BMX160 latching times are not valid for all ODRs

[timmbo]

Hey there,

if I configure the BMX160 to record 6.25 Hz acceleration data in low power mode, like that:

BMX160_ACCEL_ODR_6_25HZ

BMX160_ACCEL_BW_RES_AVG1

BMX160_ACCEL_RANGE_2G

and to generate an AnyMotion interrupt, I measure that the latching times are not as stated in the datasheet (page 72).

For the 5 ms latching setting (0b0101) I measure that the interrupt is latched for around ~160ms. For 50 Hz it seems to be correct (5ms).

Is the latching setting not constant but depending on the ODR? There is a sentence on page 72 stating that the times are selected to be 50% of the prefiltered data rate and then power 2 increments. So for 6.25 Hz it would be (0.5 * 6.25) * (2^5) = 100ms, which still isn't what I measure.

Very confusing!

Thanks & Greetings,

Timm

[BSTRobin · Accepted solution]

Hello timmbo,

Normally, the ODR required by any motion feature shall be greater than or equal to 50 Hz. Too low ODR will lead to the algorithm can not detect correctly.