H838532H datasheet(332/508 Pages) RENESAS

332 / 508 page

Section 10 Serial Communication Interface

Rev. 1.00 May 30, 2008 Page 312 of 484

REJ09B0436-0100

10.3

Operation

10.3.1

Overview

SCI3 can perform serial communication in two modes: asynchronous mode in which

synchronization is provided character by character, and synchronous mode in which

synchronization is provided by clock pulses. The serial mode register (SMR) is used to select

asynchronous or synchronous mode and the data transfer format, as shown in table 10.8.

The clock source for SCI3 is determined by bit COM in SMR and bits CKE1 and CKE0 in SCR3,

as shown in table 10.9.

(1) Synchronous Mode

• Choice of 5-, 7-, or 8-bit data length

• Choice of parity addition, and addition of 1 or 2 stop bits. (The combination of these

parameters determines the data transfer format and the character length.)

• Framing error (FER), parity error (PER), overrun error (OER), and break detection during

reception

• Choice of internal or external clock as the clock source

When internal clock is selected: SCI3 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 16 times the bit rate must be input.

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

(2) Synchronous Mode

• Data transfer format: Fixed 8-bit data length

• Overrun error (OER) detection during reception

• Choice of internal or external clock as the clock source

When internal clock is selected: SCI3 operates on the baud rate generator clock, and a serial

clock is output.

When external clock is selected: The on-chip baud rate generator is not used, and SCI3

operates on the input serial clock.

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