Operation Of Serial Interface Uart0; Operation Stop Mode - NEC 78K0 Series User Manual

14.4 Operation of Serial Interface UART0

Serial interface UART0 has the following two modes.

• Operation stop mode

• Asynchronous serial interface (UART) mode
14.4.1 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>
ASIM0 POWER0
POWER0
Note 1
0
TXE0
0
RXE0
0
Notes 1. The input from the R
2. 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/SI10/P11 and TxD0/SCK10/P10 pins as general-purpose port pins, see CHAPTER 5
PORT FUNCTIONS.
CHAPTER 14 SERIAL INTERFACE UART0
<6> <5>
TXE0 RXE0
Enables/disables operation of internal operation clock
Disables operation of the internal operation clock (fixes the clock to low level) and asynchronously
Note 2
resets the internal circuit .
Disables transmission (synchronously resets the transmission circuit).
Disables reception (synchronously resets the reception circuit).
D0 pin is fixed to high level when POWER0 = 0.
X
Preliminary User's Manual U17260EJ3V1UD
4 3
PS01 PS00 CL0
Enables/disables transmission
Enables/disables reception
2 1 0
SL0 1
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