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REV: 040104
Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device
may be simultaneously available through various sales channels. For information about device errata, click here:
www.maxim-ic.com/errata
.
FEATURES
80C52 Compatible
8051 Instruction-Set Compatible
Four 8-Bit I/O Ports
Three 16-Bit Timer/Counters
256 Bytes Scratchpad RAM
Large On-Chip Memory
16kB EPROM (OTP)
1kB Extra On-Chip SRAM for MOVX
ROMSIZE Features
Selects Effective On-Chip ROM Size from
0 to 16kB
Allows Access to Entire External Memory Map
Dynamically Adjustable by Software
Useful as Boot Block for External Flash
Nonvolatile Functions
On-Chip Real-Time Clock with Alarm Interrupt
Battery Backup Support of 1kB SRAM
High-Speed Architecture
4 Clocks/Machine Cycle (8051 = 12)
Runs DC to 33MHz Clock Rates
Single-Cycle Instruction in 121ns
Dual Data Pointer
Optional Variable Length MOVX to Access
Fast/Slow RAM /Peripherals
Power Management Mode
Programmable Clock Source Saves Power
Runs from (Crystal/64) or (Crystal/1024)
Provides Automatic Hardware and Software Exit
EMI Reduction Mode Disables ALE
Two Full-Duplex Hardware Serial Ports
High Integration Controller Includes:
Power-Fail Reset
Early-Warning Power-Fail Interrupt
Programmable Watchdog Timer
14 Total Interrupt Sources with Six External
PIN CONFIGURATIONS
DALLAS
DS87C530
DS83C530
34
46
20
8
7 1 47
21
33
PLCC
WINDOWED LCC
DALLAS
DS87C530
DS83C530
39
27
1 13
26
40
14
52
TQFP
TOP VIEW
DALLAS is a registered trademark of Dallas Semiconductor Corp.
MAXIM is a registered trademark of Maxim Integrated Products, Inc.
www.maxim-ic.com
DS87C530/DS83C530
EPROM/ROM Microcontrollers with
Real-Time Clock
The High-Speed Microcontroller User's Guide must
be used in conjunction with this data sheet. Download it
at:
www.maxim-ic.com/microcontrollers
.
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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ORDERING INFORMATION
PART TEMP
RANGE
MAX
CLOCK
SPEED
(MHz)
PIN-PACKAGE
DS87C530-QCL
0
C to +70C
33 52
PLCC
DS87C530-QNL
-40
C to +85C
33 52
PLCC
DS87C530-KCL
0
C to +70C
33 52
Windowed
LCC
DS87C530-ECL
0
C to +70C
33 52
TQFP
DS87C530-ENL
-40
C to +85C
33 52
TQFP
DS83C530-QCL
0
C to +70C
33 52
PLCC
DS83C530-QNL
-40
C to +85C
33 52
PLCC
DS83C530-ECL
0
C to +70C
33 52
TQFP
DS83C530-ENL
-40
C to +85C
33 52
TQFP
DETAILED DESCRIPTION
The DS87C530/DS83C530 EPROM/ROM microcontrollers with a real-time clock (RTC) are 8051-
compatible microcontrollers based on the Dallas high-speed core. They use 4 clocks per instruction cycle
instead of the 12 used by the standard 8051. They also provide a unique mix of peripherals not widely
available on other processors. They include an on-chip RTC and battery backup support for an on-chip
1k x 8 SRAM. The new Power Management Mode allows software to select reduced power operation
while still processing.
A combination of high-performance microcontroller core, RTC, battery-backed SRAM, and power
management makes the DS87C530/DS83C530 ideal for instruments and portable applications. They also
provide several peripherals found on other Dallas high-speed microcontrollers. These include two
independent serial ports, two data pointers, on-chip power monitor with brownout detection and a
watchdog timer.
Power Management Mode (PMM) allows software to select a slower CPU clock. While default operation
uses four clocks per machine cycle, the PMM runs the processor at 64 or 1024 clocks per cycle. There is a
corresponding drop in power consumption when the processor slows.
The EMI reduction feature allows software to select a reduced emission mode. This disables the ALE
signal when it is unneeded.
The DS83C530 is a factory mask ROM version of the DS87C530 designed for high-volume, cost-
sensitive applications. It is identical in all respects to the DS87C530, except that the 16kB of EPROM is
replaced by a user-supplied application program. All references to features of the DS87C530 will apply to
the DS83C530, with the exception of EPROM-specific features where noted. Please contact your local
Dallas Semiconductor sales representative for ordering information.
Note: The DS87C530/DS83C530 are monolithic devices. A user must supply an external battery or super
cap and a 32.768kHz timekeeping crystal to have permanently powered timekeeping or nonvolatile RAM.
The DS87C530/DS83C530 provide all the support and switching circuitry needed to manage these
resources.
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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Figure 1. Block Diagram
PIN DESCRIPTION
PIN
PLCC TQFP
NAME FUNCTION
52 45 V
CC
+5V Processor Power Supply
1, 25
18, 46
GND
Processor Digital Circuit Ground
29 22 V
CC2
+5V RTC Supply. V
CC2
is isolated from V
CC
to isolate the RTC from digital noise.
26 19 GND2
RTC Circuit Ground
12 5 RST
Reset Input. This pin contains a Schmitt voltage input to recognize external active
high reset inputs. The pin also employs an internal pulldown resistor to allow for a
combination of wired OR external reset sources. An RC is not required for power-up,
as the device provides this function internally.
23 16
XTAL2
24 17
XTAL1
Crystal Oscillator Pins. XTAL1 and XTAL2 provide support for parallel-resonant,
AT-cut crystals. XTAL1 acts also as an input if there is an external clock source in
place of a crystal. XTAL2 is the output of the crystal amplifier.
DS87C530/
DS83C530
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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PIN DESCRIPTION (continued)
PIN
PLCC TQFP
NAME FUNCTION
38 31
PSEN
Program Store-Enable Output. This active-low signal is a chip enable for optional
external ROM memory.
PSEN provides an active-low pulse and is driven high when
external ROM is not being accessed.
39 32 ALE
Address Latch-Enable Output. This pin latches the external address LSB from the
multiplexed address/data bus on Port 0. This signal is commonly connected to the
latch enable of an external 373 family transparent latch. ALE has a pulse width of
1.5 XTAL1 cycles and a period of four XTAL1 cycles. ALE is forced high when the
device is in a Reset condition. ALE can be disabled and forced high by writing
ALEOFF = 1 (PMR.2). ALE operates independently of ALEOFF during external
memory accesses.
50
43
P0.0 (AD0)
49
42
P0.1 (AD1)
48
41
P0.2 (AD2)
47
40
P0.3 (AD3)
46
39
P0.4 (AD4)
45
38
P0.5 (AD5)
44
37
P0.6 (AD6)
43 36
P0.7
(AD7)
Port 0 (AD0AD7), I/O. Port 0 is an open-drain, 8-bit, bidirectional I/O port. As an
alternate function Port 0 can function as the multiplexed address/data bus to access
off-chip memory. During the time when ALE is high, the LSB of a memory address
is presented. When ALE falls to a logic 0, the port transitions to a bidirectional data
bus. This bus is used to read external ROM and read/ write external RAM memory
or peripherals. When used as a memory bus, the port provides active high drivers.
The reset condition of Port 0 is tri-state. Pullup resistors are required when using
Port 0 as an I/O port.
3 48 P1.0
4 49 P1.1
5 50 P1.2
6 51 P1.3
7 52 P1.4
8 4 P1.5
9 2 P1.6
10 3 P1.7
Port 1, I/O. Port 1 functions as both an 8-bit, bidirectional I/O port and an alternate
functional interface for Timer 2 I/O, new External Interrupts, and new Serial Port 1.
The reset condition of Port 1 is with all bits at a logic 1. In this state, a weak pullup
holds the port high. This condition also serves as an input mode, since any external
circuit that writes to the port will overcome the weak pullup. When software writes a
0 to any port pin, the device will activate a strong pulldown that remains on until
either a 1 is written or a reset occurs. Writing a 1 after the port has been at 0 will
cause a strong transition driver to turn on, followed by a weaker sustaining pullup.
Once the momentary strong driver turns off, the port again becomes the output high
(and input) state. The alternate modes of Port 1 are outlined as follows.
Port
Alternate Function
P1.0
T2
External I/O for Timer/Counter 2
P1.1
T2EX
Timer/Counter 2 Capture/Reload Trigger
P1.2
RXD1
Serial Port 1 Input
P1.3
TXD1
Serial Port 1 Output
P1.4
INT2
External Interrupt 2 (Positive Edge Detect)
P1.5
INT3
External Interrupt 3 (Negative Edge Detect)
P1.6
INT4
External Interrupt 4 (Positive Edge Detect)
P1.7
INT5
External Interrupt 5 (Negative Edge Detect)
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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PIN DESCRIPTION (continued)
PIN
PLCC TQFP
NAME FUNCTION
30 23
P2.0
(AD8)
31 24
P2.1
(AD9)
32 25
P2.2
(AD10)
33 26
P2.3
(AD11)
34 27
P2.4
(AD12)
35 28
P2.5
(AD13)
36 29
P2.6
(AD14)
37 30
P2.7
(AD15)
Port 2 (A8A15), I/O. Port 2 is a bidirectional I/O port. The reset condition of
Port 2 is logic high. In this state, a weak pullup holds the port high. This condition
also serves as an input mode, since any external circuit that writes to the port will
overcome the weak pullup. When software writes a 0 to any port pin, the device
will activate a strong pulldown that remains on until either a 1 is written or a reset
occurs. Writing a 1 after the port has been at 0 will cause a strong transition driver
to turn on, followed by a weaker sustaining pullup. Once the momentary strong
driver turns off, the port again becomes both the output high and input state. As an
alternate function Port 2 can function as MSB of the external address bus. This
bus can be used to read external ROM and read/write external RAM memory or
peripherals.
15 8 P3.0
16 9 P3.1
17 10 P3.2
18 11 P3.3
19 12 P3.4
20 13 P3.5
21 14 P3.6
22 15 P3.7
Port 3, I/O. Port 3 functions as both an 8-bit, bi-directional I/O port and an
alternate functional interface for external interrupts, Serial Port 0, Timer 0 and 1
Inputs, and
RD and WR strobes. The reset condition of Port 3 is with all bits at a
logic 1. In this state, a weak pullup holds the port high. This condition also serves
as an input mode, since any external circuit that writes to the port will overcome
the weak pullup. When software writes a 0 to any port pin, the device will activate
a strong pulldown that remains on until either a 1 is written or a reset occurs.
