How to change the sensor output data rate (Hz) of IIS3DWB vibration sensor?

[JTam.1]

Hi, The ST BLE Sensor App can change the output data rate. However, I cannot find any detail how to change it on IIS3DWB by its register via SPI. Please advise. Thanks!

[TBomb.1 · Accepted solution]

Hi, the datasheet p.5 reports that for the IIS3DWB the ODR is fixed at 26.667Hz (with flat band up to 6kHz).

https://www.st.com/resource/en/datasheet/iis3dwb.pdf

The BLE Sensor App uses the same default for all the sensors, and you should also check if there are limitation in the data transmission via BLE.

Tom

[JTam.1]

Hi, you meant the ODR of the IIS3DWB sensor is fixed at 26.667kHz. If the BLE Sensor App do not match with the sensor's ODR (26.667kHz) and change the sampling rate to 6660Hz, was the result of FFT data wrong? Or the changed sampling rate on BLE Sensor App was just like the MCU using LPF (Low pass filter, ODR/4)? Please advise. Thanks!

[TBomb.1]

I suspect the BLE app sends to the board FW the command to set ODR 6660Hz, and the firmware manages (not using LP filter) a downsampling from 26.667kHz.

Tom

[JTam.1]

Hi ST Engineers,

If the BLE Sensor App do not match with the sensor's ODR (26.667kHz) and change the sampling rate to 6660Hz, was the result of FFT data or measuring acceleration data going wrong?  Do I need to re-correct the ODR to 26.667kHz in MCU code? Please advise. Thanks!