin configured for direct LED drive
0 = Corresponding port C pin configured for standard drive
Table 18-6. Port C Pin Functions
DDRC
Bit
PTC Bit
I/O Pin Mode
Accesses to DDRC
Accesses to PTC
Read/Write
Read
Write
0
X
(1)
Notes:
1. X = don't care.
Input, Hi-Z
(2)
2. Hi-Z = high impedance.
DDRC[7:0]
Pin
PTC[7:0]
(3)
3. Writing affects data register, but does not affect input.
1
X
Output
DDRC[7:0]
PTC[7:0]
PTC[7:0]
Address:
$000D
Bit 7
6
5
4
3
2
1
Bit 0
Read:
LEDC7
LEDC6
LEDC5
LEDC4
LEDC3
0
0
0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 18-12. Port A LED Control Register (LEDA)
Input/Output (I/O) Ports
Port D
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Input/Output (I/O) Ports
331
18.6 Port D
Port D is an 8-bit special function port that shares all of its pins with the
keyboard interrupt module. See
Section 20. Keyboard Interrupt
Module (KBI)
.
18.6.1 Port D Data Register (PTD)
The port D data register contains a data latch for each of the eight port D
pins.
PTD[7:0] -- Port D Data Bits
These read/write bits are software programmable. Data direction of
each port D pin is under the control of the corresponding bit in data
direction register D. Reset has no effect on port D data.
KBI[7:0] -- Keyboard Interrupt Pins
The keyboard interrupt enable bits, KBIE[7:0], in the keyboard
interrupt enable register (KBIER), enable the port D pins as external
interrupt pins. See
Section 20. Keyboard Interrupt Module (KBI)
.
Address:
$0003
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PTD7
PTD6
PTD5
PTD4
PTD3
PTD2
PTD1
PTD0
Write:
Reset:
Unaffected by reset
Alternative Function:
KBI7
KBI6
KBI5
KBI4
KBI3
KBI2
KBI1
KBI0
Figure 18-13. Port D Data Register (PTD)
Input/Output (I/O) Ports
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
332
Input/Output (I/O) Ports
MOTOROLA
18.6.2 Data Direction Register D (DDRD)
Data direction register D determines whether each port D pin is an input
or an output. Writing a logic 1 to a DDRD bit enables the output buffer for
the corresponding port D pin; a logic 0 disables the output buffer.
DDRD[7:0] -- Data Direction Register D Bits
These read/write bits control port D data direction. Reset clears
DDRD[7:0], configuring all port D pins as inputs.
1 = Corresponding port D pin configured as output
0 = Corresponding port D pin configured as input
NOTE:
Avoid glitches on port D pins by writing to the port D data register before
changing data direction register D bits from 0 to 1.
Figure 18-15
shows
the port D I/O logic.
Figure 18-15. Port D I/O Circuit
Address:
$0007
Bit 7
6
5
4
3
2
1
Bit 0
Read:
DDRD7
DDRD6
DDRD5
DDRD4
DDRD3
DDRD2
DDRD1
DDRD0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 18-14. Data Direction Register D (DDRD)
READ DDRD ($0007)
WRITE DDRD ($0007)
RESET
WRITE PTD ($0003)
READ PTD ($0003)
PTDx
DDRDx
PTDx
IN
TE
RN
AL DA
T
A
B
U
S
Input/Output (I/O) Ports
Port D
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Input/Output (I/O) Ports
333
When DDRDx is a logic 1, reading address $0003 reads the PTDx data
latch. When DDRDx is a logic 0, reading address $0003 reads the
voltage level on the pin. The data latch can always be written, regardless
of the state of its data direction bit.
Table 18-7
summarizes the operation of the port D pins.
Table 18-7. Port D Pin Functions
DDRD
Bit
PTD Bit
I/O Pin
Mode
Accesses
to DDRD
Accesses to PTD
Read/Write
Read
Write
0
X
(1)
Notes:
1. X = don't care.
Input, Hi-Z
(2)
2. Hi-Z = high impedance.
DDRD[7:0]
Pin
PTD[7:0]
(3)
3. Writing affects data register, but does not affect the input.
1
X
Output
DDRD[7:0]
PTD[7:0]
PTD[7:0]
Input/Output (I/O) Ports
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
334
Input/Output (I/O) Ports
MOTOROLA
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
External Interrupt (IRQ)
335
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 19. External Interrupt (IRQ)
19.1 Contents
19.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
19.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
19.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
19.5
IRQ1 and IRQ2 Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338
19.6
IRQ Module During Break Interrupts . . . . . . . . . . . . . . . . . . .339
19.7
IRQ Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
19.7.1
IRQ1 Status and Control Register . . . . . . . . . . . . . . . . . . .340
19.7.2
IRQ2 Status and Control Register . . . . . . . . . . . . . . . . . . .341
19.2 Introduction
The external interrupt (IRQ) module provides two maskable interrupt
inputs: IRQ1 and IRQ2.
19.3 Features
Features of the IRQ module include:
A dedicated external interrupt pin, IRQ1
An external interrupt pin shared with a port pin, IRQ2/PTB6
Separate IRQ interrupt control bits for IRQ1 and IRQ2
Hysteresis buffers
Programmable edge-only or edge and level interrupt sensitivity
Automatic interrupt acknowledge
Internal pullup resistor, with disable option on IRQ2
External Interrupt (IRQ)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
336
External Interrupt (IRQ)
MOTOROLA
NOTE:
References to either IRQ1 or IRQ2 may be made in the following text by
omitting the IRQ number. For example, IRQF may refer generically to
IRQ1F and IRQ2F, and IMASK may refer to IMASK1 and IMASK2.
19.4 Functional Description
A logic 0 applied to the external interrupt pin can latch a CPU interrupt
request.
Figure 19-2
and
Figure 19-3
shows the structure of the IRQ
module.
Interrupt signals on the IRQ pin are latched into the IRQ latch. An
interrupt latch remains set until one of the following actions occurs:
Vector fetch -- A vector fetch automatically generates an interrupt
acknowledge signal that clears the latch that caused the vector
fetch.
Software clear -- Software can clear an interrupt latch by writing
to the appropriate acknowledge bit in the interrupt status and
control register (INTSCR). Writing a logic 1 to the ACK bit clears
the IRQ latch.
Reset -- A reset automatically clears the interrupt latch.
The external interrupt pin is falling-edge-triggered and is software-
configurable to be either falling-edge or falling-edge and low-level-
triggered. The MODE bit in the INTSCR controls the triggering sensitivity
of the IRQ pin.
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$001C
IRQ2 Status and Control
Register
(INTSCR2)
Read:
0
PTBPUE6
0
0
IRQ2F
0
IMASK2
MODE2
Write:
ACK2
Reset:
0
0
0
0
0
0
0
0
$001E
IRQ1 Status and Control
Register
(INTSCR1)
Read:
0
0
0
0
IRQ1F
0
IMASK1
MODE1
Write:
ACK1
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 19-1. External Interrupt I/O Register Summary
External Interrupt (IRQ)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
External Interrupt (IRQ)
337
When an interrupt pin is edge-triggered only, the interrupt remains set
until a vector fetch, software clear, or reset occurs.
When an interrupt pin is both falling-edge and low-level-triggered, the
interrupt remains set until both of the following occur:
Vector fetch or software clear
Return of the interrupt pin to logic 1
The vector fetch or software clear may occur before or after the interrupt
pin returns to logic 1. As long as the pin is low, the interrupt request
remains pending. A reset will clear the latch and the MODE1 control bit,
thereby clearing the interrupt even if the pin stays low.
When set, the IMASK bit in the INTSCR mask all external interrupt
requests. A latched interrupt request is not presented to the interrupt
priority logic unless the IMASK bit is clear.
NOTE:
The interrupt mask (I) in the condition code register (CCR) masks all
interrupt requests, including external interrupt requests.
Figure 19-2. IRQ1 Block Diagram
ACK1
IMASK1
D
Q
CK
CLR
IRQ1
HIGH
INTERRUPT
TO MODE
SELECT
LOGIC
IRQ1
FF
REQUEST
V
DD
MODE1
VOLTAGE
DETECT
SYNCHRO-
NIZER
IRQ1F
TO CPU FOR
BIL/BIH
INSTRUCTIONS
VECTOR
FETCH
DECODER
INTE
RNA
L A
DDRE
S
S
B
U
S
RESET
V
DD
INTERNAL
PULLUP
DEVICE
IRQ1
External Interrupt (IRQ)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
338
External Interrupt (IRQ)
MOTOROLA
Figure 19-3. IRQ2 Block Diagram
19.5 IRQ1 and IRQ2 Pins
A logic 0 on the IRQ pin can latch an interrupt request into the IRQ latch.
A vector fetch, software clear, or reset clears the IRQ latch.
If the MODE bit is set, the IRQ pin is both falling-edge-sensitive and low-
level-sensitive. With MODE set, both of the following actions must occur
to clear IRQ:
Vector fetch or software clear -- A vector fetch generates an
interrupt acknowledge signal to clear the latch. Software may
generate the interrupt acknowledge signal by writing a logic 1 to
the ACK bit in the interrupt status and control register (INTSCR).
The ACK bit is useful in applications that poll the IRQ pin and
require software to clear the IRQ latch. Writing to the ACK bit prior
to leaving an interrupt service routine can also prevent spurious
interrupts due to noise. Setting ACK does not affect subsequent
transitions on the IRQ pin. A falling edge that occurs after writing
to the ACK bit another interrupt request. If the IRQ mask bit,
IMASK, is clear, the CPU loads the program counter with the
vector address at location defined in
Table 2-1 . Vector
Addresses
.
ACK2
IMASK2
D
Q
CK
CLR
IRQ2
INTERRUPT
IRQ2
FF
REQUEST
V
DD
MODE2
SYNCHRO-
NIZER
IRQ2F
VECTOR
FETCH
DECODER
I
N
TE
R
N
A
L
A
DDRE
S
S
B
U
S
RESET
V
DD
INTERNAL
PULLUP
DEVICE
IRQ2
PTBPUE6
External Interrupt (IRQ)
IRQ Module During Break Interrupts
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
External Interrupt (IRQ)
339
Return of the IRQ pin to logic 1 -- As long as the IRQ pin is at
logic 0, IRQ remains active.
The vector fetch or software clear and the return of the IRQ pin to logic 1
may occur in any order. The interrupt request remains pending as long
as the IRQ pin is at logic 0. A reset will clear the latch and the MODE
control bit, thereby clearing the interrupt even if the pin stays low.
If the MODE bit is clear, the IRQ pin is falling-edge-sensitive only. With
MODE clear, a vector fetch or software clear immediately clears the IRQ
latch.
The IRQF bit in the INTSCR register can be used to check for pending
interrupts. The IRQF bit is not affected by the IMASK bit, which makes it
useful in applications where polling is preferred.
Use the BIH or BIL instruction to read the logic level on the IRQ1 pin.
NOTE:
The BIH and BIL instructions do not read the logic level on the IRQ2 pin.
NOTE:
When using the level-sensitive interrupt trigger, avoid false interrupts by
masking interrupt requests in the interrupt routine.
The IRQ1 pin has a permanent internal pullup device connected, while
the IRQ2 pin has an optional pullup device that can be enabled or
disabled by the PTBPUE6 bit in the INTSCR2 register.
19.6 IRQ Module During Break Interrupts
The BCFE bit in the SIM break flag control register (SBFCR) enables
software to clear the latch during the break state. (See
Section 23.
Break Module (BRK)
.)
To allow software to clear the IRQ latch during a break interrupt, write a
logic 1 to the BCFE bit. If a latch is cleared during the break state, it
remains cleared when the MCU exits the break state.
To protect CPU interrupt flags during the break state, write a logic 0 to
the BCFE bit. With BCFE at logic 0 (its default state), writing to the ACK
bit in the IRQ status and control register during the break state has no
effect on the IRQ interrupt flags.
