Hello, We are using the BMA280 accelerometer for a remote controller (RC) which allows to change the volume on an audio device. We are currently trying to improve this product. The BMA280 is used in order to detect whether the RC is worn by the user or unused, in order to go to sleep mode when the device is unused (no movement detected after around 10 min). We face difficulties to detect that the RC is worn when the user is sitted and wears it in the pocket, because the movement are very slight (we consider that the user sometimes moves the legs, etc). In this specific case, the RC goes to sleep mode undesirably, after a few minutes without movement detection. The initial parameters were as follow: Bandwidth: 0x0b (62.5 Hz) Slope threshold (any-motion mode): 0x04 (16.65 mg in 2-g range) Low power mode 1 with sleep phase duration of 50 ms (0x0c) We already tried the following things: Lower the threshold: as we lower the threshold, obviously the RC gets more sensitive to the user movement, but it also gets more sensitive to shocks, and false positives appear in situations where the RC should go to sleep mode. Reduce the bandwidth: as the bandwidth gets lower, the RC gets more sensitive to the user movement, while the sensitivity to shocks is reduced, which is optimal. However, unfortunately this increases a lot the power consumption, as the samples update time gets higher. By increasing the number of slope above threshold before triggering interrupt (“slope_dur”), we can reduce the number of false positives induced by using a low threshold. By playing with these three parameters, we could reduce the percentage of times the RC is undesirably in sleep mode from 8% to 1.5% of the time during which the RC is worn, but this also greatly increases the power consumption due to the usage of a lower bandwidth, which is not acceptable for this product. 1) Do you have any suggestions in which way we could improve the detection for slight movements? Are there other parameters which we could play with? 2) It seems that reducing the bandwidth is visibly not a good solution because of its large effect on consumption. But if we increase the sleep phase duration (in low power mode 1), does it have somehow a similar effect? 3) Maybe the BMA280 is not the most suitable accelerometer for this application? Thank you in advance for your help!
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