PixRacer with Ardupilot

This is a discussion to focus the feedback and support of ardupilot on the PixRacer board from

We believe that all teething problems encountered are now resolved and so we recommend people load Copter-3.3.4 which is available for all multicopters through the Mission Planner's (and other GCS's) Install Firmware screens.  Note that because regular Pixhawks are still on Copter-3.3.3 the install icon may show Copter-3.3.3 but rest assured, Copter-3.3.4 will be installed (you can check the version by looking at the very top of the Mission Planner).


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                • did you load any default settings when picking frame type?

                  With todays FW  build, I tried to calibrate compass using on on board mag only and still only one compass is live. I have had two in the past. Need clarification, am I only supposed to do onboard mag cal with a fresh install or should I have chosen a quick device to configure first in the window up top? if so, which HW version?  

      • Developer

        Hmm.  Very weird.  Can you try raising that COMPASS_CAL_FIT number to something really high, like "40" and see what happens?

    • Developer

      as a side note, I did a comparison of the resulting "fit"ness of the compass calibration on a Pixhawk vs a PixRacer and found the numbers were far lower (i.e. far better) on a regular Pixhawk.  Pixhawk fitness was less than "4" for both internal and external compasses.  For Pixracer the numbers were (as mentioned above) 15.6 and 44.  Note that these numbers are not necessarily linear so I'm not saying the regular Pixhawk's compass is 4x better than the Pixracer.. I'm just pointing out that there's a hardware difference that is coming into play here.

  • Leonard

    if you have time could you look at this

    I know you requested a current build log

    Here  is my log of current Build APM:Copter V3.4-dev (f23bd7e0)

    here is what I have

    ZMR 250 Carbon

    DYS XM20A W/belhil and oneshot 125 compatable

    Multistar elite 2204  2300

    Kingkong 5 x 4

    M8N Mini from rtfq (replacing  don't trust it)

    MP 1.3.37 build 1.1.5968.13722

    Hover throttle 350

    set MOT_PWM_TYPE = 1 (oneshot) (going to change back to 2 oneshot 125, has less wobble)

    Arming switch removed only buzzer connected (had some problems when connected)

    This latest (ctrl-Q) is working for me

    I am going to test more but this looks very promising. This is my current setup and no PID tuning. What problens I have stated may very well be from my lack of knowledge on my part so If you see things please feel free to tell me.

  • I just installed the latest build of today on my Pixracer and I still do not get my compasses calibrated correctly.

    The calibration process seems to work (both. live and onbord), but during boot I see the message: 

    "PreArm: Compass not calibrated"

    I did a quick install with 3.3.3 and compass calibration is accepted.

    I have no idea, if that's related, but if noticed some wired behavior (on 3.4-dev):

    when I disconnect the Safety-Switch, Live Calibration works as usual, I need to turn the copter on each single axis and the calibration is accepted.

    With a connected Safety-Switch, Live calibration is finished after a short turn on one axis (maybe 45deg).

    In any case, PreArm-Check fails with: "PreArm: Compass not calibrated".

    is there still a bug, or am I doing something wrong?

    Best regards


    • Developer

      Hi Thomas, 

      I think this is a bug and I am looking into it.

      Could you attach a parameter file with your parameters before and after a calibration?

      Thanks for your patience!!

      • Hi leonardthall,

        attached you'll find 3 param files.

        The first one after a boot, the second one after live calibration and the third one after onbord calibration (this sequence).

        Thanks a lot for having a look into it.


        • Developer

          Thanks Thomas!!

          • Hi Leonard,

            are there any news to this topic?

            Would be great to have all compasses working perfectly before starting to try out some missions and other enhanced stuff.

            Best Regards


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