666
ICSR—I
2
C Bus Status Register
H'D9
I
2
C
Bit
Initial value
Read/Write
7
BBSY
0
R/W
6
IRIC
0
R/(W)
*
5
SCP
1
W
4
—
1
—
3
AL
0
R/(W)
*
0
ACKB
0
R/W
2
AAS
0
R/(W)
*
1
ADZ
0
R/(W)
*
Acknowledge Bit
0
Receive mode: 0 is output at acknowledge output timing
Transmit mode: indicates that the receiving device has acknowledged the data
Receive mode: 1 is output at acknowledge output timing
Transmit mode: indicates that the receiving device has not acknowledged the data
1
General Call Address Recognition Flag
0
General call address not recognized
Cleared when ICDR data is written (transmit mode) or read (receive mode)
Cleared by reading ADZ = 1, then writing 0
General call address recognized
Set when the general call address is detected in slave receive mode
Slave
0
Slave address or general call address not recognized (Initial value)
Cleared when ICDR data is written (transmit mode) or read (receive mode)
Cleared by reading AAS = 1, then writing 0
Slave address or general call address recognized
Set when the slave address or general call address is detected in slave receive mode
Arbitra
0
Bus arbitration won
Cleared when ICDR data is written (transmit mode) or read (receive mode)
Cleared by reading AL = 1, then writing 0
Arbitration lost
Set if the internal SDA and bus line disagree at the rise of SCL in master transmit mode
Set if the internal SCL is high at the fall of SCL in master transmit mode
Start C
0
1
Reading always results in 1
Writing is ignored
I
2
C Bus Interface Interrupt Request Flag
0
Waiting for transfer, or transfer in progress
Cleared by reading IRIC = 1, then writing 0
Interrupt requested
Set to 1 at the following times:
Master mode
End of data transfer
Bus arbitration lost
Slave mode (when FS = 0)
When the slave address is matched, and whenever a data transfer ends at timing of
a retransmit start condition after address matching or a stop condition is detected
When a general call address is detected, and whenever a data transfer ends at timing
of a retransmit start condition after address detection or a stop condition is detected
Slave mode (when FS = 1)
End of data transfer
Note:
*
Only 0 can be written, to
1
1
1
Writing 0 issues a start or stop condition, in combination with BBSY
1
Bus Busy
0
Bus is free
Cleared by detection
of a stop condition
Bus is busy
Set by detection
of a start condition
1