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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  • Developer

    Tridge and I played around with the onboard compass calibrator this morning and found at least two issues.

    #1. the COMPASS_CAL_FIT parameter is set too low by default (it's 8 but maybe 20 would be better) meaning the calibration is too strict.  Maybe some people here could help us figure out what the default should by by running the onbaord calibrator and tells us what "fit" values are reported for the two compasses.  For me compass #1 was 15.6, #2 was 44.5.

    3702239130?profile=original#2. Mission Planner isn't clearly reporting if the calibration is succeeding or failing (issue here).  When it completes MP shows offsets and a "fit" value (for each compass) but you only know it's successful by checking yourself if the first compass's "fit" value is under COMPASS_CAL_FIT and the 2nd compass's fit value is below 2x the COMPASS_CAL_FIT.

    So anyway.. if people could try increasing that compass-cal-fit parameter to 20 and then do an onboard calibration and report the "fit" values they see that'd help us get this default set better, thanks!

    Report Onboard compass failure · Issue #1246 · ArduPilot/MissionPlanner
    In Copter-3.4 there's a new onboard compass calibrator. When the compass calibration fails, there's no clear indication in mission planner th…
    • Randy, I did the calibration twice. All I see when it is complete is the offset for each compass. No fit number.

      • Developer


        Also I'd like to check that you're using the OnBoard compass calibrator. I've highlighted below how to kick this off from the Mission Planner.


        • Randy


          I too am having compass calibration issues

          MP 1.3.37 build 1.1.5917.13431 APM:Copter V3.4-dev(39c29820)

          I would like to be more helpful but coming from CF/BF, am not verse in issues that arise from this type of FC format

          Could you please answer the below? 

          3 things while configuring PixRacer compass in MP,

          1) at top it says select device to quick configure par's. Do I select anything here?

          2) Do you want what is boxed in pic above done in configuration as well as live calibration

          3) Here, you want this information, How does one capture that for you. Could you spell it out for me?

          I've never done that before. 

 COMPASS_CAL_FIT is 8 and has no values under the "range" column

          • 1: Don't select anything
            2: Just do the onboard calibration, which is the box in the above pic.
            3: after you do step 2, it will show you the values he's asking for.. which is what he's pointing to in the pic above. 

            4:  Enter a higher number.  If you do a compass calibration first, it will show you what you actually get (as per # 3 above), then you could enter that..   But then you'll probably have to calibrate again.
            Otherwise, just enter a higher number.. 20 or 40, then calibrate. 

            • I'm sorry, but if I do a fresh install of the FW, I get no results when I press start when doing  "on board mag calibration". I tried live calibration as well and only one compass calibrated.3702893453?profile=original

              • Developer


                You're using Copter-3.3.4 it looks like from the menu bar of MP.  Onboard compass cal is only available in Copter-3.4 which is still in "alpha" testing but can be downloaded by pushing Ctrl-Q on the MP's Install Firmware page.

                • Also check external on #1 after loading the 3.4-dev using what Randy said CTRL-Q while in the load firmware section.

            • What is currently the best flash for FW?

              • I am using the current 3.4dev as of today. This afternoon the wind died down giving me time to do a save trim and get a little flight time and it flew beautiful. I am well pleased with the progress our DEV team is making. Hope to play with ACRO tomorrow.

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