MITSUBISHI MICROCOMPUTERS
4250 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER
I/O PORT
(1) Port D (D
0
–D
3
)
Each pin of port D has an independent 1-bit wide I/O function.
Each pin has an output latch. For input/output of ports D
0
–D
3
,
select one of port D with the register Y of data pointer first. For
input use, set the latch of the specified bit to “1.” All port D
output latches can be set to “1” with the CLD instruction. The
output structure is the N-channel open-drain. Ports D
2
and D
3
are also used as ports C and K, respectively. Accordingly,
when port D
2
/C is used as port D
2
, set the port C output latch
to “1.” When port D
3
/K is used as port D
3
, set the port K output
latch to “1.”
(2) Port C
1-bit I/O port.
Port C output latch can be set to “1” with the SCP instruction.
Port C output latch can be cleared to “0” with the RCP
instruction. Port C input level can be examined by executing
the skip (SNZCP) instruction. For input use, set the latch of
the specified bit to “1.” The output structure is the N-channel
open-drain. The pull-up transistor of port C is turned on when
the bit 1 of register PU0 is set to “1” by software. Port C is also
used as port D
2
. Accordingly, when port D
2
/C is used as port
C, set the port D
2
output latch to “1.”
Pull-up control register
Pull-up control register PU0
PU0
1
PU0
0
Ports C and K
pull-up transistor control bit
Ports G
0
–G
3
0
1
0
1
(3) Port K
1-bit I/O port.
For input use, set the latch of the specified bit to “1.” The
output structure is the N-channel open-drain. The pull-up
transistor of port K is turned on when the bit 1 of register PU0
is set to “1” by software. Port K is also used as port D
3
.
Accordingly, when port D
3
/K is used as port K, set the port D
3
output latch to “1.”
(4) Port G (G
0
–G
3
)
4-bit I/O port.
For input use, set the latch of the specified bit to “1.” The
output structure is the N-channel open-drain. The pull-up
transistor of port G is turned on when the bit 0 of register PU0
is set to “1” by software. Ports G
0
and G
1
are also used as INT
pin and T
OUT
pin, respectively.
at reset : 00
2
at RAM back-up : state retained
W
Pull-up transistor OFF
Pull-up transistor ON
Pull-up transistor OFF
Pull-up transistor ON
pull-up transistor control bit
Note: “W” represents write enabled.
7
RENESAS [ RENESAS TECHNOLOGY CORP ]
