Port 4 - NEC mPD780852 Series Preliminary User's Manual

4.2.5 Port 4

Port 4 is a 5-bit input/output port with output latch. P40 to P44 pins can specify the input mode/output mode in
1-bit units with the port mode register 4 (PM4).
Alternate functions also include timer input/output.
RESET input sets port 4 to input mode.
Figure 4-6 shows a block diagram of port 4.
RD
WR
PORT
Output latch
(P40 to P44)
WR
PM
PM40 to PM44
PM: Port mode register
RD: Port 4 read signal
WR: Port 4 write signal
CHAPTER 4 PORT FUNCTIONS
Figure 4-6. P40 to P44 Block Diagram
Selector
Alternate
functions
Preliminary User's Manual U14581EJ3V0UM00
P40/TI00 to P42/TI02
P43/TIO2
P44/TIO3
81