NEC PD78F9488 - Manual (Page 40)

CHAPTER 2 PIN FUNCTIONS
User’s Manual U15331EJ4V1UD
40
2.2 Description of Pin Functions
2.2.1 P00 to P07 (Port 0)
These pins constitute an 8-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 an 8-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 B0 (PUB0) in 1-bit units.
(2) Control
mode
In this mode, P00 to P07 function as key return signal detection pins (KR0 to KR7 ( µPD789488, 78F9488),
KR00 to KR07 ( µPD789489, 78F9489)).
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 B1 (PUB1) in 1-bit units.
2.2.3 P20 to P25 (Port 2)
These pins constitute a 6-bit I/O port. In addition, these pins enable 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 P25 function as a 6-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 P25 function as the serial interface data I/O and serial clock I/O.
(a) SI20, SO20, SI10, SO10
These are the serial data I/O pins of the serial interface.
(b) SCK20, SCK10
These are the serial clock I/O pins of the serial interface.
(c) RxD20, TxD20
These are the serial data I/O pins of the asynchronous serial interface.
(d) ASCK20
This is the serial clock input pin of the asynchronous serial interface.
Caution When using P20 to P25 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 11-2 Serial
Interface 20 Operation Mode Setting and 12.3 (1) Serial operation mode register 1A0 (CSIM1A0).