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CHAPTER 3 PIN FUNCTIONS
50
(g) ASCK20
This is the serial clock input pin of asynchronous serial interface.
(h) SCL0
This is the clock I/O pin of SMB0.
(i)
SDA0
This is the data I/O pin of SMB0.
Caution
When using P20 to P26 as serial interface pins, the input/output mode and output latch must be
set according to the functions to be used. For the details of the setting, see Table 14-2.
3.2.4 P30 to P33 (Port 3)
These pins constitute a 4-bit I/O port. In addition, these pins provide the function to perform input/output to/from
the timer and to input to the external interrupt.
Port 3 can be specified in the following operation modes bit-wise.
(1)
Port mode
In port mode, P30 to P33 function as a 4-bit I/O port. Port 3 can be set in input or output mode in 1-bit units
by using the port mode register 3 (PM3). An on-chip pull-up resistor can be used in 1-bit units by using the
pull-up resistor option register B3 (PUB3), regardless of the setting made for port mode register 3 (PM3).
(2)
Control mode
In this mode, P30 to P33 function as the timer input/output and the external interrupt input.
(a) TI81
This is the external clock input pin for 8-bit timer/event counter 81.
(b) TO90, TO81, TO82
These are the output pins of 16-bit timer counter 90 and 8-bit timer counters 81 and 82.
(c) CPT90
This is the capture edge input pin of 16-bit timer counter 90.
(d) BZO90
This is the buzzer output pin of 16-bit timer counter 90.
(e) INTP0 to INTP3
These are external interrupt input pins for which the valid edge (rising edge, falling edge, and both the
rising and falling edges) can be specified.
3.2.5 P50 to P53 (Port 5)
These pins constitute an N-ch open-drain I/O port. Port 5 can be set in input or output mode in 1-bit units by
using the port mode register 5 (TM5). For a mask ROM version, an on-chip pull-up resistor can be specified by a
mask option.