Writing a 1 after the port has been at 0 will cause a strong transition driver to turn
on, followed by a weaker sustaining pullup. Once the momentary strong driver
turns off, the port again becomes both the output high and input state. The
alternate modes of Port 3 are outlined below.
Port
Alternate Function
P3.0
RXD0
Serial Port 0 Input
P3.1
TXD0
Serial Port 0 Output
P3.2
INT0
External Interrupt 0
P3.3
INT1
External Interrupt 1
P3.4
T0
Timer 0 External Input
P3.5
T1
Timer 1 External Input
P3.6
WR
External Data Memory Write Strobe
P3.7
RD
External Data Memory Read Strobe
42 35
EA
External Access Input, Active Low. Connect to ground to use an external ROM.
Internal RAM is still accessible as determined by register settings. Connect to V
CC
to use internal ROM.
51 44 V
BAT
V
BAT
Input. Connect to the power source that maintains SRAM and RTC when
V
CC
< V
BAT
. Can be connected to a 3V lithium battery or a super cap. Connect to
GND if battery will not be used with device.
27 20 RTCX2
28 21 RTCX1
Timekeeping Crystals. A 32.768kHz crystal between these pins supplies the time
base for the RTC. The devices support both 6pF and 12.5pF load capacitance
crystals as selected by an SFR bit (described later). To prevent noise from
affecting the RTC, the RTCX2 and RTCX1 pins should be guard-ringed with
GND2.
2, 11, 13,
14, 40,
41
4, 6, 7,
33, 34,
47
N.C.
Not Connected. These pins should not be connected. They are reserved for use
with future devices in the family.
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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COMPATIBILITY
The DS87C530/DS83C530 are fully static, CMOS 8051-compatible microcontrollers designed for high
performance. While remaining familiar to 8051 users, the devices have many new features. In general,
software written for existing 8051-based systems works without modification on the
DS87C530/DS83C530. The exception is critical timing since the high-speed microcontrollers perform its
instructions much faster than the original for any given crystal selection. The DS87C530/DS83C530 run
the standard 8051 instruction set. They are not pin compatible with other 8051s due to the timekeeping
crystal.
The DS87C530/DS83C530 provide three 16-bit timer/counters, full-duplex serial port (2), 256 bytes of
direct RAM plus 1kB of extra MOVX RAM. I/O ports have the same operation as a standard 8051
product. Timers will default to a 12 clock-per-cycle operation to keep their timing compatible with
original 8051 systems. However, timers are individually programmable to run at the new 4 clocks per
cycle if desired. The PCA is not supported.
The DS87C530/DS83C530 provide several new hardware features implemented by new Special Function
Registers. A summary of these SFRs is provided below.
PERFORMANCE OVERVIEW
The DS87C530/DS83C530 feature a high-speed, 8051-compatible core. Higher speed comes not just
from increasing the clock frequency, but also from a newer, more efficient design.
This updated core does not have the dummy memory cycles that are present in a standard 8051. A
conventional 8051 generates machine cycles using the clock frequency divided by 12. In the
DS87C530/DS83C530, the same machine cycle takes 4 clocks. Thus the fastest instruction, one machine
cycle, executes three times faster for the same crystal frequency. Note that these are identical instructions.
The majority of instructions on the DS87C530/DS83C530 will see the full 3-to-1 speed improvement.
Some instructions will get between 1.5 and 2.4 to 1 improvement. All instructions are faster than the
original 8051.
The numerical average of all opcodes gives approximately a 2.5 to 1 speed improvement. Improvement of
individual programs will depend on the actual instructions used. Speed-sensitive applications would make
the most use of instructions that are three times faster. However, the sheer number of 3 to 1 improved
opcodes makes dramatic speed improvements likely for any code. These architecture improvements
produce a peak instruction cycle in 121ns (8.25 MIPs). The Dual Data Pointer feature also allows the user
to eliminate wasted instructions when moving blocks of memory.
INSTRUCTION SET SUMMARY
All instructions perform the same functions as their 8051 counterparts. Their effect on bits, flags, and
other status functions is identical. However, the timing of each instruction is different. This applies both
in absolute and relative number of clocks.
For absolute timing of real-time events, the timing of software loops can be calculated using a table in the
High-Speed Microcontroller User's Guide. However, counter/timers default to run at the older 12 clocks
per increment. In this way, timer-based events occur at the standard intervals with software executing at
higher speed. Timers optionally can run at 4 clocks per increment to take advantage of faster processor
operation.
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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The relative time of two instructions might be different in the new architecture than it was previously. For
example, in the original architecture, the "MOVX A, @DPTR" instruction and the "MOV direct, direct"
instruction used two machine cycles or 24 oscillator cycles. Therefore, they required the same amount of
time. In the DS87C530/DS83C530, the MOVX instruction takes as little as two machine cycles or eight
oscillator cycles but the "MOV direct, direct" uses three machine cycles or 12 oscillator cycles. While
both are faster than their original counterparts, they now have different execution times. This is because
the DS87C530/DS83C530 usually use one instruction cycle for each instruction byte. The user concerned
with precise program timing should examine the timing of each instruction for familiarity with the
changes. Note that a machine cycle now requires just 4 clocks, and provides one ALE pulse per cycle.
Many instructions require only one cycle, but some require five. In the original architecture, all were one
or two cycles except for MUL and DIV. Refer to the High-Speed Microcontroller User's Guide for
details and individual instruction timing.
SPECIAL FUNCTION REGISTERS
Special Function Registers (SFRs) control most special features of the DS87C530/DS83C530. This
allows the device to incorporate new features but remain instruction-set compatible with the 8051.
EQUATE statements can be used to define the new SFR to an assembler or compiler. All SFRs contained
in the standard 80C52 are duplicated in this device. Table 1 shows the register addresses and bit locations.
The High-Speed Microcontroller User's Guide describes all SFRs.
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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Table 1. Special Function Register Locations
* Functions not present in the 80C52 are in bold.
REGISTER
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
ADDRESS
P0 P0.7
P0.6
P0.5
P0.4
P0.3
P0.2
P0.1
P0.0
80h
SP
81h
DPL
82h
DPH
83h
DPL1
84h
DPH1
85h
DPS 0
0
0
0
0
0
0
SEL
86h
PCON
SMOD_0
SMOD0
-- -- GF1
GF0
STOP
IDLE 87h
TCON TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
88h
TMOD GATE
C/ T
M1 M0 GATE
C/ T
M1 M0 89h
TL0
8Ah
TL1
8Bh
TH0
8Ch
TH1
8Dh
CKCON WD1
WD0
T2M
T1M T0M
MD2
MD1
MD0 8Eh
P1 P1.7
P1.6
P1.5
P1.4
P1.3
P1.2
P1.1
P1.0
90h
EXIF IE5
IE4
IE3
IE2
XT/RG
RGMD
RGSL
BGS
91h
TRIM E4K
X12/
6
TRM2
TRM2
TRM1
TRM1
TRM0
TRM0
96h
SCON0
SM0/FE_0
SM1_0 SM2_0 REN_0 TB8_0 RB8_0 TI_0 RI_0
98h
SBUF0
99h
P2 P2.7
P2.6
P2.5
P2.4
P2.3
P2.2
P2.1
P2.0
A0h
IE
EA ES1 ET2 ES0 ET1 EX1 ET0 EX0 A8h
SADDR0 A9h
SADDR1 AAh
P3 P3.7
P3.6
P3.5
P3.4
P3.3
P3.2
P3.1
P3.0
B0h
IP
-- PS1 PT2 PS0 PT1 PX1 PT0 PX0 B8h
SADEN0 B9h
SADEN1 BAh
SCON1
SM0/FE_1
SM1_1 SM2_1 REN_1 TB8_1 RB8_1 TI_1 RI_1
C0h
SBUF1
C1h
ROMSIZE
-- -- -- -- --
RMS2 RMS1 RMS0 C2h
PMR CD1
CD0
SWB
--
XTOFF
ALEOFF
DME1 DME0 C4h
STATUS PIP HIP LIP
XTUP
SPTA1 SPRA1 SPTA0 SPRA0 C5h
TA
C7h
T2CON TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C/ T2
CP/
RL2
C8h
T2MOD
-- -- -- -- -- --
T2OE DCEN C9h
RCAP2L CAh
RCAP2H CBh
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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Table 1. Special Function Register Locations (continued)
* Functions not present in the 80C52 are in bold.
REGISTER
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
ADDRESS
TL2
CCh
TH2
CDh
PSW
CY AC F0 RS1 RS0 OV FL P D0h
WDCON
SMOD_1
POR EPFI PFI WDIF WTRF EWT RWT D8h
ACC
E0h
EIE
-- --
ERTCI EWDI EX5
EX4
EX3 EX2
E8h
B
F0h
RTASS
F2h
RTAS
0 0 F3h
RTAM
0 0 F4h
RTAH
0 0 0 F5h
EIP
-- --
PRTCI PWDI PX5
PX4
PX3 PX2
F8h
RTCC SSCE
SCE
MCE
HCE
RTCRE
RTCWE
RTCIF
RTCE
F9h
RTCSS
FAh
RTCS
0 0 FBh
RTCM
0 0 FCh
RTCH
FDh
RTCD0
FEh
RTCD1
FFh
NONVOLATILE FUNCTIONS
The DS87C530/DS83C530 provide two functions that are permanently powered if a user supplies an
external energy source. These are an on-chip RTC and a nonvolatile SRAM. The chip contains all related
functions and controls. The user must supply a backup source and a 32.768kHz timekeeping crystal.
REAL-TIME CLOCK
The on-chip RTC keeps time of day and calendar functions. Its time base is a 32.768kHz crystal between
pins RTCX1 and RTCX2. The RTC maintains time to 1/256 of a second. It also allows a user to read (and
write) seconds, minutes, hours, day of the week, and date. Figure 2 shows the clock organization.
Timekeeping registers allow easy access to commonly needed time values. For example, software can
simply check the elapsed number of minutes by reading one register. Alternately, it can read the complete
time of day, including subseconds, in only four registers. The calendar stores its data in binary form.
While this requires software translation, it allows complete flexibility as to the exact value. A user can
start the calendar with a variety of selections since it is simply a 16-bit binary number of days. This
number allows a total range of 179 years beginning from 0000.
The RTC features a programmable alarm condition. A user selects the alarm time. When the RTC reaches
the selected value, it sets a flag. This will cause an interrupt if enabled, even in Stop mode. The alarm
consists of a comparator that matches the user value against the RTC actual value. A user can select a
match for 1 or more of the sub-seconds, seconds, minutes, or hours. This allows an interrupt
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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automatically to occur once per second, once per minute, once per hour, or once per day. Enabling
interrupts with no match will generate an interrupt 256 times per second.
