BMM350 - raw uncompensated magnetic data - µT / LSB and range given 24-bit widths for axes

[spkarjalainen]

Hi,

When reading in raw uncompensated 24-bit values for the magnetometer X,Y and Z axes, how many micro-Tesla per LSB ?

I know the datasheet states (approx) ~0.1µT resolution, but this doesn't seem to coincide with the stated 16-bits across a +/- 2000µT measurement range, not to mention that the raw registers are 24-bits wide?

Can anyone clarify this for me?

Kind regards,

Sam

[FAE_CA1]

Hi,

Thanks for your inquiry.

BMM350 doesn't have sensitivity parameter in the unit of micro-Tesla (uT) per LSB. Each BMM350 has trimmed values stored in its NVM before going to the market. The microcontroller (MCU) needs to read those trimmed values from BMM350 NVM. And then each time when the MCU reads new measurements or raw data from BMM350, the MCU needs to plug those trimmed values and raw data into a formula in order to get compensated magnetic field results in the unit of uT.

Please refer to the function " bmm350_get_compensated_mag_xyz_temp_data()" in bmm350.c file on the Github at https://github.com/boschsensortec/BMM350_SensorAPI for more information.

Thanks.