External Interrupt (IRQ)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
340
External Interrupt (IRQ)
MOTOROLA
19.7 IRQ Registers
Each IRQ is controlled and monitored by an status and control register.
IRQ1 Status and Control Register -- $001E
IRQ2 Status and Control Register -- $001C
19.7.1 IRQ1 Status and Control Register
The IRQ1 status and control register (INTSCR1) controls and monitors
operation of IRQ1. The INTSCR1 has the following functions:
Shows the state of the IRQ1 flag
Clears the IRQ1 latch
Masks IRQ1 interrupt request
Controls triggering sensitivity of the IRQ1 interrupt pin
IRQ1F -- IRQ1 Flag Bit
This read-only status bit is high when the IRQ1 interrupt is pending.
1 = IRQ1 interrupt pending
0 = IRQ1 interrupt not pending
ACK1 -- IRQ1 Interrupt Request Acknowledge Bit
Writing a logic 1 to this write-only bit clears the IRQ1 latch. ACK1
always reads as logic 0. Reset clears ACK1.
Address:
$001E
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
IRQ1F
0
IMASK1
MODE1
Write:
ACK1
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 19-4. IRQ1 Status and Control Register (INTSCR1)
External Interrupt (IRQ)
IRQ Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
External Interrupt (IRQ)
341
IMASK1 -- IRQ1 Interrupt Mask Bit
Writing a logic 1 to this read/write bit disables IRQ1 interrupt requests.
Reset clears IMASK1.
1 = IRQ1 interrupt requests disabled
0 = IRQ1 interrupt requests enabled
MODE1 -- IRQ1 Edge/Level Select Bit
This read/write bit controls the triggering sensitivity of the IRQ1 pin.
Reset clears MODE1.
1 = IRQ1 interrupt requests on falling edges and low levels
0 = IRQ1 interrupt requests on falling edges only
19.7.2 IRQ2 Status and Control Register
The IRQ2 status and control register (INTSCR2) controls and monitors
operation of IRQ2. The INTSCR2 has the following functions:
Enables/disables the internal pullup device on IRQ2 pin
Shows the state of the IRQ2 flag
Clears the IRQ2 latch
Masks IRQ2 interrupt request
Controls triggering sensitivity of the IRQ2 interrupt pin
PTBPUE6 -- IRQ2 Pin Pullup Enable Bit.
Setting this bit to logic 1 disables the pullup on PTB6/IRQ2 pin.
Reset clears this bit.
1 = IRQ2 pin internal pull-up is disabled
0 = IRQ2 pin internal pull-up is enabled
Address:
$001C
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
PTBPUE6
0
0
IRQ2F
0
IMASK2
MODE2
Write:
ACK2
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 19-5. IRQ2 Status and Control Register (INTSCR2)
External Interrupt (IRQ)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
342
External Interrupt (IRQ)
MOTOROLA
IRQ2F -- IRQ2 Flag Bit
This read-only status bit is high when the IRQ2 interrupt is pending.
1 = IRQ2 interrupt pending
0 = IRQ2 interrupt not pending
ACK2 -- IRQ2 Interrupt Request Acknowledge Bit
Writing a logic 1 to this write-only bit clears the IRQ2 latch. ACK2
always reads as logic 0. Reset clears ACK2.
IMASK2 -- IRQ2 Interrupt Mask Bit
Writing a logic 1 to this read/write bit disables IRQ2 interrupt requests.
Reset clears IMASK2.
1 = IRQ2 interrupt requests disabled
0 = IRQ2 interrupt requests enabled
MODE2 -- IRQ2 Edge/Level Select Bit
This read/write bit controls the triggering sensitivity of the IRQ2 pin.
Reset clears MODE2.
1 = IRQ2 interrupt requests on falling edges and low levels
0 = IRQ2 interrupt requests on falling edges only
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Keyboard Interrupt Module (KBI)
343
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 20. Keyboard Interrupt Module (KBI)
20.1 Contents
20.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343
20.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
20.4
I/O Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
20.5
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
20.5.1
Keyboard Initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347
20.6
Keyboard Interrupt Registers . . . . . . . . . . . . . . . . . . . . . . . . . 347
20.6.1
Keyboard Status and Control Register. . . . . . . . . . . . . . . . 348
20.6.2
Keyboard Interrupt Enable Register . . . . . . . . . . . . . . . . . . 349
20.7
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .349
20.8
Wait Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349
20.9
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 349
20.10 Keyboard Module During Break Interrupts . . . . . . . . . . . . . . .350
20.2 Introduction
The keyboard interrupt module (KBI) provides eight independently
maskable external interrupts which are accessible via PTD0PTD7.
When a port pin is enabled for keyboard interrupt function, an internal
30k
pullup device is also enabled on the pin.
Keyboard Interrupt Module (KBI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
344
Keyboard Interrupt Module (KBI)
MOTOROLA
20.3 Features
Features of the keyboard interrupt module include the following:
Eight keyboard interrupt pins with pullup devices
Separate keyboard interrupt enable bits and one keyboard
interrupt mask
Programmable edge-only or edge- and level- interrupt sensitivity
Exit from low-lower modes
20.4 I/O Pins
The eight keyboard interrupt pins are shared with standard port I/O pins.
The full name of the KBI pins are listed in
Table 20-1
.
The generic pin
name appear in the text that follows.
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$001A
Keyboard Status
and Control Register
(KBSCR)
Read:
0
0
0
0
KEYF
0
IMASKK
MODEK
Write:
ACKK
Reset:
0
0
0
0
0
0
0
0
$001B
Keyboard Interrupt Enable
Register (KBIER)
Read:
KBIE7
KBIE6
KBIE5
KBIE4
KBIE3
KBIE2
KBIE1
KBIE0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 20-1. KBI I/O Register Summary
Table 20-1. Pin Name Conventions
KBI
Generic Pin Name
Full MCU Pin Name
Pin Selected for KBI Function by
KBIEx Bit in KBIER
KBI0KBI7
PTD0/KBI0PTD7/KBI7
KBIE0KBIE7
Keyboard Interrupt Module (KBI)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Keyboard Interrupt Module (KBI)
345
20.5 Functional Description
Figure 20-2. Keyboard Interrupt Block Diagram
Writing to the KBIE7KBIE0 bits in the keyboard interrupt enable register
independently enables or disables each port D pin as a keyboard
interrupt pin. Enabling a keyboard interrupt pin in port D also enables its
internal pull-up device. A logic 0 applied to an enabled keyboard
interrupt pin latches a keyboard interrupt request.
A keyboard interrupt is latched when one or more keyboard pins goes
low after all were high. The MODEK bit in the keyboard status and
control register controls the triggering mode of the keyboard interrupt.
If the keyboard interrupt is edge-sensitive only, a falling edge on a
keyboard pin does not latch an interrupt request if another
keyboard pin is already low. To prevent losing an interrupt request
on one pin because another pin is still low, software can disable
the latter pin while it is low.
If the keyboard interrupt is falling edge- and low level-sensitive, an
interrupt request is present as long as any keyboard pin is low.
If the MODEK bit is set, the keyboard interrupt pins are both falling edge-
and low level-sensitive, and both of the following actions must occur to
clear a keyboard interrupt request:
KBIE0
KBIE7
.
.
.
D
Q
CK
CLR
V
DD
MODEK
IMASKK
KEYBOARD
INTERRUPT FF
VECTOR FETCH
DECODER
ACKK
INTERNAL BUS
RESET
KBI7
KBI0
SYNCHRONIZER
KEYF
Keyboard
Interrupt
Request
TO PULLUP ENABLE
TO PULLUP ENABLE
Keyboard Interrupt Module (KBI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
346
Keyboard Interrupt Module (KBI)
MOTOROLA
Vector fetch or software clear -- A vector fetch generates an
interrupt acknowledge signal to clear the interrupt request.
Software may generate the interrupt acknowledge signal by
writing a logic 1 to the ACKK bit in the keyboard status and control
register KBSCR. The ACKK bit is useful in applications that poll
the keyboard interrupt pins and require software to clear the
keyboard interrupt request. Writing to the ACKK bit prior to leaving
an interrupt service routine can also prevent spurious interrupts
due to noise. Setting ACKK does not affect subsequent transitions
on the keyboard interrupt pins. A falling edge that occurs after
writing to the ACKK bit latches another interrupt request. If the
keyboard interrupt mask bit, IMASKK, is clear, the CPU loads the
program counter with the vector address at locations $FFE0 and
$FFE1.
Return of all enabled keyboard interrupt pins to logic 1 -- As long
as any enabled keyboard interrupt pin is at logic 0, the keyboard
interrupt remains set.
The vector fetch or software clear and the return of all enabled keyboard
interrupt pins to logic 1 may occur in any order.
If the MODEK bit is clear, the keyboard interrupt pin is falling-edge-
sensitive only. With MODEK clear, a vector fetch or software clear
immediately clears the keyboard interrupt request.
Reset clears the keyboard interrupt request and the MODEK bit, clearing
the interrupt request even if a keyboard interrupt pin stays at logic 0.
The keyboard flag bit (KEYF) in the keyboard status and control register
can be used to see if a pending interrupt exists. The KEYF bit is not
affected by the keyboard interrupt mask bit (IMASKK) which makes it
useful in applications where polling is preferred.
To determine the logic level on a keyboard interrupt pin, use the data
direction register to configure the pin as an input and read the data
register.
NOTE:
Setting a keyboard interrupt enable bit (KBIEx) forces the corresponding
keyboard interrupt pin to be an input, overriding the data direction
register. However, the data direction register bit must be a logic 0 for
software to read the pin.
Keyboard Interrupt Module (KBI)
Keyboard Interrupt Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Keyboard Interrupt Module (KBI)
347
20.5.1 Keyboard Initialization
When a keyboard interrupt pin is enabled, it takes time for the internal
pull-up to reach a logic 1. Therefore a false interrupt can occur as soon
as the pin is enabled.
To prevent a false interrupt on keyboard initialization:
1. Mask keyboard interrupts by setting the IMASKK bit in the
keyboard status and control register.
2. Enable the KBI pins by setting the appropriate KBIEx bits in the
keyboard interrupt enable register.
3. Write to the ACKK bit in the keyboard status and control register
to clear any false interrupts.
4. Clear the IMASKK bit.
An interrupt signal on an edge-triggered pin can be acknowledged
immediately after enabling the pin. An interrupt signal on an edge- and
level-triggered interrupt pin must be acknowledged after a delay that
depends on the external load.
Another way to avoid a false interrupt:
1. Configure the keyboard pins as outputs by setting the appropriate
DDR bits in data direction register.
2. Write logic 1s to the appropriate data register bits.
3. Enable the KBI pins by setting the appropriate KBIEx bits in the
keyboard interrupt enable register.
20.6 Keyboard Interrupt Registers
Two registers control the operation of the keyboard interrupt module:
Keyboard Status and Control Register -- $001A
Keyboard Interrupt Enable Register -- $001B
Keyboard Interrupt Module (KBI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
348
Keyboard Interrupt Module (KBI)
MOTOROLA
20.6.1 Keyboard Status and Control Register
Flags keyboard interrupt requests
Acknowledges keyboard interrupt requests
Masks keyboard interrupt requests
Controls keyboard interrupt triggering sensitivity
KEYF -- Keyboard Flag Bit
This read-only bit is set when a keyboard interrupt is pending.
Reset clears the KEYF bit.
1 = Keyboard interrupt pending
0 = No keyboard interrupt pending
ACKK -- Keyboard Acknowledge Bit
Writing a logic 1 to this write-only bit clears the keyboard interrupt
request. ACKK always reads as logic 0. Reset clears ACKK.
IMASKK -- Keyboard Interrupt Mask Bit
Writing a logic 1 to this read/write bit prevents the output of the
keyboard interrupt mask from generating interrupt requests. Reset
clears the IMASKK bit.
1 = Keyboard interrupt requests masked
0 = Keyboard interrupt requests not masked
MODEK -- Keyboard Triggering Sensitivity Bit
This read/write bit controls the triggering sensitivity of the keyboard
interrupt pins. Reset clears MODEK.
