R28 datasheet(331/473 Pages) RENESAS

331 / 473 page

R8C/28 Group, R8C/29 Group

16. Clock Synchronous Serial Interface

Rev.2.10

Sep 26, 2008

Page 312 of 441

REJ09B0279-0210

16.3.8

Notes on I2C bus Interface

Set the IICSEL bit in the PMR register to 1 (select I2C bus interface function) to use the I2C bus interface.

16.3.8.1

Multimaster Operation

The following actions must be performed to use the I2C bus interface in multimaster operation.

• Transfer rate

Set the transfer rate by 1/1.8 or faster than the fastest rate of the other masters. For example, if the fastest

transfer rate of the other masters is set to 400 kbps, the I2C-bus transfer rate in this MCU should be set to

223 kbps (= 400/1.18) or more.

• Bits MST and TRS in the ICCR1 register setting

(a) Use the MOV instruction to set bits MST and TRS.

(b) When arbitration is lost, confirm the contents of bits MST and TRS. If the contents are other than the

MST bit set to 0 and the TRS bit set to 0 (slave receive mode), set the MST bit to 0 and the TRS bit to 0

again.

16.3.8.2

Master Receive Mode

Either of the following actions must be performed to use the I2C bus interface in master receive mode.

(a) In master receive mode while the RDRF bit in the ICSR register is set to 1, read the ICDRR register

before the rising edge of the 8th clock.

(b) In master receive mode, set the RCVD bit in the ICCR1 register to 1 (disables the next receive

operation) to perform 1-byte communications.

R28 Datasheet(PDF) 331 Page - Renesas Technology Corp