AK09915D Datasheet, PDF (16/43 Pages) Asahi Kasei Microsystems – 3-axis Electronic Compass

[AK09915D]
9.4. Description of Each Operation Mode
9.4.1. 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.
9.4.2. Single Measurement Mode
When Single measurement mode (MODE[4:0] bits = “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 AK09915D transits to Power-down mode automatically. On
transition to Power-down mode, MODE[4:0] bits turns to “00000”. At the same time, DRDY bit in ST1
register turns to “1”. This is called “Data Ready”. When any of measurement data registers (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. When DRDY bit turn to “1”, ODDRDY pin is “L”. When DRDY bit turn to “0”, ODDRDY pin is “H”.
ODDRDY pin is low active.(Figure 9.2)
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 9.3)
Operation Mode: Single measuremnet
Power-down
(1)
(2)
(3)
Measurement period
Measurement Data Register
Last Data
Measurement Data (1)
Data(2)
Data(3)
DRDY bit
Data read
Data(1)
Data(3)
Register Write MODE[4:0]="00001"
MODE[4:0]="00001" MODE[4:0]="00001"
Figure 9.2 Single measurement mode when data is read out of measurement period
Operation Mode: Single measuremnet
Power-down
(1)
(2)
(3)
Measurement period
Measurement Data Register
Last Data
Measurement Data (1)
Data(3)
DRDY bit
Data read
Data(1)
Register Write MODE[4:0]="00001"
MODE[4:0]="00001" MODE[4:0]="00001"
Figure 9.3 Single measurement mode when data read started during measurement period
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