CHAPTER 12 SERIAL INTERFACE 20
User’s Manual U15075EJ2V1UD
220
Table 12-2. Serial Interface 20 Operating Mode Settings
(1) Operation stop mode
ASIM20 CSIM20
TXE20 RXE20 CSIE20 DIR20
CSCK20
PM25 P25 PM24
P24 PM23
P23 First
Bit
Shift
Clock
P25/SI20/
RxD20 Pin
Function
P24/SO20/
TxD20 Pin
Function
P23/SCK20/
ASCK20 Pin
Function
0 0 0
×
×
×
Note 1
×
Note 1
×
Note 1
×
Note 1
×
Note 1
×
Note 1
−
−
P25 P24 P23
Other than above
Setting prohibited
(2) 3-wire serial I/O mode
ASIM20 CSIM20
TXE20 RXE20 CSIE20 DIR20
CSCK20
PM25 P25 PM24
P24 PM23
P23 First
Bit
Shift
Clock
P25/SI20/
RxD20 Pin
Function
P24/SO20/
TxD20 Pin
Function
P23/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
×
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
PM25 P25 PM24
P24 PM23
P23 First
Bit
Shift
Clock
P25/SI20/
RxD20 Pin
Function
P24/SO20/
TxD20 Pin
Function
P23/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)
P23
1
×
External
clock
ASCK20
input
0 1 0 0 0 1
×
×
Note 1
×
Note 1
×
Note 1
×
Note 1
Internal
clock
P24
P23
1
×
External
clock
ASCK20
input
1 1 0 0 0 1
×
0 1
×
Note 1
×
Note 1
LSB
Internal
clock
RxD20
TxD20
(CMOS output)
P23
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 P25 (CMOS I/O).
Remark
×
: don’t care.