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CHAPTER 3 PIN FUNCTIONS
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3.2 Description of Pin Functions
3.2.1 P00 to P05 (Port 0)
These pins constitute a 6-bit I/O port and can be set in the input or output port mode in 1-bit units by using port
mode register 0 (PM0). When these pins are used as an input port, an on-chip pull-up resistor can be used in the
pull-up resistor option register 0 (PU0).
3.2.2 P10, P11 (Port 1)
These pins constitute a 2-bit I/O port. Can be set in the input or output port mode in 1-bit units by using port
mode register 1 (PM1). When these pins are used as an input port, an on-chip pull-up resistor can be used in the
pull-up resistor option register 0 (PU0).
3.2.3 P20 to P26 (Port 2)
These pins constitute a 7-bit I/O port. In addition, these pins provide a function to perform input/output to/from
the timer, to input/output the data and clock of the serial interface, and to input/output the data of SMB.
Port 2 can be specified in the following operation modes bit-wise.
(1)
Port mode
In port mode, P20 to P26 function as a 7-bit I/O port. Port 2 can be set in input or output mode in 1-bit units
by using the port mode register 2 (PM2). P20 to P22, P25, and P26 pins can use on-chip pull-up resistors
in 1-bit units by using the pull-up resistor option register B2 (PUB2), regardless of the setting of port mode
register 2 (PM2).
P23 and P24 are N-ch open-drain I/O ports.
(2)
Control mode
In this mode, P20 to P26 function as the timer input/output, the data input/output and the clock input/output
of the serial interface, and input/output of SMB data.
(a) TI80
This is the external clock input pin for 8-bit timer/event counter 80.
(b) TO80
This is the timer output pin of the 8-bit timer/event counter 80.
(c) SI20, SO20
These are the serial data I/O pins of the serial interface.
(d) SCK20
These are the serial clock I/O pins of the serial interface.
(e) SS20
This is the chip select input pin of serial interface.
(f) RxD20, TxD20
These are the serial data I/O pins of asynchronous serial interface.