Software enables the timekeeper oscillator using the RTC enable bit in the RTC Control register (F9h).
This starts the clock. It can disable the oscillator to preserve the life of the backup energy-source if
unneeded. Values in the RTC Control register are maintained by the backup source through power failure.
Once enabled, the RTC maintains time for the life of the backup source even when V
CC
is removed.
The RTC will maintain an accuracy of
2 minutes per month at 25C. Under no circumstances are
negative voltages, of any amplitude, allowed on any pin while the device is in data retention mode
(V
CC
< V
BAT
). Negative voltages will shorten battery life, possibly corrupting the contents of internal
SRAM and the RTC.
Figure 2. Real-Time Clock
NONVOLATILE RAM
The 1k x 8 on-chip SRAM can be nonvolatile if an external backup energy source is used. This allows the
device to log data or to store configuration settings. Internal switching circuits will detect the loss of V
CC
and switch SRAM power to the backup source on the V
BAT
pin. The 256 bytes of direct RAM are not
affected by this circuit and are volatile.
CRYSTAL AND BACKUP SOURCES
To use the unique functions of the DS87C530/DS83C530, a 32.768kHz timekeeping crystal and a backup
energy source are needed. The following describes guidelines for choosing these devices.
Timekeeping Crystal
The DS87C530/DS83C530 can use a standard 32.768kHz crystal as the RTC time base. There are two
versions of standard crystals available, with 6pF and 12.5pF load capacitance. The tradeoff is that the 6pF
uses less power, giving longer life while V
CC
is off, but is more sensitive to noise and board layout. The
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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12.5pF crystal uses more power, giving a shorter battery backed life, but produces a more robust
oscillator. Bit 6 in the RTC Trim register (TRIM; 96h) must be programmed to specify the crystal type
for the oscillator. When TRIM.6 = 1, the circuit expects a 12.5pF crystal. When TRIM.6 = 0, it expects a
6pF crystal. This bit will be nonvolatile so these choices will remain while the backup source is present.
A guard ring (connected to the RTC ground) should encircle the RTCX1 and RTCX2 pins.
Backup Energy Source
The DS87C530/DS83C530 use an external energy source to maintain timekeeping and SRAM data
without V
CC
. This source can be either a battery or 0.47F super cap and should be connected to the V
BAT
pin. The nominal battery voltage is 3V. The V
BAT
pin will not source current. Therefore, a super cap
requires an external resistor and diode to supply charge.
The backup lifetime is a function of the battery capacity and the data retention current drain. This drain is
specified in the electrical specifications. The circuit loads the V
BAT
only when V
CC
has fallen below V
BAT
.
Thus the actual lifetime depends not only on the current and battery capacity, but also on the portion of
time without power. A very small lithium cell provides a lifetime of more than 10 years.
Figure 3. Internal Backup Circuit
IMPORTANT APPLICATION NOTE
The pins on the DS87C530/DS83C530 are generally as resilient as other CMOS circuits. They have no
unusual susceptibility to electrostatic discharge (ESD) or other electrical transients. However, no pin on
the DS87C530/DS83C530 should ever be taken to a voltage below ground. Negative voltages on any
pin can turn on internal parasitic diodes that draw current directly from the battery. If a device pin is
connected to the "outside world" where it may be handled or come in contact with electrical noise,
protection should be added to prevent the device pin from going below -0.3V. Some power supplies can
give a small undershoot on power-up, which should be prevented. Application Note 93: Design
Guidelines for Microcontrollers Incorporating NV RAM discusses how to protect the
DS87C530/DS83C530 against these conditions.
MEMORY RESOURCES
Like the 8051, the DS87C530/DS83C530 use three memory areas. The total memory configuration of the
device is 16kB of ROM, 1kB of data SRAM and 256 bytes of scratchpad or direct RAM. The 1kB of data
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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space SRAM is read/write accessible and is memory mapped. This on-chip SRAM is reached by the
MOVX instruction. It is not used for executable memory. The scratchpad area is 256 bytes of register
mapped RAM and is identical to the RAM found on the 80C52. There is no conflict or overlap among the
256 bytes and the 1kB as they use different addressing modes and separate instructions.
OPERATIONAL CONSIDERATION
The erasure window of the windowed LCC should be covered without regard to the
programmed/unprogrammed state of the EPROM. Otherwise, the device may not meet the AC and DC
parameters listed in the data sheet.
PROGRAM MEMORY ACCESS
On-chip ROM begins at address 0000h and is contiguous through 3FFFh (16kB). Exceeding the
maximum address of on-chip ROM will cause the DS87C530/DS83C530 to access off-chip memory.
However, the maximum on-chip decoded address is selectable by software using the ROMSIZE feature.
Software can cause the microcontroller to behave like a device with less on-chip memory. This is
beneficial when overlapping external memory, such as Flash, is used.
The maximum memory size is dynamically variable. Thus a portion of memory can be removed from the
memory map to access off-chip memory, then restored to access on-chip memory. In fact, all the on-chip
memory can be removed from the memory map allowing the full 64kB memory space to be addressed
from off-chip memory. ROM addresses that are larger than the selected maximum are automatically
fetched from outside the part via Ports 0 and 2. Figure 4 shows a depiction of the ROM memory map.
The ROMSIZE register is used to select the maximum on-chip decoded address for ROM. Bits RMS2,
RMS1, RMS0 have the following effect:
RMS2
RMS1
RMS0
MAXIMUM ON-CHIP ROM ADDRESS
0 0 0
0kB
0 0 1
1kB
0 1 0
2kB
0 1 1
4kB
1 0 0
8kB
1 0 1
16kB
(default)
1 1 0
Invalid--reserved
1 1 1
Invalid--reserved
The reset default condition is a maximum on-chip ROM address of 16kB. Thus no action is required if
this feature is not used. When accessing external program memory, the first 16kB would be inaccessible.
To select a smaller effective ROM size, software must alter bits RMS2RMS0. Altering these bits
requires a timed-access procedure.
Care should be taken so that changing the ROMSIZE register does not corrupt program execution. For
example, assume that a device is executing instructions from internal program memory near the 12kB
boundary (~3000h) and that the ROMSIZE register is currently configured for a 16kB internal program
space. If software reconfigures the ROMSIZE register to 4kB (0000h0FFFh) in the current state, the
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device will immediately jump to external program execution because program code from 4kB to 16kB
(1000h3FFFh) is no longer located on-chip. This could result in code misalignment and execution of an
invalid instruction. The recommended method is to modify the ROMSIZE register from a location in
memory that will be internal (or external) both before and after the operation. In the above example, the
instruction which modifies the ROMSIZE register should be located below the 4kB (1000h) boundary, so
that it will be unaffected by the memory modification. The same precaution should be applied if the
internal program memory size is modified while executing from external program memory.
Off-chip memory is accessed using the multiplexed address/data bus on P0 and the MSB address on P2.
While serving as a memory bus, these pins are not I/O ports. This convention follows the standard 8051
method of expanding on-chip memory. Off-chip ROM access also occurs if the
EA
pin is a logic 0.
EA
overrides all bit settings. The
PSEN
signal will go active (low) to serve as a chip enable or output enable
when Ports 0 and 2 fetch from external ROM.
Figure 4. ROM Memory Map
DATA MEMORY ACCESS
Unlike many 8051 derivatives, the DS87C530/DS83C530 contain on-chip data memory. The devices also
contain the standard 256 bytes of RAM accessed by direct instructions. These areas are separate. The
MOVX instruction accesses the on-chip data memory. Although physically on-chip, software treats this
area as though it was located off-chip. The 1kB of SRAM is between address 0000h and 03FFh.
Access to the on-chip data RAM is optional under software control. When enabled by software, the data
SRAM is between 0000h and 03FFh. Any MOVX instruction that uses this area will go to the on-chip
RAM while enabled. MOVX addresses greater than 03FFh automatically go to external memory through
Ports 0 and 2.
When disabled, the 1kB memory area is transparent to the system memory map. Any MOVX directed to
the space between 0000h and FFFFh goes to the expanded bus on Ports 0 and 2. This also is the default
condition. This default allows the DS87C530/DS83C530 to drop into an existing system that uses these
addresses for other hardware and still have full compatibility.
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The on-chip data area is software selectable using 2 bits in the Power Management Register at location
C4h. This selection is dynamically programmable. Thus access to the on-chip area becomes transparent to
reach off-chip devices at the same addresses. The control bits are DME1 (PMR.1) and DME0 (PMR.0).
They have the following operation:
Table 2. Data Memory Access Control
DME1
DME0
DATA MEMORY ADDRESS
MEMORY FUNCTION
0
0
0000hFFFFh
External Data Memory (default condition)
0000h03FFh
Internal SRAM Data Memory
0 1
0400hFFFFh
External Data Memory
1 0
Reserved
Reserved
0000h03FFh
Internal SRAM Data Memory
0400hFFFBh
Reserved--no external access
FFFCh
Read access to the status of lock bits
1 1
FFFDhFFFh
Reserved--no external access
Notes on the status byte read at FFFCh with DME1, 0 = 1, 1: Bits 2-0 reflect the programmed status of
the security lock bits LB2LB0. They are individually set to a logic 1 to correspond to a security lock bit
that has been programmed. These status bits allow software to verify that the part has been locked before
running if desired. The bits are read-only.
Note: After internal MOVX SRAM has been initialized, changing bits DEM0/1 has no effect on the
contents of the SRAM.
STRETCH MEMORY CYCLE
The DS87C530/DS83C530 allow software to adjust the speed of off-chip data memory access. The
microcontrollers can perform the MOVX in as few as two instruction cycles. The on-chip SRAM uses
this speed and any MOVX instruction directed internally uses two cycles. However, the time can be
stretched for interface to external devices. This allows access to both fast memory and slow memory or
peripherals with no glue logic. Even in high-speed systems, it may not be necessary or desirable to
perform off-chip data memory access at full speed. In addition, there are a variety of memory-mapped
peripherals such as LCDs or UARTs that are slow.
The Stretch MOVX is controlled by the Clock Control Register at SFR location 8Eh as described below.
It allows the user to select a Stretch value between 0 and 7. A Stretch of 0 will result in a two-machine
cycle MOVX. A Stretch of 7 will result in a MOVX of nine machine cycles. Software can dynamically
change this value depending on the particular memory or peripheral.
On reset, the Stretch value will default to a 1, resulting in a three-cycle MOVX for any external access.
