Magnometer used as odometer


Hi Eric.

We have found out that we can use the magnometer in the MetaMotionR as a odometer by adding a magnet to the wheel at a bike.

We do not use the magnometer input in sensor fusion, so we think we could use the magnometer as an odometer instead.

But is this really a good idea as we also want to have a good estimate of the angles (pitch, yaw and roll). When switching of the magnometer in sensorfusion (IMUPlus mode), is the magnometer still used for other purposes (ex minimizing drift in gyroscope)?

Do you see any arguments for having a magnet passing by the sensor several times Per second affecting sensor fusion (withou magnometer input) or affecting acc and gyr readings?

Further; it seems that the frequence of the magnometer maximum can be 25Hz - any possibility to increase that to up 50Hz?


  • Offhand, the IMU and fused data should be unaffected however, you will want to confirm this with with your own testing.

    No, 50Hz is not supported. Alternatively, you could attach a reed switch to the GPIO pins and simply detect when the digital signal changes to high rather than continuously sampling magnetic field strength.

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