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Stepper Motor via 2 bits — Parallax Forums

Stepper Motor via 2 bits

Rob311Rob311 Posts: 83
edited 2006-04-09 21:15 in BASIC Stamp
Im trying to control a stepper motor with only 2 inputs.
Actually Im trying to control 3 steppers with only 2 inputs each.
Im using a bs2, and I had no problem getting it working with a Darlington array and 4 inputs.
Following this idea from BASIC Stamp 1 Application Notes I can’t really get anywhere…
http://www.eettaiwan.com/ARTICLES/2002MAR/PDF/2002MAR08_AMD_MPC_AN81.PDF
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Any comments as to if it works or doesn’t work?
Btw Im not using the uln2003, but the uln2805a (I think its 2805, its defiantly 280xA) but from what Im told there isn’t really any difference, except for the extra transistor.

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-04-06 23:52
    Perhaps I am missing something...Are you saying the Stepper Motors only have two wires each?

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  • Rob311Rob311 Posts: 83
    edited 2006-04-07 00:03
    Please follow the link.
    Its a 5 wire motor, 4 phases and 1 12power (i dont know if i explained it right)
    But it does sound posible
    2 bits can output 4 settings
    aa
    ab
    ba
    bb
    Im just trying to figure out if the way they explain it in the link will work.
    I tryed it and it didnt... so i dont know if i did something wrong or what.
  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-04-07 03:53
    Do you know which wire is common and which phase each of the remaining wires are (at least thier colors, do they match the schematic)?

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  • Rob311Rob311 Posts: 83
    edited 2006-04-07 10:59
    Yes, i was able to get the stepper working with a darlington array. this however requires 4 pins on my stamp.
    The method used in the attached link only requires 2 pins per mottor.
  • BeanBean Posts: 8,129
    edited 2006-04-07 11:22
    Rob,
    · In the link, they are using two channels of the UN2003 as inverters. If you look at the state diagram, coil 1 & 3 are mutually exclusive (when 1 is on, 3 is off; when 1 is off, 3 is on) same with coil 2 & 4.

    · If you are using darlington array you will either have to wire two of the channels as inverters, or use two inverters.

    · So output A (let's call it) will control coil 1, and output A through an inverter will control coil 3.
    · Output B will control coil 2, and output B through an inverter will control coil 4.

    Bean.

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  • Rob311Rob311 Posts: 83
    edited 2006-04-08 01:00
    ok so the theory behind it holds.
    the problem is that im not getting the correct output from them, ill have to check my circutry
  • Rob311Rob311 Posts: 83
    edited 2006-04-09 21:15
    ok, ive tested my hardware.. everything seems right.. but its still not working...
    anyone have another idea how to run a 4 phase stepper motor via 2 outputs on my bs2?

    perhaps logic level "and" chips to drive my transistor?
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