SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for
INFRARED REMOTE CONTROL TRANSMITTER
DESCRIPTION
The 4551 Group is a 4-bit single-chip microcomputer designed
with CMOS technology. Its CPU is that of the 4500 series using
a simple, high-speed instruction set. The computer is equipped
with an 8-bit timer with a reload register, a 14-bit timer which is
also used as a watchdog timer, a 4-bit timer with a reload register,
a carrier wave output circuit and an LCD control circuit.
The mask ROM version and built-in PROM version of 4551 Group
are produced as shown in the table below.
FEATURES
q
Minimum instruction execution time ............................. 3.0
s
(f(X
IN
)=4.0 MHz, V
DD
=3.0 V, system clock = f(X
IN
)/4)
q
Supply voltage
............................. 2.5 V to 5.5 V (One Time PROM version)
....................................... 2.2 V to 5.5 V (Mask ROM version)
q
System clock switch function
........................................... Clock divided by 4 or not divided
q
LCD control circuit
Segment output ................................................................... 20
Common output .................................................................... 4
q
Carrier wave frequency switch function
System clock, system clock/2, system clock/8,
system clock/12, system clock/16, system clock/24, "H" fixed
q
Timers
Timer 1 ................................ 8-bit timer with a reload register
Timer 2 ............... 14-bit timer also used as a watchdog timer
Timer LC ............................. 4-bit timer with a reload register
q
Interrupt ................................................................... 3 sources
q
Voltage drop detection circuit ............................................... 1
q
Clock generating circuit (ceramic resonance and quartz-crystal
oscillation)
APPLICATION
Remote control transmitter
Product
M34551M4-XXXFP
M34551E8-XXXFP
(Note)
ROM type
Mask ROM
One Time PROM
Package
48P6S-A
48P6S-A
RAM size
(
!
4 bits)
280 words
280 words
ROM (PROM) size
(
!
10 bits)
4096 words
8192 words
Note: Shipped after writing (shipped in blank: M34551E8FP)
PIN CONFIGURATION (TOP VIEW)
M34551M4-XXXFP
Outline 48P6S-A
1
2
3
4
5
6
7
8
9
10 11 12 13 14
38 37 36 35 34 33 32 31 30 29 28 27 26 25
15
16
17
18
19
20
21
22
23
24
48
47
46
45
44
43
42
41
40
39
SEG
2
SEG
3
SEG
4
SEG
5
SEG
6
SEG
7
SEG
8
COM
2
COM
3
SEG
0
SEG
1
M34551M4-XXXFP
SEG
11
SEG
14
SEG
15
SEG
9
V
SS
X
OUT
X
IN
P1
0
P1
1
P1
2
P1
3
D
1
D
2
D
3
D
4
P0
0
P0
1
P0
2
P0
3
D
0
RESET
D
7
/X
COUT
D
6
/X
CIN
CARR
V
DD
CNV
SS
V
SS
D
5
/ INT
COM
1
COM
0
SEG
10
SEG
13
SEG
12
P2
3
/ SEG
19
P2
2
/ SEG
18
P2
0
/ SEG
16
P2
1
/ SEG
17
MITSUBISHI MICROCOMPUTERS
4551 Group
2
MITSUBISHI MICROCOMPUTERS
4551 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for
INFRARED REMOTE CONTROL TRANSMITTER
BLOCK DIAGRAM
RAM
280 words
!
4 bits
(LCD RAM
20 words
!
4 bits included)
ROM (Note)
4096 to 8192 words
!
10 bits
Port P0
Port P1
4500 Series
CPU core
Memory
I/O port
Internal peripheral functions
LCD drive control circuit
(max. 20 segments
!
4 common)
Timers
Timer 1 (8 bits)
System clock generating circuit
Timer 2 (14 bits)
X
IN
X
OUT
(Main clock)
X
CIN
X
COUT
(Sub-clock)
Remote control carrier wave output
Register B (4 bits)
Register A (4 bits)
Register D (3 bits)
Register E (8 bits)
Stack registers SKs (8 levels)
Interrupt stack register SDP(1 level)
ALU(4 bits)
Port D
Port P2
8
4
4
4
Timer LC (4 bits)
Segment output
Common output
4
20
Note: PROM 8192 words
!
10 bits
3
MITSUBISHI MICROCOMPUTERS
4551 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for
INFRARED REMOTE CONTROL TRANSMITTER
PERFORMANCE OVERVIEW
Function
92
1.5
s (f(X
IN
) = 8.0 MHz:system clock = f(X
IN
)/4: V
DD
= 5.0 V)
4096 words
!
