NEC PD78F9488 - Manual (Page 78)

CHAPTER 4 PORT FUNCTIONS
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User’s Manual U15331EJ4V1UD
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 1-bit units by using pull-up resistor option register B1 (PUB1).
RESET input sets this port to input mode.
Figure 4-3 shows a block diagram of port 1.
Figure 4-3. Block Diagram of P10 and P11
PUB1: Pull-up resistor option register B1
PM:
Port mode register
RD: Port 1 read signal
WR: Port 1 write signal
WR PU0
RD
WR
PORT
WR
PM
PUB10, PUB11
PM10, PM11
V
DD
P-ch
P10, P11
Internal bus
Selector
Output latch
(P10, P11)