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BS2 interface to Bipolar stepper motor needed — Parallax Forums

BS2 interface to Bipolar stepper motor needed

strostro Posts: 4
edited 2013-02-03 07:29 in BASIC Stamp
Hello everyone- I am new to the forum and this seems like a great place for advice and ideas.

The purpose of this e-mail is to ask for specifics about how any of you (who are willing to share) may have actually interfaced a BS2 to a bipolar stepper motor.

I have searched through the forums already and found several threads about using stepper motors with Parallax products. There are many suggestions and many ideas people have had on how they *would* or *might* do it, but I was wondering if there is anyone out there who has *actually* done it and what their advice might be regarding the various interface boards/chipsets commercially available. Please note that I am not trying to diminish the value of suggestions, but would like to tap some actual experience, if possible, as I do have a budget and do not want to purchase a bunch of $20 boards which might not work.

My application:

A single, two-phase, bipolar stepper motor, 1.7A/phase, 1.6 ohms/phase, holding torque around 60 oz-in, Basic step angle = 1.8 deg.

I have a Basic Stamp 2, Board of Education.

I do not need speed as much as torque and repeatability while using 1/16 microstepping.

I liked the idea of the motor protection features built into the Little Step-U but it appears to only work with unipolar steppers. Please correct me if I am wrong about that.

Many thanks.

Cheers,
stro

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2013-02-01 12:47
    Welcome to the forums! You're right about the Little Step-U...it can only handle Unipolar Stepper Motors. I myself have driven a Bipolar Stepper Motor using the PDB (Professional Development Board) we sell which contains a driver chip, L293D, which is a push-pull driver. It can be used to drive both Unipolar and Bipolar Stepper Motors. Experiment #27 of the StampWorks manual explains how to wire up a Unipolar Stepper Motor to this IC and gives working code for the BASIC Stamp 2 Module which would drive either type of stepper motor connected to the L293D.

    The StampWorks manual can be downloaded free in PDF format from the following link and I am also including another link on using the L293D to drive a Bipolar Stepper Motor.

    http://www.parallax.com/Portals/0/Downloads/docs/books/sw/Web-SW-v2.1.pdf

    http://www.seattlerobotics.org/encoder/may98/steppers.html

    On experiment #27 the only difference between the example shown and a Bipolar motor would be the lack of the common (ground) wire shown. If you place the other coils wires in order on the four outputs the code will work the same. I hope this helps.
  • strostro Posts: 4
    edited 2013-02-02 17:39
    Hi Chris!

    Many, many thanks for the information. I'll give the L293D a shot and see if I can "get there from here".

    Again, thanks for sharing.

    -Stro
  • ercoerco Posts: 20,257
    edited 2013-02-03 07:29
    L298 h-bridges modules are $4 on ebay and can drive bipolars.

    I just ordered some 297s off ebay too. Dedicated stepper controllers, they can handle anything.
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