
CHAPTER 4 PORT FUNCTIONS
User’s Manual U15075EJ2V1UD
81
4.2.2 Port 1
This is a 2-bit I/O port with an output latch. Port 1 can be specified in the input or output mode in 1-bit units by
using port mode register 1 (PM1). When using the P10 and P11 pins as input port pins, on-chip pull-up resistors can
be connected in 2-bit units by setting pull-up resistor option register 0 (PU0).
This port is set in the input mode when the RESET signal is input.
Figure 4-4 shows a block diagram of port 1.
Figure 4-4. Block Diagram of P10 and P11
PU0:
Pull-up resistor option register 0
PM:
Port mode register
RD:
Port 1 read signal
WR:
Port 1 write signal
WR
PU0
RD
WR
PORT
WR
PM
PU01
PM10, PM11
V
DD
P-ch
P10, P11
Internal bus
Selector
Output latch
(P10, P11)