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CHAPTER 13 SERIAL INTERFACE (UART0)
Preliminary User’s Manual U16035EJ1V0UM
13.4 Operations of Serial Interface
This section explains the three modes of the serial interface (UART0).
13.4.1 Operation stop mode
Because serial transfer is not performed during this mode, the power consumption can be reduced.
In addition, pins can be used as normal ports.
(1) Register settings
Operation stop mode is set by the asynchronous serial interface mode register 0 (ASIM0).
ASIM0 is set by a 1-bit or 8-bit memory manipulation instruction.
RESET input sets ASIM0 to 00H.
Address: FFA0H After reset: 00H R/W
Symbol
7
6
5
4
3
2
1
0
ASIM0
TXE0
RXE0
PS01
PS00
CL0
SL0
ISRM0
IRDAM0
TXE0
RXE0
Operation mode
RxD0/P23 pin function
TxD0/P24 pin function
0
0
Operation stop
Port function (P23)
Port function (P24)
0
1
UART mode
Serial function (RxD0)
(receive only)
1
0
UART mode
Port function (P23)
Serial function (TxD0)
(transmit only)
1
1
UART mode
Serial function (RxD0)
(transmit and receive)
Caution
Do not switch the operation mode until the current serial transmit/receive operation has
stopped.