Zubax compass won't initialize on UAVcan via onboard power?

@rdbachtell and I are experiencing the same issue with our Cube 2.1 flight controllers on ChibiOS with the Zubax GNSS. Randy is running the latest master of AP, and I’m running 3.6.5. When we power up the drone via battery power and the cube power module, the Zubax’s on-board compass will not initialize. If we boot up the cube via USB power, and then switch over to on-board power, the Zubax compass initializes successfully. Any idea what’s going on? This is not an issue on Nutt. I have an impending deadline to deliver 2 of our companies utility inspection drones and would love to have this sorted as soon as possible. @rmackay9 @tridge any ideas? We’re stumped. Cheers!


It could be that AP is trying to communicate with the compass before it’s ready (perhaps ChibiOS starts a little quicker than NuttX). Or pehaps it is a hardware issue involving the speed of the voltage rise at startup. I suspect if the compass is powered from an external BEC it works OK.

I’ve added it to our 3.6 issues list but I think if Copter-3.6.x on NuttX works then it would be best to stick with that for now because I can’t guarantee when we will get to it.

By the way, for companies that are reliant on ArduPilot (and there are many!) it’s possible to speed up resolution of items by hiring a developer short-term (see our commercial support page) and/or becoming a Partner also helps. I’m not in any way trying to push you to pay of course, we try and resolve issues from everyone as best we can.

1 Like

For what it’s worth. Some zubax GPS have an on board power issue. I believe that was how they described it to me. I had to have them replace it. Not saying it’s the same thing…but putting it out there.

1 Like

Once we have a couple more sales we are eager to become a partner at the very least! We are very grateful for ardupilot and the community behind it.


Hmm, looks like this may impact us as well. Initial thinking it’s what @rmackay9 indicated - that the AP is enumerating the compasses before the Zubax unit has completed initialisation - because a soft reboot of the AP without touching the GNSS will then detect the compass as expected.

@tridge & @peterbarker - could you confirm whether this seems to be the case on your hardware?