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PWM

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  • modaltbM Offline
    modaltbM Offline
    modaltb
    ModalAI Team
    wrote on last edited by
    #5

    Hi @Andrew-Keefe ,

    On the setup that doesn't have a PWM device, have you selected any airframe? I've seen this is the mixer isn't loaded, and the mixer not loading is normally from no airframe (although you are doing some custom stuff, so not positive).

    This is where the output device gets selected:

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    File not found · PX4/PX4-Autopilot

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    • Andrew KeefeA Offline
      Andrew KeefeA Offline
      Andrew Keefe
      wrote on last edited by
      #6

      I'm sure that's it. I remember now that I had selected a different airframe last time, though I'm not really using the airframe for my code.

      Andrew KeefeA 1 Reply Last reply
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      • Andrew KeefeA Andrew Keefe

        I'm sure that's it. I remember now that I had selected a different airframe last time, though I'm not really using the airframe for my code.

        Andrew KeefeA Offline
        Andrew KeefeA Offline
        Andrew Keefe
        wrote on last edited by
        #7

        @modaltb I have my PWM code working when I run it manually, but it does not work if I try and run it automatically at startup. I put it in rc.board_sensors even though it's technically not a sensor, it controls PWM actuators.

        What's happening is, the PWM device is not yet available when it tries to run, and it appears to be blocking everything.

        Is there a better way to schedule my module?

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        • modaltbM Offline
          modaltbM Offline
          modaltb
          ModalAI Team
          wrote on last edited by
          #8

          I'm not 100% sure as I've not tried, but this is where the output device gets set to PWM:
          https://github.com/modalai/px4-firmware/blob/modalai-1.10/ROMFS/px4fmu_common/init.d/rc.interface#L57

          And the device itself gets setup:
          https://github.com/modalai/px4-firmware/blob/modalai-1.10/ROMFS/px4fmu_common/init.d/rc.interface#L160

          Assuming you have a multicopter (mc), perhaps later on in the startup process in here?

          Link Preview Image
          px4-firmware/ROMFS/px4fmu_common/init.d/rc.mc_apps at modalai-1.10 · modalai/px4-firmware

          PX4 Autopilot Software. Contribute to modalai/px4-firmware development by creating an account on GitHub.

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          In rc.mc_apps, things like EKF2 are getting started, which is later in the startup process.

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          • Andrew KeefeA Offline
            Andrew KeefeA Offline
            Andrew Keefe
            wrote on last edited by
            #9

            Thanks, I'll try that. I actually am running a standard plane, bormatec maja.

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            • Andrew KeefeA Offline
              Andrew KeefeA Offline
              Andrew Keefe
              wrote on last edited by
              #10

              Yes, that worked. I placed it in rc.fw_apps

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              • Andrew KeefeA Offline
                Andrew KeefeA Offline
                Andrew Keefe
                wrote on last edited by
                #11

                Do you know why the 5V on the J7 PWM connector is for "reference only"? If I need to provide 5V to my PWM logic on the center rail of the 8-channel breakout, then I need to cut into the cable? Or I suppose I can provide 5V power on one of the other channels since I'm currently only using 4 of them, but now I need to find 5V from somewhere.

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                • modaltbM Offline
                  modaltbM Offline
                  modaltb
                  ModalAI Team
                  wrote on last edited by
                  #12

                  @Andrew-Keefe how much current are you looking to source from it? It's likely OK to use, but we put that message there to prevent trying to drive some heavy load.

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                  • Andrew KeefeA Offline
                    Andrew KeefeA Offline
                    Andrew Keefe
                    wrote on last edited by
                    #13

                    Good question. These servos don't specify the logic power so I'll have to measure it.
                    I'm not seeing 5V at all though on the PWM breakout board. It should be the middle set of pins, correct?

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                    • modaltbM Offline
                      modaltbM Offline
                      modaltb
                      ModalAI Team
                      wrote on last edited by
                      #14

                      Well, we aren't routing the 5V on that little M0022 board to prevent it being used to drive servos (for this concern). But 5V does come down to the connector, so it could be soldered to, and you could create solder bridges on the bottom of the board. Not ideal, but 5V is there, just not routed....

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