
CHAPTER 4 PIN FUNCTIONS (
PD789316 SUBSERIES)
User’s Manual U14800EJ3V0UD
46
(e)
ASCK20
This is the serial clock input pin of the asynchronous serial interface.
Caution
When using P20 to P26 as serial interface pins, the I/O mode and output latch must be set
according to the functions to be used. For the details of the setting, refer to Table 13-2 Settings
of Serial Interface 10 Operating Mode and Table 14-2 Settings of Serial Interface 20 Operating
Mode.
4.2.4 P30 to P33 (Port 3)
These pins constitute a 4-bit I/O port. In addition, they also function as timer I/O and external interrupt input.
Port 3 can be specified in the following operation modes in 1-bit units.
(1)
Port mode
In this mode, port 3 functions as a 4-bit I/O port. Port 3 can be set in the input or output port mode in 1-bit
units by port mode register 3 (PM3). When used as an input port, use of an on-chip pull-up resistor can be
specified by pull-up resistor option register B3 (PUB3) in 1-bit units.
(2)
Control mode
In this mode, the pins function as timer I/O and external interrupt input.
(a)
TMI40
This is the external clock input pin to timer 40.
(b)
TO30, TO40
These are the timer output pins of timer 30 and timer 40
(c)
CPT20
This is the capture edge input pin for 16-bit timer 20.
(d)
INTP0 to INTP3
These are external interrupt input pins for which valid edges (rising edge, falling edge, or both rising and
falling edges) can be specified.
4.2.5 P50 to P53 (Port 5)
These pins function as a 4-bit N-ch open-drain I/O port. Port 5 can be set in the input or output port mode in 1-bit
units by port mode register 5 (PM5). In the mask ROM version, use of an on-chip pull-up resistor can be specified by
a mask option.
4.2.6 S0 to S23
These pins are segment signal output pins for the LCD controller/driver.
4.2.7 COM0 to COM3
These pins are common signal output pins for the LCD controller/driver.
4.2.8 VLC0 to VLC2
These pins are power supply voltage pins to drive the LCD.