1 = Keyboard interrupt requests on falling edges and low levels
0 = Keyboard interrupt requests on falling edges only
Address:
$001A
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
KEYF
0
IMASKK
MODEK
Write:
ACKK
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 20-3. Keyboard Status and Control Register (KBSCR)
Keyboard Interrupt Module (KBI)
Low-Power Modes
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Keyboard Interrupt Module (KBI)
349
20.6.2 Keyboard Interrupt Enable Register
The port-D keyboard interrupt enable register enables or disables each
port-D pin to operate as a keyboard interrupt pin.
KBIE7KBIE0 -- Keyboard Interrupt Enable Bits
Each of these read/write bits enables the corresponding keyboard
interrupt pin to latch interrupt requests. Reset clears the keyboard
interrupt enable register.
1 = KBIx pin enabled as keyboard interrupt pin
0 = KBIx pin not enabled as keyboard interrupt pin
20.7 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
20.8 Wait Mode
The keyboard interrupt module remains active in wait mode. Clearing the
IMASKK bit in the keyboard status and control register enables keyboard
interrupt requests to bring the MCU out of wait mode.
20.9 Stop Mode
The keyboard interrupt module remains active in stop mode. Clearing
the IMASKK bit in the keyboard status and control register enables
keyboard interrupt requests to bring the MCU out of stop mode.
Address:
$001B
Bit 7
6
5
4
3
2
1
Bit 0
Read:
KBIE7
KBIE6
KBIE5
KBIE4
KBIE3
KBIE2
KBIE1
KBIE0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 20-4. Keyboard Interrupt Enable Register (KBIER)
Keyboard Interrupt Module (KBI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
350
Keyboard Interrupt Module (KBI)
MOTOROLA
20.10 Keyboard Module During Break Interrupts
The system integration module (SIM) controls whether the keyboard
interrupt latch can be cleared during the break state. The BCFE bit in the
SIM break flag control register (BFCR) enables software to clear status
bits during the break state.
To allow software to clear the keyboard interrupt latch during a break
interrupt, write a logic 1 to the BCFE bit. If a latch is cleared during the
break state, it remains cleared when the MCU exits the break state.
To protect the latch during the break state, write a logic 0 to the BCFE
bit. With BCFE at logic 0 (its default state), writing to the keyboard
acknowledge bit (ACKK) in the keyboard status and control register
during the break state has no effect.
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Computer Operating Properly (COP)
351
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 21. Computer Operating Properly (COP)
21.1 Contents
21.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351
21.3
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352
21.4
I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
21.4.1
ICLK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
21.4.2
STOP Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
21.4.3
COPCTL Write . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
21.4.4
Power-On Reset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
21.4.5
Internal Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354
21.4.6
Reset Vector Fetch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354
21.4.7
COPD (COP Disable) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .354
21.4.8
COPRS (COP Rate Select) . . . . . . . . . . . . . . . . . . . . . . . . 354
21.5
COP Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355
21.6
Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355
21.7
Monitor Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355
21.8
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .355
21.8.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356
21.8.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356
21.9
COP Module During Break Mode . . . . . . . . . . . . . . . . . . . . . .356
21.2 Introduction
The computer operating properly (COP) module contains a free-running
counter that generates a reset if allowed to overflow. The COP module
helps software recover from runaway code. Prevent a COP reset by
clearing the COP counter periodically. The COP module can be disabled
through the COPD bit in the configuration register 1 (CONFIG1).
Computer Operating Properly (COP)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
352
Computer Operating Properly (COP)
MOTOROLA
21.3 Functional Description
Figure 21-1
shows the structure of the COP module.
Figure 21-1. COP Block Diagram
The COP counter is a free-running 6-bit counter preceded by a 12-bit
prescaler counter. If not cleared by software, the COP counter overflows
and generates an asynchronous reset after 2
18
2
4
or 2
13
2
4
ICLK
cycles, depending on the state of the COP rate select bit, COPRS, in the
CONFIG1 register. With a 2
13
2
4
ICLK cycle overflow option, a 24-kHz
ICLK gives a COP timeout period of 341ms. Writing any value to location
$FFFF before an overflow occurs prevents a COP reset by clearing the
COP counter and stages 12 through 5 of the prescaler.
NOTE:
Service the COP immediately after reset and before entering or after
exiting STOP Mode to guarantee the maximum time before the first COP
counter overflow.
COPCTL WRITE
ICLK
RESET VECTOR FETCH
RESET CIRCUIT
RESET STATUS REGISTER
INTERNAL RESET SOURCES
12-BIT COP PRESCALER
C
L
E
A
R
AL
L
ST
AGE
S
6-BIT COP COUNTER
COP DISABLE
RESET
COPCTL WRITE
CLEAR
COPEN (FROM SIM)
COP COUNTER
COP CLOCK
COP
TI
M
E
OUT
STOP INSTRUCTION
(COPD FROM CONFIG1)
COP RATE SEL
(COPRS FROM CONFIG1)
CLE
A
R S
T
A
G
E
S
5
12
Computer Operating Properly (COP)
I/O Signals
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Computer Operating Properly (COP)
353
A COP reset pulls the RST pin low for 32 ICLK cycles and sets the COP
bit in the SIM reset status register (SRSR).
In monitor mode, the COP is disabled if the RST pin or the IRQ1 is held
at V
TST
. During the break state, V
TST
on the RST pin disables the COP.
NOTE:
Place COP clearing instructions in the main program and not in an
interrupt subroutine. Such an interrupt subroutine could keep the COP
from generating a reset even while the main program is not working
properly.
21.4 I/O Signals
The following paragraphs describe the signals shown in
Figure 21-1
.
21.4.1 ICLK
ICLK is the internal oscillator output signal. ICLK frequency is
approximately equal to 24kHz. See
Section 24. Electrical
Specifications
for ICLK parameters.
21.4.2 STOP Instruction
The STOP instruction clears the COP prescaler.
21.4.3 COPCTL Write
Writing any value to the COP control register (COPCTL) (see
21.5 COP
Control Register
) clears the COP counter and clears bits 12 through 5
of the prescaler. Reading the COP control register returns the low byte
of the reset vector.
21.4.4 Power-On Reset
The power-on reset (POR) circuit clears the COP prescaler 4096 ICLK
cycles after power-up.
Computer Operating Properly (COP)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
354
Computer Operating Properly (COP)
MOTOROLA
21.4.5 Internal Reset
An internal reset clears the COP prescaler and the COP counter.
21.4.6 Reset Vector Fetch
A reset vector fetch occurs when the vector address appears on the data
bus. A reset vector fetch clears the COP prescaler.
21.4.7 COPD (COP Disable)
The COPD signal reflects the state of the COP disable bit (COPD) in the
CONFIG1 register. (See
Figure 21-2
and
Section 5. Configuration
and Mask Option Registers (CONFIG & MOR)
.)
21.4.8 COPRS (COP Rate Select)
The COPRS signal reflects the state of the COP rate select bit (COPRS)
in the CONFIG1 register.
COPRS -- COP Rate Select
COPRS selects the COP time-out period. Reset clears COPRS.
1 = COP time out period = 2
13
2
4
ICLK cycles
0 = COP time out period = 2
18
2
4
ICLK cycles
COPD -- COP Disable Bit
COPD disables the COP module.
1 = COP module disabled
0 = COP module enabled
Address:
$001F
Bit 7
6
5
4
3
2
1
Bit 0
Read:
COPRS
LVISTOP LVIRSTD LVIPWRD LVI5OR3
SSREC
STOP
COPD
Write:
Reset:
0
0
0
0
0*
0
0
0
* Reset by POR only.
Figure 21-2. Configuration Register 1 (CONFIG1)
Computer Operating Properly (COP)
COP Control Register
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Computer Operating Properly (COP)
355
21.5 COP Control Register
The COP control register is located at address $FFFF and overlaps the
reset vector. Writing any value to $FFFF clears the COP counter and
starts a new timeout period. Reading location $FFFF returns the low
byte of the reset vector.
21.6 Interrupts
The COP does not generate CPU interrupt requests.
21.7 Monitor Mode
When monitor mode is entered with V
TST
on the IRQ1 pin, the COP is
disabled as long as V
TST
remains on the IRQ1 pin or the RST pin. When
monitor mode is entered by having blank reset vectors and not having
V
TST
on the IRQ1 pin, the COP is automatically disabled until a POR
occurs.
21.8 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
Address:
$FFFF
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Low byte of reset vector
Write:
Clear COP counter
Reset:
Unaffected by reset
Figure 21-3. COP Control Register (COPCTL)
Computer Operating Properly (COP)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
356
Computer Operating Properly (COP)
MOTOROLA
21.8.1 Wait Mode
The COP remains active during wait mode. To prevent a COP reset
during wait mode, periodically clear the COP counter in a CPU interrupt
routine.
21.8.2 Stop Mode
Stop mode turns off the ICLK input to the COP and clears the COP
prescaler. Service the COP immediately before entering or after exiting
stop mode to ensure a full COP timeout period after entering or exiting
stop mode.
To prevent inadvertently turning off the COP with a STOP instruction, a
configuration option is available that disables the STOP instruction.
When the STOP bit in the configuration register has the STOP
instruction is disabled, execution of a STOP instruction results in an
illegal opcode reset.
21.9 COP Module During Break Mode
The COP is disabled during a break interrupt when V
TST
is present on
the RST pin.
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Low-Voltage Inhibit (LVI)
357
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 22. Low-Voltage Inhibit (LVI)
22.1 Contents
22.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
22.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357
22.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
22.4.1
Polled LVI Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359
22.4.2
Forced Reset Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 360
22.4.3
Voltage Hysteresis Protection . . . . . . . . . . . . . . . . . . . . . . 360
22.4.4
LVI Trip Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360
22.5
LVI Status Register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
22.6
LVI Interrupts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361
22.7
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .361
22.7.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362
22.7.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362
22.2 Introduction
This section describes the low-voltage inhibit (LVI) module, which
monitors the voltage on the V
DD
pin and can force a reset when the V
DD
voltage falls below the LVI trip falling voltage, V
TRIPF
.
22.3 Features
Features of the LVI module include:
Programmable LVI reset
Selectable LVI trip voltage
Programmable stop mode operation
Low-Voltage Inhibit (LVI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
358
Low-Voltage Inhibit (LVI)
MOTOROLA
22.4 Functional Description
Figure 22-2
shows the structure of the LVI module. The LVI is enabled
out of reset. The LVI module contains a bandgap reference circuit and
comparator. Clearing the LVI power disable bit, LVIPWRD, enables the
LVI to monitor V
DD
voltage. Clearing the LVI reset disable bit, LVIRSTD,
enables the LVI module to generate a reset when V
DD
falls below a
voltage, V
TRIPF
. Setting the LVI enable in stop mode bit, LVISTOP,
enables the LVI to operate in stop mode. Setting the LVI 5V or 3V trip
point bit, LVI5OR3, enables the trip point voltage, V
TRIPF
, to be
configured for 5V operation. Clearing the LVI5OR3 bit enables the trip
point voltage, V
TRIPF
, to be configured for 3V operation. The actual trip
points are shown in
Section 24. Electrical Specifications
.
Figure 22-2. LVI Module Block Diagram
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$FE0F
Low-Voltage Inhibit Status
Register
(LVISR)
Read: LVIOUT
0
0
0
0
0
0
0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 22-1. LVI I/O Register Summary
LOW V
DD
DETECTOR
LVIPWRD
STOP INSTRUCTION
LVI RESET
V
DD
>
V
TRIPR
= 0
V
DD
V
TRIPF
= 1
FROM CONFIG
FROM CONFIG1
V
DD
FROM CONFIG1
LVI5OR3
FROM CONFIG1
TO LVISR
LVIOUT
LVISTOP
LVIRSTD
Low-Voltage Inhibit (LVI)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Low-Voltage Inhibit (LVI)
359
NOTE:
After a power-on reset (POR) the LVI's default mode of operation is 3V.
