CMA3000-D0X Datasheet, PDF (9/35 Pages) VTI technologies – 3-axis accelerometer

CMA3000-D0X Series
Figure 3. The MD band-pass filter's frequency response.
Threshold level can be controlled by MDTHR[6:0] bits and the time condition – how long the
threshold should be exceeded to trigger – by MDTMR[3:0] bits.
Acceleration exceeds
Acceleration _{the threshold level}
X, Y or Z
due to motion ∆T
period of time
∆T
+TL
T1
T2
T3
T4
T5
T6
T7
T8 Time
-TL
INT output
"1"
"0"
T1
T2
T3
T4
T5
T6
T7
T8
Figure 4. Motion detector operation
2.4.2 Usage
The MD mode can be enabled by setting the MODE[2:0] bits in the MODE register to "100". The
trigger condition, threshold and duration, can be defined by setting MDTHR and MDFFTMR
registers respectively. The device can be configured to switch automatically into 400Hz
measurement mode by setting the MDET_EXIT bit in CTRL register. See section 3.3 register and
section 2.6 for the interrupt functionality details.
In MD mode, band pass filtered acceleration data with 10Hz output data rate is available in
registers DOUTX, DOUTY and DOUTZ.
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Rev. 0.12