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  4. Is it possible to use uORB directly in a voxl module?

Is it possible to use uORB directly in a voxl module?

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  • D Offline
    D Offline
    Dan
    Contributor
    wrote on last edited by
    #1

    Hi ModalAI devs,

    I'm wondering if it's possible to subscribe to a uORB topic in a voxl module. I want to subscribe to the barometer sensor and there isn't an MPA server for this.

    The reason I ask is that when using the voxl-cross docker container I'm unsure which dependency is required to install to get access to the uORB headers etc.

    Thanks,
    Dan

    Eric KatzfeyE 1 Reply Last reply
    0
    • ? Offline
      ? Offline
      A Former User
      wrote on last edited by
      #2

      Hi Dan,

      You can directly subscribe to the mavlink output using the mavlink_to_px4 pipe and check for messages of type MAVLINK_MSG_ID_ALTITUDE to receive barometer updates in an MPA server.

      See here for a code example.

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      • ? A Former User

        Hi Dan,

        You can directly subscribe to the mavlink output using the mavlink_to_px4 pipe and check for messages of type MAVLINK_MSG_ID_ALTITUDE to receive barometer updates in an MPA server.

        See here for a code example.

        D Offline
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        Dan
        Contributor
        wrote on last edited by
        #3

        @Matt-Turi

        Hi Matt,

        Thanks for the quick reply and thanks for the example that's super useful.

        Just to clarify what you're saying. From my understanding when I do uorb top the topic name sensor_baro is available and I can call px4-listener sensor_baro to get an update from what I believe to be a uorb message? Are you saying that there are mavlink messages also published that will give me the same information and I can use something similar to your example to then create a barometer MPA server?

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        • D Dan

          Hi ModalAI devs,

          I'm wondering if it's possible to subscribe to a uORB topic in a voxl module. I want to subscribe to the barometer sensor and there isn't an MPA server for this.

          The reason I ask is that when using the voxl-cross docker container I'm unsure which dependency is required to install to get access to the uORB headers etc.

          Thanks,
          Dan

          Eric KatzfeyE Offline
          Eric KatzfeyE Offline
          Eric Katzfey
          ModalAI Team
          wrote on last edited by
          #4

          @Dan There is no uorb to pipe bridge so not really possible. But you can run the system command px4-listener and parse the output of it. Or if what you really need is something in a Mavlink message then you can go the route Matt suggested.

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          • ? Offline
            ? Offline
            A Former User
            wrote on last edited by
            #5

            There is a mavlink message you can parse for barometer data, that is the code example I sent above. In that file as well, there is an example of calling px4-listener programmatically and parsing its output - see here

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            • Eric KatzfeyE Eric Katzfey

              @Dan There is no uorb to pipe bridge so not really possible. But you can run the system command px4-listener and parse the output of it. Or if what you really need is something in a Mavlink message then you can go the route Matt suggested.

              D Offline
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              Dan
              Contributor
              wrote on last edited by
              #6

              @Eric-Katzfey

              No problem. I was wondering if I could do that bridging myself by subscribing to the uORB topic sensor_baro and then publishing onto a barometer MPA server but wasn't sure if it was possibly to subscribe to uORB topics in the voxl SDK.

              @Matt-Turi

              Thanks for the clarification. I'll take a look at the px4-listener parsing too.

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              • ? A Former User

                There is a mavlink message you can parse for barometer data, that is the code example I sent above. In that file as well, there is an example of calling px4-listener programmatically and parsing its output - see here

                D Offline
                D Offline
                Dan
                Contributor
                wrote on last edited by
                #7

                @Matt-Turi

                Apologies. Final question for now. Who is the producer of the mavlink message for the barometer data?

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                • Chad SweetC Offline
                  Chad SweetC Offline
                  Chad Sweet
                  ModalAI Team
                  wrote on last edited by
                  #8

                  The PX4 flight control software

                  D 1 Reply Last reply
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                  • Chad SweetC Chad Sweet

                    The PX4 flight control software

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                    Dan
                    Contributor
                    wrote on last edited by
                    #9

                    @Chad-Sweet

                    Thanks Chad.👍

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