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]

Hello timmbo,

Please note that the mimimum ODR of accelerometer was 12.5 Hz.

[timmbo]

Dear BSTRobin,

thanks for your feedback. So all interrupts should only be activated with an ODR >= 12.5 Hz?

Best, Timm

[BSTRobin]

Hello timmbo,

The minimum ODR required by BMX160 is 12.5 Hz.

[timmbo]

Dear BSTRobin,

sorry, but I think this is not true. The BMX can be configured down to 0.78 Hz, which can be seen in Table 9. All interrupts also work at lower ODRs, but as I said, the latching of the interrupt pin seems different.

Best, Timm