Port 1; Block Diagram Of P10 To P17 - NEC switch User Manual

4.2.2 Port 1

This is an 8-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 the P10 to P17 pins are used as input port pins, on-chip pull-up resistors
can be connected in 8-bit units by using pull-up resistor option register 0 (PU0). CMOS output or N-ch open-drain
output can also be specified in 8-bit unit by using port output mode register 0 (POM0).
Port 0 is set in the input mode when the RESET signal is input.
Figure 4-3 shows a block diagram of port 1.
WR
POM0
WR
PU0
RD
WR
PORT
Output latch
(P10 to P17)
WR
PM
PM10 to PM17
POM0: Port output mode register 0
PU0: Pull-up resistor option register 0
PM: Port mode register
RD: Port 1 read signal
WR: Port 1 write signal
CHAPTER 4
Figure 4-3. Block Diagram of P10 to P17
POM01
PU01
User's Manual U12978EJ3V0UD
PORT FUNCTIONS
V
DD0
P-ch
P10 to P17
V
DD0
P-ch
N-ch
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