NEC UPD789426 Series User Manual page 219

(1) Operation stop mode
ASIM20 CSIM20
TXE20 RXE20 CSIE20 DIR20
×
0 0 0
(2) 3-wire serial I/O mode
ASIM20 CSIM20
TXE20 RXE20 CSIE20 DIR20
0 0 1 0
1 1
(3) Asynchronous serial interface mode
ASIM20 CSIM20
TXE20 RXE20 CSIE20 DIR20
1 0 0 0
0 1 0 0
1 1 0 0
Notes 1. These pins can be used for port functions.
2. When only transmission is used, this pin can be used as P25 (CMOS I/O).
×: don't care.
Remark
220
CHAPTER 12 SERIAL INTERFACE 20
Table 12-2. Serial Interface 20 Operating Mode Settings
PM25 P25 PM24
CSCK20
× × × × ×
Note 1 Note 1 Note 1
Other than above
PM25 P25 PM24
CSCK20
× ×
Note 2 Note 2
0 0
1
0
1
Other than above
PM25 P25 PM24
CSCK20
× ×
Note 1 Note 1
0 0
× × ×
Note 1
0 1
×
0 1 0
Other than above
User's Manual U15075EJ2V1UD
P24 PM23 P23 First Shift
Bit Clock
× × − −
Note 1 Note 1 Note 1
Setting prohibited
P24 PM23 P23 First Shift
Bit Clock
×
1 1 MSB
External
clock
0 1
Internal
clock
×
1 LSB
External
clock
0 1
Internal
clock
Setting prohibited
P24 PM23 P23 First Shift
Bit Clock
×
1 1 LSB
External
clock
× ×
Note 1 Note 1
Internal
clock
×
Note 1
1
External
clock
× ×
Note 1 Note 1
Internal
clock
×
1 1
External
clock
× ×
Note 1 Note 1
Internal
clock
Setting prohibited
P25/SI20/ P24/SO20/ P23/SCK20/
RxD20 Pin TxD20 Pin ASCK20 Pin
Function Function Function
P25 P24 P23
P25/SI20/ P24/SO20/ P23/SCK20/
RxD20 Pin TxD20 Pin ASCK20 Pin
Function Function Function
Note 2
SI20 SO20 SCK20
input
(CMOS output)
SCK20
output
SCK20
input
SCK20
output
P25/SI20/ P24/SO20/ P23/SCK20/
RxD20 Pin TxD20 Pin ASCK20 Pin
Function Function Function
P22 TxD20 ASCK20
input
(CMOS output)
P23
RxD20 P24 ASCK20
input
P23
TxD20 ASCK20
input
(CMOS output)
P23