Cannot get APM 2.8 External Compass to work


I purchased an APM 2.8 “clone”. I am unable to calibrate the external compass using Mission Planner 3.3.1.

I have removed the jumper next to the MAG connector, as instructed, to use an external GPS/MAG. When I go to do the Live Calibration in Mission Planner, there is no rotation around the axis. With the jumper in place for using the internal compass, the sampling seems to be taking place in only one quadrant of the axis.

I have tried soldering a jumper across the “MUX_SDA and MUX_SCL” points on the back of the board (I2C Port), nothing!!
In Mission Planner, the “Compass_External” setting is set to “1”… don’t know what is going on.

Really would appreciate the help to get this thing to work.



Try swapping the two wires in the i2c connector. Also, make sure you are using the correct port and make sure the GPS is getting power and can get a fix.