SH7125_08 Datasheet, PDF (462/774 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family

Section 12 Serial Communication Interface (SCI)
12.4 Operation
12.4.1 Overview
For serial communication, the SCI has an asynchronous mode in which characters are
synchronized individually, and a clock synchronous mode in which communication is
synchronized with clock pulses.
Asynchronous or clock synchronous mode is selected and the transmit format is specified in the
serial mode register (SCSMR) as shown in table 12.13. The SCI clock source is selected by the
combination of the C/A bit in SCSMR and the CKE1 and CKE0 bits in the serial control register
(SCSCR) as shown in table 12.14.
(1) Asynchronous Mode (Channels 0 to 2 in the SH7125, Channels 0 to 2 in the SH7124)
• Data length is selectable: 7 or 8 bits.
• Parity bit is selectable. So is the stop bit length (1 or 2 bits). The combination of the preceding
selections constitutes the communication format and character length.
• In receiving, it is possible to detect framing errors, parity errors, overrun errors, 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 clock supplied by the on-
chip baud rate generator and can output a clock with a frequency 16 times 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.)
(2) Clock Synchronous Mode (Channels 0 to 2 in the SH7125, Channels 0 and 2 in the
SH7124)
• The transmission/reception format has a fixed 8-bit data length.
• In receiving, it is possible to detect overrun errors.
• 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 signal 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.
Rev. 4.00 Jul. 25, 2008 Page 442 of 750
REJ09B0243-0400