Servo on Fan output



  • I am in the process of building my custom made toolchanger.
    For this I use a TowerPro MG90D digital servo connected to my Duex5.
    Everything works fine but there is one thing that is bugging me. I would like to completely turn off the servo after a toolchange. If I just disable the PWM output by sending M42 P3 S0 the servo does not deactivate and "holds" the current position and the servo gets warm after a while.
    I was thinking to move the servo power connection to one of the FAN outputs and control that output to cut the power to the servo:

    duex_servo.png

    Would this a feasible idea?



  • Anyone, @T3P3Tony or @dc42 ?



  • Would have to switch the V-FAN jumper over to 5V AUX.

    Code in your tool change macro might look something like this:

    M106 F7 S255 ; turn fan on full power
    M280 P3 Snnn In ; servo command
    G4 Pnnn ; wait nnn ms for command to execute
    M106 F7 S0 ; turn fan 7 off
    

    It might be possible to unmap the fan and instead use the M42 command, something like this, not sure the practical difference

    M106 F7 I-1 ; disable fan 7 (to open up pin for general purpose use)
    M42 P27 S255 ; set pin27 to 255 (power on)
    M280 P3 Snnn In ; servo command
    G4 Pnnn ; wait nnn ms for command to execute
    M42 P27 S0 ; set pin 27 to 0 (power off)
    

    Note I haven't tried any of this but it might work 😄


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