CHAPTER 4 PORT FUNCTIONS
Preliminary User’s Manual U16846EJ1V0UD
76
4.2.5 Port 12
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
using port mode register 12 (PM12). When the P120 pin is used as an input port, use of an on-chip pull-up resistor
can be specified by pull-up resistor option register 12 (PU12).
This port can also be used for external interrupt input.
RESET input sets port 12 to input mode.
Figure 4-12 shows a block diagram of port 12.
Figure 4-12. Block Diagram of P120
P120/INTP0
WR
PU
RD
WR
PORT
WR
PM
PU120
Alternate
function
Output latch
(P120)
PM120
PU12
PM12
V
DD
P-ch
Selector
Internal bus
PU12: Pull-up resistor option register 12
PM12: Port mode register 12
RD: Read
signal
WR
××
: Write
signal