Port 1 - NEC mPD789426 Series User Manual

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 using 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.
WR
PU0
RD
WR
PORT
WR
PM
PU0: Pull-up resistor option register 0
PM: Port mode register
RD: Port 1 read signal
WR: Port 1 write signal
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CHAPTER 4 PORT FUNCTIONS
Figure 4-4. Block Diagram of P10 and P11
PU01
Output latch
(P10, P11)
PM10, PM11
User's Manual U15075EJ1V0UM00
V
DD
P-ch
P10, P11