If a 5V system is used, the user must set the LVI5OR3 bit to raise the
trip point to 5V operation. Note that this must be done after every power-
on reset since the default will revert back to 3V mode after each power-
on reset. If the V
DD
supply is below the 5V mode trip voltage but above
the 3V mode trip voltage when POR is released, the MCU will operate
because V
TRIPF
defaults to 3V mode after a POR. So, in a 5V system
care must be taken to ensure that V
DD
is above the 5V mode trip voltage
after POR is released.
NOTE:
If the user requires 5V mode and sets the LVI5OR3 bit after a power-on
reset while the V
DD
supply is not above the V
TRIPF
for 5V mode, the
MCU will immediately go into reset. The LVI in this case will hold the
MCU in reset until either V
DD
goes above the rising 5V trip point, V
TRIPR
,
which will release reset or V
DD
decreases to approximately 0V which will
re-trigger the power-on reset and reset the trip point to 3V operation.
LVISTOP, LVIPWRD, LVI5OR3, and LVIRSTD are in the configuration
register 1 (CONFIG1). See
Section 5. Configuration and Mask Option
Registers (CONFIG & MOR)
for details of the LVI's configuration bits.
Once an LVI reset occurs, the MCU remains in reset until V
DD
rises
above a voltage, V
TRIPR
, which causes the MCU to exit reset. See
9.4.2.5 Low-Voltage Inhibit (LVI) Reset
for details of the interaction
between the SIM and the LVI. The output of the comparator controls the
state of the LVIOUT flag in the LVI status register (LVISR).
An LVI reset also drives the RST pin low to provide low-voltage
protection to external peripheral devices.
22.4.1 Polled LVI Operation
In applications that can operate at V
DD
levels below the V
TRIPF
level,
software can monitor V
DD
by polling the LVIOUT bit. In the configuration
register 1 (CONFIG1), the LVIPWRD bit must be at logic 0 to enable the
LVI module, and the LVIRSTD bit must be at logic 1 to disable LVI
resets.
Low-Voltage Inhibit (LVI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
360
Low-Voltage Inhibit (LVI)
MOTOROLA
22.4.2 Forced Reset Operation
In applications that require V
DD
to remain above the V
TRIPF
level,
enabling LVI resets allows the LVI module to reset the MCU when V
DD
falls below the V
TRIPF
level. In the configuration register 1 (CONFIG1),
the LVIPWRD and LVIRSTD bits must be at logic 0 to enable the LVI
module and to enable LVI resets.
22.4.3 Voltage Hysteresis Protection
Once the LVI has triggered (by having V
DD
fall below V
TRIPF
), the LVI
will maintain a reset condition until V
DD
rises above the rising trip point
voltage, V
TRIPR
. This prevents a condition in which the MCU is
continually entering and exiting reset if V
DD
is approximately equal to
V
TRIPF
. V
TRIPR
is greater than V
TRIPF
by the hysteresis voltage, V
HYS
.
22.4.4 LVI Trip Selection
The LVI5OR3 bit in the CONFIG1 register selects whether the LVI is
configured for 5V or 3V protection.
NOTE:
The MCU is guaranteed to operate at a minimum supply voltage. The trip
point (V
TRIPF
[5 V] or V
TRIPF
[3 V]) may be lower than this.
(See
Section 24. Electrical Specifications
for the actual trip point
voltages.)
Low-Voltage Inhibit (LVI)
LVI Status Register
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Low-Voltage Inhibit (LVI)
361
22.5 LVI Status Register
The LVI status register (LVISR) indicates if the V
DD
voltage was
detected below the V
TRIPF
level.
LVIOUT -- LVI Output Bit
This read-only flag becomes set when the V
DD
voltage falls below the
V
TRIPF
trip voltage (see Table 22-1). Reset clears the LVIOUT bit.
22.6 LVI Interrupts
The LVI module does not generate interrupt requests.
22.7 Low-Power Modes
The STOP and WAIT instructions put the MCU in low power-
consumption standby modes.
Address:
$FE0F
Bit 7
6
5
4
3
2
1
Bit 0
Read:
LVIOUT
0
0
0
0
0
0
0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 22-3. LVI Status Register
Table 22-1. LVIOUT Bit Indication
V
DD
LVIOUT
V
DD
>
V
TRIPR
0
V
DD
<
V
TRIPF
1
V
TRIPF
<
V
DD
<
V
TRIPR
Previous value
Low-Voltage Inhibit (LVI)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
362
Low-Voltage Inhibit (LVI)
MOTOROLA
22.7.1 Wait Mode
If enabled, the LVI module remains active in wait mode. If enabled to
generate resets, the LVI module can generate a reset and bring the MCU
out of wait mode.
22.7.2 Stop Mode
If enabled in stop mode (LVISTOP = 1), the LVI module remains active
in stop mode. If enabled to generate resets (LVIRSTD = 0), the LVI
module can generate a reset and bring the MCU out of stop mode.
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Break Module (BRK)
363
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 23. Break Module (BRK)
23.1 Contents
23.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363
23.3
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364
23.4
Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364
23.4.1
Flag Protection During Break Interrupts . . . . . . . . . . . . . . .366
23.4.2
CPU During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . 366
23.4.3
TIM1 and TIM2 During Break Interrupts . . . . . . . . . . . . . . .366
23.4.4
COP During Break Interrupts . . . . . . . . . . . . . . . . . . . . . . . 366
23.5
Low-Power Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .366
23.5.1
Wait Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 366
23.5.2
Stop Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367
23.6
Break Module Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . .367
23.6.1
Break Status and Control Register. . . . . . . . . . . . . . . . . . . 367
23.6.2
Break Address Registers . . . . . . . . . . . . . . . . . . . . . . . . . .368
23.6.3
SIM Break Status Register . . . . . . . . . . . . . . . . . . . . . . . . . 368
23.6.4
SIM Break Flag Control Register . . . . . . . . . . . . . . . . . . . . 370
23.2 Introduction
This section describes the break module. The break module can
generate a break interrupt that stops normal program flow at a defined
address to enter a background program.
Break Module (BRK)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
364
Break Module (BRK)
MOTOROLA
23.3 Features
Features of the break module include:
Accessible input/output (I/O) registers during the break interrupt
CPU-generated break interrupts
Software-generated break interrupts
COP disabling during break interrupts
23.4 Functional Description
When the internal address bus matches the value written in the break
address registers, the break module issues a breakpoint signal to the
CPU. The CPU then loads the instruction register with a software
interrupt instruction (SWI) after completion of the current CPU
instruction. The program counter vectors to $FFFC and $FFFD ($FEFC
and $FEFD in monitor mode).
The following events can cause a break interrupt to occur:
A CPU-generated address (the address in the program counter)
matches the contents of the break address registers.
Software writes a logic 1 to the BRKA bit in the break status and
control register.
When a CPU-generated address matches the contents of the break
address registers, the break interrupt begins after the CPU completes its
current instruction. A return-from-interrupt instruction (RTI) in the break
routine ends the break interrupt and returns the MCU to normal
operation.
Figure 23-1
shows the structure of the break module.
Break Module (BRK)
Functional Description
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Break Module (BRK)
365
Figure 23-1. Break Module Block Diagram
IAB15IAB8
IAB7IAB0
8-BIT COMPARATOR
8-BIT COMPARATOR
CONTROL
BREAK ADDRESS REGISTER LOW
BREAK ADDRESS REGISTER HIGH
IAB15IAB0
BREAK
Addr.
Register Name
Bit 7
6
5
4
3
2
1
Bit 0
$FE00
SIM Break Status Register
(SBSR)
Read:
R
R
R
R
R
R
SBSW
R
Write:
Note
Reset:
0
$FE03
SIM Break Flag Control
Register (SBFCR)
Read:
BCFE
R
R
R
R
R
R
R
Write:
Reset:
0
$FE0C
Break Address Register
High (BRKH)
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
0
0
0
0
0
0
0
0
$FE0D
Break Address Register
Low (BRKL)
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
0
0
0
0
0
0
0
0
$FE0E
Break Status and Control
Register (BRKSCR)
Read:
BRKE
BRKA
0
0
0
0
0
0
Write:
Reset:
0
0
0
0
0
0
0
0
Note: Writing a logic 0 clears SBSW.
= Unimplemented
R
= Reserved
Figure 23-2. Break Module I/O Register Summary
Break Module (BRK)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
366
Break Module (BRK)
MOTOROLA
23.4.1 Flag Protection During Break Interrupts
The BCFE bit in the SIM break flag control register (SBFCR) enables
software to clear status bits during the break state.
23.4.2 CPU During Break Interrupts
The CPU starts a break interrupt by:
Loading the instruction register with the SWI instruction
Loading the program counter with $FFFC and $FFFD
($FEFC and $FEFD in monitor mode)
The break interrupt begins after completion of the CPU instruction in
progress. If the break address register match occurs on the last cycle of
a CPU instruction, the break interrupt begins immediately.
23.4.3 TIM1 and TIM2 During Break Interrupts
A break interrupt stops the timer counters.
23.4.4 COP During Break Interrupts
The COP is disabled during a break interrupt when V
TST
is present on
the RST pin.
23.5 Low-Power Modes
The WAIT and STOP instructions put the MCU in low power-
consumption standby modes.
23.5.1 Wait Mode
If enabled, the break module is active in wait mode. In the break routine,
the user can subtract one from the return address on the stack if SBSW
is set (see
Section 9. System Integration Module (SIM)
). Clear the
SBSW bit by writing logic 0 to it.
Break Module (BRK)
Break Module Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Break Module (BRK)
367
23.5.2 Stop Mode
A break interrupt causes exit from stop mode and sets the SBSW bit in
the break status register.
23.6 Break Module Registers
These registers control and monitor operation of the break module:
Break status and control register (BRKSCR)
Break address register high (BRKH)
Break address register low (BRKL)
SIM break status register (SBSR)
SIM break flag control register (SBFCR)
23.6.1 Break Status and Control Register
The break status and control register (BRKSCR) contains break module
enable and status bits.
BRKE -- Break Enable Bit
This read/write bit enables breaks on break address register matches.
Clear BRKE by writing a logic 0 to bit 7. Reset clears the BRKE bit.
1 = Breaks enabled on 16-bit address match
0 = Breaks disabled on 16-bit address match
Address:
$FE0E
Bit 7
6
5
4
3
2
1
Bit 0
Read:
BRKE
BRKA
0
0
0
0
0
0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 23-3. Break Status and Control Register (BRKSCR)
Break Module (BRK)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
368
Break Module (BRK)
MOTOROLA
BRKA -- Break Active Bit
This read/write status and control bit is set when a break address
match occurs. Writing a logic 1 to BRKA generates a break interrupt.
Clear BRKA by writing a logic 0 to it before exiting the break routine.
Reset clears the BRKA bit.
1 = (When read) Break address match
0 = (When read) No break address match
23.6.2 Break Address Registers
The break address registers (BRKH and BRKL) contain the high and low
bytes of the desired breakpoint address. Reset clears the break address
registers.
23.6.3 SIM Break Status Register
The SIM break status register (SBSR) contains a flag to indicate that a
break caused an exit from wait mode. The flag is useful in applications
requiring a return to wait mode after exiting from a break interrupt.
Address:
$FE0C
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 15
14
13
12
11
10
9
Bit 8
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 23-4. Break Address Register High (BRKH)
Address:
$FE0D
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 7
6
5
4
3
2
1
Bit 0
Write:
Reset:
0
0
0
0
0
0
0
0
Figure 23-5. Break Address Register Low (BRKL)
Break Module (BRK)
Break Module Registers
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Break Module (BRK)
369
SBSW -- Break Wait Bit
This status bit is set when a break interrupt causes an exit from wait
mode or stop mode. Clear SBSW by writing a logic 0 to it. Reset clears
SBSW.
