NEC mPD780973 Series Preliminary User's Manual page 172

(a) Asynchronous serial interface mode register (ASIM)
ASIM is set with a 1-bit or 8-bit memory manipulation instruction.
When RESET is input, its value is 00H.
Caution In UART mode, set the port mode register (PM5X) as follows. Besides that, set all output
latches to 0.
• When receiving
Set P53 (R
• When transmitting
Set P54 (T
• When transceiving
Set P53 to the input mode and P54 to the output mode
Address: FF85H After Reset: 00H
Symbol 7
ASIM TXE
TXE
0
0
1
1
PS1
0
0
1
1
CL
0
1
SL
0
1
ISRM
0
1
Cautions 1. Do not switch the operation mode until after the current serial transmit/receive
operation has stopped.
2. Bit 0 must be set to 0.
172
CHAPTER 14 SERIAL INTERFACE UART
D) to the input mode (PM53 = 1)
X
D) to the output mode (PM54 = 0)
X
R/W
6 5
RXE PS1 PS0
RXE Operation Mode
0 Operation stop
1 UART mode
(receive only)
0 UART mode
(transmit only)
1 UART mode
(transmit and receive)
PS0
0 No parity
1 Zero parity always added during transmission
No parity detection during reception (parity errors do not occur)
0 Odd parity
1 Even parity
Character Length Specification
7 bits
8 bits
Stop Bit Length Specification for Transmit Data
1 bit
2 bits
Receive Completion Interrupt Control when Error Occurs
Receive completion interrupt is issued when an error occurs
Receive completion interrupt is not issued when an error occurs
4 3 2
CL SL
RxD/P53 Pin Function
Port function
Serial function
Port function
Serial function
Parity Bit Specification
1 0
ISRM 0
TxD/P54 Pin Function
Port function
Port function
Serial function
Serial function