Navigator+Pi4 disconnects from network when I plug in a servo

I’m trying to set up the Navigator + Raspberry pi 4 controller, using Blue OS and Q Ground Control.

My computer is connected to the Navigator/Pi4 controller using Ethernet, and successfully receiving a MAVLink heartbeat.
The problem is, whenever I physically connect a servo to the Navigator board, the Navigator disconnects from the network (and QGroundControl). Power-cycling the Navigator with the servo plugged in, and it won’t re-connect. When I unplug the servo, the Navigator re-connects to the network.

Similar issue when I plug a radio receiver into the Navigator. It doesn’t disconnect, but also won’t calibrate, giving the error “Detected 0 radio channels. To operatePX4, you need at least 5 channels”.
Power-cycling the Navigator with the radio receiver connected, the Navigator/Pi4 won’t re-connect to the network/QGroundControl. I also try ping and it times out with 100% packet loss.
Unplugging the radio receiver, power-cycling and the Navigator is re-connected.

Question 1: Why does the Navigator disconnect from the network when I plug in a servo?
Question 2: Can I connect my computer to the Navigator using USB on a Navigator serial port? (instead of through Ethernet)
Question 3: Can’t seem to flash firmware using QGroundControl, do I have to use BlueOS for this?

Thanks for input or ideas!

Blue OS
Version: tags/1.0.1-0-gbc26236
Build: 4/6/2022, 3:04:28 PM

QGroundControl version v4.2.3

Hi @north, welcome to the forum :slight_smile:

That is not the case for mine, so I assume there’s either a short-circuit in your servo wires/internals, or your power supply to the Navigator has insufficient capacity. Are you using our 5V 6A supply connected to both the MAIN 5V and AUX 5V power headers on your Navigator, or do you have some other power setup?

That might be possible by configuring the relevant serial port to communicate with MAVLink2 and manually setting up the connection in QGroundControl, but I wasn’t able to get it to work. I’ll ask about it internally.

On QGroundControl’s Vehicle Setup / Firmware page it specifies

Navigator is not one of those device options.

The Navigator firmware runs on the Raspberry Pi (the Navigator is effectively an expansion board with IMU sensors, LEDs, connectors, and a PWM driver), so if you’re using BlueOS to run it then I expect BlueOS will be the only thing that can update the firmware. If you need to do an update then you may wish to turn on Pirate Mode and update to a recent beta version of BlueOS first for the best experience.

Presumably it’s technically also possible to run ArduSub on a Raspberry Pi + Navigator setup without using BlueOS, in which case the process for updating the firmware would be dependent on the software running it, but that’s not a configuration we’ve tried or that we actively support.

Following up, turns out this does work - I just forgot to cross the RX and TX wires :sweat_smile:

My setup had

  • Hardware:
    • Navigator
      • Independent power (via MAIN 5V pins or Raspberry Pi USB-C port)
      • Communication: Serial 3: [+ (5V), TX, RX, … (disconnected), …, - (GND)]
    • BLUART (USB to TTL Serial converter)
      • FTDI port: [+ (5V), RX, TX, …, …, - (GND)]
      • micro USB port
    • Topside Computer:
      • USB port
  • ArduSub parameters:
    • SERIAL3_BAUD: 115200
    • SERIAL3_PROTOCOL: Mavlink2
  • QGroundControl Setup:
    1. Go to Application Settings / Comm Links
    2. Add a new serial connection
      • Name: Navigator
      • Automatically Connect on Start (if you want, I didn’t bother)
      • Type: Serial
      • Serial Port: Select as relevant (probably USB or FTDI something)
      • Baud Rate: 115200
    3. Press Ok, then select your new one and press Connect

Other baud rates should also be possible, and potentially also other serial ports, but I’d suggest testing with with the above setup first to confirm.

1 Like

Thanks for the quick reply Eliot!

Re Question1:
I am using the blue robotics 5V 6A Power Supply for both MAIN 5V and 5V servo headers. BUT I realized that my bench power supply limits to 0.5A. I switched to powering the Navigator with a 3S LiPo battery, and now have no disconnect issues with the servo :blush:

Re Question 2:
Thanks for your feedback/instructions here, I will try your USB-TTL setup.

Re Question 3:
Using the blueos I’ve flashed Sub and Plane firmware which seems to be working. In the Navigator Software Setup it says “ArduCopter – unreleased”. I am building a coaxial UAV rotorcraft so would like to use ArduCopter. I just downloaded the firmware from the Ardupilot website and used the blueos “Upload custom file” to flash the ArduCopter firmware. Seems to be working just fine.

Glad to hear you found and resolved the issue :slight_smile:

I asked about this and was told Copter-4.2.3 should work, so presumably we forgot to update it earlier. I’ve fixed the guide :slight_smile: