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    Higher fidelity on PWM on DUEX5

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    • injoi9000
      injoi9000 last edited by

      I am using the PWM ports on the DUEX5 to control a fan with a speed controller. It appears I only have a resolution of S4... as in there is no change in speed between S70 until S74. Is there a way to get higher fidelity using the PWM M280 commands?

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      • dc42
        dc42 administrators last edited by

        The resolution should be 8 bits, because the SX1509B chip on the DueX provides 8 bit intensity control on the PWM output. Have you measured the output pulse timing using an oscilloscope?

        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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        • injoi9000
          injoi9000 @dc42 last edited by

          @dc42 I don't really understand...Does the 8 bit resolution map to a single "S1" digit?

          Unfortunately, I don't have an oscilloscope, is there any other way to debug this?

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          • dc42
            dc42 administrators last edited by dc42

            I am sorry, I misread your post. I now see that you are using the PWM ports, not the fan ports.

            Please see this post https://forum.duet3d.com/topic/8453/microsecond-resolution-when-using-m280-for-servo-control. In summary, the following should improve the resolution:

            • Use firmware 2.03RC2 instead of firmware 2.02
            • Or use a PWM port controlled by a timer channel instead of a PWM channel

            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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