Therefore, off-chip RAM access is not at full speed. This is a convenience to existing designs that may
not have fast RAM in place. Internal SRAM access is always at full speed regardless of the Stretch
setting. When desiring maximum speed, software should select a Stretch value of 0. When using very
slow RAM or peripherals, select a larger Stretch value. Note that this affects data memory only and the
only way to slow program memory (ROM) access is to use a slower crystal.
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Using a Stretch value between 1 and 7 causes the microcontroller to stretch the read/write strobe and all
related timing. Also, setup and hold times are increased by 1 clock when using any Stretch greater than 0.
This results in a wider read/write strobe and relaxed interface timing, allowing more time for
memory/peripherals to respond. The timing of the variable speed MOVX is in the Electrical
Specifications section. Table 3 shows the resulting strobe widths for each Stretch value. The memory
Stretch uses the Clock Control Special Function Register at SFR location 8Eh. The Stretch value is
selected using bits CKCON.20. In the table, these bits are referred to as M2 through M0. The first
Stretch (default) allows the use of common 120ns RAMs without dramatically lengthening the memory
access.
Table 3. Data Memory Cycle Stretch Values
CKCON.20
M2 M1 M0
MEMORY CYCLES
RD OR WR STROBE
WIDTH IN CLOCKS
STROBE WIDTH TIME
AT 33MHz
(ns)
0 0 0
2
(forced
internal)
2
60
0 0 1
3
(default
external)
4
121
0 1 0
4
8
242
0 1 1
5
12
364
1 0 0
6
16
485
1 0 1
7
20
606
1 1 0
8
24
727
1 1 1
9
28
848
DUAL DATA POINTER
The timing of block moves of data memory is faster using the Dual Data Pointer (DPTR). The standard
8051 DPTR is a 16-bit value that is used to address off-chip data RAM or peripherals. In the
DS87C530/DS83C530, the standard data pointer is called DPTR, located at SFR addresses 82h and 83h.
These are the standard locations. Using DPTR requires no modification of standard code. The new DPTR
at SFR 84h and 85h is called DPTR1. The DPTR Select bit (DPS) chooses the active pointer. Its location
is the lsb of the SFR location 86h. No other bits in register 86h have any effect and are 0. The user
switches between data pointers by toggling the lsb of register 86h. The increment (INC) instruction is the
fastest way to accomplish this. All DPTR-related instructions use the currently selected DPTR for any
activity. Therefore it takes only one instruction to switch from a source to a destination address. Using the
Dual Data Pointer saves code from needing to save source and destination addresses when doing a block
move. The software simply switches between DPTR and 1 once software loads them. The relevant
register locations are as follows.
DPL
82h
Low byte original DPTR
DPH
83h
High byte original DPTR
DPL1
84h
Low byte new DPTR
DPH1
85h
High byte new DPTR
DPS
86h
DPTR Select (lsb)
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POWER MANAGEMENT
Along with the standard Idle and power-down (Stop) modes of the standard 80C52, the
DS87C530/DS83C530 provide a new Power Management Mode. This mode allows the processor to
continue functioning, yet to save power compared with full operation. The DS87C530/DS83C530 also
feature several enhancements to Stop mode that make it more useful.
POWER MANAGEMENT MODE (PMM)
Power Management Mode offers a complete scheme of reduced internal clock speeds that allow the CPU
to run software but to use substantially less power. During default operation, the DS87C530/DS83C530
use four clocks per machine cycle. Thus the instruction cycle rate is (Clock/4). At 33MHz crystal speed,
the instruction cycle speed is 8.25MHz (33/4). In PMM, the microcontroller continues to operate but uses
an internally divided version of the clock source. This creates a lower power state without external
components. It offers a choice of two reduced instruction cycle speeds (and two clock sources - discussed
below). The speeds are (Clock/64) and (Clock/1024).
Software is the only mechanism to invoke the PMM. Table 4 illustrates the instruction cycle rate in PMM
for several common crystal frequencies. Since power consumption is a direct function of operating speed,
PMM 1 eliminates most of the power consumption while still allowing a reasonable speed of processing.
PMM 2 runs very slowly and provides the lowest power consumption without stopping the CPU. This is
illustrated in Table 5.
Note that PMM provides a lower power condition than Idle mode. This is because in Idle, all clocked
functions such as timers run at a rate of crystal divided by 4. Since wake-up from PMM is as fast as or
faster than from Idle and PMM allows the CPU to operate (even if doing NOPs), there is little reason to
use Idle mode in new designs.
Table 4. Machine Cycle Rate
CRYSTAL SPEED
(MHz)
FULL OPERATION
(4 CLOCKS)
(MHz)
PMM1
(64 CLOCKS)
(kHz)
PMM2
(1024 CLOCKS)
(kHz)
11.0592 2.765 172.8 10.8
16 4.00 250.0 15.6
25 6.25 390.6 24.4
33 8.25 515.6 32.2
Table 5. Typical Operating Current in PMM
CRYSTAL SPEED
(MHz)
FULL OPERATION
(4 CLOCKS)
(mA)
PMM1
(64 CLOCKS)
(mA)
PMM2
(1024 CLOCKS)
(mA)
11.0592 13.1 5.3
4.8
16 17.2 6.4 5.6
25 25.7 8.1 7.0
33 32.8 9.8 8.2
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CRYSTAL-LESS PMM
A major component of power consumption in PMM is the crystal amplifier circuit. The
DS87C530/DS83C530 allow the user to switch CPU operation to an internal ring oscillator and turn off
the crystal amplifier. The CPU would then have a clock source of approximately 2MHz to 4MHz, divided
by either 4, 64, or 1024. The ring is not accurate, so software cannot perform precision timing. However,
this mode allows an additional saving of between 0.5mA and 6.0mA, depending on the actual crystal
frequency. While this saving is of little use when running at 4 clocks per instruction cycle, it makes a
major contribution when running in PMM1 or PMM2.
PMM OPERATION
Software invokes the PMM by setting the appropriate bits in the SFR area. The basic choices are divider
speed and clock source. There are three speeds (4, 64, and 1024) and two clock sources (crystal, ring).
Both the decisions and the controls are separate. Software will typically select the clock speed first. Then,
it will perform the switch to ring operation if desired. Lastly, software can disable the crystal amplifier if
desired.
There are two ways of exiting PMM. Software can remove the condition by reversing the procedure that
invoked PMM or hardware can (optionally) remove it. To resume operation at a divide-by-4 rate under
software control, simply select 4 clocks per cycle, and then crystal-based operation if relevant. When
disabling the crystal as the time base in favor of the ring oscillator, there are timing restrictions associated
with restarting the crystal operation. Details are described below.
There are three registers containing bits that are concerned with PMM functions. They are Power
Management Register (PMR; C4h), Status (STATUS; C5h), and External Interrupt Flag (EXIF; 91h)
Clock Divider
Software can select the instruction cycle rate by selecting bits CD1 (PMR.7) and CD0 (PMR.6) as
follows:
CD1 CD0
CYCLE
RATE
0 0
Reserved
0
1
4 clocks (default)
1 0
64
clocks
1 1
1024
clocks
The selection of instruction cycle rate will take effect after a delay of one instruction cycle. Note that the
clock divider choice applies to all functions including timers. Since baud rates are altered, it will be
difficult to conduct serial communication while in PMM. There are minor restrictions on accessing the
clock selection bits. The processor must be running in a 4-clock state to select either 64 (PMM1) or 1024
(PMM2) clocks. This means software cannot go directly from PMM1 to PMM2 or visa versa. It must
return to a 4-clock rate first.
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Switchback
To return to a 4-clock rate from PMM, software can simply select the CD1 and CD0 clock control bits to
the 4 clocks per cycle state. However, the DS87C530/DS83C530 provide several hardware alternatives
for automatic Switchback. If Switchback is enabled, then the device will automatically return to a 4-clock
per cycle speed when an interrupt occurs from an enabled, valid external interrupt source. A Switchback
will also occur when a UART detects the beginning of a serial start bit if the serial receiver is enabled
(REN = 1). Note the beginning of a start bit does not generate an interrupt; this occurs on reception of a
complete serial word. The automatic Switchback on detection of a start bit allows hardware to correct
baud rates in time for a proper serial reception. A Switchback will also occur when a byte is written to the
SBUF0 or SBUF1 for transmission.
Switchback is enabled by setting the SWB bit (PMR.5) to a 1 in software. For an external interrupt,
Switchback will occur only if the interrupt source could really generate the interrupt. For example, if
INT0
is enabled but has a low priority setting, then Switchback will not occur on
INT0
if the CPU is
servicing a high priority interrupt.
Status
Information in the Status register assists decisions about switching into PMM. This register contains
information about the level of active interrupts and the activity on the serial ports.
The DS87C530/DS83C530 support three levels of interrupt priority. These levels are Power-fail, High,
and Low. Bits STATUS.75 indicate the service status of each level. If PIP (Power-fail Interrupt Priority;
STATUS. 7) is 1, then the processor is servicing this level. If either HIP (High Interrupt Priority;
STATUS.6) or LIP (Low Interrupt Priority; STATUS.5) is high, then the corresponding level is in
service.
Software should not rely on a lower priority level interrupt source to remove PMM (Switchback) when a
higher level is in service. Check the current priority service level before entering PMM. If the current
service level locks out a desired Switchback source, then it would be advisable to wait until this condition
clears before entering PMM.
Alternately, software can prevent an undesired exit from PMM by entering a low priority interrupt service
level before entering PMM. This will prevent other low priority interrupts from causing a Switchback.
Status also contains information about the state of the serial ports. Serial Port Zero Receive Activity
(SPRA0; STATUS.0) indicates a serial word is being received on Serial Port 0 when this bit is set to a 1.
Serial Port 0 Transmit Activity (SPTA0; STATUS.1) indicates that the serial port is still shifting out a
serial transmission. STATUS.2 and STATUS.3 provide the same information for Serial Port 1,
respectively. These bits should be interrogated before entering PMM1 or PMM2 to ensure that no serial
port operations are in progress. Changing the clock divisor rate during a serial transmission or reception
will corrupt the operation.
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Crystal/Ring Operation
The DS87C530/DS83C530 allow software to choose the clock source as an independent selection from
the instruction cycle rate. The user can select crystal-based or ring oscillator-based operation under
software control. Power-on reset default is the crystal (or external clock) source. The ring may save
power depending on the actual crystal speed. To save still more power, software can then disable the
crystal amplifier. This process requires two steps. Reversing the process also requires two steps.
