Compass Error when connecting to RPi through telem2 port


I am using a Pixhawk 2.1 cube with Here GNSS and connecting it with a raspberry pi to send dronekit commands through the telem2 port. Now this is giving me a bad compass error and the magfield value in the status tab of Mission Planner just freezes. Pixhawk just stops reading the Here compass data. This happens as soon as I connect the pi to the telem2 port. I have a 3DR telemetry module connected to the telem1 port so I am using the telem2 port to connect to the pi.

At first I was scratching my head as why the error is showing up when I flew it, on RC without Pi without any issues and all 3 compass were showing up in the calibration menu. When I connected the Pi to the Telem2 port, the compass1 just shut off and it didn’t show in the calibration either. It’s only happening as soon as I give power to the pi through the port.

Is this supposed to happen, or is my unit defective? Or is there some option or parameter I have to set in order to make it work.

Thank you,

I had a feeling that the current draw would not be enough but had to be sure.

Can I power it through the AUX ports on the pixhawk? Or is another ESC or BEC (or buck converter) the only option?


Well using the AUX ports it works perfectly… Probably because the ESCs are also giving power at the rail. So now I’m power the Pi from the AUX pins and using the RX,TX and GND of the Telem2 port.