UPD78F0138 NEC, UPD78F0138 Datasheet - Page 105

• Manufacturer Part Number: UPD78F0138
• Description: (UPD78xxxx) 8-Bit Single-Chip Microcontrollers
• Manufacturer: NEC

4.2.5 Port 4
using port mode register 4 (PM4). Use of an on-chip pull-up resistor can be specified in 1-bit units with pull-up resistor
option register 4 (PU4).
Port 4 is a 4-bit I/O port with an output latch. Port 4 can be set to the input mode or output mode in 1-bit units
RESET input sets port 4 to input mode.
Figure 4-14 shows a block diagram of port 4.
PU4:
PM4:
RD:
WR××: Write signal
WR
WR
WR
RD
PORT
Read signal
Pull-up resistor option register 4
Port mode register 4
PU
PM
PU40 to PU43
PM40 to PM43
(P40 to P43)
Output latch
PM4
PU4
Figure 4-14. Block Diagram of P40 to P43
CHAPTER 4 PORT FUNCTIONS
User’s Manual U16228EJ2V0UD
Selector
EV
DD
P-ch
P40 to P43
105