Drotek XXL GPS + compass = inconsistent compasses?

It is killing me. I spent whole day anf whole night (it is 6AM now) trying to get consistent results.

I have mounted my XXL unit, twisted signal wires, packed them into alu-tape, did the same for power wires, than packed it into nice termo-tube… And all of it for nothing. I believe my unit is broken…

Arducopter 3.4.2
Pixhawk solid mounted at 0 degree
XXL GPS is solid mounted at 90 degrees counter clock wise (arrow left)

What I tried

  1. 180 roll 270 yaw
  2. 180 roll 90 yaw
  3. 180 Pitch


  • For some reason results are super inconsistent, even with telemetry, osd, and buzzer unplugged. For example Roll 180 is missing north by 20degree now. I calibrate again and off by 15degree and imidiate message Inconsistent Compasses
  • 180 pitch looks at the opposite direction and still misses it by 20 degree
  • Roll 180 yaw 315 give the best result x7 y93 z197 vs about x76 y76 z200 for the rest! after calibration it is almost spot on!

all of that with Compass 2 not used (internal)

My question, why the hell would compass give best result at -45degree yaw angle?? Further more after a minute it would suddenly start moving away and end up looking 90 degree off…

If I chose manual declanation instead of automatic, my compas direction can change by about 60-80 degrees, is it normal?

also the 5985 compass installed so that X is to the left, Y is towards you z is looking at the floor (that is if you hold it in front of you with arrow foreword), but pixhawk/px4 have X forward (not left), Y to the right (not at you), and Z looking up (not down)

  • so in theory when it is looking forward (according to arrow) one would have to set it as 180Roll and 90Yaw - that is way for me 180Roll would be on spot, as I have it installed 90Yaw CW.

Please advice what can that be… I have many years experience testing equipment, but that is just all over the place (Iphone Compass is so much more reliable than that)

You have to choose roll180 option to configure the XXL GPS. You should move the GPS away from the Dropix and calibrate the magneto in the right way.

created new topic, more elaborate.