4
MITSUBISHI MICROCOMPUTERS
4250 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER
PIN DESCRIPTION
Name
Power supply
Ground
CNVSS
Reset input
System clock input
System clock output
I/O port F
I/O port G
I/O port S
I/O port D
I/O port C
I/O port K
Timer output
Interrupt input
Input/Output
—
Input
Output
I/O
Output
Input
Function
Connected to a plus power supply.
Connected to a 0 V power supply.
Connect CNVSS to VSS and apply “L” (0V) to CNVSS certainly.
Reset pulse input pin
I/O pins of the system clock generating circuit. Connect pins XIN and XOUT directly.
Then, pull up XIN pin through a resistor and pull down XOUT pin through a capacitor.
2-bit I/O port; for input use, set the latch of the specified bit to “1.” The output
structure is N-channel open-drain.
4-bit I/O port. For input use, set the latch of the specified bit 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.
Ports G0 and G1 are also used as pins INT and TOUT, respectively.
4-bit I/O port. For input use, set the latch of the specified bit to “1.” The output
structure is N-channel open-drain. Every pin of the ports has a key-on wakeup
function which can be switched by software. Also, it is used to perform the logic
operation using register A.
Each pin of port D has an independent 1-bit wide I/O function. For input use, set
the latch of the specified bit to “1.” The output structure is N-channel open-drain.
Ports D2 and D3 are also used as ports C and K, respectively.
1-bit I/O port. For input use, set the latch of the specified bit to “1.” The output
structure is N-channel open-drain. Port C has a pull-up function which can be
switched by software. It is also used as port D2.
1-bit I/O port. For input use, set the latch of the specified bit to “1.” The output
structure is N-channel open-drain. Port K has a pull-up function which can be
switched by software. It is also used as port D3.
TOUT pin has the function to output the timer 1 underflow signal divided by 2. It is
also used as port G1.
INT pin accepts an external interrupt. It also accepts the input signal to return the
system from the RAM back-up state. It is also used as port G0.
Pin
VDD
VSS
CNVSS
RESET
XIN
XOUT
F0, F1
G0–G3
S0–S3
D0–D3
C
K
TOUT
INT