Datasheet

Section 15 I
2
C Bus Interface (IIC)
Rev. 3.00 Sep. 28, 2009 Page 342 of 710
REJ09B0384-0300
Bit Bit Name
Initial
Value
R/W Description
2
0
BBSY
SCP
0
1
R/W*
W
Bus Busy
Start Condition/Stop Condition Prohibit
In master mode
• Writing 0 in BBSY and 0 in SCP: A stop condition is
issued
• Writing 1 in BBSY and 0 in SCP: A start condition and
a restart condition are issued
In slave mode
• Writing to the BBSY flag is disabled.
[BBSY setting condition]
• When the SDA level changes from high to low under
the condition of SCL = high, assuming that the start
condition has been issued.
[BBSY clearing conditions]
• When the SDA level changes from low to high under
the condition of SCL = high, assuming that the stop
condition has been issued.
To issue a start/stop condition, use the MOV instruction.
The I
2
C bus interface must be set in master transmit mode
before the issue of a start condition. Set MST to 1 and
TRS to 1 before writing 1 in BBSY and 0 in SCP.
The BBSY flag can be read to check whether the I
2
C bus
(SCL, SDA) is busy or free.
Note: * If the BBSY bit is written to, the value of the flag is not changed.