SH7101 datasheet(335/560 Pages) RENESAS

335 / 560 page

Section 10 Serial Communication Interface (SCI)

Rev.1.00 Sep. 18, 2008 Page 301 of 522

REJ09B0069-0100

10.4

Operation in Asynchronous Mode

Figure 10.2 shows the general format for asynchronous serial communication. One frame consists

of a start bit (low level), followed by data, a parity bit, and finally stop bits (high level). In

asynchronous serial communication, the transmission 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 transfer.

LSB

Start

bit

MSB

Idle state

(mark state)

Stop bit

Transmit/receive data

0/1

Serial

data

Parity

bit

1 bit

1 or 2 bits

7 or 8 bits

1 bit

none

One unit of transfer data (character or frame)

Figure 10.2 Data Format in Asynchronous Communication (Example with 8-Bit Data,

Parity, Two Stop Bits)

10.4.1

Data Transfer Format

Table 10.8 shows the data transfer formats that can be used in asynchronous mode. Any of 12

transfer formats can be selected according to the SMR setting. For details on the multiprocessor

bit, refer to section 10.5, Multiprocessor Communication Function.

SH7101 Datasheet(PDF) 335 Page - Renesas Technology Corp