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4.2.1 Port 0
This is an 8-bit I/O port with an output latch. Port 0 can be specified in the input or output mode in 1-bit units by
using port mode register 0 (PM0). When the P00 to P07 pins are used as input port pins, on-chip pull-up resistors can
be connected in 1-bit units by using pull-up resistor option register B0 (PUB0).
This port is also used for key return signal input.
RESET input sets this port to input mode.
Figure 4-2 shows a block diagram of port 0.
WR
PUO
PUB00 to PUB07
RD
WR
KRM00
KRM004 to KRM007
WR
PORT
W
RPM
PM00 to PM07
Alternate function
KRM00: Key return mode register 00
PUB0:
Pull-up resistor option register B0
PM:
Port mode register
RD:
Port 0 read signal
WR:
Port 0 write signal
Notes 1. When
2. When
CHAPTER 4 PORT FUNCTIONS
Figure 4-2. Block Diagram of P00 to P07
KRM000,
Output latch
(P00 to P07)
µ
PD789488, 78F9488 is used
µ
PD789489, 78F9489 is used
User's Manual U15331EJ4V1UD
V
DD
P-ch
P00/KR0 to
Note 1
P07/KR7
or
P00/KR00 to
Note 2
P07/KR07
77
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