Shop OBEX P1 Docs P2 Docs Learn Events
BS2... L293D and stepper motors — Parallax Forums

BS2... L293D and stepper motors

JohnnyBJohnnyB Posts: 13
edited 2006-08-02 05:35 in BASIC Stamp
This seems to be a common field of interest but I'm having trouble finding what I need.

How about a basic, idiot proof (ok..almost)...schematic for hooking up something like a Mitsumi M42SP-7 Stepper motor to a BS2 on a Homework board.

The stepper is a five wire (black, red, tan, brown, yellow) Mitsumi M42SP-7 taken out of an inkjet printer.

Driver is a L293D

Try as I might the only thing I could get to happen is one of the outputs to the motor to go high and stay there. I've tried various programs as I found in the Paralax resources....yes BS2 programs.

The basic connections seem straightforward...but I was having some problems sorting out the seperate power supply for the motor/L293D and how they connect.

Are there any well labeled schematics out there that translate directly to connections I would find on the Homework board and L293D? I've downloaded the tech sheet for the L293D so pin ID is no problem.
Thanks a bunch,
JohnnyB

Comments

  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-08-01 08:21
    JohnnyB-

    The attached document isn't exactly what you asked for, but it is the same series·Mitsumi motor, which should give you a clue as to the 4 phases for this unipolar stepper similar to the one Parallax sells. Unfortunately it uses a different driver chip, but both chips drive each of the 4 phases in a similar manner.

    You will have to check the wires with your own meter, but I suspect this is how the phasing is going to work out, if I've guessed correctly:

    BLACK - Phase 1

    TAN - Phase 2

    BROWN - Phase 3

    YELLOW - Phase 4

    RED - Common

    Internally I would expect it to ring out something like this:

    ·OOOOO OOOOO
    |·········· |········ ·|
    |·········· |········ ·|
    Blk······Red····· Tan
    Ph1·····Com···· Ph2

    Common RED exits motor housing as a single wire, connected internally.

    ·OOOOO OOOOO
    |········· ·|······· · |
    |·········· |········ ·|
    Brn·····Red······ Yel
    Ph3····Com····· Ph4

    PLEASE ring it out yourself, before relying on my best guess! If I am wrong, try switching the meanings of BLK and RED. BLK may be the COMMON rather than RED.

    Regards,

    Bruce Bates
    pdf
    pdf
    Stepper_Motor_27964.pdf
    1M
  • JohnnyBJohnnyB Posts: 13
    edited 2006-08-01 17:42
    Bruce,

    Thanks, I've reviewed that document a few times in the past. Close...but not being the smartest guy in the world I was looking for specific pin connections for the L293D. Like what power source the enable pins should be hooked up to, what power source for the logic voltage, and what source for the motor voltage.

    I was getting a bit confused by the difference between Vss (logic supply voltage) and Vs (Supply voltage).

    I was assuming the Vss would supply power to the L293D circuitry...and the Vs would supply voltage to the motors.

    If I had a plain pin to pin schematic for using the L293D with the Homework board I could work backwards and get a grasp on things.

    With the stepper I am using I get 77 ohms between the black wire and ANY of the other four. Between the other four I get 155 ohms in any combination.· So I assumed black was the common (wires are connected to the motor with a very small PC board attached to the motor, looking at the etchings I can see that there are actually 6 wires to the motor...the black wire attaches to two center connection points).

    I have been previously been running the same BS2 program as listed in your attached document. Using a VOM on the output leads of the L293D to look at voltage the only response I could get was one output going high whenever power was applied to the BS2. I'm pretty sure my problem is somewhere in the supply/ground wiring to the L293D.

    Thanks for you help,

    JohnnyB
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-08-01 19:25
    Hello,

    ·· There is an example of using the L293D on the PDB in the Stamp Works 2 manual.· You can download a free PDF of it at the following link.· I hope this helps.· Take care.

    http://www.parallax.com/detail.asp?product_id=27220

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • JohnnyBJohnnyB Posts: 13
    edited 2006-08-01 22:45
    Chris....you are a tech support savage [noparse]:)[/noparse].

    If that schematic doesn't do it for me I don't deserve to succeed. Downloaded the whole manual.
    Thanks a bunch!
    JohnnyB
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-08-02 05:35
    Well I hope it helps.· Let us know how you make out with it.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
Sign In or Register to comment.