Servers by jDrones

Compass working or not?

I have a “new” Pixhawk 2.4.8 from an Amazon seller. My older Pixhawk board was getting flaky readings from the Z accelerometer so I replaced it. I’m very much a novice, I build a quad like 4 years ago, did a couple hover tests, and haven’t really touched it until the past month or so.

Anyway, since my past unit went bad, I have my Pixhawk connected via USB (2 meter cable) to my laptop, no other hardware connected. I’ve tried in Mission Planner and QGroundControl, and I can’t get the compass calibration to work. The green bar does not move/fill at all when I move the Pixhawk around.

I’m not sure whether I have a bad board or what.
First off, is there a way to view the readings from the onboard compass(es) to see if they’re responding when I move the Pixhawk around? At least in QGC, the heading appears to change when I rotate the device, but that may just be because I calibrated the accelerometers and it can tell it’s moving.

Second, if the compass does work, how do I get the calibration to work?

I intend to use the Pixhawk with a Neo-7M GPS but if the board is bad I will return it for replacement before I go on with rebuilding my quad.

I have Copter 4.0.3 loaded if that matters. This seems more like hardware but what do I know?


Start up NOT facing north and see if the Missionplanner HUD matches that, that is shown as facing something other than north. Then see if rotations and the HUD track the real direction.
If it always shows as facing north when you start up then there’s no calibrated/functioning compass.

Starting up in a different orientation makes it “think” North is in a different spot, so that’s good, I guess. Sitting still on my desk, though, the compass drifts slowly in one direction.

I relaxed the compass calibration fitness, still will not calibrate. COMPASS_CAL_FIT is set to 32, but the calibration “green bar” does not advance.

I’ll try calibrating it powered by battery. If that doesn’t work, I will contact the seller on Amazon, as I believe the board is bad.

If you start upfacing south the HUD should immediately show south (not north).
Anything else indicates your compass is not working.

W/o a compass it will always point N on boot regardless of which direction it’s pointing and then wander around from the Z-axis gyro after that. Post a screenshot of thr HW ID screen in Mission Planner after connection.

Also, whether it works or not its pointless to calibrate the compass w/o it being on the completed craft with a battery powering it. The whole point is to compensate for mag interference from the craft.

Don’t worry about the internal compass. Just disable it and use the external compass on the GPS.

Speaking of GPS, an M8N is much better than that 7 you have…

Pointless for actual use, sure. Not pointless for seeing if the board functions nominally before the merchant’s return window closes. This board appears to be bad - the onboard compasses appear inoperative. Also, after calibrating accels and level, the z accelerometer is throwing random accelerations between -2 and +2 m/s on every reading, whether it’s just sitting on the desk, or being manually moved in the z axis.

its not common for these boards, even the cheapest ones, to have hardware problems as you suggest. Post the HW ID screen to troubleshoot it or return it, up to you.

I’ve set up a return/refund. Ordered a Beaglebone Blue + new Neo 8 GPS, so that’ll give me something to tinker with for a while. :smiley:

Servers by jDrones