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Stepper only rotates one way?

2016-06-29
2016-06-29
  • Richard Barlow

    Richard Barlow - 2016-06-29

    Hi all!

    I've built the full version with the CH340G Nano, the DRV8825 board, and the OLED. Everything is working fine - the arduino code loads fine, the Windows app connects fine and displays all of the correct info except for one small issue.

    Both buttons drive the steper in thesame direction and so does the "jog" and step selection button in the app. It rotates one way no matter what I set.

    I've dug into the PCB and all of my connections and I can't see any issues. Has anyone seen this issue before and can give me a hint on where to start?

    Rich

     
  • brownrb

    brownrb - 2016-06-29

    Hi Rich.
    We dont know the stepper motor you are using and what sort of supply voltage for the stepper motor.

    I would probably look at the stepper wiring.
    If the stepper moves then the DRV8825 is probably OK, the 12V is working etc

    Now you have the OLED, so a question is this, when you send say -10 does the new position on the OLED show its now 10 steps less than before, and if +10 then the LED shows new position 10 steps more?

    If the stepper is moving then probably the vpot ref voltage is set correctly on the DRV8825 board?
    Did you adjust the vref pot?
    Make sure that coil power is ON when adjusting the VREF

    If you enable RD does the stepper still move in the same direction or is it now moving in opposite direction?

    1. Use a multimeter and measure the resistance between the 4 wires. With a low resistance of probably 10-30 ohms between each pair of wires.
    2. So now you have two pairs. Lets say RED/GREEN and BLACK/YELLOW
    3. The combinations are RG and BY, or GR and BY or RG and YB or GR and YB (4 possible cominations)
    4. Test each combination in turn, using the program found here
      https://sourceforge.net/projects/arduinoascomfocuserpro2diy/files/Testing/BasicDRV8825HW203Test.ino/download

    One combination should work.
    Cheers
    Robert

     
  • brownrb

    brownrb - 2016-06-29

    And make sure you use FULL STEPS only till its working ok and the vref voltage on the DRV8825 is set correctly

     

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