I am using the python app (eMPL-client.py) found in the MotionFit SDK v5.1 release to look at the performance of the MPU-9150.
With the "pygame window" in focus I can use the following commands to affect the output of the MotionFit (concerning magnetometer):
- invh: toggle heading display
- invc: toggle compass display
- inv1: reduce sampling to 10Hz (easier to read output)
- invx: resets micro (so things return to defaults)
- inv0: toggle compass sensor on/off (compass values will stop displaying if compass is off)
I really want a heading that is relative to North, but the heading is always relative to the startup position for the device. Also, I don't notice much help from the compass in terms of drift compensation in the heading value. Each time I rotate the sensor a full 360 I get a heading value that's 2-4 degrees off from where it started. If I keep rotating in the same direction, this becomes very obvious either with the compass on or off.
It seems the magnetometer is not yet effectively utilized. Could anyone comment on this?