Section 17 I2C Bus Interface 2 (IIC2)
[Legend]
S:
Start condition. The master device drives SDA from high to low while SCL is high.
SLA: Slave address
R/W: Indicates the direction of data transfer: from the slave device to the master device when
R/W is 1, or from the master device to the slave device when R/W is 0.
Acknowledge. The receive device drives SDA to low.
A:
DATA: Transfer data
P:
Stop condition. The master device drives SDA from low to high while SCL is high.
17.4.2
Master Transmit Operation
In master transmit mode, the master device outputs the transmit clock and transmit data, and the
slave device returns an acknowledge signal. For master transmit mode operation timing, refer to
figures 17.5 and 17.6. The transmission procedure and operations in master transmit mode are
described below.
1. Set the ICE bit in ICCR1 to 1. Set the MLS and WAIT bits in ICMR and the CKS3 to CKS0
bits in ICCR1 to 1. (Initial setting)
2. Read the BBSY flag in ICCR2 to confirm that the bus is free. Set the MST and TRS bits in
ICCR1 to select master transmit mode. Then, write 1 to BBSY and 0 to SCP using MOV
instruction. (Start condition issued) This generates the start condition.
3. After confirming that TDRE in ICSR has been set, write the transmit data (the first byte data
show the slave address and R/W) to ICDRT. At this time, TDRE is automatically cleared to 0,
and data is transferred from ICDRT to ICDRS. TDRE is set again.
4. When transmission of one byte data is completed while TDRE is 1, TEND in ICSR is set to 1
at the rise of the 9th transmit clock pulse. Read the ACKBR bit in ICIER, and confirm that the
slave device has been selected. Then, write second byte data to ICDRT. When ACKBR is 1,
the slave device has not been acknowledged, so issue the stop condition. To issue the stop
condition, write 0 to BBSY and SCP using MOV instruction. SCL is fixed low until the
transmit data is prepared or the stop condition is issued.
5. The transmit data after the second byte is written to ICDRT every time TDRE is set.
6. Write the number of bytes to be transmitted to ICDRT. Wait until TEND is set (the end of last
byte data transmission) while TDRE is 1, or wait for NACK (NACKF in ICSR = 1) from the
receive device while ACKE in ICIER is 1. Then, issue the stop condition to clear TEND or
NACKF.
7. When the STOP bit in ICSR is set to 1, the operation returns to the slave receive mode.
Rev. 3.00 Sep. 10, 2007 Page 346 of 528
REJ09B0216-0300
RENESAS [ RENESAS TECHNOLOGY CORP ]