The XT/
RG
bit (EXIF.3) selects the crystal or ring as the clock source. Setting XT/
RG
= 1 selects the
crystal. Setting XT/
RG
= 0 selects the ring. The RGMD (EXIF.2) bit serves as a status bit by indicating
the active clock source. RGMD = 0 indicates the CPU is running from the crystal. RGMD = 1 indicates it
is running from the ring. When operating from the ring, disable the crystal amplifier by setting the
XTOFF bit (PMR.3) to a 1. This can only be done when XT/
RG
= 0.
When changing the clock source, the selection will take effect after a one-instruction-cycle delay. This
applies to changes from crystal to ring and vise versa. However, this assumes that the crystal amplifier is
running. In most cases, when the ring is active, software previously disabled the crystal to save power. If
ring operation is being used and the system must switch to crystal operation, the crystal must first be
enabled. Set the XTOFF bit to 0. At this time, the crystal oscillation will begin. The
DS87C530/DS83C530 then provide a warm-up delay to make certain that the frequency is stable.
Hardware will set the XTUP bit (STATUS.4) to 1 when the crystal is ready for use. Then software should
write XT/
RG
to 1 to begin operating from the crystal. Hardware prevents writing XT/
RG
to 1 before
XTUP = 1. The delay between XTOFF = 0 and XTUP = 1 will be 65,536 crystal clocks in addition to the
crystal cycle startup time.
Switchback has no affect on the clock source. If software selects a reduced clock divider and enables the
ring, a Switchback will only restore the divider speed. The ring will remain as the time base until altered
by software. If there is serial activity, Switchback usually occurs with enough time to create proper baud
rates. This is not true if the crystal is off and the CPU is running from the ring. If sending a serial
character that wakes the system from crystal-less PMM, then it should be a dummy character of no
importance with a subsequent delay for crystal startup.
Table 6 is a summary of the bits relating to PMM and its operation. The flow chart below illustrates a
typical decision set associated with PMM.
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Table 6. PMM Control and Status Bit Summary
NAME LOCATION
FUNCTION
RESET WRITE
ACCESS
XT/ RG
EXIF.3
Control. XT/ RG =1, runs from crystal or external
clock; XT/ RG =0, runs from internal ring oscillator.
X
0 to 1 only when
XTUP = 1 and
XTOFF= 0
RGMD EXIF.2
Status. RGMD=1, CPU clock = ring; RGMD = 0,
CPU clock = crystal.
0 None
CD1, CD0
PMR7, PMR.6
Control. CD1, 0 = 01, 4 clocks; CS1, 0 = 10, PMM1;
CD1, 0 = 11, PMM2.
0, 1
Write CD1, 0 = 10 or
11 only from CD1, 0 =
01
SWB PMR.5
Control. SWB = 1, hardware invokes switchback to 4
clocks, SWB = 0, no hardware switchback.
0 Unrestricted
XTOFF PMR.3
Control. Disables crystal operation after ring is
selected.
0
1 only when XT/ RG
= 0
PIP STATUS.7
Status. 1 indicates a power-fail interrupt in service.
0 None
HIP STATUS.6
Status. 1 indicates high priority interrupt in service.
0 None
LIP STATUS.5
Status. 1 indicates low priority interrupt in service.
0 None
XTUP STATUS.4
Status. 1 indicates that the crystal has stabilized.
1 None
SPTA1 STATUS.3
Status. Serial transmission on serial port 1.
0 None
SPRA1 STATUS.2
Status. Serial word reception on serial port 1.
0 None
SPTA0 STATUS.1
Status. Serial transmission on serial port 0.
0 None
SPRA0 STATUS.0
Status. Serial word reception on serial port 0.
0 None
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Figure 5. Invoking and Clearing PMM
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IDLE MODE
Setting the lsb of the Power Control register (PCON; 87h) invokes the Idle mode. Idle will leave internal
clocks, serial ports and timers running. Power consumption drops because the CPU is not active. Since
clocks are running, the Idle power consumption is a function of crystal frequency. It should be
approximately one-half the operational power at a given frequency. The CPU can exit the Idle state with
any interrupt or a reset. Idle is available for backward software compatibility. The system can now reduce
power consumption to below Idle levels by using PMM1 or PMM2 and running NOPs.
STOP MODE ENHANCEMENTS
Setting bit 1 of the Power Control register (PCON; 87h) invokes the Stop mode. Stop mode is the lowest
power state since it turns off all internal clocking. The I
CC
of a standard Stop mode is approximately 1
mA
but is specified in the Electrical Specifications. The CPU will exit Stop mode from an external interrupt
or a reset condition. Internally generated interrupts (timer, serial port, watchdog) are not useful since they
require clocking activity. One exception is that a RTC interrupt can cause the device to exit Stop mode.
This provides a very power efficient way of performing infrequent yet periodic tasks.
The DS87C530/DS83C530 provide two enhancements to the Stop mode. As documented below, the
device provides a bandgap reference to determine Power-fail Interrupt and Reset thresholds. The default
state is that the bandgap reference is off while in Stop mode. This allows the extremely low-power state
mentioned above. A user can optionally choose to have the bandgap enabled during Stop mode. With the
bandgap reference enabled, PFI and Power-fail Reset are functional and are a valid means for leaving
Stop mode. This allows software to detect and compensate for a brownout or power supply sag, even
when in Stop mode.
In Stop mode with the bandgap enabled, I
CC
will be approximately 50
mA compared with 1mA with the
bandgap off. If a user does not require a Power-fail Reset or Interrupt while in Stop mode, the bandgap
can remain disabled. Only the most power sensitive applications should turn off the bandgap, as this
results in an uncontrolled power-down condition.
The control of the bandgap reference is located in the Extended Interrupt Flag register (EXIF; 91h).
Setting BGS (EXIF.0) to a 1 will keep the bandgap reference enabled during Stop mode. The default or
reset condition is with the bit at a logic 0. This results in the bandgap being off during Stop mode. Note
that this bit has no control of the reference during full power, PMM, or Idle modes.
The second feature allows an additional power saving option while also making Stop easier to use. This is
the ability to start instantly when exiting Stop mode. It is the internal ring oscillator that provides this
feature. This ring can be a clock source when exiting Stop mode in response to an interrupt. The benefit
of the ring oscillator is as follows.
Using Stop mode turns off the crystal oscillator and all internal clocks to save power. This requires that
the oscillator be restarted when exiting Stop mode. Actual startup time is crystal-dependent, but is
normally at least 4ms. A common recommendation is 10ms. In an application that will wake up, perform
a short operation, then return to sleep, the crystal startup can be longer than the real transaction. However,
the ring oscillator will start instantly. Running from the ring, the user can perform a simple operation and
return to sleep before the crystal has even started. If a user selects the ring to provide the startup clock and
the processor remains running, hardware will automatically switch to the crystal once a power-on reset
interval (65,536 clocks) has expired. Hardware uses this value to assure proper crystal start even though
power is not being cycled.
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The ring oscillator runs at approximately 2MHz to 4MHz but will not be a precise value. Do not conduct
real-time precision operations (including serial communication) during this ring period. Figure 6 shows
how the operation would compare when using the ring, and when starting up normally. The default state
is to exit Stop mode without using the ring oscillator.
The RGSL ring-select bit at EXIF.1 (EXIF; 91h) controls this function. When RGSL = 1, the CPU will
use the ring oscillator to exit Stop mode quickly. As mentioned above, the processor will automatically
switch from the ring to the crystal after a delay of 65,536 crystal clocks. For a 3.57MHz crystal, this is
approximately 18ms. The processor sets a flag called RGMD- Ring Mode, located at EXIF.2, that tells
software that the ring is being used. The bit will be a logic 1 when the ring is in use. Attempt no serial
communication or precision timing while this bit is set, since the operating frequency is not precise.
Figure 6. Ring Oscillator Exit from Stop Mode
EMI REDUCTION
One of the major contributors to radiated noise in an 8051-based system is the toggling of ALE. The
DS87C530/DS83C530 allow software to disable ALE when not used by setting the ALEOFF (PMR.2) bit
to 1. When ALEOFF = 1, ALE will still toggle during an off-chip MOVX. However, ALE will remain in
a static when performing on-chip memory access. The default state of ALEOFF = 0 so ALE toggles with
every instruction cycle.
NOTE: DIAGRAM ASSUMES THAT THE OPERATION FOLLOWING STOP REQUIRES LESS THAN 18ms TO COMPLETE.
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PERIPHERAL OVERVIEW
The DS87C530/DS83C530 provide several of the most commonly needed peripheral functions in
microcomputer-based systems. These new functions include a second serial port, power-fail reset, Power-
fail interrupt, and a programmable watchdog timer. These are described below, and more details are
available in the High-Speed Microcontroller User's Guide.
SERIAL PORTS
The DS87C530/DS83C530 provide a serial port (UART) that is identical to the 80C52. In addition it
includes a second hardware serial port that is a full duplicate of the standard one. This port optionally
uses pins P1.2 (RXD1) and P1.3 (TXD1). It has duplicate control functions included in new SFR
locations.
Both ports can operate simultaneously but can be at different baud rates or even in different modes. The
second serial port has similar control registers (SCON1; C0h, SBUF1; C1h) to the original. The new
serial port can only use Timer 1 for timer-generated baud rates.
TIMER RATE CONTROL
There is one important difference between the DS87C530/DS83C530 and 8051 regarding timers. The
original 8051 used 12 clocks per cycle for timers as well as for machine cycles. The
DS87C530/DS83C530 architecture normally uses 4 clocks per machine cycle. However, in the area of
timers and serial ports, the DS87C530/DS83C530 will default to 12 clocks per cycle on reset. This allows
existing code with real-time dependencies such as baud rates to operate properly.
If an application needs higher speed timers or serial baud rates, the user can select individual timers to run
at the 4-clock rate. The Clock Control register (CKCON; 8Eh) determines these timer speeds. When the
relevant CKCON bit is logic 1, the DS87C530/DS83C530 use 4 clocks per cycle to generate timer
speeds. When the bit is a 0, the DS87C530 uses 12 clocks for timer speeds. The reset condition is a 0.
CKCON.5 selects the speed of Timer 2. CKCON.4 selects Timer 1 and CKCON.3 selects Timer 0.
Unless a user desires very fast timing, it is unnecessary to alter these bits. Note that the timer controls are
independent.
POWER-FAIL RESET
The DS87C530/DS83C530 use a precision bandgap voltage reference to decide if V
CC
is out of tolerance.
While powering up, the internal monitor circuit maintains a reset state until V
CC
rises above the V
RST
level. Once above this level, the monitor enables the crystal oscillator and counts 65,536 clocks. It then
exits the reset state. This power-on reset (POR) interval allows time for the oscillator to stabilize.
