Datasheet

Section 17 I
2
C Bus Interface (IIC)
Rev. 3.00 Sep. 28, 2009 Page 518 of 910
REJ09B0350-0300
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 condition]
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.
The SCP bit is always read as 1. If 0 is written, the data
is not stored.
Note: * The value in BBSY flag does not change even if written.