AHRS Orientation and Compass Orientation help

I'm going mental.  Can someone please tell me how to set AHRS Orientation and Compass Orientation for the following setup:

PX4 upside down and front pointing to the left of the vehicle

GPS module upright and front to the front of the vehicle


I thought AHRS orientation should be "14", but I can't work out how to determine the Compass orientation relative to that.  I'm getting a compass heading that's about 45 degrees off the actual vehicle heading.

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  • Gaah!!  The GPS is upside down in its housing - http://rover.ardupilot.com/wiki/common-installing-3dr-ublox-gps-com...


    According to Mission Planner, the COMPASS_ORIENT for PX4 should be set independent of the AHRS_ORIENTATION, which seems to mean COMPASS_ORIENT should be "8" in my config regardless of PX4 orientation.


    However, I still seem to be having some odd compass issues - it loses calibration or orientation and ends up at about 90 degrees to the vehicle orientation, and I get "BAD COMPASS HEALTH" messages coming up. Any thoughts?

    • Did you found a solution MikeRover? 

      I do have the very same problem.


      • What's your particular problem?  It turned out I'd misread the doco and the PX4 / Pixhawk "knows" that the compass is upside down. The upshot is, if you have the pixhawk and the GPS module mounted in their normal orientation, you just select (I think it's called) "pixhawk" normal orientation.


        I think all my problems were due to telling the system the compass was upside down when it already knew.


        What's your exact config?

    • Have you gotten it to work? 

      I am working on building a copter atm but I would like to know about how hard it would be to set px4 sideways. (Mechanical design is such that the size of px4 creates a requirement for it to be sideways to flight direction.) 

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