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Companion computer not communicating


I am trying to use an RPi 3 as my companion computer. I’ve flashed the raspbian image onto the pi, loaded firmware onto the Pixhawk and set up the static IP on my surface computer. I am connected to the pi via ethernet and I have the pixhawk connected via USB, but when I start up QGroundControl, no vehicle connection is detected. I tried testing the MAVproxy as instructed on the troubleshooting page of the Ardusub gitbook, and i got the output shown below.

pi@raspberrypi:~ screen -r mavproxy There is no screen to be resumed matching mavproxy. pi@raspberrypi:~ ~/companion/scripts/start_mavproxy_telem_splitter.sh
Connect /dev/serial/by-id/usb-3D_Robotics_PX4_FMU_v2.x_0-if00,115200 source_system=200
Failed to connect to /dev/serial/by-id/usb-3D_Robotics_PX4_FMU_v2.x_0-if00,115200 : [Errno 2] could not open port /dev/serial/by-id/usb-3D_Robotics_PX4_FMU_v2.x_0-if00: [Errno 2] No such file or directory: '/dev/serial/by-id/usb-3D_Robotics

Are there any additional steps that I need to take in order to make mavproxy work? Any help would be appreciated.


I saw in another post that ardusub is only supported on pi 3b at the moment so maybe a bit of code conflict going on

I am using a 3B, so I can’t imagine there would be any conflict.

Hi Isaac,

Run lsusb or ls /dev | grep ACM to see if the pixhawk is connected to the raspberry.
Check the USB cable to make sure.


Hi Patrick

So I used the commands you suggested and I got this response, but I’m not really sure how to interpret this. Does this mean the Pixhawk is connected?


Yes. Try ls /dev/serial/by-id if you see usb-3D_Robotics_PX4_FMU_v2.x_0-if00 there then you will not get the error in your original post.

Hi Jacob,

I tried it and it worked. I’m not exactly sure what I did to fix it, but everything seems to be working now. I started up QGroundControl and the vehicle has been detected.

Thank you for your help

Hi Jacob,

I connected a spare PI 3 + low light USB from your electronics package to my computer
and wanted to check if I get the video on QGC.
I do this in order to test a more complex installation with a switch and additional camera prior to doing it really on the ROV which is currently in operation for a project.

I previously flashed the companion program from ardusub on a micro SD card. I connected the PI to a USB for power and configured the ethernet network as for the ROV with the ethernet cable. Nonetheless, I do not get any connection btw the PI and the computer.

The power led is red, the ACT led does not flash and the ethernet led does not flash so it seems to be a problem with the PI. Does the PI need to be connected to a pixhawk absolutely in order to work properly?

Any other idea?

Thank you in advance


There is no support for Pi 3B+. Only Pi 3B.

This is a Pi 3B , sorry for the misunderstanding. I meant PI 3 AND low light USB camera.

Try a stronger power supply, the ACT light should blink when you plug it in.

No, you may disconnect the pixhawk and try (the pixhawk draws extra power).