1 = Stop mode or wait mode was exited by break interrupt
0 = Stop mode or wait mode was not exited by break interrupt
SBSW can be read within the break interrupt routine. The user can
modify the return address on the stack by subtracting 1 from it. The
following code is an example.
Address:
$FE00
Bit 7
6
5
4
3
2
1
Bit 0
Read:
R
R
R
R
R
R
SBSW
R
Write:
Note
Reset:
0
Note: Writing a logic 0 clears SBSW.
R
= Reserved
Figure 23-6. SIM Break Status Register (SBSR)
;
;
;
This code works if the H register has been pushed onto the stack in the break
service routine software. This code should be executed at the end of the break
service routine software.
HIBYTE
EQU
5
LOBYTE
EQU
6
;
If not SBSW, do RTI
BRCLR
SBSW,SBSR, RETURN
;
;
See if wait mode or stop mode was exited by
break.
TST
LOBYTE,SP
;If RETURNLO is not zero,
BNE
DOLO
;then just decrement low byte.
DEC
HIBYTE,SP
;Else deal with high byte, too.
DOLO
DEC
LOBYTE,SP
;Point to WAIT/STOP opcode.
RETURN
PULH
RTI
;Restore H register.
Break Module (BRK)
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
370
Break Module (BRK)
MOTOROLA
23.6.4 SIM Break Flag Control Register
The SIM break flag control register (SBFCR) contains a bit that enables
software to clear status bits while the MCU is in a break state.
BCFE -- Break Clear Flag Enable Bit
This read/write bit enables software to clear status bits by accessing
status registers while the MCU is in a break state. To clear status bits
during the break state, the BCFE bit must be set.
1 = Status bits clearable during break
0 = Status bits not clearable during break
Address:
$FE03
Bit 7
6
5
4
3
2
1
Bit 0
Read:
BCFE
R
R
R
R
R
R
R
Write:
Reset:
0
R
= Reserved
Figure 23-7. SIM Break Flag Control Register (SBFCR)
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Electrical Specifications
371
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 24. Electrical Specifications
24.1 Contents
24.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372
24.3
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . .372
24.4
Functional Operating Range. . . . . . . . . . . . . . . . . . . . . . . . . . 373
24.5
Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373
24.6
5.0V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . 374
24.7
3.0V DC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . 376
24.8
5.0V Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
24.9
3.0V Control Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
24.10 5.0V Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 378
24.11 3.0V Oscillator Characteristics . . . . . . . . . . . . . . . . . . . . . . . . 379
24.12 5.0V ADC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . 380
24.13 3.0V ADC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . 381
24.14 Analog Module Electrical Characteristics . . . . . . . . . . . . . . . . 382
24.14.1 Temperature Sensor Electrical Characteristics . . . . . . . . . 382
24.14.2 Current Detection Electrical Characteristics. . . . . . . . . . . . 382
24.14.3 Two-Stage Amplifier Electrical Characteristics. . . . . . . . . . 382
24.15 Timer Interface Module Characteristics . . . . . . . . . . . . . . . . . 383
24.16 MMIIC Electrical Characteristics. . . . . . . . . . . . . . . . . . . . . . . 383
24.17 CGM Electrical Specifications. . . . . . . . . . . . . . . . . . . . . . . . . 385
24.18 FLASH Memory Characteristics . . . . . . . . . . . . . . . . . . . . . . . 386
Electrical Specifications
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
372
Electrical Specifications
MOTOROLA
24.2 Introduction
This section contains electrical and timing specifications.
24.3 Absolute Maximum Ratings
Maximum ratings are the extreme limits to which the MCU can be
exposed without permanently damaging it.
NOTE:
This device is not guaranteed to operate properly at the maximum
ratings. Refer to
24.6 5.0V DC Electrical Characteristics
for
guaranteed operating conditions.
NOTE:
This device contains circuitry to protect the inputs against damage due
to high static voltages or electric fields; however, it is advised that normal
precautions be taken to avoid application of any voltage higher than
maximum-rated voltages to this high-impedance circuit. For proper
operation, it is recommended that V
IN
and V
OUT
be constrained to the
range V
SS
(V
IN
or V
OUT
)
V
DD
. Reliability of operation is enhanced if
unused inputs are connected to an appropriate logic voltage level (for
example, either V
SS
or V
DD
.)
Table 24-1. Absolute Maximum Ratings
(1)
Notes:
1. Voltages referenced to V
SS
.
Characteristic
Symbol
Value
Unit
Supply voltage
V
DD
0.3 to +6.0
V
Input voltage
All pins (except IRQ1)
IRQ1 pin
V
IN
V
SS
0.3 to V
DD
+0.3
V
SS
0.3 to 8.5
V
Maximum current per pin
excluding V
DD
and V
SS
I
25
mA
Maximum current out of V
SS
I
MVSS
100
mA
Maximum current into V
DD
I
MVDD
100
mA
Storage temperature
T
STG
55 to +150
C
Electrical Specifications
Functional Operating Range
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Electrical Specifications
373
24.4 Functional Operating Range
24.5 Thermal Characteristics
Table 24-2. Operating Range
Characteristic
Symbol
Value
Unit
Operating temperature range
T
A
40 to +125
40 to +85
C
Operating voltage range
V
DD
--
5V
10%
3V
10%
5V
10%
V
Table 24-3. Thermal Characteristics
Characteristic
Symbol
Value
Unit
Thermal resistance
42-pin SDIP
48-pin LQFP
JA
60
80
C/W
C/W
I/O pin power dissipation
P
I/O
User determined
W
Power dissipation
(1)
Notes:
1. Power dissipation is a function of temperature.
P
D
P
D
= (I
DD
V
DD
) + P
I/O
=
K/(T
J
+ 273
C)
W
Constant
(2)
2. K constant unique to the device. K can be determined for a known T
A
and measured
P
D.
With this value of K, P
D
and T
J
can be determined for any value of T
A
.
K
P
D
x
(T
A
+ 273
C)
+ P
D
2
JA
W/
C
Average junction temperature
T
J
T
A
+ (P
D
JA
)
C
Electrical Specifications
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
374
Electrical Specifications
MOTOROLA
24.6 5.0V DC Electrical Characteristics
Table 24-4. 5V DC Electrical Characteristics
Characteristic
(1)
Symbol
Min
Typ
(2)
Max
Unit
Output high voltage (I
LOAD
= 2.0 mA)
PTA[0:7], PTB[4:6], PTC[0:7], PTD[0:7]
V
OH
V
DD
0.8
--
--
V
Output low voltage (I
LOAD
= 1.6mA)
PTA[0:7], PTB[0:6], PTC[0:7], PTD[0:7]
V
OL
--
--
0.4
V
LED sink current (V
Drain
= 4.0V)
PTA[0:5], PTC[3:7]
I
OL
--
15
--
mA
Input high voltage
PTA[0:7], PTB[0:6], PTC[0:7], PTD[0:7], RST, IRQ1,
IRQ2, OSC1.
V
IH
0.7
V
DD
--
V
DD
V
Input low voltage
PTA[0:7], PTB[0:6], PTC[0:7], PTD[0:7], RST, IRQ1,
IRQ2, OSC1
V
IL
V
SS
--
0.3
V
DD
V
V
DD
supply current
Run
(3)
, f
OP
= 8.0 MHz
with ADC on
with ADC off
Wait
(4)
, f
OP
= 8.0 MHz
Stop
(5)
25
C (with OSC, TBM, current sense, LVI)
25
C (with OSC, TBM, current sense)
25
C (with OSC, TBM)
25
C
40
C to 85
C (with OSC, TBM, current sense, LVI)
40
C to 85
C (with OSC, TBM, current sense)
40
C to 85
C (with OSC, TBM)
40
C to 85
C
40
C to 125
C (with OSC, TBM, current sense, LVI)
40
C to 125
C (with OSC, TBM, current sense)
40
C to 125
C (with OSC, TBM)
40
C to 125
C
I
DD
--
--
--
--
--
--
--
--
--
--
--
--
--
--
--
24
18
7.5
50
12
9
1
--
--
--
--
--
--
--
--
40
30
15
150
40
30
10
180
50
40
15
200
60
50
25
mA
mA
mA
A
A
A
A
A
A
A
A
A
A
A
A
Digital I/O ports Hi-Z leakage current
I
IL
--
--
10
A
Input current
I
IN
--
--
1
A
Capacitance
Ports (as input or output)
C
OUT
C
IN
--
--
--
--
12
8
pF
POR re-arm voltage
(6)
V
POR
0
--
100
mV
Electrical Specifications
5.0V DC Electrical Characteristics
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Electrical Specifications
375
POR rise-time ramp rate
(7)
R
POR
0.035
--
--
V/ms
Monitor mode entry voltage
V
TST
1.4
V
DD
--
8
V
Pullup resistors
(8)
PTD[0:7] configured as KBI[0:7]
RST, IRQ1, IRQ2
R
PU1
R
PU2
24
24
35
35
42
42
k
k
Low-voltage inhibit, trip falling voltage
V
LVII5
3.80
4.15
4.45
V
Low-voltage inhibit, trip rising voltage
V
LVII5
3.95
4.30
4.60
V
Schmitt trigger input low level trip voltage
RST, IRQ1, IRQ2, KBI[0:7]
V
SCMTL
--
1.21
--
V
Schmitt trigger input high level trip voltage
RST, IRQ1, IRQ2, KBI[0:7]
V
SCMTH
--
1.65
--
V
Notes:
1. V
DD
= 4.5 to 5.5 Vdc, V
SS
= 0 Vdc, T
A
= T
L
to T
H
, unless otherwise noted.
2. Typical values reflect average measurements at midpoint of voltage range, 25
C only.
3. Run (operating) I
DD
measured using external square wave clock source. All inputs 0.2 V from rail. No dc loads. Less than
100 pF on all outputs. C
L
= 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly affects run I
DD
.
Measured with all modules enabled.
4. Wait I
DD
measured using external square wave clock source. All inputs 0.2 V from rail. No dc loads. Less than 100 pF on
all outputs. C
L
= 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly affects wait I
DD
.
5. STOP I
DD
measured with OSC1 grounded, no port pins sourcing current.
6. Maximum is highest voltage that POR is guaranteed.
7. If minimum V
DD
is not reached before the internal POR reset is released,
RST
must be driven low externally until minimum
V
DD
is reached.
