CHAPTER 2 PIN FUNCTIONS
2.2 Description of Pin Functions
2.2.1 P00 to P03 (Port 0)
These pins constitute a 4-bit I/O port. In addition, these pins enable key return signal detection.
Port 0 can be specified in the following operation modes in 1-bit units.
(1) Port mode
These pins constitute a 4-bit I/O port and can be set in the input or output port mode in 1-bit units by port
mode register 0 (PM0). When used as an input port, use of an on-chip pull-up resistor can be specified by
pull-up resistor option register 0 (PU0) in port units.
(2) Control mode
In this mode, P00 to P03 function as key return signal detection pins (KR0 to KR3).
2.2.2 P10, P11 (Port 1)
These pins constitute a 2-bit I/O port and can be set in the input or output port mode in 1-bit units by port mode
register 1 (PM1). When used as an input port, use of an on-chip pull-up resistor can be specified by pull-up resistor
option register 0 (PU0) in port units.
2.2.3 P20 to P26 (Port 2)
These pins constitute a 7-bit I/O port. In addition, these pins enable buzzer output, timer output, serial interface
data I/O, and serial clock I/O.
Port 2 can be specified in the following operation modes in 1-bit units.
(1) Port mode
In this mode, P20 to P26 function as a 7-bit I/O port. Port 2 can be set in the input or output port mode in 1-
bit units by port mode register 2 (PM2). When used as an input port, use of an on-chip pull-up resistor can
be specified by pull-up resistor option register B2 (PUB2) in 1-bit units.
(2) Control mode
In this mode, P20 to P26 function as the buzzer output, timer output, serial interface data I/O, and serial
clock I/O.
(a) Buzzer output
This is the buzzer output pin of 16-bit timer 90.
(b) TO90
This is the timer output pin of 16-bit timer 90.
(c) SI20, SO20
These are the serial data I/O pins of the serial interface.
(d) SCK20
This is the serial clock I/O pin of the serial interface.
(e) RxD20, TxD20
These are the serial data I/O pins of the asynchronous serial interface.
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User’s Manual U15075EJ1V0UM00
NEC [ NEC ]
