Stepper Motor Indexer ..

Discussion in 'Embedded Systems and Microcontrollers' started by poison3000, Oct 17, 2010.

  1. poison3000

    Thread Starter New Member

    Oct 3, 2010
    22
    0
    Hello people ...

    I have read alot of good information about stepper motors , and I understand that to make the motor rotate u will need an indexer and a driver.

    >Indexer take a command from PC or PIC and generate pulses and direction (CW/CCW).
    >Driver translates the pulses inputs and direction into currents through the coils of stepper motor.
    > stepper motor will "step" accordingly ..

    sounds easy , but what I dont understand is the Indexer part , what kind of inputs does it accept ? and how it generates the pulses ?

    what Im thinking about is building the indexer , the indexer will take BCD codes and generate a number of pulses equals what actually the BCD represents ( like 0010 = 2 pulses , 0101 = 5 pulses and so .. ) is it possible ? how ? waiting ur ideas ... thank u !
     
  2. nerdegutta

    Moderator

    Dec 15, 2009
    2,515
    785
    Hi,

    I build a step motor controller with a ULN2003.

    Actually, I made this

    It's working just fine. Made it to learn.

    Maybe I didn't understand your question...
     
  3. poison3000

    Thread Starter New Member

    Oct 3, 2010
    22
    0

    thank u for ur try ... but this is the driver part , data 0 maybe for pulses - steps , and data 1 for direction - CW/CCW ...

    I would like to understand how indexer accepts data and generate the pulses and direction sent to the driver ... so somthing like this would happen : BCD --> Indexer --> pulses and direction --> driver --> current through coils --> motor doing some steps !
     
  4. nerdegutta

    Moderator

    Dec 15, 2009
    2,515
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    Ah I see... Sorry, out of my league. I know it was a shot in the dark.

    Good luck. :)
     
  5. shortbus

    AAC Fanatic!

    Sep 30, 2009
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  6. Rbeckett

    Member

    Sep 3, 2010
    205
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    Poison, actually an indexer is used to accurately position a stepper or servo motor. Servos use an indexer more frequently, but it is possible to use one on a stepper too. The stepper controller is a board that issues the different pin high commands and corrects the order they are sent so that the motor turns in the correct direction for your intended purpose. Most stepper motors are driven in excess of the label voltage at peak amperage to get acceleration torque, holding torque and to avoid cogging or running rough due to the number of discrete steps in a full revolution of the armature. You might go to the Univ of Iowa and read the paper "Jones On Stepper Motors" it is very iluminating and is the basis from which all who tinker with steppers work from. There are literally thousands of off the shelf boards designed to do anything you could ever desire, but you must take the time to properly select and spec them or you will be dissappointed with the result. So do a little more studying on steppers and servos and I for one, will help you out when you get in a jamb.
    Bob
     
  7. poison3000

    Thread Starter New Member

    Oct 3, 2010
    22
    0

    well , I read that paper .. but its the same concepts right here http://www.ams2000.com/stepping101/stepping101_Driver_3.html ..

    anyway , I still want to figure out how to build a circuit that would accept BCD codes and generate a number of pulses equals what actually the BCD represents ( like 0010 = 2 pulses , 0101 = 5 pulses and so .. ) .. this behavior is much similar to what indexer do ....
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    A counter will do that. Load it with the desired number of steps and decrement it to 0.
     
    poison3000 likes this.
  9. poison3000

    Thread Starter New Member

    Oct 3, 2010
    22
    0
    interesting one .. Im studying counters in detail .. will come back to this soon .. thx !
     
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