UPD78F0138 NEC, UPD78F0138 Datasheet - Page 109

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

4.2.9 Port 12
using port mode register 12 (PM12). When used as an input port, use of an on-chip pull-up resistor can be specified
by pull-up resistor option register 12 (PU12).
Port 12 is a 1-bit I/O port with an output latch. Port 12 can be set to the input mode or output mode in 1-bit units
This port can also be used for external interrupt input.
RESET input sets port 12 to input mode.
Figure 4-18 shows a block diagram of port 12.
PU12:
PM12:
RD:
WR××: Write signal
WR
WR
WR
RD
PORT
PM
PU
Read signal
Pull-up resistor option register 12
Port mode register 12
Output latch
Alternate
function
PU120
PM120
(P120)
PM12
PU12
Figure 4-18. Block Diagram of P120
CHAPTER 4 PORT FUNCTIONS
User’s Manual U16228EJ2V0UD
EV
DD
P-ch
P120/INTP0
109