A system needs no external components to generate a power-related reset. Anytime V
CC
drops below
V
RST
, as in power failure or a power drop, the monitor will generate and hold a reset. It occurs
automatically, needing no action from the software. Refer to the Electrical Specifications section for the
exact value of V
RST
.
POWER-FAIL INTERRUPT
The voltage reference that sets a precise reset threshold also generates an optional early warning power-
fail interrupt (PFI). When enabled by software, the processor will vector to program memory address
0033h if V
CC
drops below V
PFW
. PFI has the highest priority. The PFI enable is in the Watchdog Control
SFR (WDCOND8h). Setting WDCON.5 to logic 1 will enable the PFI. Application software can also
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
25 of 46
read the PFI flag at WDCON.4. A PFI condition sets this bit to a 1. The flag is independent of the
interrupt enable and software must manually clear it. If the PFI is enabled and the bandgap select bit
(BGS) is set, a PFI will bring the device out of Stop mode.
WATCHDOG TIMER
To prevent software from losing control, the DS87C530/DS83C530 include a programmable watchdog
timer. The Watchdog is a free-running timer that sets a flag if allowed to reach a preselected timeout. It
can be (re)started by software.
A typical application is to select the flag as a reset source. When the Watchdog times out it sets its flag,
which generates reset. Software must restart the timer before it reaches its timeout or the processor is
reset.
Software can select one of four timeout values. Then, it restarts the timer and enables the reset function.
After enabling the reset function, software must then restart the timer before its expiration or hardware
will reset the CPU. Both the Watchdog Reset Enable and the Watchdog Restart control bits are protected
by a "Timed Access" circuit. This prevents errant software from accidentally clearing the Watchdog.
Timeout values are precise since they are a function of the crystal frequency as shown in Table 7. For
reference, the time periods at 33MHz also are shown.
The Watchdog also provides a useful option for systems that do not require a reset circuit. It will set an
interrupt flag 512 clocks before setting the reset flag. Software can optionally enable this interrupt source.
The interrupt is independent of the reset. A common use of the interrupt is during debug, to show
developers where the Watchdog times out. This indicates where the Watchdog must be restarted by
software. The interrupt also can serve as a convenient time-base generator or can wake-up the processor
from power saving modes.
The Watchdog function is controlled by the Clock Control (CKCON8Eh), Watchdog Control
(WDCOND8h), and Extended Interrupt Enable (EIEE8h) SFRs. CKCON.7 and CKCON.6 are WD1
and WD0, respectively, and they select the Watchdog timeout period as shown in Table 7.
Table 7. Watchdog Timeout Values
WD1 WD0
INTERRUPT
TIMEOUT
TIME (33MHz)
RESET TIMEOUT
TIME (33MHz)
0 0
2
17
clocks
3.9718ms
2
17
+ 512 clocks
3.9874ms
0 1
2
20
clocks
31.77ms
2
20
+ 512 clocks
31.79ms
1 0
2
23
clocks
254.20ms
2
23
+ 512 clocks
254.21ms
1 1
2
26
clocks
2033.60ms
2
26
+ 512 clocks
2033.62ms
As shown above, the Watchdog Timer uses the crystal frequency as a time base. A user selects one of
four counter values to determine the timeout. These clock counter lengths are 2
17
= 131,072 clocks; 2
20
=
1,048,576; 2
23
= 8,388,608 clocks; and 2
26
= 67,108,864 clocks. The times shown in Table 7 are with a
33MHz crystal frequency. Once the counter chain has completed a full interrupt count, hardware will set
an interrupt flag. Regardless of whether the user enables this interrupt, there are then 512 clocks left until
the reset flag is set. Software can enable the interrupt and reset individually. Note that the Watchdog is a
free-running timer and does not require an enable.
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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There are five control bits in special function registers that affect the Watchdog Timer and two status
flags that report to the user. WDIF (WDCON.3) is the interrupt flag that is set at timer termination when
there are 512 clocks remaining until the reset flag is set. WTRF (WDCON.2) is the flag that is set when
the timer has completely timed out. This flag is normally associated with a CPU reset and allows software
to determine the reset source. EWT (WDCON.1) is the enable for the Watchdog Timer reset function.
RWT (WDCON.0) is the bit that software uses to restart the Watchdog Timer. Setting this bit restarts the
timer for another full interval. Application software must set this bit before the timeout. Both of these bits
are protected by Timed Access discussed below. As mentioned previously, WD1 and 0 (CKCON .7 and
6) select the timeout. The Reset Watchdog Timer bit (WDCON.0) should be asserted prior to modifying
the Watchdog Timer Mode Select bits (WD1, WD0) to avoid corruption of the watchdog count. Finally,
the user can enable the Watchdog Interrupt using EWDI (EIE.4).
INTERRUPTS
The DS87C530/DS83C530 provide 14 interrupt sources with three priority levels. The Power-Fail
Interrupt (PFI) has the highest priority. Software can assign high or low priority to other sources. All
interrupts that are new to the 8051 family, except for the PFI, have a lower natural priority than the
originals.
Table 8. Interrupt Sources and Priorities
NAME FUNCTION VECTOR
NATURAL
PRIORITY
8051/DALLAS
PFI Power-Fail
Interrupt
33h
1
DALLAS
INT0
External Interrupt 0
03h
2
8051
TF0 Timer
0
0Bh
3
8051
INT1
External Interrupt 1
13h
4
8051
TF1 Timer
1
1Bh
5
8051
SCON0
TI0 or RI0 from Serial Port 0
23h
6
8051
TF2 Timer
2
2Bh
7
8051
SCON1
TI1 or RI1 from Serial Port 1
3Bh
8
DALLAS
INT2
External Interrupt 2
43h
9
DALLAS
INT3
External Interrupt 3
4Bh
10
DALLAS
INT4
External Interrupt 4
53h
11
DALLAS
INT5
External Interrupt 5
5Bh
12
DALLAS
WDTI
Watchdog Timeout Interrupt
63h
13
DALLAS
RTCI RTC
Interrupt
6Bh
14
DALLAS
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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TIMED-ACCESS PROTECTION
It is useful to protect certain SFR bits from an accidental write operation. The Timed-Access procedure
stops an errant CPU from accidentally changing these bits. It requires that the following instructions
precede a write of a protected bit.
MOV
0C7h,
#0AAh
MOV
0C7h,
#55h
Writing an AAh and then a 55h to the Timed-Access register (location C7h) opens a three-cycle window
for write access. The window allows software to modify a protected bit(s). If these instructions do not
immediately precede the write operation, then the write will not take effect. The protected bits are:
EXIF.0 BGS Bandgap
Select
WDCON.6
POR
Power-On Reset flag
WDCON.1
EWT
Enable Watchdog Reset
WDCON.0 RWT
Restart
Watchdog
WDCON.3
WDIF
Watchdog Interrupt Flag
ROMSIZE.2
RMS2
ROM Size Select 2
ROMSIZE.1
RMS1
ROM Size Select 1
ROMSIZE.0
RMS0
ROM Size Select 0
TRIM.70
--
All RTC Trim Functions
RTCC.2
RTCWE
RTC Write Enable
RTCC.0
RTCE
RTC Oscillator Enable
EPROM PROGRAMMING
The DS87C530 follows standards for a 16kB EPROM version in the 8051 family. It is available in a UV
erasable, ceramic windowed package and in plastic packages for one-time user-programmable versions.
The part has unique signature information so programmers can support its specific EPROM options.
PROGRAMMING PROCEDURE
The DS87C530 should run from a clock speed between 4MHz and 6MHz when programmed. The
programming fixture should apply address information for each byte to the address lines and the data
value to the data lines. The control signals must be manipulated as shown in Table 9. The diagram in
Figure 5 shows the expected electrical connection for programming. Note that the programmer must
apply addresses in demultiplexed fashion to Ports 1 and 2 with data on Port 0. Waveforms and timing are
provided in the Electrical Specifications section. Program the DS87C530 as follows:
1)
Apply the address value,
2)
Apply the data value,
3)
Select the programming option from
Table 9
using the control signals,
4)
Increase the voltage on V
PP
from 5V to 12.75V if writing to the EPROM,
5)
Pulse the
PROG signal five times for EPROM array and 25 times for encryption table, lock bits, and other
EPROM bits,
6)
Repeat as many times as necessary.
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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DS87C530 SECURITY OPTIONS
The DS87C530 employs a standard three-level lock that restricts viewing of the EPROM contents. A 64-
byte Encryption Array allows the authorized user to verify memory by presenting the data in encrypted
form.
Lock Bits
The security lock consists of 3 lock bits. These bits select a total of 4 levels of security. Higher levels
provide increasing security but also limit application flexibility. Table 10 shows the security settings.
Note that the programmer cannot directly read the state of the security lock. User software has access to
this information as described in the Memory section.
Encryption Array
The Encryption Array allows an authorized user to verify EPROM without allowing the true memory to
be dumped. During a verify, each byte is Exclusive NORed (XNOR) with a byte in the Encryption Array.
This results in a true representation of the EPROM while the Encryption is unprogrammed (FFh). Once
the Encryption Array is programmed in a non-FFh state, the verify value will be encrypted.
For encryption to be effective, the Encryption Array must be unknown to the party that is trying to verify
memory. The entire EPROM also should be a non-FFh state or the Encryption Array can be discovered.
The Encryption Array is programmed as shown in Table 9. Note that the programmer cannot read the
array. Also note that the verify operation always uses the Encryption Array. The array has no impact
while FFh. Simply programming the array to a non-FFh state will cause the encryption to function.
Other EPROM Options
The DS87C530 has user-selectable options that must be set before beginning software execution. These
options use EPROM bits rather than SFRs.
Program the EPROM selectable options as shown in Table 9. The Option Register sets or reads these
selections. The bits in the Option Control Register have the following function:
Bits 7 to 4
Reserved, program to 1.
Bit 3
Watchdog POR default. Set = 1; Watchdog reset function is disabled on power-up.
Set = 0; Watchdog reset function is enabled automatically.
Bits 2 to 0
Reserved. Program to 1.
DS87C530 Signature
The Signature bytes identify the product and programming revision to EPROM programmers. This
information is at programming addresses 30h, 31h, and 60h. This information is as follows:
ADDRESS VALUE MEANING
30h DAh
Manufacturer
31h 30h Model
60h 01h
Extension
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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Table 9. EPROM Programming Modes
MODE RST
PSEN
ALE/
PROG
EA/VPP P2.6 P2.7 P3.3 P3.6 P3.7
Program
Code
Data H L
PL
12.75V L H H H H
Verify Code Data
H
L
H
H
L
L
L
H
H
Program Encryption
Array Address 0-3Fh
H L
PL
12.75V L H H L H
LB1 H L
PL
12.75V H H H H H
LB2 H L
PL
12.75V H H H L L
Program Lock
Bits
LB3 H L
PL
12.75V H L H H L
Program Option
Register Address FCh
H L
PL 12.75V L H H L L
Read Signature or
Option Registers 30,
31, 60, FCh
H L
H
H L L L L L
*
PL indicates pulse to a logic low.
