AK09915D Datasheet, PDF (18/43 Pages) Asahi Kasei Microsystems – 3-axis Electronic Compass

[AK09915D]
9.4.3.2. Normal Read Sequence
(1)Check Data Ready or not by any of the following method.
Polling DRDY bit of ST1 register
Monitor ODDRDY pin
When Data Ready, proceed to the next step.
(2)Read ST1 register (not needed when polling ST1)
DRDY bit: Shows Data Ready or not. Not when “0”, Data Ready when “1”.
ODDRDY pin (connect to pull-up resister): Shows Data Ready or not. Not when “H”, Data Ready when
“L”.
DOR: Shows if any data has been skipped before the current data or not. There are no skipped data when
“0”, there are skipped data when “1”.
(3)Read measurement data
When any of measurement data registers (HXL to TMPS) or ST2 register is read, AK09915D judges that
data reading is started. When data reading is started, DRDY bit and DOR bit turns to “0”.
(4)Read ST2 register (required)
HOFL: Shows if magnetic sensor is overflowed or not. “0” means not overflowed, “1” means
overflowed.
When ST2 register is read, AK09915D judges that data reading is finished. Stored measurement data is
protected during data reading and data is not updated. By reading ST2 register, this protection is released. It
is required to read ST2 register after data reading.
(N-1)th Nth
(N+1)th
PD Measurement
PD
Measurement
PD
Measurement Data Register
(N-1)th
Nth
(N+1)th
DRDY bit
Data read
ST1 Data(N)
ST2
ST1 Data(N+1) ST2
Figure 9.5 Normal read sequence
9.4.3.3. Data Read Start during Measurement
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. If data is started to be read
during measurement period, previous data is read.
(N-1)th Nth
(N+1)th
PD Measurement
PD
Measurement
PD
Measurement Data Register
(N-1)th
Nth
DRDY
Data read
ST1 Data(N)
ST2
ST1 Data(N)
ST2
Figure 9.6 Data read start during measuring
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