NEC PD78F9488 - Manual (Page 192)

CHAPTER 11 SERIAL INTERFACE 20
192
User’s Manual U15331EJ4V1UD
Table 11-2. Serial Interface 20 Operation Mode Settings
(1) Operation stop mode
ASIM20 CSIM20
TXE20 RXE20 CSIE20 DIR20 CSCK20
PM22 P22 PM21 P21 PM20 P20 First
Bit
Shift
Clock
P22/SI20/
RxD20 Pin
Function
P21/SO20/
TxD20 Pin
Function
P20/SCK20/
ASCK20 Pin
Function
0 0 0 Ч Ч Ч Note 1 × Note 1 × Note 1 × Note 1 × Note 1 × Note 1 − − P22 P21 P20
Other than above Setting prohibited
(2) 3-wire serial I/O mode
ASIM20 CSIM20
TXE20 RXE20 CSIE20 DIR20 CSCK20
PM22 P22 PM21 P21 PM20 P20 First
Bit
Shift
Clock
P22/SI20/
RxD20 Pin
Function
P21/SO20/
TxD20 Pin
Function
P20/SCK20/
ASCK20 Pin
Function
0 1 × External
clock
SCK20
input
1 0
1 0 1
MSB
Internal
clock
SCK20
output
0 1 × External
clock
SCK20
input
0 0
1 1
1
1 Note 2 × Note 2 0 1
0 1
LSB
Internal
clock
SI20 Note 2 SO20
(CMOS output)
SCK20
output
Other than above Setting prohibited
(3) Asynchronous serial interface mode
ASIM20 CSIM20
TXE20 RXE20 CSIE20 DIR20 CSCK20
PM22 P22 PM21 P21 PM20 P20 First
Bit
Shift
Clock
P22/SI20/
RxD20 Pin
Function
P21/SO20/
TxD20 Pin
Function
P20/SCK20/
ASCK20 Pin
Function
1 × External
clock
ASCK20
input
1 0 0 0 0 × Note 1 × Note 1 0 1
× Note 1 × Note 1
Internal
clock
P22 TxD20
(CMOS output)
P20
1 × External
clock
ASCK20
input
0 1 0 0 0 1 Ч Ч Note 1 × Note 1
× Note 1 × Note 1
Internal
clock
P21
P20
1 × External
clock
ASCK20
input
1 1 0 0 0 1 Ч 0 1
Ч Note 1 × Note 1
LSB
Internal
clock
RxD20
TxD20
(CMOS output)
P20
Other than above Setting prohibited
Notes 1. These pins can be used for port functions.
2. When only transmission is used, this pin can be used as P22 (CMOS I/O).
Remark
×: don’t care