Asynchronous Serial Interface Transmit/Receive Data Format - NEC PD78081(A) User Manual

(2) Communication operation
(a) Data format
The transmit/receive data format is as shown in Figure 11-7.
Figure 11-7. Asynchronous Serial Interface Transmit/Receive Data Format
1 Data frame is configured from the following bits.
• Start bits ..................
• Character bits .........
• Parity bits ................
• Stop bit(s) ...............
The specification of character bit length, parity selection, and specification of stop bit length for each data
frame is carried out with asynchronous serial interface mode register (ASIM).
When 7 bits are selected as the number of character bits, only the lower 7 bits (bits 0 to 6) are valid; in
transmission the most significant bit (bit 7) is ignored, and in reception the most significant bit (bit 7) is
always "0".
The serial transfer rate is selected by means of the ASIM and the baud rate generator control register
(BRGC).
If a serial data receive error is generated, the receive error contents can be determined by reading the
status of the asynchronous serial interface status register (ASIS).
CHAPTER 11 SERIAL INTERFACE CHANNEL 2
Start
D0 D1 D2 D3
Bit
Character Bit
1 bit
7 bits/8 bits
Even parity/odd parity/0 parity/no parity
1 bit/2 bits
One Data Frame
Parity
D4 D5 D6 D7 Stop Bit
Bit
157