PreArm: Check mag field (xy diff:1xx>100) doesn't go away

ArduCopter
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1

I’m having a pretty bad issue with my drone. Whenever I take it out, usually it will arm and fly for one flight, no matter how long(5sec-5min). Then, when I land it will not arm again and will give the message:

[19:27:56.355] Critical: PreArm: Check mag field (xy diff:118>100)

The first number(in this instance 118) does vary a bit, the highest I’ve seen is 158. This issue just started, and I’m not sure why or what caused it. Nothing really changed with my build. My specs are:

  • 30a ESCs
  • 3s 5ah LiPo
  • Matek H743-Slim
  • Matek M10Q 5883

Attached are some photos of the setup. I’ve checked for motor/compass interference before, and noticed practically none. I’ve tried re-calibrating the compass so many times, but it either serves as a one-flight fix, or just doesn’t work at all.




2

Redo the compass calibration.

You can also increase ARMING_MAGTHRESH from 100 to 160

3 Likes
3

Would changing the arming max impact performance? I’ve tried recalibration about 25 times with no luck.

4

Try using the magfit tool.

While you claim there is little interference, your real world results suggest perhaps another story.

1 Like
5

I received this message as well. was not sure how to get rid of it. I go back and fix it later but for now i can use the below:

“ARMING_MAGTHRESH from 100 to 160” Thanks!

6

Thank you very much for this idea. I’ve used MP’s magnetic interference testing and even at 100%(no props), it’s remained at less than 5% interference. This could, however, be environmental because I was flying off of a rooftop which had a few AC units one building down.

7

The magfit didn’t work. The drone flew the first arm, then refused to take off again. Here’s a compass graph of my last flight. Does it look like vibration is impacting the compass?

compassgraph
compassgraph1213×670 36.1 KB

8

Also please note that vibration is a severe issue with this model. To my knowledge, however, this is doesn’t cause compass issues.

9

If you try calibrate your compass, compass vs motor interference calibration still had the same problem. The9/10 your compass position is too near interference source

1 Like
10

Yeah I agree. The compass is 6 inches from motor and 5 inches from ESC. I’ll buy a proper motor mount instead of using this plastic boba straw and a zip tie lol.

11

By any chance you are using matek compass and gnss? Those are incredibly prone to this error