Port 1 - NEC mPD789101 User Manual

5.2.2 Port 1

This is a 2-bit I/O port with output latches. Port 1 can be specified as input or output mode in 1-bit units by using
port mode register 1 (PM1). When pins P10 and P11 are used 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).
RESET input sets port 1 to input mode.
Figure 5-3 shows the 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 5 PORT FUNCTIONS
Figure 5-3. Block Diagram of P10 and P11
PU01
Output latch
(P10, P11)
PM10, PM11
User's Manual U13045EJ2V0UM00
V
DD
P-ch
P10, P11