uBlox compass configuration problems - east is west

Hi all,
I can’t find a good description of how to calibrate your compass and I also have some problems with my compass’ readings.

I have a Pixhawk autopilot module and a 3DR uBlox GPS/compass module. Connecting this module is simple (my compass is connected through the I2C splitter so not directly to the Pixhawk). In mission planner I want to set-up my compass so I did the following:

  1. Connect via COM to Pixhawk
  2. Go to: ‘Initial setup’ -> ‘Mandatory Hardware’ -> ‘Compass’.
  3. Choose the option: ‘APM with External Compass’ AND select ‘rotation_none’ from the drop down menu next to ‘Manual’. I selected ‘rotation_none’ because my GPS/compass module is upside down and the arrow is pointing in the same direction as the arrow on the Pixhawk, so a belly-to-belly set-up.
  4. Click ‘Live Calibration’ and turn a bit with the Pixhawk.

But… when I now check my compass readings in ‘Flight Data’ I get this very weird result: North is not were North is AND East and West are switched. So if I turn 90degrees clockwise starting from North my compass says he is looking to the West…

Note: how do you know if the new settings “external compass” have been saved? Because when I open the compass tab a second time the checkbox is at ‘Manual’ again and not 'External’
Also, I’ve read that if you connect the uBlox module to Pixhawk, the internal compass is automatically turned off, although I have a fealing that both are turned on, because if you turn (yawing) either of the two modules seperately the measured heading in mission planner changes.
Can anyone help me?

Since your FC is a Pixhawk, you need to select “Pixhawk/PX4” in the compass FC selection menu and not “APM with External Compass”.


You can check the parameters:
copter.ardupilot.com/wiki/arduco … ASS_ORIENT
copter.ardupilot.com/wiki/arduco … S_EXTERNAL

To access the parameters go to config/tuning, planner, check the Advanced view checkbox (on the bottom right), click again in config/tuning, go to full parameter list