HD6432142 datasheet(575/1177 Pages) RENESAS

575 / 1177 page

Section 16 I

2C Bus Interface [Option]

Rev. 4.00 Sep 27, 2006 page 531 of 1130

REJ09B0327-0400

16.3.5

Slave Transmit Operation

In slave transmit mode, the slave device outputs the transmit data, while the master device outputs

the receive clock and returns an acknowledge signal. The transmission procedure and operations in

slave transmit mode are described below.

[1] Set the ICE bit in ICCR to 1. Set the MLS bit in ICMR and the MST and TRS bits in ICCR

according to the operating mode.

[2] When the slave address matches in the first frame following detection of the start condition,

the slave device drives SDA low at the 9th clock pulse and returns an acknowledge signal. At

the same time, the IRIC flag in ICCR is set to 1. If the IEIC bit in ICCR has been set to 1, an

interrupt request is sent to the CPU. If the 8th data bit (R/

W) is 1, the TRS bit in ICCR is set to

1, and the mode changes to slave transmit mode automatically. The TDRE internal flag is set

to 1. The slave device drives SCL low from the fall of the transmit clock until ICDR data is

written.

[3] After clearing the IRIC flag to 0, write data to ICDR. The TDRE internal flag is cleared to 0.

The written data is transferred to ICDRS, and the TDRE internal flag and the IRIC and IRTR

flags are set to 1 again. After clearing the IRIC flag to 0, write the next data to ICDR. The

slave device sequentially sends the data written into ICDR in accordance with the clock output

by the master device at the timing shown in figure 16.11.

[4] When one frame of data has been transmitted, the IRIC flag in ICCR is set to 1 at the rise of

the 9th transmit clock pulse. If the TDRE internal flag has been set to 1, this slave device

drives SCL low from the fall of the transmit clock until data is written to ICDR. The master

device drives SDA low at the 9th clock pulse, and returns an acknowledge signal. As this

acknowledge signal is stored in the ACKB bit in ICSR, this bit can be used to determine

whether the transfer operation was performed normally. When the TDRE internal flag is 0, the

data written into ICDR is transferred to ICDRS, transmission is started, and the TDRE internal

flag and the IRIC and IRTR flags are set to 1 again.

[5] To continue transmission, clear the IRIC flag to 0, then write the next data to be transmitted

into ICDR. The TDRE internal flag is cleared to 0.

Transmit operations can be performed continuously by repeating steps [4] and [5]. To end

transmission, write H'FF to ICDR to release SDA on the slave side. When SDA is changed from

low to high when SCL is high, and the stop condition is detected, the BBSY flag in ICCR is

cleared to 0.

HD6432142 Datasheet(PDF) 575 Page - Renesas Technology Corp