Table 10. EPROM Lock Bits
LOCK BITS
LEVEL
LB1 LB2 LB3
PROTECTION
1 U U U
No program lock. Encrypted verify if encryption table was
programmed.
2 P U U
Prevent MOVC instructions in external memory from reading
program bytes in internal memory.
EA is sampled and latched on
reset. Allow no further programming of EPROM.
3 P P U
Level 2 plus no verify operation. Also, prevent MOVX instructions in
external memory from reading SRAM (MOVX) in internal memory.
4
P
P
P
Level 3 plus no external execution.
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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Figure 7. EPROM Programming Configuration
ROM-SPECIFIC FEATURES (DS83C530)
The DS83C530 supports a subset of the EPROM features found on the DS87C530.
SECURITY OPTIONS
Lock Bits
The DS83C530 employs a lock that restricts viewing of the ROM contents. When set, the lock will
prevent MOVC instructions in external memory from reading program bytes in internal memory. When
locked, the
EA
pin is sampled and latched on reset. The lock setting is enabled or disabled when the
devices are manufactured according to customer specifications. The lock bit cannot be read in software,
and its status can only be determined by observing the operation of the device.
Encryption Array
The DS83C530 Encryption Array allows an authorized user to verify ROM without allowing the true
memory contents to be dumped. During a verify, each byte is Exclusive NORed (XNOR) with a byte in
the Encryption Array. This results in a true representation of the ROM while the Encryption is
unprogrammed (FFh). Once the Encryption Array is programmed in a non-FFh state, the Encryption
Array is programmed (or optionally left unprogrammed) when the devices are manufactured according to
customer specifications.
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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DS83C530 ROM Verification
The DS83C530 memory contents can be verified using a standard EPROM programmer. The memory
address to be verified is placed on the pins shown in Figure 7, and the programming control pins are set to
the levels shown in Table 9. The data at that location is then asserted on port 0.
DS83C530 Signature
The Signature bytes identify the DS83C530 to EPROM programmers. This information is at
programming addresses 30h, 31h, and 60h. Because Mask ROM devices are not programmed in device
programmers, most designers will find little use for the feature, and it is included only for compatibility.
ADDRESS VALUE MEANING
30h DAh
Manufacturer
31h 31h Model
60h 01h
Extension
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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ABSOLUTE MAXIMUM RATINGS
Voltage Range on Any Pin Relative to Ground................................................................-0.3V to (V
CC
+ 0.5V)
Voltage Range on V
CC
Relative to Ground.............................................................................-0.3V to +6.0V
Operating Temperature Range..............................................................................................0C to +70C
Storage Temperature Range.................................................................................-55C to +125C (Note 1)
Soldering Temperature...................................................................................See IPD/JEDEC J-STD-020A
This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation
sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.
DC ELECTRICAL CHARACTERISTICS
(V
CC
= 4.5V to 5.5V, T
A
= -40C to +85C.) (Note 2)
PARAMETER SYMBOL
MIN
TYP
MAX
UNITS
NOTES
Supply Voltage
V
CC
4.5 5.0 5.5 V 3
Power-Fail Warning
V
PFW
4.25 4.38 4.5 V 3
Minimum Operating Voltage
V
RST
4.0 4.13
4.25 V 3
Backup Battery Voltage
V
BAT
2.5 3.0
V
CC
-0.7 V
Supply Current Active Mode at 33MHz
I
CC
30
46
mA
4
Supply Current Idle Mode at 33MHz
I
Idle
15
25
mA
5
Supply Current Stop Mode, Bandgap Disabled
(0C to +70C)
1
100
mA
6
Supply Current Stop Mode, Bandgap Disabled
(-40C to +85C)
I
Stop
1
150
mA
6
Supply Current Stop Mode, Bandgap Enabled
(0C to +70C)
50
170
mA
6
Supply Current Stop Mode, Bandgap Enabled
(-40C to +85C)
I
SPBG
50
195
mA
6
Backup Supply Current, Data-Retention Mode
(0C to +70C)
0
0.5
mA
7
Backup Supply Current, Data-Retention Mode
(-40C to +85C)
I
BAT
0 1
mA
7
Input Low Level
V
IL
-0.3
+0.8
V 3
Input High Level
V
IH
2.0
V
CC
+0.3 V
3
Input High Level XTAL1 and RST
V
IH2
3.5
V
CC
+0.3 V
3
Output Low Voltage at I
OL
= 1.6mA
V
OL1
0.15
0.45
V 3
Output Low Voltage Ports 0, 2, ALE, and
PSEN
at I
OL
= 3.2mA
V
OL2
0.15
0.45
V 3
Output High Voltage Ports 1, 2, 3, ALE,
PSEN at
I
OH
= -50
mA
V
OH1
2.4 V
3,
8
Output High Voltage Ports 1, 2, 3
at I
OH
= -1.5mA
V
OH2
2.4 V
3,
9
Output High Voltage Port 0 in Bus Mode
I
OH
= -8mA
V
OH3
2.4 V
3,
10
Input Low Current Ports 1, 2, 3 at 0.45V
I
IL
-70
mA
11
Transition Current from 1 to 0 Ports 1, 2, 3 at 2V
I
TL
-800
mA
12
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
33 of 46
DC ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 4.5V to 5.5V, T
A
= -40C to +85C.)
PARAMETER SYMBOL
MIN
TYP
MAX
UNITS
NOTES
Input Leakage Port 0,
EA, Pins, I/O Mode
I
L
-10
+10
mA
13
Input Leakage Port 0, Bus Mode
I
L
-300
+300
mA
14
RST Pulldown Resistance
R
RST
50
200
k
W
Note 1:
Storage temperature is defined as the temperature of the device when V
CC
= 0V and V
BAT
= 0V. In this state, the contents of
SRAM are not battery backed and are undefined.
Note 2:
All parameters apply to both commercial and industrial temperature operation unless otherwise noted.
Note 3:
All voltages are referenced to ground.
Note 4:
Active current measured with 33MHz clock source on XTAL1, V
CC
= RST = 5.5V, other pins disconnected.
Note 5:
Idle mode current measured with 33MHz clock source on XTAL1, V
CC
= 5.5V, RST at ground, other pins disconnected.
Note 6:
Stop mode current measured with XTAL1 and RST grounded, V
CC
= 5.5V, all other pins disconnected.
Note 7:
V
CC
= 0V, V
BAT
= 3.3V. 32.768kHz crystal with 12.5pF load capacitance between RTCX1 and RTCX2 pins. RTCE bit set to 1.
Note 8:
RST = V
CC
. This condition mimics operation of pins in I/O mode. Port 0 is tri-stated in reset and when at a logic high state during
I/O mode.
Note 9:
During a 0-to-1 transition, a one-shot drives the ports hard for two clock cycles. This measurement reflects port in transition
mode.
Note 10:
When addressing external memory. This specification only applies to the first clock cycle following the transition.
Note 11:
This is the current required from an external circuit to hold a logic low level on an I/O pin while the corresponding port latch bit is
set to 1. This is only the current required to hold the low level; transitions from 1 to 0 on an I/O pin will also have to overcome the
transition current.
Note 12:
Ports 1, 2, and 3 source transition current when being pulled down externally. It reaches its maximum at approximately 2V.
Note 13:
0.45 < V
IN
< V
CC
. RST = V
CC
. This condition mimics operation of pins in I/O mode.
Note 14: 0.45
<
V
IN
< V
CC
. Not a high-impedance input. This port is a weak address holding latch in Bus Mode. Peak current occurs near
the input transition point of the latch, approximately 2V.
TYPICAL I
CC
vs. FREQUENCY
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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AC ELECTRICAL CHARACTERISTICS (Note 1)
33MHz VARIABLE
CLOCK
PARAMETER SYMBOL
MIN MAX MIN
MAX
UNITS
External Oscillator
0
33
0
33
Oscillator
Frequency
External Crystal
1/t
CLCL
1 33 1
33
MHz
ALE Pulse Width
t
LHLL
40
1.5t
CLCL
-5 ns
Port 0 Address Valid to ALE Low
t
AVLL
10
0.5t
CLCL
-5 ns
Address Hold after ALE Low
t
LLAX1
(Note 2)
(Note 2)
ns
ALE low to Valid Instruction In
t
LLIV
43 2.5t
CLCL
-33 ns
ALE Low to
PSEN
Low
t
LLPL
4
0.5t
CLCL
-11 ns
PSEN
Pulse Width
t
PLPH
55 2t
CLCL
-5 ns
PSEN
Low to Valid Instruction In
t
PLIV
37 2t
CLCL
-24 ns
Input Instruction Hold after
PSEN
t
PXIX
0 0
ns
Input Instruction Float after
PSEN
t
PXIZ
26 t
CLCL
-5 ns
Port 0 Address to Valid Instruction In
t
AVIV1
59 3t
CLCL
-32 ns
Port 2 Address to Valid Instruction In
t
AVIV2
68 3.5t
CLCL
-38 ns
PSEN
Low to Address Float
t
PLAZ
(Note 2)
(Note 2)
ns
Note 1: All parameters apply to both commercial and industrial temperature range operation unless otherwise noted. Specifications to
-40C are guaranteed by design and are not production tested. AC electrical characteristics are not 100% tested, but are
characterized and guaranteed by design. All signals are characterized with load capacitance of 80pF except Port 0, ALE,
PSEN, RD
and
WR with 100pF. Interfacing to memory devices with float times (turn off times) over 25ns may cause contention. This will not
damage the parts, but will cause an increase in operating current. Specifications assume a 50% duty cycle for the oscillator. Port 2
and ALE timing will change in relation to duty cycle variation.
Note 2:
Address is driven strongly until ALE falls, and is then held in a weak latch until overdriven externally.
