AK09912 Datasheet, PDF (25/42 Pages) HuaXinAn Electronics CO.,LTD – 3-axis Electronic Compass

[AK09912]
7.2.1.3. Acknowledge
The IC that is transmitting data releases the SDA line (in the “High” state) after sending 1-byte data.
The IC that receives the data drives the SDA line to “Low” on the next clock pulse. This operation is referred as
acknowledge. With this operation, whether data has been transferred successfully can be checked.
AK09912 generates an acknowledge after reception of a start condition and slave address.
When a WRITE instruction is executed, AK09912 generates an acknowledge after every byte is received.
When a READ instruction is executed, AK09912 generates an acknowledge then transfers the data stored at the specified
address. Next, AK09912 releases the SDA line then monitors the SDA line. If a master IC generates an acknowledge
instead of a stop condition, AK09912 transmits the 8-bit data stored at the next address. If no acknowledge is generated,
AK09912 stops data transmission.
Clock pulse
for acknowledge
SCL FROM
MASTER
1
8
9
DATA
OUTPUT BY
TRANSMITTER
DATA
OUTPUT BY
RECEIVER
START
CONDITION
Figure 7.5 Generation of Acknowledge
not acknowledge
acknowledge
7.2.1.4. Slave Address
The slave address of AK09912 can be selected from the following list by setting CAD0/1 pin. When CAD pin is fixed to
VSS, the corresponding slave address bit is “0“. When CAD pin is fixed to VDD, the corresponding slave address bit is “1“.
Table 7.1 Slave Address and CAD0/1 pin
CAD1
0
0
1
1
CAD0
0
1
0
1
Slave Address
0CH
0DH
0EH
0FH
MSB
LSB
0
0
0
1
1 CAD1 CAD0 R/W
Figure 7.6 Slave Address
The first byte including a slave address is transmitted after a start condition, and an IC to be accessed is selected from the
ICs on the bus according to the slave address.
When a slave address is transferred, the IC whose device address matches the transferred slave address generates an
acknowledge then executes an instruction. The 8th bit (least significant bit) of the first byte is a R/W bit.
When the R/W bit is set to “1“, READ instruction is executed. When the R/W bit is set to “0“, WRITE instruction is
executed.
MS1547-E-02
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