UPD780078 Datasheet, PDF (258/592 Pages) NEC – 8-Bit Single-Chip Microcontrollers

CHAPTER 14 SERIAL INTERFACE UART0
(2) Communication operations
(a) Data format and waveform example
Figures 14-8 and 14-9 show the format and waveform example of the transmit/receive data.
Figure 14-8. Example of Transmit/Receive Data Format in Asynchronous Serial Interface
1 data frame
Start
bit
D0
D1
D2
D3
D4
D5
D6
D7
Parity
bit
Character bits
Stop bit
1 data frame consists of the following bits.
• Start bit ............. 1 bit
• Character bits ... 7 bits or 8 bits (LSB first)
• Parity bit ........... Even parity, odd parity, zero parity, or no parity
• Stop bit(s) ......... 1 bit or 2 bits
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.
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User’s Manual U14260EJ3V1UD