SH7018 datasheet(261/431 Pages) RENESAS

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12.3.4

Clock Synchronous Operation

In the clock synchronous mode, the SCI1 transmits and receives data in synchronization with

clock pulses. This mode is suitable for high-speed serial communication.

The SCI1 transmitter and receiver are independent, so full duplex communication is possible while

sharing the same clock. The transmitter and receiver are also double buffered, so continuous

transmitting or receiving is possible by reading or writing data while transmitting or receiving is in

progress.

Figure 12.14 shows the general format in clock synchronous serial communication.

Bit 0

Bit 1

Bit 2

Bit 3

Bit 4

Bit 5

Bit 6

Bit 7

LSB

MSB

Synchroni-

zation clock

Serial data

Transfer direction

One unit (character or frame) of communication data

Note: * High except in continuous transmitting or receiving.

Figure 12.14 Data Format in Clock Synchronous Communication

In clock synchronous serial communication, each data bit is output on the communication line

from one falling edge of the serial clock to the next. Data are guaranteed valid at the rising edge of

the serial clock. In each character, the serial data bits are transmitted in order from the LSB (first)

to the MSB (last). After output of the MSB, the communication line remains in the state of the

MSB. In the clock synchronous mode, the SCI1 transmits or receives data by synchronizing with

the falling edge of the synchronization clock.

Communication Format: The data length is fixed at eight bits. No parity bit or multiprocessor bit

can be added.

Clock: An internal clock generated by the on-chip baud rate generator or an external clock input

from the SCK pin can be selected as the SCI1 transmit/receive clock. The clock source is selected

by the C/

A bit in the serial mode register (SMR1) and bits CKE1 and CKE0 in the serial control

When the SCI1 operates on an internal clock, it outputs the clock signal at the SCK pin. Eight

clock pulses are output per transmitted or received character. When the SCI1 is not transmitting or

receiving, the clock signal remains in the high state.

SH7018 Datasheet(PDF) 261 Page - Renesas Technology Corp

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