Description Of Pin Functions; P00 To P03 (Port 0); P10, P11 (Port 1); P20 To P25 (Port 2) - NEC mPD789101 User Manual

3.2 Description of Pin Functions

3.2.1 P00 to P03 (Port 0)

These pins constitute a 4-bit I/O port and can be set in 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, use of an on-chip pull-up resistor can be specified by
means of pull-up resistor option register 0 (PU0).

3.2.2 P10, P11 (Port 1)

These pins constitute a 2-bit I/O port and can be set in 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, use of an on-chip pull-up resistor can be specified by
means of pull-up resistor option register 0 (PU0).

3.2.3 P20 to P25 (Port 2)

These pins constitute a 6-bit I/O port. In addition, they function as timer input/outputs, external interrupt inputs,
and serial interface data and clock input/outputs.
Port 2 can be specified in the following operation modes in 1-bit units.
(1) Port mode
In this mode, P20 to P25 function as a 6-bit I/O port. Port 2 can be specified as input or output mode in 1-
bit units by using port mode register 2 (PM2). Use of an on-chip pull-up resistor can be specified in 1-bit units
by using pull-up resistor option register B2 (PUB2), regardless of the setting of port mode register 2 (PM2).
(2) Control mode
In this mode, P20 to P25 function as the timer input/output, the external interrupt input, and the clock input/
output of the serial interface and the data input/output.
(a) TI80
This is the external clock input pin for 8-bit timer/event counter 80.
(b) TO20, TO80
TO20 is the output pin of the 16-bit timer. TO80 is the output pin of the 8-bit timer.
(c) CPT20
This is the input pin of the capture edge.
(d) INTP0 to INTP2
These are external interrupt input pins for which the valid edge (rising edge, falling edge, and both rising
and falling edges) can be specified.
(e) SI20, SO20
These are the serial data I/O pins of the serial interface.
(f) SCK20
These are the serial clock I/O pins of the serial interface.
(g) SS20
This is the chip select input pin of the serial interface.
CHAPTER 3 PIN FUNCTIONS
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