8. R
PU1
and
R
PU2
are measured at
V
DD
= 5.0V
Table 24-4. 5V DC Electrical Characteristics
Characteristic
(1)
Symbol
Min
Typ
(2)
Max
Unit
Electrical Specifications
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
376
Electrical Specifications
MOTOROLA
24.7 3.0V DC Electrical Characteristics
Table 24-5. 3V DC Electrical Characteristics
Characteristic
(1)
Symbol
Min
Typ
(2)
Max
Unit
Output high voltage (I
LOAD
= 1.0mA)
PTA[0:7], PTB[4:6], PTC[0:7], PTD[0:7]
V
OH
V
DD
0.4
--
--
V
Output low voltage (I
LOAD
= 0.8mA)
PTA[0:7], PTB[0:6], PTC[0:7], PTD[0:7]
V
OL
--
--
0.4
V
LED sink current (V
Drain
= 2.0V)
PTA[0:5], PTC[3:7]
V
OL
--
5
--
mA
Input high voltage
PTA[0:7], PTB[0:6], PTC[0:7], PTD[0:7], RST, IRQ1,
IRQ2, OSC1
V
IH
0.7
V
DD
--
V
DD
V
Input low voltage
PTA[0:7], PTB[0:6], PTC[0:7], PTD[0:7], RST, IRQ1,
IRQ2, OSC1
V
IL
V
SS
--
0.3
V
DD
V
V
DD
supply current
Run
(3)
, f
OP
= 4.0 MHz
with ADC on
with ADC off
Wait
(4)
, f
OP
= 4.0 MHz
Stop
(5)
25
C (with OSC, TBM, LVI)
25
C (with OSC, TBM)
25
C
40
C to 85
C (with OSC, TBM, LVI)
40
C to 85
C (with OSC, TBM)
40
C to 85
C
I
DD
--
--
--
--
--
--
--
--
--
7
5
2.5
27
5
0.5
--
--
--
16
12
6
80
12
5
100
15
5
mA
mA
mA
A
A
A
A
A
A
Digital I/O ports Hi-Z leakage current
I
IL
--
--
10
A
Input current
I
IN
--
--
1
A
Capacitance
Ports (as input or output)
C
OUT
C
IN
--
--
--
--
12
8
pF
POR re-arm voltage
(6)
V
POR
0
--
100
mV
POR rise-time ramp rate
(7)
R
POR
0.035
--
--
V/ms
Monitor mode entry voltage
V
HI
1.4
V
DD
--
2.0
V
DD
V
Pullup resistors
(8)
PTD[0:7] configured as KBI[0:7]
RST, IRQ1, IRQ2
R
PU1
R
PU2
24
24
35
35
42
42
k
k
Electrical Specifications
5.0V Control Timing
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Electrical Specifications
377
24.8 5.0V Control Timing
24.9 3.0V Control Timing
Low-voltage inhibit, trip voltage
(No hysteresis implemented for 3V LVI)
V
LVI3
2.32
2.49
2.68
V
Schmitt trigger input low level trip voltage
RST, IRQ1, IRQ2, KBI[0:7]
V
SCMTL
--
0.8
--
V
Schmitt trigger input high level trip voltage
RST, IRQ1, IRQ2, KBI[0:7]
V
SCMTH
--
1.2
--
V
Notes:
1. V
DD
= 2.7 to 3.3 Vdc, V
SS
= 0 Vdc, T
A
= T
L
to T
H
, unless otherwise noted.
2. Typical values reflect average measurements at midpoint of voltage range, 25
C only.
3. Run (operating) I
DD
measured using external square wave clock source. All inputs 0.2 V from rail. No dc loads. Less than
100 pF on all outputs. C
L
= 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly affects run I
DD
.
Measured with all modules enabled.
4. Wait I
DD
measured using external square wave clock source. All inputs 0.2 V from rail. No dc loads. Less than 100 pF on
all outputs. C
L
= 20 pF on OSC2. All ports configured as inputs. OSC2 capacitance linearly affects wait I
DD
.
5. STOP I
DD
measured with OSC1 grounded, no port pins sourcing current.
6. Maximum is highest voltage that POR is guaranteed.
7. If minimum V
DD
is not reached before the internal POR reset is released,
RST
must be driven low externally until minimum
V
DD
is reached.
8. R
PU1
and
R
PU2
are measured at
V
DD
= 5.0V.
Table 24-6. 5V Control Timing
Characteristic
(1)
Notes:
1. V
SS
= 0 Vdc; timing shown with respect to 20% V
DD
and 70% V
DD
, unless otherwise noted.
Symbol
Min
Max
Unit
Internal operating frequency
(2)
2. Some modules may require a minimum frequency greater than dc for proper operation; see appropriate table for this
information.
f
OP
--
8.0
MHz
RST input pulse width low
(3)
3. Minimum pulse width reset is guaranteed to be recognized. It is possible for a smaller pulse width to cause a reset.
t
IRL
750
--
ns
Table 24-7. 3V Control Timing
Characteristic
(1)
Notes:
1. V
SS
= 0 Vdc; timing shown with respect to 20% V
DD
and 70% V
DD
, unless otherwise noted.
Symbol
Min
Max
Unit
Internal operating frequency
(2)
2. Some modules may require a minimum frequency greater than dc for proper operation; see appropriate table for this
information.
f
OP
--
4.0
MHz
RST input pulse width low
(3)
3. Minimum pulse width reset is guaranteed to be recognized. It is possible for a smaller pulse width to cause a reset.
t
IRL
1.5
--
s
Table 24-5. 3V DC Electrical Characteristics
Characteristic
(1)
Symbol
Min
Typ
(2)
Max
Unit
Electrical Specifications
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
378
Electrical Specifications
MOTOROLA
24.10 5.0V Oscillator Characteristics
Figure 24-1. RC vs. Bus Frequency (5V @25
C)
Table 24-8. 5V Oscillator Specifications
Characteristic
Symbol
Min
Typ
Max
Unit
Internal oscillator clock frequency
f
ICLK
19.2 k
24k
28.8 k
Hz
External reference clock to OSC1
(1)
Notes:
1. No more than 10% duty cycle deviation from 50%.
f
OSC
dc
--
20M
Hz
Crystal reference frequency
(2)
2. Fundamental mode crystals only.
f
XCLK
32.768k
4.9152M
Hz
Crystal load capacitance
(3)
3. Consult crystal manufacturer's data.
C
L
--
--
--
Crystal fixed capacitance
C
1
--
2
C
L
(25p)
--
F
Crystal tuning capacitance
C
2
--
2
C
L
(25p)
--
F
Feedback bias resistor
R
B
--
10M
--
Series resistor
(4)
4. Not Required for high frequency crystals.
R
S
--
100k
--
External RC clock frequency
f
RCCLK
2M
-- 18M
Hz
External resistor
R
EXT
See
Figure 24-1
External capacitor
C
EXT
--
10
--
pF
R
EXT
C
EXT
OSC1
V
DD
MCU
0
0
2
4
6
8
10
5
4
3
2
1
Resistor R
EXT
(k
)
B
u
s
Fr
equ
enc
y
,
f
OP
(M
H
z
)
C
EXT
= 10 pF
5V @ 25
C
f
RCCLK
= f
OP
4
Electrical Specifications
3.0V Oscillator Characteristics
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Electrical Specifications
379
24.11 3.0V Oscillator Characteristics
Figure 24-2. RC vs. Bus Frequency (3V @25
C)
Table 24-9. 3V Oscillator Specifications
Characteristic
Symbol
Min
Typ
Max
Unit
Internal oscillator clock frequency
f
ICLK
13.8 k
17.2 k
20.6 k
Hz
External reference clock to OSC1
(1)
Notes:
1. No more than 10% duty cycle deviation from 50%.
f
OSC
dc
--
16M
Hz
Crystal reference frequency
(2)
2. Fundamental mode crystals only.
f
XCLK
32.768k
4.9152M
Hz
Crystal load capacitance
(3)
3. Consult crystal manufacturer's data.
C
L
--
--
--
Crystal fixed capacitance
C
1
--
2
C
L
(25p)
--
F
Crystal tuning capacitance
C
2
--
2
C
L
(25p)
--
F
Feedback bias resistor
R
B
--
10M
--
Series resistor
(4)
4. Not Required for high frequency crystals.
R
S
--
100k
--
External RC clock frequency
f
RCCLK
2M
--
10M
Hz
External resistor
R
EXT
See
Figure 24-2
External capacitor
C
EXT
--
10
--
pF
R
EXT
C
EXT
OSC1
V
DD
MCU
0
0
5
10
15
20
2.5
2
1.5
1
0.5
Resistor R
EXT
(k
)
B
u
s Fre
que
ncy
,
f
OP
(M
H
z
)
f
RCCLK
= f
OP
4
3
C
EXT
= 10 pF
3V @ 25
C
Electrical Specifications
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
380
Electrical Specifications
MOTOROLA
24.12 5.0V ADC Electrical Characteristics
Table 24-10. 5V ADC Electrical Characteristics
Characteristic
Symbol
Min
Max
Unit
Notes
Supply voltage
V
DDA
4.5
5.5
V
V
DDA
is an dedicated pin and
should be tied to V
DD
on the
PCB with proper decoupling.
Input range
V
ADIN
0
V
DDA
V
V
ADIN
V
DDA
Resolution
B
AD
10
10
bits
Absolute accuracy
A
AD
--
1.5
LSB
Includes quantization.
0.5 LSB =
1 ADC step.
ADC internal clock
f
ADIC
500k
2M
Hz
t
ADIC
= 1/f
ADIC
Conversion range
R
AD
V
REFL
V
REFH
V
ADC voltage
reference high
V
REFH
--
V
DDA
+ 0.1
V
ADC voltage
reference low
V
REFL
V
SSA
0.1
--
V
Conversion time
t
ADC
16
17
t
ADIC
cycles
Sample time
t
ADS
5
--
t
ADIC
cycles
Monotonicity
M
AD
Guaranteed
Zero input reading
Z
ADI
000
001
HEX
V
ADIN
= V
REFL
Full-scale reading
F
ADI
3FD
3FF
HEX
V
ADIN
= V
REFH
Input capacitance
C
ADI
--
20
pF
Not tested.
Input impedance
R
ADI
20M
--
V
REFH
/V
REFL
I
VREF
--
1.6
mA
Not tested.
Electrical Specifications
3.0V ADC Electrical Characteristics
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Electrical Specifications
381
24.13 3.0V ADC Electrical Characteristics
Table 24-11. 3V ADC Electrical Characteristics
Characteristic
Symbol
Min
Max
Unit
Notes
Supply voltage
V
DDA
2.7
3.3
V
V
DDA
is an dedicated pin and
should be tied to V
DD
on the
PCB with proper decoupling.
Input range
V
ADIN
0
V
DDA
V
V
ADIN
V
DDA
Resolution
B
AD
10
10
bits
Absolute accuracy
A
AD
--
1.5
LSB
Includes quantization.
0.5 LSB =
1 ADC step.
ADC internal clock
f
ADIC
500 k
2 M
Hz
t
ADIC
= 1/f
ADIC
Conversion range
R
AD
V
REFL
V
REFH
V
ADC voltage
reference high
V
REFH
--
V
DDA
+ 0.1
V
ADC voltage
reference low
V
REFL
V
SSA
0.1
--
V
Conversion time
t
ADC
16
17
t
ADIC
cycles
Sample time
t
ADS
5
--
t
ADIC
cycles
Monotonicity
M
AD
Guaranteed
Zero input reading
Z
ADI
000
001
HEX
V
ADIN
= V
REFL
Full-scale reading
F
ADI
3FD
3FF
HEX
V
ADIN
= V
REFH
Input capacitance
C
ADI
--
20
pF
Not tested.
Input impedance
R
ADI
20M
--
Measured at 5V
V
REFH
/V
REFL
I
VREF
--
1.6
mA
Not tested.
Electrical Specifications
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
382
Electrical Specifications
MOTOROLA
24.14 Analog Module Electrical Characteristics
24.14.1 Temperature Sensor Electrical Characteristics
24.14.2 Current Detection Electrical Characteristics
24.14.3 Two-Stage Amplifier Electrical Characteristics
Table 24-12. Temperature Sensor Electrical Characteristics
Characteristic
Symbol
Min
Typ
Max
Unit
Temperature range
20
--
70
C
Temperature slope
V
DD
=5V 10%, GAINA=2, GAINB=6
V
DD
=3V 10%, GAINA=2, GAINB=4
1.275
1.048
1.338
1.089
1.372
1.146
ADC steps/
C
Table 24-13. Current Detection Electrical Characteristics
Characteristic
Symbol
Min
Typ
Max
Unit
Trip point
(1)
Notes:
1. The current detect comparator is designed for V
DD
=5V 10% only.
V
DET
6
--
+12
mV
Table 24-14. Two-Stage Amplifier Electrical Characteristics
Characteristic
Symbol
Min
Typ
Max
Unit
Amplifier input signal hold time
t
AMH
10 + [(GAINA 1)
2]
t
AM
cycles
(1)
Notes:
1. t
AM
is the AMCLK.
