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Chapter 18
I
2
C Bus (IIC)
Preliminary User’s Manual U17566EE1V2UM00
condition”, “data”, and “stop condition” output via the I
2
C bus’s serial data bus
is shown below.
Figure 18-5
I
2
C bus serial data transfer timing
The master device outputs the start condition, slave address, and stop
condition.
The acknowledge signal (ACK) can be output by either the master or slave
device (normally, it is output by the device that receives 8-bit data).
The serial clock (SCLn) is continuously output by the master device. However,
in the slave device, the SCLn pin’s low-level period can be extended and a wait
can be inserted.
18.6.1
Start condition
A start condition is met when the SCLn pin is high level and the SDAn pin
changes from high level to low level. The start condition for the SCLn and
SDAn pins is a signal that the master device outputs to the slave device when
starting a serial transfer. The slave device can defect the start condition.
Figure 18-6
Start condition
A start condition is output when the IICCn.STTn bit is set (1) after a stop
condition has been detected (IICSn.SPDn bit = 1). When a start condition is
detected, the IICSn.STDn bit is set (1).
By setting IICCN.STTn=1 the master
device will also cancel its own wait status.
1 to 7
8
9
1 to 7
8
9
1 to 7
8
9
S
CLn
S
DAn
S
t
a
rt
condition
Addre
ss
R/W
ACK
D
a
t
a
D
a
t
a
S
top
condition
ACK
ACK
H
S
CLn
S
DAn
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