10 bits
8192 words
!
10 bits
280 words
!
4 bits (LCD RAM 20 words
!
4 bits included)
Eight independent output ports
4-bit I/O port; each pin is equipped with a pull-up function.
4-bit I/O port; each pin is equipped with a pull-up function.
4-bit input port
1-bit output port (CMOS output)
8-bit timer with a reload register
14-bit timer/
Fixed dividing frequency timer
4-bit timer with a reload register
3 (one for external and two for timer)
1 level
8 levels (however, only 7 levels can be used when an interrupt is used or the TABP p instruction
is executed)
1/2, 1/3 bias
2, 3, 4 duty
4
20
200 k
!
3
CMOS silicon gate
48-pin plastic molded QFP
20
C to 70
C
2.2 V to 5.5 V (One Time PROM version: 2.5 V to 5.5 V)
2.5 mA (f(X
IN
) = 8.0 MHz system clock = f(X
IN
)/4, V
DD
=5 V)
27.5
A (at main clock oscillation stop, sub-clock oscillation frequency: 32.0 kHz, V
DD
=5 V)
0.1
A (at main clock oscillation stop, sub-clock oscillation stop, Ta=25
C, V
DD
=5V)
Parameter
Number of basic instructions
Minimum instruction execution time
Memory sizes
Input/Output
ports
Timers
Interrupt
Subroutine nesting
LCD
Device structure
Package
Operating temperature range
Supply voltage
Power
dissipation
(typical value)
ROM
RAM
D
0
D
7
P0
0
P0
3
P1
0
P1
3
P2
0
P2
3
CARR
Timer 1
Timer 2/
Watchdog timer
Timer LC
Sources
Nesting
Selective bias value
Selective duty value
Common output
Segment output
Internal resistor for
power supply
at active
at clock operating
at RAM back-up
M34551M4
M34551E8
Output
I/O
I/O
Input
Output
DEFINITION OF CLOCK AND CYCLE
q
System clock (STCK)
The system clock is the basic clock for controlling this product.
The system clock can be selected by bits 0 and 3 of the clock
control register MR as shown in the table below.
Table Selection of system clock
q
Instruction clock (INSTK)
The instruction clock is the standard clock for controlling CPU.
The instruction clock is a signal derived from dividing the
system clock by 3. The one cycle of the instruction clock is
equivalent to the one machine cycle.
q
Machine cycle
The machine cycle is the standard cycle required to execute
the instruction.
Note: f(X
IN
)/4 is selected immediately after system is released
from reset.
Register MR
MR
3
0
0
1
1
MR
0
0
1
0
1
System clock (STCK)
f(X
IN
)
f(X
CIN
)
f(X
IN
)/4
f(X
CIN
)/4
4
MITSUBISHI MICROCOMPUTERS
4551 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for
INFRARED REMOTE CONTROL TRANSMITTER
PIN DESCRIPTION
Name
Power supply
Ground
CNV
SS
Reset input
Main clock input
Main clock output
Output port D
Output port D
Output port D
Output port D
I/O port P0
I/O port P1
Input port P2
Carrier wave output
for remote control
Segment output
Common output
Pin
V
DD
V
SS
CNV
SS
RESET
X
IN
X
OUT
D
0
D
4
D
5
/INT
D
6
/X
CIN
D
7
/X
COUT
P0
0
P0
3
P1
0
P1
3
P2
0
/SEG
16
P2
3
/SEG
19
CARR
SEG
0
SEG
15
COM
0
COM
3
Input/Output
--
--
Input
I/O
Input
Output
Output
I/O
I/O
Output
I/O
I/O
I/O
Output
Output
Output
Function
Connected to a plus power supply.
Connected to a 0 V power supply.
Connect CNV
SS
to V
SS
and apply "L" (0V) to CNV
SS
certainly.
An N-channel open-drain I/O pin for a system reset. A pull-up resistor is built-in
this pin. When the watchdog timer causes the system to be reset or the low-
supply voltage is detected, the RESET pin outputs "L" level.
I/O pins of the main clock generating circuit. A ceramic resonator can be connected
between X
IN
pin and X
OUT
pin. A feedback resistor is built-in between them.
Each pin of port D has an independent 1-bit wide output function. The output
structure is N-channel open-drain.
