Port 8 - NEC mPD780852 Series Preliminary User's Manual

4.2.8 Port 8

Port 8 is a 7-bit input/output port with output latch. P81 to P87 pins can specify the input mode/output mode in
1-bit units with the port mode register 8 (PM8).
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 8 to input mode.
Figure 4-9 shows block diagram of port 8.
RD
WR
PORT
Output latch
(P81 to P87)
WR
PM
PM81 to PM87
Segment output
PM: Port mode register
RD: Port 8 read signal
WR: Port 8 write signal
84
CHAPTER 4 PORT FUNCTIONS
Figure 4-9. P81 to P87 Block Diagram
Selector
function
Preliminary User's Manual U14581EJ3V0UM00
P81/S19 to P87/S13