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Question about mavlink communication with APM and Arduino

Posted by Peicong Liu on July 8, 2015 at 2:47pm

I am very new to mavlink communication and I have couple of questions about communicating between APM and Arduino Uno (or Mega).

Does APM board send out heartbeat message automatically? If so, should I able to catch it in Arduino IDE's serial monitor by connecting RX/TX port from Arduino to the telemetry port in APM board?

Any help will be great! Thank you!

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Replies

Stephen Dade July 9, 2015 at 1:42pm

When it is powered, the telemetry port on the APM will automatically send out a MAVLink stream. You can definitely use the Arduino to read these messages.

Edit:

If you're wanting to go APM->Arduino->PC, you will need to program the Arduino to route the telemetry messages from the APM->Arduino side to the Arduino->PC side.
- Peicong Liu > Stephen Dade July 9, 2015 at 5:15pm
  
  Hi Stephen,
  
  Thank you for your reply. How should connect the wires? TX from APM telemetry to RX on Arudino and RX form APM telemetry to TX Arduino?
  
  Cuz when I do it that way, serial.avaible() on Arudino side never received anything.
  
  Thanks
  - Stephen Dade > Peicong Liu July 11, 2015 at 3:28am
    
    That wire connection should work. Did you connect ground between them too?
    
    This site, although for a different project, might give you some pointers: http://vizual54.github.io/APM-Mavlink-to-FrSky/
    
    Apm-mavlink-to-frsky
    
    Apm-mavlink-to-frsky : Arducopter Mavlink telemetry to FrSky Taranis
    - Peicong Liu > Stephen Dade July 13, 2015 at 5:52pm
      
      I am getting the heartbeat package from APM board now. However, all I got was #0 and #253 pack. Even after I send out mavlink_msg_request_data_stream_pack.
      - Stephen Dade > Peicong Liu July 14, 2015 at 12:06pm
        
        I'm not sure why that would be the case.
        
        Maybe try a ground station program (Mission Planner, APM Planner, MAVProxy, etc) to confirm that you can get the telemetry.
        
        Otherwise, it might be worth looking through the source code of the above programs and see how they implement the communications.