NEC mPD780852 Series, Preliminary User'S Manual

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CHAPTER 4 PORT FUNCTIONS
Preliminary User’s Manual U14581EJ3V0UM00
4.2.9 Port 9
Port 9 is an 8-bit input/output port with output latch. P90 to P97 pins can specify the input mode/output mode in
1-bit units with the port mode register 9 (PM9).
Alternate functions also include segment signal output of the LCD controller/driver.
Segment output and input/output port can be switched by setting the LCD display control register (LCDC).
RESET input sets port 9 to input mode.
Figure 4-10 shows a block diagram of port 9.
Figure 4-10. P90 to P97 Block Diagram
P90/S12 to P97/S5
WR
PORT
WR
PM
Output latch
(P90 to P97)
PM90 to PM97
Segment output
latch
RD
Selector
Internal bus
PM: Port mode register
RD: Port 9 read signal
WR: Port 9 write signal