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CHAPTER 4 PORT FUNCTIONS
User’s Manual U15798EJ2V0UD
4.2.8 Port 9
Port 9 is an 8-bit I/O port with an output latch. The P90 to P97 pins can be set to input mode/output mode in 1-
bit units using port mode register 9 (PM9).
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 9 (PF9).
RESET input sets port 9 to input mode.
Figure 4-15 shows a block diagram of port 9.
Figure 4-15. Block Diagram of P90 to P97
RD
P90/S20
to
P97/S27
WR
PORT
WR
PM
Output latch
(P90 to P97)
PM90 to PM97
Selector
Segment output
WR
PF
PF90 to PF97
Selector
Internal bus
PF:
Pin function switching register
PM: Port mode register
RD: Port 9 read signal
WR: Port 9 write signal