4 port 3 – NEC PD78F9488 User Manual
Page 84
CHAPTER 4 PORT FUNCTIONS
84
User’s Manual U15331EJ4V1UD
4.2.4 Port 3
This is a 5-bit I/O port with an output latch. Port 3 can be specified in the input or output mode in 1-bit units by
using port mode register 3 (PM3). When using the P30 to P34 pins as input port pins, on-chip pull-up resistors can be
connected in 1-bit units by using pull-up resistor option register B3 (PUB3).
This port is also used for external interrupt input, capture input, timer I/O, and remote control receive data input
Note
.
RESET input sets this port to input mode.
Figures 4-9 and 4-10 show block diagrams of port 3.
Note
µ PD789489 and 78F9489 only
Figure 4-9. Block Diagram of P30 to P33
PUB3: Pull-up resistor option register B3
PM:
Port mode register
RD:
Port 3 read signal
WR:
Port 3 write signal
P30/INTP0/TO50/
TMI60,
P31/INTP1/TO60,
P32/INTP2/TO61/
TMI61
P33/INTP3/TO20/
CPT20
WR
PUB3
RD
WR
PORT
WR
PM
PUB30 to PUB33
PM30 to PM33
V
DD
P-ch
Internal bus
Alternate
function
Selector
Output latch
(P30 to P33)
Alternate
function