CHAPTER 12 SERIAL INTERFACE 20
User’s Manual U15075EJ2V1UD
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12.3 Serial Interface 20 Control Registers
Serial interface 20 is controlled by the following six registers.
•
Serial operation mode register 20 (CSIM20)
•
Asynchronous serial interface mode register 20 (ASIM20)
•
Asynchronous serial interface status register 20 (ASIS20)
•
Baud rate generator control register 20 (BRGC20)
•
Port mode register 2 (PM2)
•
Port 2 (P2)
(1) Serial operation mode register 20 (CSIM20)
CSIM20 is used to make the settings related to 3-wire serial I/O mode.
CSIM20 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets CSIM20 to 00H.
Figure 12-3. Format of Serial Operation Mode Register 20
CSIE20
0
1
3-wire serial I/O mode operation control
CSIE20 SSE20
0
0
DAP20 DIR20 CSCK20 CKP20
CSIM20
Symbol
Address
After reset
R/W
FF72H
00H
R/W
<7>
6
5
4
3
2
1
0
Operation disabled
Operation enabled
DIR20
0
1
First-bit specification
MSB
LSB
CSCK20
0
1
3-wire serial I/O mode clock selection
External clock input to the SCK20 pin
Output of the dedicated baud rate generator
SSE20
0
1
Not used
Used
DAP20
0
1
3-wire serial I/O mode data phase selection
Outputs at the falling edge of SCK20
Outputs at the rising edge of SCK20
SS20 pin selection
Function of SS20/P22 pin
Port function
0
1
Communication status
Communication enabled
Communication enabled
Communication disabled
CKP20
0
1
3-wire serial I/O mode clock phase selection
Clock is low active, and SCK20 is at high level in the idle state
Clock is high active, and SCK20 is at low level in the idle state
Cautions 1. Bits 4 and 5 must be set to 0.
2. CSIM20 must be cleared to 00H if UART mode is selected.
