BMi270 No Motion graph explanation

[ak0]

Hi,

I am terying to understand the No Motion visualisation presented through Graphical images on the page No 46 of the datasheet.

As per the image, the slopw in second graph should be zero, when acceleration is peaking (in first graph).

Can someone explain this behaviour, or how are we actually calculating slope of Acceleration and how to relate that to the second graph?

Regards

[BSTRobin]

Hi ak0,

Thanks for your inquiry.
No motion detection interrupt is generated when the slope on all selected axis remains smaller than a programmable threshold for a programmable time.
Duration defines the number of consecutive slope data points of the selected axis which must stay under the threshold for an interrupt to be asserted.
For example, red 1 on the graph, although the slope is smaller than the threshold, the duration does not meet the duration requirements and no interrupt is triggered. Red 1 on the graph, not only is the slope smaller than the threshold, but the duration also meets the duration requirements, an interrupt is triggered.

[ak0]

Thanks for the reply.

My confusion is how the slope is calculated and represented in the "Slope vs samples"graph.

1. What is delta"t" here, is it the time gap between next sample? Is it fixed?
2. At the peak of the signal (first blue marker), slope seems maximum. and at second blue line slope seems minimum, Is that correct?
3. If above pint is correct, why third blue line is not minimum slope (as it has the lowest Acc value)?
4. Are these rough graphs or this slope calculation is accurate?

Regards,

Anurag