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Got stepper motor working. Cant get normal motor working? — Parallax Forums

Got stepper motor working. Cant get normal motor working?

neotericneoteric Posts: 144
edited 2006-01-07 23:43 in Robotics
OK.· I have another question for anyone interested in helping.·· I just want to move a DC motor forward.· No reverse.· I will set pin 4 high.

Using a ULN2003.

Could someone look at my setup and tell me if it is ok?

THANKS TO ALL for helping me.· Project is coming along fairly well.
dcmotor.jpg
600 x 439 - 11K

Comments

  • BeanBean Posts: 8,129
    edited 2006-01-06 17:42
    neoteric,
    The ULN2003 will ground the motor connection. So the other motor connection needs to to +12 not ground.
    Bean

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  • neotericneoteric Posts: 144
    edited 2006-01-07 19:07
    OK, I have tried the attached.·· No matter what, I get power to the motor if the board is on.· Doesn't matter whether I set pin high or low.· Any suggestions?· This seems to be how the tutorials and google would suggest.· tried with different board, different ul2003.

    THANKS in advance!· (this one really has me puzzled.)· I am a beginner, but have some knowledge!
    dcmotor2.jpg
    600 x 439 - 10K
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2006-01-07 19:38
    This article may help: http://www.parallax.com/dl/docs/cols/nv/vol1/col/nv6.pdf

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    Applications Engineer, Parallax
  • neotericneoteric Posts: 144
    edited 2006-01-07 20:03
    Thanks for your help.· I read that article.· Thats how I learned about ULN2003's.· Having a great time with all this stuff, but getting frustrated.· Can't believe with no electrical experience 1 week ago, today I have both 12v stepper motors working.· But I can't get the simple dc motor working in a simple matter.· Which means my robot can steer, but not turn.· (I'm rebuilding an old robot.· head turns, steering works, but can't get the dc motor for drive to work....)

    I swear I am not one of those guys that forsakes research by just asking on the forum.· I'm doing this to learn, and I am doing the research.· Just can't figure out what I am missing...

    I believe my second diagram is as the article shows....

    Thanks again.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-01-07 20:56
    Is P4 being brought HIGH?· Is the ground for the ULN common with the Stamp Module Vss/Ground?· They need to be.

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    Parallax Tech Support
    csavage@parallax.com
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-01-07 21:20
    neoteric -

    Make sure some else checks me out on this before you make any permanent changes and test this, but I think you have Vss and ground reversed in your wiring. As I remember, the ULN2003's usually supply a switched ground, rather than switched power. Thus, positive power goes directly to the motor, and the ground lead comes from the switched side of the IC.

    Regards,

    Bruce Bates
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-01-07 23:43
    Actually, the +12V is going directly to the motor in the last diagram he posted.· The COM terminal is designed for only one purpose, which is not to provide voltage to the ULN2x03, but rather to provide a connection to the clamping diodes inside the package.· They won't work unless connected to the positive power supply.· And Ground and VSS are the same connection, BTW.· =)


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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
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