Operation; Overview - Renesas H8S Series Hardware Manual

14.3

Operation

14.3.1

Overview

The SCI can carry out serial communication in two modes: asynchronous mode in which synchronization is achieved
character by character, and clocked synchronous mode in which synchronization is achieved with clock pulses.
Selection of asynchronous or clocked synchronous mode and the transmission format is made using SMR as shown in
table 14-8. The SCI clock is determined by a combination of the C/A bit in SMR and the CKE1 and CKE0 bits in SCR, as
shown in table 14-9.
Asynchronous Mode
• Data length: Choice of 7 or 8 bits
• Choice of parity addition, multiprocessor bit addition, and addition of 1 or 2 stop bits (the combination of these
parameters determines the transfer format and character length)
• Detection of framing, parity, and overrun errors, and breaks, during reception
• Choice of internal or external clock as SCI clock source
 When internal clock is selected:
The SCI operates on the baud rate generator clock and a clock with the same frequency as the bit rate can be output
 When external clock is selected:
A clock with a frequency of 16 times the bit rate must be input (the on-chip baud rate generator is not used)
Clocked Synchronous Mode
• Transfer format: Fixed 8-bit data
• Detection of overrun errors during reception
• Choice of internal or external clock as SCI clock source
 When internal clock is selected:
The SCI operates on the baud rate generator clock and a serial clock is output off-chip
 When external clock is selected:
The on-chip baud rate generator is not used, and the SCI operates on the input serial clock
Rev.6.00 Oct.28.2004 page 487 of 1016
REJ09B0138-0600H