AK09912 Datasheet, PDF (16/42 Pages) HuaXinAn Electronics CO.,LTD – 3-axis Electronic Compass

6.4. Description of Each Operation Mode
[AK09912]
6.4.1. Power-down Mode
Power to almost all internal circuits is turned off. All registers are accessible in Power-down mode. Data stored in
read/write registers are remained. They can be reset by soft reset.
6.4.2. Single Measurement Mode
When Single measurement mode (MODE[4:0]=“00001”) is set, magnetic sensor measurement is started. After magnetic
sensor measurement and signal processing is finished, measurement magnetic data is stored to measurement data registers
(HXL to HZH), then AK09912 transits to Power-down mode automatically. On transition to Power-down mode,
MODE[4:0] turns to “00000”. When temperature sensor is enabled (TEM =“1”), temperature sensor measurement is started
together with magnetic sensor measurement and measurement temperature data is stored to measurement data registers
(TMPS). At the same time, DRDY bit in ST1 register turns to “1”. This is called “Data Ready”. When any of measurement
data register (HXL to TMPS) or ST2 register is read, DRDY bit turns to “0”. It remains “1” on transition from Power-down
mode to another mode. DRDY pin is in the same state as DRDY bit. (Figure 6.2)
When sensor is measuring (Measurement period), measurement data registers (HXL to TMPS) keep the previous data.
Therefore, it is possible to read out data even in measurement period. Data read out in measurement period are previous data.
(Figure 6.3)
Operation Mode: Single measuremnet
Power-down
(1)
(2)
(3)
Measurement period
Measurement Data Register
Last Data
Measurement Data (1)
Data(2)
Data(3)
DRDY
Data read
Data(1)
Data(3)
Register Write MODE[4:0]="00001"
MODE[4:0]="00001" MODE[4:0]="00001"
Figure 6.2 Single measurement mode when data is read out of measurement period
Operation Mode: Single measuremnet
Power-down
(1)
(2)
Measurement period
Measurement Data Register
Last Data
Measurement Data (1)
(3)
Data(3)
DRDY
Data read
Data(1)
Register Write MODE[4:0]="00001"
MODE[4:0]="00001" MODE[4:0]="00001"
Figure 6.3 Single measurement mode when data read started during measurement period
MS1547-E-02
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2014/7