Mini PWM Servo - Check if I am doing anything wrong?



  • I am converting a printer which uses a mini 3 Wire PWM Servo to rotate the Z-Probe down 90 degrees.

    It is a EMAX ES08 II , 12g, 1500 - 1900 usec, 200mA

    I have already managed to cook it. Probably because I was over driving it, but could someone be kind enough to run their eye over what I am doing? ( I am all very new to this stuff).

    Duet 2 Wifi.

    0:/sys/config.g (in the main config file to enable the pin for PWM)
    "`"
    ; Servos Setup

    M307 H3 A-1 C-1 D-1 Disabling the Heater 3 Pin on the Expansion Slot (Is this Required?)
    M950 S0 C"exp.8" Q50 Enabling Pin8 as GPIO Port 0 on the Expansion Slot for PWM @ 50Hz
    M42 P0 S0 Switching GPIO Port 0 Off
    "`"

    I was then using (and numbers inbetween)

    M280 P0 S125 and M280 P0 S20 - Manually in the Console to test rotating the the servo between the two positions. I looked away for a bit and it let out the smoke)

    Ideas before I cook the replacement

    In the deployprobe.g file I could run-

    M280 P0 S125 ; Move to position
    G4 P300 ; Dwell xxx Milli Seconds to allow full deployment
    M42 P0 S0 ; Switch output off again

    Am I missing anything, or doing anything wrong? The servo was jittering.

    Thanks in advance.


  • Moderator

    @AC2345 said in Mini PWM Servo - Check if I am doing anything wrong?:

    M307 H3 A-1 C-1 D-1 Disabling the Heater 3 Pin on the Expansion Slot (Is this Required?)

    No longer required in RRF3.

    Adding a delay is fine.

    Not sure about the jittering.

    What led you to choose 50hz for the PWM frequency?



  • Thank you for your Input.

    New motor fitted and working with settings above.

    Wanted to make sure I wasn't doing anything completely daft, other than trying to overdrive the position and leaving it on too long.

    (FYI - 50 Hz - because it worked at this frequency and wouldn't at 500)


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