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    Duet3 MB6HC Rev1.0 firmware 3.0beta12 can’t control PWM fan

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    • Jimmykc
      Jimmykc last edited by

      My fans configuration is showed below.
      666.jpg
      I jump wire to check the PWM signal by the oscilloscope.
      333.jpg
      I try to key the different fan command to control PWM.
      M106 P0 S0
      M106 P0 S1
      M106 P0 S100
      And I also slide the icon on DWC menu.
      555.jpg
      The PWM signal on the oscilloscope is no different.

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      • dc42
        dc42 administrators last edited by

        Please upgrade first to RRF 3.0 and then to RRF 3.01-RC9, and see if the problem still exists.

        Duet WiFi hardware designer and firmware engineer
        Please do not ask me for Duet support via PM or email, use the forum
        http://www.escher3d.com, https://miscsolutions.wordpress.com

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        • Jimmykc
          Jimmykc last edited by

          @dc42 Thanks for your help.
          After I update to RRF 3.01-RC9, I can control PWM fan. But I have new question.
          After I measure the out4 pin to check PWM signal, it is different from the PWM which I configure the io4.out as PWM.
          The figure of PWM comparison is showed below
          compare1.jpg
          The Ch2’s PWM is configured from the io4.out.
          The Ch3’s PWM is configured from the OUT4.
          May I use fan PWM to control the servo ? or
          Could you give me the suggestion how to use fan PWM to control the servo ?

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          • dc42
            dc42 administrators last edited by

            The fan output are open-drain, so the signals on them won't make much sense unless you connect a fan or other load (e.g. a resistor) between the two pins.

            It's possible to use a Fan- output to control a servo by adding a pullup resistor between that output and +5V, but why would you want to do that if you have a free IO_x_OUT pin?

            Duet WiFi hardware designer and firmware engineer
            Please do not ask me for Duet support via PM or email, use the forum
            http://www.escher3d.com, https://miscsolutions.wordpress.com

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            • Jimmykc
              Jimmykc last edited by

              @dc42 I have servos more than IO_x_OUT pin so I want to use fan PWM to control them. OK, I will add a pullup resistor to try it. Thanks for your help.

              dc42 1 Reply Last reply Reply Quote 0
              • dc42
                dc42 administrators @Jimmykc last edited by

                @Jimmykc said in Duet3 MB6HC Rev1.0 firmware 3.0beta12 can’t control PWM fan:

                @dc42 I have servos more than IO_x_OUT pin so I want to use fan PWM to control them. OK, I will add a pullup resistor to try it. Thanks for your help.

                You will also need to invert the pin in the M950 command that creates a servo output using a fan pin.

                Duet WiFi hardware designer and firmware engineer
                Please do not ask me for Duet support via PM or email, use the forum
                http://www.escher3d.com, https://miscsolutions.wordpress.com

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                • Jimmykc
                  Jimmykc last edited by

                  I add a pullup 3.3k resistor to 3.3V to try it.
                  P_20200427_101000.jpg
                  It can work, but I have a new question.
                  What is the limitation of voltage for the fan pin if I want to pullup voltage more than 3.3V?

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                  • dc42
                    dc42 administrators last edited by dc42

                    The limit is the VIN voltage.

                    Duet WiFi hardware designer and firmware engineer
                    Please do not ask me for Duet support via PM or email, use the forum
                    http://www.escher3d.com, https://miscsolutions.wordpress.com

                    Jimmykc 1 Reply Last reply Reply Quote 0
                    • Jimmykc
                      Jimmykc @dc42 last edited by

                      @dc42 I see, thanks.

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