Amplifier response time
t
AMR
70 + (8
GAINA) + (6
GAINB)
t
AM
cycles
Amplifier gain tolerance
V
DD
=5V 10%, GAINA=4, GAINB=16
V
IN
= 10mV to 30mV
V
IN
= 30mV to 65mV
V
DD
=5V 10%, GAINA=6, GAINB=16
V
IN
= 10mV to 30mV
V
IN
= 30mV to 44mV
V
DD
=3V 10%, GAINA=4, GAINB=16
V
IN
= 10mV to 38mV
V
DD
=3V 10%, GAINA=6, GAINB=16
V
IN
= 10mV to 24mV
3.5
1.5
3.5
1.5
3.5
3.5
--
--
--
--
--
--
+3.5
+1.5
+3.5
+1.5
+3.5
+3.5
%
Electrical Specifications
Timer Interface Module Characteristics
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Electrical Specifications
383
24.15 Timer Interface Module Characteristics
24.16 MMIIC Electrical Characteristics
Figure 24-3. MMIIC Signal Timings
See
Table 24-16
for MMIIC timing parameters.
Characteristic
Symbol
Min
Max
Unit
Input capture pulse width
tTIH, tTIL
1
--
t
cyc
Table 24-15. MMIIC DC Electrical Characteristics
Characteristic
(1)
Notes:
1. V
DD
= 2.7 to 5.5Vdc, V
SS
= 0 Vdc, T
A
= T
L
to T
H
, unless otherwise noted.
Symbol
Min
Typ
Max
Unit
Comments
Input low
V
IL
0.5
0.8
V
Data, clock input low.
Input high
V
IH
2.1
5.5
V
Data, clock input high.
Output low
V
OL
0.4
V
Data, clock output low;
@I
PULLUP,MAX
Input leakage
I
LEAK
5
A
Input leakage current
Pullup current
I
PULLUP
100
350
A
Current through pull-up
resistor or current source.
See note.
(2)
2. The I
PULLUP
(max) specification is determined primarily by the need to accommodate a maximum of 1.1k
equivalent se-
ries resistor of removable SMBus devices, such as the smart battery, while maintaining the V
OL
(max) of the bus.
tHD.STA
tLOW
tHIGH
tSU.DAT
tHD.DAT
tSU.STO
SDA
SCL
tSU.STA
Electrical Specifications
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
384
Electrical Specifications
MOTOROLA
Table 24-16. MMIIC Interface Input/Output Signal Timing
Characteristic
Symbol
Min
Typ
Max
Unit
Comments
Operating frequency
f
SMB
10
100
kHz
MMIIC operating frequency
Bus free time
t
BUF
4.7
s
Bus free time between STOP and
START condition
Repeated start hold time.
t
HD.STA
4.0
s
Hold time after (repeated) START
condition. After this period, the
first clock is generated.
Repeated start setup time.
t
SU.STA
4.7
s
Repeated START condition setup
time.
Stop setup time
t
SU.STO
4.0
s
Stop condition setup time.
Hold time
t
HD.DAT
300
ns
Data hold time.
Setup time
t
SU.DAT
250
ns
Data setup time.
Clock low time-out
t
TIMEOUT
25
35
ms
Clock low time-out.
(1)
Clock low
t
LOW
4.7
s
Clock low period
Clock high
t
HIGH
4.0
s
Clock high period.
(2)
Slave clock low extend time
t
LOW.SEXT
25
ms
Cumulative clock low extend time
(slave device)
(3)
Master clock low extend time
t
LOW.MEXT
10
ms
Cumulative clock low extend time
(master device)
(4)
Fall time
t
F
300 ns
Clock/Data Fall Time
(5)
Rise time
t
R
1000
ns
Clock/Data Rise Time
(5)
Notes:
1. Devices participating in a transfer will timeout when any clock low exceeds the value of T
TIMEOUT
min. of 25ms. Devices
that have detected a timeout condition must reset the communication no later than T
TIMEOUT
max of 35ms. The maximum
value specified must be adhered to by both a master and a slave as it incorporates the cumulative limit for both a master
(10 ms) and a slave (25 ms).
Software should turn-off the MMIIC module to release the SDA and SCL lines.
2. T
HIGH MAX
provides a simple guaranteed method for devices to detect the idle conditions.
3. T
LOW.SEXT
is the cumulative time a slave device is allowed to extend the clock cycles in one message from the initial start
to the stop. If a slave device exceeds this time, it is expected to release both its clock and data lines and reset itself.
4. T
LOW.MEXT
is the cumulative time a master device is allowed to extend its clock cycles within each byte of a message as
defined from start-to-ack, ack-to-ack, or ack-to-stop.
5. Rise and fall time is defined as follows: T
R
= (V
ILMAX
0.15) to (V
IHMIN
+ 0.15), T
F
= 0.9
V
DD
to (V
ILMAX
0.15).
Electrical Specifications
CGM Electrical Specifications
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Electrical Specifications
385
24.17 CGM Electrical Specifications
Characteristic
Symbol
Min
Typ
Max
Unit
Reference frequency
f
RDV
30
32.768
100
kHz
Range nominal multiplies
f
NOM
--
38.4
--
kHz
VCO center-of-range frequency
f
VRS
38.4k
--
40.0M
Hz
VCO range linear range multiplier
L
1
--
255
VCO power-of-two-range multiplier
2
E
1
--
4
VCO multiply factor
N
1
--
4095
VCO prescale multiplier
2
P
1
--
8
Reference divider factor
R
1
1
15
VCO operating frequency
f
VCLK
38.4k
--
40.0M
Hz
Manual acquisition time
t
LOCK
--
--
50
ms
Automatic lock time
t
LOCK
--
--
50
ms
Automatic lock time
Wake up from stop with OSC enabled
(1)
Notes:
1. Test condition: V
DD
= 5.0Vdc / 3.0Vdc, V
SS
= 0 Vdc. Reference frequency = 32.768kHz, locking to 4MHz bus frequency.
t
LOCK
--
10
15
ms
PLL jitter
(2)
2. Deviation of average bus frequency over 2ms. N = VCO multiplier.
f
J
0
--
f
RCLK
0.025%
2
P
N/4
Hz
Electrical Specifications
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
386
Electrical Specifications
MOTOROLA
24.18 FLASH Memory Characteristics
Table 24-17. FLASH Memory Electrical Characteristics
Characteristic
Symbol
Min.
Max.
Unit
Data retention voltage
V
RDR
1.3
--
V
Number of rows per page
2
Rows
Number of bytes per page
128
Bytes
Read bus clock frequency
f
Read
(1)
Notes:
1. f
Read
is defined as the frequency range for which the FLASH memory can be read.
32k
8M
Hz
Page erase time
t
Erase
(2)
2. If the page erase time is longer than t
Erase
(Min.), there is no erase-disturb, but it reduces the endurance of the FLASH
memory.
1
--
ms
Mass erase time
t
MErase
(3)
3. If the mass erase time is longer than t
MErase
(Min.), there is no erase-disturb, but is reduces the endurance of the FLASH
memory.
4
--
ms
PGM/ERASE to HVEN setup time
t
nvs
10
--
s
High-voltage hold time
t
nvh
5
--
s
High-voltage hold time (mass erase)
t
nvhl
100
--
s
Program hold time
t
pgs
5
--
s
Program time
t
Prog
30 40
s
Address/data setup time
t
ads
--
30
ns
Address/data hold time
t
adh
--
30
ns
Recovery time
t
rcv
(4)
4. It is defined as the time it needs before the FLASH can be read after turning off the high voltage charge pump, by clearing
HVEN to logic 0.
1
--
s
Cumulative HV period
t
hv
(5)
5. t
hv
is the cumulative high voltage programming time to the same row before next erase, and the same address can not be
programmed twice before next erase.
--
25
ms
Row erase endurance
(6)
6. The minimum row endurance value specifies each row of the FLASH memory is guaranteed to work for at least this many
erase/program cycles.
--
10k
--
Cycles
Row program endurance
(7)
7. The minimum row endurance value specifies each row of the FLASH memory is guaranteed to work for at least this many
erase/program cycle.
--
10k
--
Cycles
Data retention time
(8)
8. The FLASH is guaranteed to retain data over the entire operating temperature range for at least the minimum time
specified.
--
10
--
Years
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Mechanical Specifications
387
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 25. Mechanical Specifications
25.1 Contents
25.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387
25.3
48-Pin Plastic Low Quad Flat Pack (LQFP) . . . . . . . . . . . . . . 388
25.4
42-Pin Shrink Dual In-Line Package (SDIP) . . . . . . . . . . . . . . 389
25.2 Introduction
This section gives the dimensions for:
48-pin plastic low quad flat pack (case 932-02)
42-pin shrink dual in-line package (case 858-01)
The following figure shows the latest package drawing at the time of this
publication. To make sure that you have the latest package
specifications, contact one of the following:
Local Motorola Sales Office
World Wide Web at http://www.motorola.com/semiconductors/
Follow the World Wide Web on-line instructions to retrieve the current
mechanical specifications.
Mechanical Specifications
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
388
Mechanical Specifications
MOTOROLA
25.3 48-Pin Plastic Low Quad Flat Pack (LQFP)
Figure 25-1. 48-Pin Plastic Low Quad Flat Pack (LQFP)
A
A1
Z
0.200 AB TU
4X
Z
0.200 AC TU
4X
B
B1
1
12
13
24
25
36
37
48
S1
S
V
V1
P
AE
AE
T, U, Z
DETAIL Y
DETAIL Y
BASE METAL
N
J
F
D
TU
M
0.080
Z
AC
SECTION AEAE
AD
G
0.080 AC
M
TOP & BOTTOM
L
W
K
AA
E
C
H
0.250
R
9
DETAIL AD
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME
Y14.5M, 1994.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DATUM PLANE AB IS LOCATED AT BOTTOM OF
LEAD AND IS COINCIDENT WITH THE LEAD
WHERE THE LEAD EXITS THE PLASTIC BODY AT
THE BOTTOM OF THE PARTING LINE.
4. DATUMS T, U, AND Z TO BE DETERMINED AT
DATUM PLANE AB.
5. DIMENSIONS S AND V TO BE DETERMINED AT
SEATING PLANE AC.
6. DIMENSIONS A AND B DO NOT INCLUDE MOLD
PROTRUSION. ALLOWABLE PROTRUSION IS
0.250 PER SIDE. DIMENSIONS A AND B DO
INCLUDE MOLD MISMATCH AND ARE
DETERMINED AT DATUM PLANE AB.
7. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. DAMBAR PROTRUSION SHALL
NOT CAUSE THE D DIMENSION TO EXCEED
0.350.
8. MINIMUM SOLDER PLATE THICKNESS SHALL BE
0.0076.
9. EXACT SHAPE OF EACH CORNER IS OPTIONAL.
T
U
Z
AB
AC
GAUGE PLANE
DIM
A
MIN
MAX
7.000 BSC
MILLIMETERS
A1
3.500 BSC
B
7.000 BSC
B1
3.500 BSC
C
1.400
1.600
D
0.170
0.270
E
1.350
1.450
F
0.170
0.230
G
0.500 BSC
H
0.050
0.150
J
0.090
0.200
K
0.500
0.700
M
12
REF
N
0.090
0.160
P
0.250 BSC
L
1
5
R
0.150
0.250
S
9.000 BSC
S1
4.500 BSC
V
9.000 BSC
V1
4.500 BSC
W
0.200 REF
AA
1.000 REF
Mechanical Specifications
42-Pin Shrink Dual In-Line Package (SDIP)
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Mechanical Specifications
389
25.4 42-Pin Shrink Dual In-Line Package (SDIP)
Figure 25-2. 42-Pin Shrink Dual In-Line Package (SDIP)
A
42
22
1
21
B
SEATING
PLANE
T
S
A
M
0.25 (0.010)
T
S
B
M
0.25 (0.010)
T
L
H
M
J
42 PL
D
42 PL
F
G
N
K
C
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L TO CENTER OF LEAD WHEN
FORMED PARALLEL.
4. DIMENSIONS A AND B DO NOT INCLUDE MOLD
FLASH. MAXIMUM MOLD FLASH 0.25 (0.010).
