Hi Carlo,
The motion detection function is an analysis of low-pass filtered data only, even if the high-pass filter is enabled (HPF_OUT = 1). I would recommend using the transient detection function instead as it analyzes high-pass filtered data unless the HPF_BYP bit is set. For more information on the transient detection function including example register setting please refer to the AN4071.
I hope it helps.
Regards,
Tomas
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