102
CHAPTER 4 PORT FUNCTIONS
User’s Manual U15798EJ2V0UD
4.2.7 Port 8
Port 8 is an 8-bit I/O port with an output latch. The P80 to P87 pins can be set to input mode/output mode in 1-
bit units using port mode register 8 (PM8).
This port can also be used for LCD controller/driver segment output. This port can be switched between an I/O
port and a segment output port in 1-bit units by pin function switching register 8 (PF8).
RESET input sets port 8 to input mode.
Figure 4-14 shows a block diagram of port 8.
Figure 4-14. Block Diagram of P80 to P87
PF:
Pin function switching register
PM: Port mode register
RD: Port 8 read signal
WR: Port 8 write signal
RD
P80/S12
to
P87/S19
WR
PORT
WR
PM
Output latch
(P80 to P87)
PM80 to PM87
Selector
Segment output
WR
PF
PF80 to PF87
Selector
Internal bus