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CHAPTER 13 SERIAL INTERFACE (UART0)
Preliminary User’s Manual U16035EJ1V0UM
(2) Communication operations
(a) Data format
Figure 13-7 shows the format of the transmit/receive data.
Figure 13-7. Format of Transmit/Receive Data in Asynchronous Serial Interface
D0
D1
D2
D3
D4
D5
D6
D7
Start
bit
Parity
bit
Stop bit
1 data frame
Character bits
1 data frame consists of the following bits.
• Start bit ............. 1 bit
• Character bits ... 7 bits or 8 bits
• Parity bit ........... Even parity, odd parity, zero parity, or no parity
• Stop bit(s) ......... 1 bit or 2 bits
The asynchronous serial interface mode register 0 (ASIM0) is used to set the character bit length, parity
selection, and stop bit length within each data frame.
When “7 bits” is selected as the number of character bits, only the lower 7 bits (bits 0 to 6) are valid, so that
during a transmission the highest bit (bit 7) is ignored and during reception the highest bit (bit 7) must be
set to “0”.
The ASIM0 and the baud rate generator control register 0 (BRGC0) are used to set the serial transfer rate.
If a receive error occurs, information about the receive error can be recognized by reading the asynchronous
serial interface status register 0 (ASIS0).