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As Much Information I have About Driving a Stepping Motor — Parallax Forums

As Much Information I have About Driving a Stepping Motor

kenwtnkenwtn Posts: 250
edited 2008-08-22 18:51 in BASIC Stamp
··I am trying to drive a stepping motor.
· In the past I have been told that I have not provided enough information, so this time I have attached a drawing of my circuit, a PDF of the Motor I am using and the program I am using to test it all with. When I attach everything as indicated in my drawing and run the program the motor does nothing. Before you ask I have several of these type of motors and have tried several with same result. I have tried using a 470 ohm resistor connected to a LED to test the pins on the motor and the LED does light as expected. I guess I either have the motor connected wrong or maybe it is a power issue. Please help.

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When you spend 10 times what it cost to build it yourself - That's when it becomes a HOBBY !

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Post Edited (kenwtn) : 8/22/2008 3:11:08 PM GMT
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My Stepping Motor.bmp
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Stepper Test Program.BS2
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Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2008-08-22 15:06
    I would recommend starting with a descriptive subject. The one you have doesn’t give any indication what your message is about. Our forum guidelines explain that a descriptive subject is required in all messages.

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    Chris Savage
    Parallax Engineering
  • kenwtnkenwtn Posts: 250
    edited 2008-08-22 15:11
    I am simply trying to get any stepping motor to step with a ULN2803 so far I have fail at every attempt.

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    When you spend 10 times what it cost to build it yourself - That's when it becomes a HOBBY !

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  • Dave-WDave-W Posts: 94
    edited 2008-08-22 15:45
    Ken,

    That stepper does not have a common + input. Only four wires. The ULN you are using only provides a ground return and no power for the coils. The stepper you are using requires·two bridge type drivers to provide the power input on one side of the coil and a ground return on the other.

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    D. A. Wreski
  • kenwtnkenwtn Posts: 250
    edited 2008-08-22 15:51
    Dave,
    That makes sense and explians why it will not step. Thanks for the information. Here is a another dumb question. Can the motor be stepped by simply applying power to A+ then no power to A+ and power to B+ ETC...

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    When you spend 10 times what it cost to build it yourself - That's when it becomes a HOBBY !

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  • Dave-WDave-W Posts: 94
    edited 2008-08-22 16:45
    Ken,

    To answer your question, no. You need a current path through the windings to get it to step. If you ground A2 and B3 the most you would get is two steps out of the four for a full revolution.

    On the PDF spec sheet it has a chart on the lower right. It shows the polarity of the two windings. First step is A1 and B3 is ground with A2 and B1 being supply at +5 volts. Then the second step is shown on the next line down.

    The Polou Micro Dual Serial Motor controller from Parallax MAY work for you. I do not know if it is fast enough for this application but may be worth looking into.

    Go to the Parallax site and check this out.

    Pololu Micro Dual Serial Motor Controller Documentation (.pdf)

    However, you most likely have to build your own·discrete bridge from four transistors. And don't forget the protection diodes.



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    D. A. Wreski
  • kenwtnkenwtn Posts: 250
    edited 2008-08-22 16:49
    Dave,

    ·· I will look into that. I really want to thank you for the time you have spent helping me to understand what I have.



    Thanks Again,

    · Ken

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    When you spend 10 times what it cost to build it yourself - That's when it becomes a HOBBY !

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  • Dave-WDave-W Posts: 94
    edited 2008-08-22 18:02
    Ken,

    Here are two ways to make a H-bridge to drive your stepper motor. See attached or go to this web site for a good explaination on stepper motor drivers.

    http://www.cs.uiowa.edu/~jones/step/circuits.html



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  • kenwtnkenwtn Posts: 250
    edited 2008-08-22 18:51
    Dave,

    Thanks so much for the information, Yes that is a big HELP!

    Ken

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    When you spend 10 times what it cost to build it yourself - That's when it becomes a HOBBY !

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