Operation Of Serial Interface Uart0; Operation Stop Mode - NEC 78K0/KD1 Series User Manual

13.4 Operation of Serial Interface UART0

This section explains the two modes of serial interface UART0.

13.4.1 Operation stop mode

In this mode, serial transfer cannot be executed, thus reducing the power consumption. In addition, the pins can
be used as ordinary port pins in this mode.
(1) Register setting
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 input sets this register to 01H.
Address: FF70H After reset: 01H R/W
Symbol 7
ASIM0 POWER0
POWER0
Note
0
1
TXE0
0
1
RXE0
0
1
Note The input from the R
Cautions 1. At startup, set POWER0 to 1 and then set TXE0 to 1. Clear TXE0 to 0 first, and then clear
POWER0 to 0.
2. At startup, set POWER0 to 1 and then set RXE0 to 1. Clear RXE0 to 0 first, and then clear
POWER0 to 0.
3. TXE0 and RXE0 are synchronized with the base clock (f
transmission unit may not be initialized if TXE0 = 1 is not set again 2 clocks after TXE0 = 0 is
set. Similarly, the reception unit may not be initialized if RXE0 = 1 is not set again 2 clocks
after RXE0 = 0 is set.
CHAPTER 13 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
resets the internal circuit.
Enables operation of the internal operation clock.
Disables transmission (synchronously resets the transmission circuit).
Enables transmission.
Disables reception (synchronously resets the reception circuit).
Enables reception.
D0 pin is fixed to high level when POWER0 = 0.
X
Preliminary User's Manual U16315EJ1V0UD
4 3
PS01 PS00 CL0
Enables/disables transmission
Enables/disables reception
XCLK
2 1 0
SL0 1
) set by BRGC0. Therefore, the
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