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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MOVX CHARACTERISTICS USING STRETCH MEMORY CYCLES
VARIABLE CLOCK
PARAMETER SYMBOL
MIN MAX
UNITS STRETCH
1.5t
CLCL
-5
t
MCS
=0
Data Access ALE Pulse Width
t
LHLL2
2t
CLCL
-5
ns
t
MCS
>0
0.5t
CLCL
-5
t
MCS
=0
Port 0 Address Valid to ALE Low
t
AVLL2
t
CLCL
-5
ns
t
MCS
>0
0.5t
CLCL
-10
t
MCS
=0
Address Hold After ALE Low for
MOVX Write
t
LLAX2
t
CLCL
-7
ns
t
MCS
>0
2t
CLCL
-5
t
MCS
=0
RD
Pulse Width
t
RLRH
t
MCS
-10
ns
t
MCS
>0
2t
CLCL
-5
t
MCS
=0
WR Pulse Width
t
WLWH
t
MCS
-10
ns
t
MCS
>0
2t
CLCL
-22 t
MCS
=0
RD
Low Valid Data In
t
RLDV
t
MCS
-24
ns
t
MCS
>0
Data Hold After Read
t
RHDX
0
ns
--
t
CLCL
-5 ns
t
MCS
=0
Data Float After Read
t
RHDZ
2t
CLCL
-5
t
MCS
>0
2.5t
CLCL
-31 t
MCS
=0
ALE Low to Valid Data In
t
LLDV
t
MCS
+t
CLCL
-26
ns
t
MCS
>0
3t
CLCL
-29 t
MCS
=0
Port 0 Address to Valid Data In
t
AVDV1
t
MCS
+2
CLCL
-29
ns
t
MCS
>0
3.5t
CLCL
-37 t
MCS
=0
Port 2 Address to Valid Data In
t
AVDV2
t
MCS
+2.5
LCL
-37
ns
t
MCS
>0
0.5t
CLCL
-10 0.5t
CLCL
+5 t
MCS
=0
ALE Low to RD or WR Low
t
LLWL
t
CLCL
-5 t
CLCL
+5
ns
t
MCS
>0
t
CLCL
-9
t
MCS
=0
Port 0 Address to RD or WR Low
t
AVWL1
2t
CLCL
-7
ns
t
MCS
>0
1.5t
CLCL
-17
t
MCS
=0
Port 2 Address to RD or WR Low
t
AVWL2
2.5t
CLCL
-16
ns
t
MCS
>0
Data Valid to WR Transition
t
QVWX
-6
ns
t
CLCL
-5
t
MCS
=0
Data Hold After Write
t
WHQX
2t
CLCL
-6
ns
t
MCS
>0
RD
Low to Address Float
t
RLAZ
(Note
1)
ns
-4 10
t
MCS
=0
RD
or WR High to ALE High
t
WHLH
t
CLCL
-5 t
CLCL
+5
ns
t
MCS
>0
Note 1:
t
MCS
is a time period related to the Stretch memory cycle selection. The following table shows the value of t
MCS
for each Stretch
selection.
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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MOVX CHARACTERISTICS USING STRETCH MEMORY CYCLES (continued)
M2 M1 M0
MOVX
CYCLES
t
MCS
0 0 0
2
machine
cycles
0
0
0
1
3 machine cycles (default)
4 t
CLCL
0
1
0
4 machine cycles
8 t
CLCL
0
1
1
5 machine cycles
12 t
CLCL
1
0
0
6 machine cycles
16 t
CLCL
1
0
1
7 machine cycles
20 t
CLCL
1
1
0
8 machine cycles
24 t
CLCL
1
1
1
9 machine cycles
28 t
CLCL
EXTERNAL CLOCK CHARACTERISTICS
PARAMETER SYMBOL
MIN
TYP
MAX
UNITS
Clock High Time
t
CHCX
10 ns
Clock Low Time
t
CLCX
10 ns
Clock Rise Time
t
CLCL
5
ns
Clock Fall Time
t
CHCL
5
ns
SERIAL PORT MODE 0 TIMING CHARACTERISTICS
PARAMETER SYMBOL CONDITIONS
MIN
TYP
MAX
UNITS
SM2 = 0, 12 clocks per cycle
12t
CLCL
Serial Port Clock Cycle
Time
t
XLXL
SM2 = 1, 4 clocks per cycle
4t
CLCL
ns
SM2 = 0, 12 clocks per cycle
10t
CLCL
Output Data Setup to
Clock Rising
t
QVXH
SM2 = 1, 4 clocks per cycle
3t
CLCL
ns
SM2 = 0, 12 clocks per cycle
2t
CLCL
Output Data Hold from
Clock Rising
t
XHQX
SM2 = 1, 4 clocks per cycle
t
CLCL
ns
SM2 = 0, 12 clocks per cycle
t
CLCL
Input Data Hold after
Clock Rising
t
XHDX
SM2 = 1, 4 clocks per cycle
t
CLCL
ns
SM2 = 0, 12 clocks per cycle
11t
CLCL
Clock Rising Edge to
Input Data Valid
t
XHDV
SM2 = 1, 4 clocks per cycle
3t
CLCL
ns
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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EXPLANATION OF AC SYMBOLS
In an effort to remain compatible with the original 8051 family, this device specifies the same parameters
as such devices, using the same symbols. For completeness, the following is an explanation of the
symbols.
t Time
A Address
C Clock
D Input data
H Logic level high
L Logic level low
I
Instruction
P
PSEN
Q
Output data
R
RD signal
V
Valid
W
WR signal
X
No longer a valid logic
level
Z
Tri-State
POWER-CYCLE TIMING CHARACTERISTICS
PARAMETER SYMBOL
MIN
TYP
MAX
UNITS
NOTES
Cycle Startup Time
t
CSU
1.8 ms 1
Power-On Reset Delay
t
POR
65,536
t
CLCL
2
Note 1:
Startup time for crystals varies with load capacitance and manufacturer. Time shown is for an 11.0592MHz crystal manufactured by
Fox.
Note 2:
Reset delay is a synchronous counter of crystal oscillations after crystal startup. At 33MHz, this time is 1.99ms.
EPROM PROGRAMMING AND VERIFICATION
(V
CC
= 4.5V to 5.5V, T
A
= +21C to +27C.)
PARAMETER SYMBOL
MIN
TYP
MAX
UNITS
NOTES
Programming Voltage
V
PP
12.5 13.0 V 1
Programming Supply Current
I
PP
50
mA
Oscillator Frequency
1/t
CLCL
4 6
MHz
Address Setup to
PROG
Low
t
AVGL
48t
CLCL
Address Hold after
PROG
t
GHAX
48t
CLCL
Data Setup to
PROG
Low
t
DVGL
48t
CLCL
Data Hold after
PROG
t
GHDX
48t
CLCL
Enable High to V
PP
t
EHSH
48t
CLCL
V
PP
Setup to
PROG
Low
t
SHGL
10 ms
V
PP
Hold after
PROG
t
GHSL
10 ms
PROG
Width
t
GLGH
90 110
ms
Address to Data Valid
t
AVQV
48t
CLCL
Enable Low to Data Valid
t
ELQV
48t
CLCL
Data Float after Enable
t
EHQZ
0
48t
CLCL
PROG
High to
PROG
Low
t
GHGL
10 ms
Note 1: All voltages are referenced to ground.
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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EXTERNAL PROGRAM MEMORY READ CYCLE
EXTERNAL DATA MEMORY READ CYCLE
t
VALL2
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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DATA MEMORY WRITE CYCLE
DATA MEMORY WRITE WITH STRETCH = 1
t
AVLL2
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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DATA MEMORY WRITE WITH STRETCH = 2
EXTERNAL CLOCK DRIVE
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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SERIAL PORT MODE 0 TIMING
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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POWER-CYCLE TIMING
EPROM PROGRAMMING AND VERIFICATION WAVEFORMS
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
43 of 46
PACKAGE INFORMATION
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline
information, go to
www.maxim-ic.com/DallasPackInfo
.)
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
44 of 46
PACKAGE INFORMATION (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline
information, go to
www.maxim-ic.com/DallasPackInfo
.)
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
45 of 46
PACKAGE INFORMATION (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package
outline information, go to
www.maxim-ic.com/DallasPackInfo
.)
PKG 52-PIN
DIM MIN NOM MAX
A
-- -- 1.20
A1
0.05 0.10 0.15
A2
0.95 1.00 1.05
b
0.25 0.32 0.40
c
0.09 -- 0.20
D
11.80 12.00 12.20
D1
10.00 BSC
E
11.80 12.00 12.20
E1
10.00 BSC
e
0.65 BSC
L
0.45 0.60 0.75
DS87C530/DS83C530 EPROM/ROM Microcontrollers with Real-Time Clock
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Maxim/Dallas Semiconductor cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim/Dallas Semiconductor product.
No circuit patent licenses are implied. Maxim/Dallas Semiconductor reserves the right to change the circuitry and specifications without notice at any time.
Ma xi m I nt e gr at e d Pr o du ct s, 1 2 0 S a n G abr i el Dr i ve, S un n yv al e, C A 94 0 8 6 40 8- 7 37- 7 60 0
2004 Maxim Integrated Products
Printed USA
DATA SHEET REVISION SUMMARY
REVISION DESCRIPTION
040104
1) Removed "Preliminary" status.
2) Soldering temperature parameter now references JEDEC specification.
3) Added note to absolute maximums clarifying voltages referenced to ground and storage temperature.
4) Updated
I
CC
, I
IDLE
, I
STOP
, I
SPBG
, I
IL
, and I
TL
to incorporate errata conditions.
5) Added note clarifying DC electrical test conditions.
6) Added note clarifying V
OH3
specification applies to first clock cycle following the transition.
7) Updated AC and MOVX electrical characteristics with final characterization values.
8) Added
t
AVLL2
specification and corrected MOVX timing diagrams to show t
AVLL2
instead of t
AVLL
.
9) Updated
I
BAT
to incorporate errata conditions.
112299
Contact factory for details.
070798
1) Added DS83C530 to data sheet.
2) Updated PMM operating current estimates.
3) Added note to clarify I
IL
specification.
4) Added note to prevent accidental corruption of Watchdog Timer count while changing counter length.
5) Changed
I
BAT
specification to 1
mA over extended temperature range.
6) Changed minimum oscillator frequency to 1MHz when using external crystal.
7) Changed RST pulldown resistance from 170k
W to 200kW maximum.
8) Corrected "Data memory write with stretch" diagrams to show falling edge of ALE coincident with
rising edge of C3 clock.
022097
1) Updated ALE pin description.
2) Added note pertaining to erasure window.
3) Added note pertaining to internal MOVX SRAM.
4) Changed Note 6 from RST=5.5V to RST=V
CC
.
5) Changed Note 10 from RST=5.5V to RST=V
CC
.
6) Changed serial port mode 0 timing diagram label from t
QVXL
to t
QVXH
.
7) Added information pertaining to 52-pin TQFP package.
060895 Initial
release.
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