AN101
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11 July 2019
Page 26 of 27
Free fall Detect Interrupt Not Working
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Make sure the Free fall engine is enabled (FFIE bit in Free Fall Control Register FFCNTL)
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Try adjusting the threshold requirements to achieve desired operation by adjusting the
threshold value in the FFTH register. If the part is generating interrupts two often, try
increasing the delay/debounce time in the FFC register. If the interrupt is not firing at all,
perhaps the threshold is set too high.
7.
Accelerometer Placement and Orientation
Placement
– It is important to note that the placement of the accelerometer within the target device can
have a significant effect on tap/double-tap direction resolution. If tap detection is desired, the part should
be placed as far away from the edges of the device housing as possible, with the ideal location being at
the target device’s center of mass.
Orientation
– While it is recommended to align the accelerometer’s axes with those of the target device,
it will sometimes be desirable or ne
cessary to alter the part’s orientation with respect to the device
housing. Rotating about the Z axis at intervals of 90 degrees or about the X or Y axes at intervals of 180
degrees should not impact functionality. However, it is highly recommended that the device is not rotated
90 or 270 degrees about the X or Y axes. Due to the asymmetrical nature of the tilt position function,
altering the orientation of the Z axis in this manner can cause incorrect screen rotation direction
resolution.
