SH7708 datasheet(382/633 Pages) RENESAS

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13.3

Operation

13.3.1

Overview

For serial communication, the SCI has an asynchronous mode in which characters are

synchronized individually, and a synchronous mode in which communication is synchronized with

clock pulses. Asynchronous/synchronous mode and the transmission format are selected in the

serial mode register (SCSMR), as shown in table 13.9. The SCI clock source is selected by the

combination of the C/

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

the serial control register (SCSCR), as shown in table 13.10.

Asynchronous Mode:

• Data length is selectable: seven or eight bits.

• Parity and multiprocessor bits are selectable, as is the stop bit length (one or two bits). The

combination of the preceding selections constitutes the communication format and character

length.

• In receiving, it is possible to detect framing errors (FER), parity errors (PER), overrun errors

(ORER) and breaks.

• An internal or external clock can be selected as the SCI clock source.

 When an internal clock is selected, the SCI operates using the on-chip baud rate generator,

and can output a serial clock signal with a frequency matching the bit rate.

 When an external clock is selected, the external clock input must have a frequency 16

times the bit rate. (The on-chip baud rate generator is not used.)

Synchronous Mode:

• The transmission/reception format has a fixed eight-bit data length.

• In receiving, it is possible to detect overrun errors (ORER).

• An internal or external clock can be selected as the SCI clock source.

 When an internal clock is selected, the SCI operates using the on-chip baud rate generator,

and outputs a serial clock to external devices.

 When an external clock is selected, the SCI operates on the input serial clock. The on-chip

baud rate generator is not used.

SH7708 Datenblatt(PDF) 382 Page - Renesas Technology Corp