1-bit output port. Port D
5
is also used as an INT input pin. When D
5
/INT pin is
used as the INT input pin, set the output latch to "1." The output structure is N-
channel open-drain.
Each pin of port D has an independent 1-bit output function. Ports D
6
and D
7
are
also used as pins X
CIN
and X
COUT
for the sub-clock generating circuit, respectively.
When pins D
6
/X
CIN
and D
7
/X
COUT
are used as the pins for the sub-clock generating
circuit, a 32.0 kHz quartz-crystal oscillator can be connected between X
CIN
pin
and X
COUT
pin. A feedback resistor is built-in between them.
4-bit I/O port. It can be used as an input port when the output latch is set to "1."
The output structure is N-channel open-drain. Every pin of the ports has a key-on
wakeup function and a pull-up function.
4-bit I/O port. It can be used as an input port when the output latch is set to "1."
The output structure is N-channel open-drain. Every pin of the ports has a key-on
wakeup function and a pull-up function. Both functions can be switched by software.
4-bit input port. Ports P2
0
P2
3
are also used as the segment output pins SEG
16
SEG
19
, respectively.
Carrier wave output pin for remote control transmit. The output structure is the
CMOS circuit.
LCD segment output pins.
LCD common output pins. Pins COM
0
and COM
1
are used at 1/2 duty, pins COM
0
COM
2
are used at 1/3 duty and pins COM
0
COM
3
are used at 1/4 duty.
5
MITSUBISHI MICROCOMPUTERS
4551 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for
INFRARED REMOTE CONTROL TRANSMITTER
MULTIFUNCTION
Notes 1: Pins except above have just single function.
2: The port D
5
is the output port and ports P2
0
P2
3
are the input ports.
CONNECTIONS OF UNUSED PINS
Connection
Connect to V
SS
, or set the output latch to
"0" and open.
Select ports D
6
and D
7
and connect to V
SS
,
or set the output latch to "0" and open.
Select port P2 and connect to V
SS
, or select
the segment output function and open.
Connection
Open
Open
Open
Set the output latch to "1" and open.
Open or connect to V
SS
(Note)
Pin
CARR
SEG
0
SEG
15
COM
0
COM
3
P0
0
P0
3
P1
0
P1
3
Pin
D
0
D
4
D
5
/INT
D
6
/X
CIN
D
7
/X
COUT
P 2
0
/ S E G
1 6
P 2
3
/
SEG
19
Pin
D
5
D
6
D
7
P2
0
P2
1
P2
2
P2
3
Multifunction
INT
X
CIN
X
COUT
SEG
16
SEG
17
SEG
18
SEG
19
Multifunction
D
5
D
6
D
7
P2
0
P2
1
P2
2
P2
3
Pin
INT
X
CIN
X
COUT
SEG
16
SEG
17
SEG
18
SEG
19
PORT FUNCTION
Port
Port D
Port P0
Port P1
Port P2
Control
bits
1
4
4
4
Control
instructions
SD
RD
CLD
OP0A
IAP0
OP1A
IAP1
IAP2
Control
registers
MR
PU0
Output structure
N-channel open-drain
N-channel open-drain
N-channel open-drain
Input/
Output
Output
(8)
I/O
(4)
I/O
(4)
Input
(4)
Remark
Pull-up functions
Key-on wakeup functions
Pull-up functions
(programmable)
Key-on wakeup functions
(programmable)
Pin
D
0
D
4
, D
5
/INT,
D
6
/X
CIN
,
D
7
/X
COUT
P0
0
P0
3
P1
0
P1
3
P2
0
/SEG
16
P2
3
/SEG
19
Note: In order to connect ports P1
0
P1
3
to V
SS
, turn off their pull-up transistors (Pull-up control register PU0
i
="0") by software. In
order to make these pins open, turn on their pull-up transistors (register PU0
i
="1") by software, or turn off their pull-up
transistors (register PU0i="0") and set the output latch to "0" (
i = 0, 1, 2, or 3
).
Be sure to select the key-on wakeup function and the pull-up function with every one port.
(Note in order to set the output latch to "0" and make pins open)
After system is released from reset, a port is in a high-impedance state until the output latch of the port is set to "0" by software.
Accordingly, the voltage level of pins is undefined and the excess of the supply current may occur.
To set the output latch periodically is recommended because the value of output latch may change by noise or a program run away
(caused by noise).
(Note in order to connect unused pins to V
SS
or V
DD
)
To avoid noise, connect the unused pins to V
SS
or V
DD
at the shortest distance using a thick wire.
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