UPD78F0411GA-GAM-AX Datasheet, PDF (325/564 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 13 SERIAL INTERFACE UART0
13.4 Operation of Serial Interface UART0
Serial interface UART0 has the following two modes.
• Operation stop mode
• Asynchronous serial interface (UART) mode
13.4.1 Operation stop mode
In this mode, serial communication cannot be executed, thus reducing the power consumption. In addition, the
pins can be used as ordinary port pins in this mode. To set the operation stop mode, clear bits 7, 6, and 5 (POWER0,
TXE0, and RXE0) of ASIM0 to 0.
(1) Register used
The operation stop mode is set by asynchronous serial interface operation mode register 0 (ASIM0).
ASIM0 can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation sets this register to 01H.
Address: FF70H After reset: 01H R/W
Symbol
<7>
<6>
<5>
4
3
2
1
0
ASIM0
POWER0
TXE0
RXE0
PS01
PS00
CL0
SL0
1
POWER0
0^{Note 1}
Enables/disables operation of internal operation clock
Disables operation of the internal operation clock (fixes the clock to low level) and asynchronously
resets the internal circuit^{Note 2}.
TXE0
0
Enables/disables transmission
Disables transmission (synchronously resets the transmission circuit).
RXE0
0
Enables/disables reception
Disables reception (synchronously resets the reception circuit).
Notes 1.
2.
The input from the RXD0 pin is fixed to high level when POWER0 = 0.
Asynchronous serial interface reception error status register 0 (ASIS0), transmit shift register 0 (TXS0),
and receive buffer register 0 (RXB0) are reset.
Caution Clear POWER0 to 0 after clearing TXE0 and RXE0 to 0 to set the operation stop mode.
To start the communication, set POWER0 to 1, and then set TXE0 or RXE0 to 1.
Remark To use the RxD0/KR3/<RxD6>/P12 and TxD0/KR4/<TxD6>/P13 pins as general-purpose port pins, see
CHAPTER 4 PORT FUNCTIONS.
User’s Manual U18698EJ1V0UD
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