4 serial interface channel 2 operation, 1 operation stop mode – NEC uPD78P078 User Manual
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CHAPTER 20 SERIAL INTERFACE CHANNEL 2
20.4 Serial Interface Channel 2 Operation
Serial interface channel 2 has the following three modes.
• Operation stop mode
• Asynchronous serial interface (UART) mode
• 3-wire serial I/O mode
20.4.1 Operation stop mode
In the operation stop mode, serial transfer is not performed, and therefore power consumption can be reduced.
In the operation stop mode, the P70/SI2/RxD, P71/SO2/TxD and P72/SCK2/ASCK pins can be used as normal
input/output ports.
(1) Register setting
Operation stop mode is set using serial operating mode register 2 (CSIM2) and the asynchronous serial
interface mode register (ASIM).
(a) Serial operating mode register 2 (CSIM2)
CSIM2 is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets CSIM2 to 00H.
CSIM
22
6
5
4
3
2
1
0
<7>
Symbol
CSIM2 CSIE2
0
0
0
0
CSCK
0
FF72H 00H R/W
Address After Reset R/W
CSIE2
0
1
Operation Control in 3-wire Serial I/O Mode
Operation stopped
Operation enabled
Caution Ensure that bit 0 and bits 3 through 6 are set to 0.