bmm150 data

[lmn]

hi,
i am using bmm150，x,y, z dataout are shown in pictures.it is tested in three fixed heading directions at one place.black line is x,red line is y , blue line is z. as we can see ,the data is undulant at a fixed heading direction,the minimum wave is 0.4uT. i want to know if it's correct or not,is it decided by the resolution? Thank you!

[FAE_CA1]

Hi,

Thanks for your inquiry.

BMM150 noise is related to the settings of nXY and nZ as shown below on page 13 of BMM150 datasheet. When write values to register 0x51 and 0x52, then nXY and nZ will be determined.

From Table 3 above, when nXY = 9 and nZ = 15, it is so called Regular preset. BMM150 will take 9 measurements on X and Y axis and then average them as the final results. BMM150 will then put these results in X and Y axes data registers respectively. Similarly BMM150 will take 15 measurements on Z axis and then average them as the final result. BMM150 will then put this result in Z axis data registers. Then the typical noise (1-sigma) on X/Y/Z is 0.6/0.6/0.6uT meaning that when BMM150 is not moving and the external magnetic field doesn't change BMM150 X/Y/Z data will jump up and down within +/-0.6uT range.

If you want to have cleaner data, then you can increase nXY and nZ according to Table 3. But the trade-off is the increase of current consumption.

Thanks.