RX610 Group
22. I
2
C Bus Interface (RIIC)
R01UH0032EJ0120 Rev.1.20
Page 727 of 1006
Feb 20, 2013
22.3
Operation
22.3.1
Communication Data Format
The I
2
C bus format consists of 8-bit data and 1-bit acknowledge. The frame following a start condition or restart
condition is an address frame used to specify a slave device with which the master device communicates. The specified
slave is valid until a new slave is specified or a stop condition is issued.
Figure 22.3 shows the I
2
C bus format, and figure 22.4 shows the I
2
C bus timing.
[7-bit address format]
S
R/W#
A
A
A/A#
P
S
SLA (7 bits)
W#
A
A
A/A#
P
SLA (8 bits)
SLA(2 bits)
DATA (8 bits)
A
S
W#
A
A
A/A#
P
SLA (8 bits)
SLA(2 bits)
A
Sr SLA(2 bits)
R
DATA (8 bits)
1
7
1
1
1
1
1
8
A
DATA (8 bits)
1
7
1
1
1
1
1
8
1
1
1
8
1
8
1
7
1
1
1
8
1
1
7
1
[10-bit address format]
n (n = 1 or more)
n (n = 1 or more)
n (n = 1 or more)
n: Number of transfer frames
Figure 22.3 I
2
C Bus Format
S
SLA
R/W#
A
Data
A
Data
A
P
SDA
1 to 7
8
9
1 to 7
8
9
1 to 7
8
9
SCL
Figure 22.4 I
2
C Bus Timing (SLA = 7 Bits)
[Legend]
S:
Start condition. The master device drives the SDAn line low from high level while the SCLn line is at a high level.
SLA:
Slave address, by which the master device selects a slave device.
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.
A:
Acknowledge. The receive device drives the SDAn line low. (In master transmit mode, the slave device returns acknowledge.
In master receive mode, the master device returns acknowledge.)
Sr:
Restart condition. The master device drives the SDAn line low from the high level after the setup time has elapsed with the
SCLn line at the high level.
DATA:
Transmitted or received data
P:
Stop condition. The master device drives the SDAn line high from low level while the SCLn line is at a high level.