[AK09916]
9.4.3. Continuous Measurement Mode 1, 2, 3 and 4
When Continuous measurement mode 1 (MODE[4:0] bits = “00010”), 2 (MODE[4:0] bits = “00100”), 3
(MODE[4:0] bits = “00110”) or 4 (MODE[4:0] bits = “01000”) is set, magnetic sensor measurement is
started periodically at 10 Hz, 20 Hz, 50 Hz or 100 Hz respectively. After magnetic sensor measurement and
signal processing is finished, measurement magnetic data is stored to measurement data registers (HXL to
HZH) and all circuits except for the minimum circuit required for counting cycle length are turned off (PD).
When the next measurement timing comes, AK09916 wakes up automatically from PD and starts
measurement again.
Continuous measurement mode ends when Power-down mode (MODE[4:0] bits = “00000”) is set. It repeats
measurement until Power-down mode is set.
When Continuous measurement mode 1 (MODE[4:0] bits = “00010”), 2 (MODE[4:0] bits = “00100”), 3
(MODE[4:0] bits = “00110”) or 4 (MODE[4:0] bits = “01000”) is set again while AK09916 is already in
Continuous measurement mode, a new measurement starts. ST1, ST2 and measurement data registers (HXL
to TMPS) will not be initialized by this.
(N-1)th
PD
Nth
Measurement
(N+1)th
Measurement
PD
PD
10Hz,20Hz,50Hz or 100Hz
Figure 9.4. Continuous measurement mode
9.4.3.1. Data Ready
When measurement data is stored and ready to be read, DRDY bit in ST1 register turns to “1”. This is called
“Data Ready”. When measurement is performed correctly, AK09916 becomes Data Ready on transition to
PD after measurement.
9.4.3.2. Normal Read Sequence
(1) Check Data Ready or not by polling DRDY bit of ST1 register
DRDY: Shows Data Ready or not. Not when “0”, Data Ready when “1”.
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”.
(2) Read measurement data
When any of measurement data register (HXL to TMPS) or ST2 register is read, AK09916 judges
that data reading is started. When data reading is started, DRDY bit and DOR bit turns to “0”.
(3) 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, AK09916 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
Data read
ST1 Data(N)
ST2
ST1 Data(N+1)
ST2
Figure 9.5. Normal read sequence
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015007392-E-02
2015/12
AKM [ ASAHI KASEI MICROSYSTEMS ]
