Operation In Asynchronous Mode; Figure 12.2 Data Format In Asynchronous Communication (Example With 8-Bit Data, Parity, Two Stop Bits) - Renesas H8SX/1520 Series Hardware Manual

32-bit cisc microcomputer

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Operation in Asynchronous Mode

Figure 12.2 shows the general format for asynchronous serial communication. One frame consists

of a start bit (low level), followed by transmit/receive data, a parity bit, and finally stop bits (high

level). In asynchronous serial communication, the communication line is usually held in the mark

state (high level). The SCI monitors the communication line, and when it goes to the space state

(low level), recognizes a start bit and starts serial communication. Inside the SCI, the transmitter

and receiver are independent units, enabling full-duplex communication. Both the transmitter and

the receiver also have a double-buffered structure, so that data can be read or written during

transmission or reception, enabling continuous data transmission and reception.

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Transmit/receive data

One unit of transfer data (character or frame)

Figure 12.2 Data Format in Asynchronous Communication

(Example with 8-Bit Data, Parity, Two Stop Bits)

Section 12 Serial Communication Interface (SCI)

(mark state)

Rev. 3.00 Mar. 14, 2006 Page 405 of 804

REJ09B0104-0300

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