Port 5 - NEC mPD780852 Series Preliminary User's Manual

4.2.6 Port 5

Port 5 is a 5-bit input/output port with output latch. P50 to P54 pins can specify the input mode/output mode in
1-bit units with the port mode register 5 (PM5).
Alternate functions include serial interface data input/output and clock input/output.
RESET input sets port 5 to input mode.
Figure 4-7 shows a block diagram of port 5.
Caution When port 0 is used as the serial interface pins, an I/O and output latches must be set according
to the functions to be used. For an explanation of how to set these latches, refer to the
description of the format of the serial operation mode register.
RD
WR
PORT
WR
PM
PM: Port mode register
RD: Port 5 read signal
WR: Port 5 write signal
82
CHAPTER 4 PORT FUNCTIONS
Figure 4-7. P50 to P54 Block Diagram
Selector
Output latch
(P50 to P54)
PM50 to PM54
Alternate
functions
Preliminary User's Manual U14581EJ3V0UM00
P50/SCK3
P51/SO3
P52/SI3
P53/RxD
P54/TxD