DIM
MIN
MAX
MIN
MAX
MILLIMETERS
INCHES
A
1.435
1.465
36.45
37.21
B
0.540
0.560
13.72
14.22
C
0.155
0.200
3.94
5.08
D
0.014
0.022
0.36
0.56
F
0.032
0.046
0.81
1.17
G
0.070 BSC
1.778 BSC
H
0.300 BSC
7.62 BSC
J
0.008
0.015
0.20
0.38
K
0.115
0.135
2.92
3.43
L
0.600 BSC
15.24 BSC
M
0
15
0
15
N
0.020
0.040
0.51
1.02
Mechanical Specifications
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
390
Mechanical Specifications
MOTOROLA
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
Ordering Information
391
Technical Data -- MC68HC908SR12MC68HC08SR12
Section 26. Ordering Information
26.1 Contents
26.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391
26.3
MC Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391
26.2 Introduction
This section contains ordering numbers for the MC68HC908SR12.
26.3 MC Order Numbers
Table 26-1. MC Order Numbers
MC order number
Operating
temperature range
Package
MC68HC908SR12CB
40
C to +85
C
42-Pin SDIP
(1)
Notes:
1. SDIP = Shrink Dual In-Line Package.
MC68HC908SR12MB
(2)
2. Temperature grade "M" is available for 5V operating voltage only.
40
C to +125
C
MC68HC908SR12CFA
40
C to +85
C
48-pin LQFP
(3)
3. LQFP = Low Quad Flat Pack.
MC68HC908SR12MFA
(2)
40
C to +125
C
Ordering Information
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
392
Ordering Information
MOTOROLA
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
MC68HC08SR12
393
Technical Data -- MC68HC908SR12MC68HC08SR12
Appendix A. MC68HC08SR12
A.1 Contents
A.2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
A.3
MCU Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
A.4
Memory Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
A.5
Mask Option Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
A.6
Reserved Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
A.7
Monitor ROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
A.8
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
A.8.1
Memory Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 397
A.9
ROM Order Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398
MC68HC08SR12
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
394
MC68HC08SR12
MOTOROLA
A.2 Introduction
This section introduces the MC68HC08SR12, the ROM part equivalent
to the MC68HC908SR12. The entire data book apply to this ROM
device, with exceptions outlined in this appendix.
A.3 MCU Block Diagram
Figure A-1
shows the block diagram of the MC68HC08SR12.
A.4 Memory Map
The MC68HC08SR12 has 12,288 bytes of user ROM from $C000 to
$EFFF, and 38 bytes of user ROM vectors from $FFDA to $FFFF. On
the MC68HC908SR12, these memory locations are FLASH memory.
Figure A-2
shows the memory map of the MC68HC08SR12
Table A-1. Summary of MC68HC08SR12 and MC68HC908SR12 Differences
MC68HC08SR12
MC68HC908SR12
Memory ($C000$EFFF)
12,288 bytes ROM
12,288 bytes FLASH
User vectors ($FFDA$FFFF)
38 bytes ROM
38 bytes FLASH
Register at $FF80
Mask option register; defined
by mask; read only.
$FF80 -- MOR
Mask option register; defined
by programming FLASH
location $FF80.
$FF80 -- MOR
Registers at $FE08 and $FF09
Not used;
locations are reserved.
FLASH related registers.
$FE08 -- FLCR
$FF09 -- FLBPR
Monitor ROM ($FE10$FF7F)
Used for testing purposes
only.
Used for testing and FLASH
programming/erasing.
MC6
8
HC9
08S
R12
MC6
8
HC08
S
R1
2
--
Rev
.
4.0
T
ech
n
i
c
a
l
Da
ta
MO
T
O
RO
LA
M
C
68H
C08S
R12
3
9
5
MC6
8
HC08
S
R1
2
Figure A-1. MC68HC08SR12 Block Diagram
CLOCK GENERATOR MODULE
SYSTEM INTEGRATION
MODULE
TIMEBASE
2-CHANNEL TIMER INTERFACE
MODULE 2
LOW-VOLTAGE
INHIBIT MODULE
8-BIT KEYBOARD
ARITHMETIC/LOGIC
UNIT (ALU)
CPU
REGISTERS
M68HC08 CPU
CONTROL AND STATUS REGISTERS -- 96 BYTES
USER ROM -- 12,288 BYTES
USER RAM -- 512 BYTES
MONITOR ROM -- 368 BYTES
EXTERNAL IRQ
MODULE
DD
RB
PO
RT
B
INTERNAL BUS
OSC1
OSC2
CGMXFC
* RST
* IRQ1
MODULE
INTERRUPT MODULE
COMPUTER OPERATING
PROPERLY MODULE
V
REFH
PTB6/IRQ2
PTB5/T2CH1
PTB4/T2CH0
PTB3//SCL1/RxD
PTB2/SDA1/TxD
PTB1/SCL0
PTB0/SDA0
V
REFL
2-CHANNEL TIMER INTERFACE
MODULE 1
PHASE-LOCKED LOOP
SERIAL COMMUNICATIONS
INTERFACE MODULE
POWER-ON RESET
MODULE
POWER
V
SS
V
DD
V
SSA
V
DDA
* Pin contains integrated pullup device.
** Pin contains configurable pullup device.
*** Pin contains integrated pullup device for KBI functions.
Pin is open-drain when configured as output.
High current drive pin (for LED).
# Pin not bonded on 42-pin SDIP.
10-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
PULSE WIDTH MODULATOR
MODULE
PO
RTA
DD
RA
PTA5/ATD7 PTA0/ATD2
DD
RC
PO
RT
C
PTC7/ATD12
#
PTC6/ATD11
#
PTC5/ATD10
PTC4/ATD9
PTC3/ATD8
PTC2/PWM2
PTC1/PWM1
PTC0/PWM0/CD
PO
RT
D
DD
RD
PTD7/KBI7 PTD0/KBI0 ***
** IRQ2
MULTI-MASTER IIC (SMBUS)
INTERFACE MODULE
ANALOG
MODULE
OPIN1/ATD0
#
OPIN2/ATD1
PTA7/T1CH1
PTA6/T1CH0
V
SSAM
X-TAL OSCILLATOR
RC OSCILLATOR
INTERNAL OSCILLATOR
OSCILLATORS AND
USER ROM VECTORS -- 38 BYTES
Shaded blocks indicate differences to MC68HC908SR12
MC68HC08SR12
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
396
MC68HC08SR12
MOTOROLA
$0000
$005F
I/O Registers
96 Bytes
$0060
$025F
RAM
512 Bytes
$0260
$BFFF
Unimplemented
48,544 Bytes
$C000
$EFFF
ROM
12,288 Bytes
$F000
$FDFF
Unimplemented
3,584 Bytes
$FE00
SIM Break Status Register (SBSR)
$FE01
SIM Reset Status Register (SRSR)
$FE02
Reserved
$FE03
SIM Break Flag Control Register (SBFCR)
$FE04
Interrupt Status Register 1 (INT1)
$FE05
Interrupt Status Register 2 (INT2)
$FE06
Interrupt Status Register 3 (INT3)
$FE07
Reserved
$FE08
Reserved
$FE09
Reserved
$FE0A
Reserved
$FE0B
Reserved
$FE0C
Break Address Register High (BRKH)
$FE0D
Break Address Register Low (BRKL)
$FE0E
Break Status and Control Register (BRKSCR)
$FE0F
LVI Status Register (LVISR)
$FE10
$FF7F
Monitor ROM
368 Bytes
$FF80
Mask Option Register
$FF81
$FFD9
Reserved
89 Bytes
$FFDA
$FFFF
ROM Vectors
38 Bytes
Figure A-2. MC68HC08SR12 Memory Map
MC68HC08SR12
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
Technical Data
MOTOROLA
MC68HC08SR12
397
A.5 Mask Option Register
The mask option register (MOR) at $FF80 is a read-only register on the
MC68HC08SR12. It is defined by a mask option (hard-wired connection)
specified at the same time as the ROM code submission.
On the MC68HC908SR12, the MOR is a byte located in FLASH
memory, and is written by a FLASH programming routine.
A.6 Reserved Registers
The two registers at $FE08 and $FF09 are reserved locations on the
MC68HC08SR12.
On the MC68HC908SR12, these two locations are the FLASH control
register and the FLASH block protect register respectively.
A.7 Monitor ROM
The monitor program (monitor ROM, $FE10$FF7F) on the
MC68HC08SR12 is for device testing only.
A.8 Electrical Specifications
Electrical specifications for the MC68HC908SR12 apply to the
MC68HC08SR12, except for the parameters indicated below.
A.8.1 Memory Characteristics
Characteristic
Symbol
Min
Max
Unit
RAM data retention voltage
V
RDR
1.3
--
V
Notes:
Since MC68HC08SR12 is a ROM device, FLASH memory electrical characteristics do not apply.
MC68HC08SR12
Technical Data
MC68HC908SR12MC68HC08SR12 -- Rev. 4.0
398
MC68HC08SR12
MOTOROLA
A.9 ROM Order Numbers
These part numbers are generic numbers only. To place an order, ROM
code must be submitted to the ROM Processing Center (RPC).
Table A-2. MC68HC08SR12 Order Numbers
MC order number
Operating
temperature range
Package
MC68HC08SR12CB
40
C to +85
C
42-Pin SDIP
(1)
Notes:
1. SDIP = Shrink Dual In-Line Package.
MC68HC08SR12MB
(2)
2. Temperature grade "M" is available for 5V operating voltage only.
40
C to +125
C
MC68HC08SR12CFA
40
C to +85
C
48-pin LQFP
(3)
3. LQFP = Low Quad Flat Pack.
MC68HC08SR12MFA
(2)
40
C to +125
C
HOW TO REACH US:
USA/EUROPE/LOCATIONS NOT LISTED:
Motorola Literature Distribution;
P.O. Box 5405, Denver, Colorado 80217
1-303-675-2140 or 1-800-441-2447
JAPAN:
Motorola Japan Ltd.; SPS, Technical Information Center,
3-20-1, Minami-Azabu Minato-ku, Tokyo 106-8573 Japan
81-3-3440-3569
ASIA/PACIFIC:
Motorola Semiconductors H.K. Ltd.;
Silicon Harbour Centre, 2 Dai King Street,
Tai Po Industrial Estate, Tai Po, N.T., Hong Kong
852-26668334
TECHNICAL INFORMATION CENTER:
1-800-521-6274
HOME PAGE:
http://www.motorola.com/semiconductors
Information in this document is provided solely to enable system and software
implementers to use Motorola products. There are no express or implied copyright
licenses granted hereunder to design or fabricate any integrated circuits or
integrated circuits based on the information in this document.
Motorola reserves the right to make changes without further notice to any products
herein. Motorola makes no warranty, representation or guarantee regarding the
suitability of its products for any particular purpose, nor does Motorola assume any
liability arising out of the application or use of any product or circuit, and specifically
disclaims any and all liability, including without limitation consequential or incidental
damages. "Typical" parameters which may be provided in Motorola data sheets
and/or specifications can and do vary in different applications and actual
performance may vary over time. All operating parameters, including "Typicals"
must be validated for each customer application by customer's technical experts.
Motorola does not convey any license under its patent rights nor the rights of
others. Motorola products are not designed, intended, or authorized for use as
components in systems intended for surgical implant into the body, or other
applications intended to support or sustain life, or for any other application in which
the failure of the Motorola product could create a situation where personal injury or
death may occur. Should Buyer purchase or use Motorola products for any such
unintended or unauthorized application, Buyer shall indemnify and hold Motorola
and its officers, employees, subsidiaries, affiliates, and distributors harmless
against all claims, costs, damages, and expenses, and reasonable attorney fees
arising out of, directly or indirectly, any claim of personal injury or death associated
with such unintended or unauthorized use, even if such claim alleges that Motorola
was negligent regarding the design or manufacture of the part.
Motorola and the Stylized M Logo are registered in the U.S. Patent and Trademark
Office. digital dna is a trademark of Motorola, Inc. All other product or service
names are the property of their respective owners. Motorola, Inc. is an Equal
Opportunity/Affirmative Action Employer.
Motorola, Inc. 2002
MC68HC908SR12/D
PDF 
ZIP