IBM uPD78082 - Manual (Page 82)

59
CHAPTER 4 PORT FUNCTIONS
4.2.4 Port 5
Port 5 is an 8-bit input/output port with output latch. P50 to P57 pins can specify the input mode/output mode in
1-bit units with the port mode register 5 (PM5). When P50 to P57 pins are used as input ports, an on-chip pull-up
resistor can be used to them in 8-bit units with a pull-up resistor option register L (PUOL).
A maximum of 7 out of 8 ports can drive LEDs directly.
RESET input sets port 5 to input mode.
Figure 4-6 shows a block diagram of port 5.
Figure 4-6. P50 to P57 Block Diagram
PUO : Pull-up resistor option register
PM : Port mode register
RD : Port 5 read signal
WR : Port 5 write signal
P-ch
WR PM
WR PORT
RD
WR PUO
V
DD
Selector
PUO5
Output Latch
(P50 to P57)
PM50-PM57
Internal bus
P50-P57