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controlling many DC motors — Parallax Forums

controlling many DC motors

ArchiverArchiver Posts: 46,084
edited 2004-03-16 13:10 in General Discussion
I would like to use the Basic Stamp for controlling many DCmotors
independently from eachother, for an art project.
I have no idea what I need to extend the number of (only) 16 pins of
the stamp.
I heard something on "multiplier" and something of using the pins in
a binairy way.
Since being totally newn in this field: anyone can help me?

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2004-03-15 16:52
    A "multiplexer", yes.

    Think of a multiplexer this way... You have two hands. And with
    your two hands you can operate two buttons. That's it, that's your
    limit, two. But with a board and some pegs you could construct a
    simple device to operate, say, 8 buttons. So you use your two hands
    to setup the sequence of pegs on the board and then that board is
    used to operate the 8 buttons. It's slower than the direct method,
    but it allows you to extend your limit of two hands.

    This is how a multiplexer works. You typically use two or three pins
    to set the bit sequence of a shift register (or 3-to-8 multiplexer or
    similar device). The outputs from the shift register are then used
    to control, usually, 8 things.

    Depending on how you want to control your motors (PWM?) and how many
    you might have to do some fancy coding.

    Check out these two links:
    http://www-2.cs.cmu.edu/~RAS/Docs/space/mux.html
    ftp://nutsvolts.com/stampaps/st_ap5.pdf

    Mike




    --- In basicstamps@yahoogroups.com, "vandevendel1696"
    <vandevendel1696@y...> wrote:
    > I would like to use the Basic Stamp for controlling many DCmotors
    > independently from eachother, for an art project.
    > I have no idea what I need to extend the number of (only) 16 pins
    of
    > the stamp.
    > I heard something on "multiplier" and something of using the pins
    in
    > a binairy way.
    > Since being totally newn in this field: anyone can help me?
  • ArchiverArchiver Posts: 46,084
    edited 2004-03-15 22:40
    --- In basicstamps@yahoogroups.com, "vandevendel1696"
    <vandevendel1696@y...> wrote:
    > I would like to use the Basic Stamp for controlling many DCmotors
    > independently from eachother, for an art project.
    > I have no idea what I need to extend the number of (only) 16 pins
    of
    > the stamp.
    > I heard something on "multiplier" and something of using the pins
    in
    > a binairy way.
    > Since being totally newn in this field: anyone can help me?



    Hi,

    I'm not sure of the queston, but can take a stab at it anyway.

    First, I missed how many motors you want/need to run.

    A DC motor can be switched ON or OFF so it runs at full speed, or it
    can be controlled with a variable speed/variable voltage.

    The ON/OFF is easy as it can be one transistor per motor for single
    direction, or 4 to make an H-bridge (but uses 2 output pins)

    Variable speed is more complicated, but if you use pwm out on a pin,
    and can run the transistors in the analogue range you can control the
    motor speed.

    Multiple motors can be run from one signal, but they would run
    exactly the same (direction or speed)

    Can you describe your project in a little more detail ? or, at least
    your needs and quantities for the motors ?

    As you multiplex outputs, you need to use serial comm and that can
    slow signals down.

    For machine control, I would not recomend serial comm unless the data
    speed is higher than the machine speed.

    For an art project, it may not be a problem.

    Dave
  • ArchiverArchiver Posts: 46,084
    edited 2004-03-16 13:10
    You could use multiple stamp modules each controlling several motors and
    talk to them serially from a main computer. A board that can drive 8 motors
    and has provisions for serial input is available from this web site
    http://www.geocities.com/jimforkin2003/
    jim

    Original Message
    From: Dave Mucha [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=m7x68otHfxTy-KEUJRHe--4AAlWqFivyVx9XYVVHZYsxQOFtU-qdQVWCdZ-nNyL-7k-7eiQ_nT94CUPb7g]davemucha@j...[/url
    Sent: Monday, March 15, 2004 5:40 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Re: controlling many DC motors


    --- In basicstamps@yahoogroups.com, "vandevendel1696"
    <vandevendel1696@y...> wrote:
    > I would like to use the Basic Stamp for controlling many DCmotors
    > independently from eachother, for an art project.
    > I have no idea what I need to extend the number of (only) 16 pins
    of
    > the stamp.
    > I heard something on "multiplier" and something of using the pins
    in
    > a binairy way.
    > Since being totally newn in this field: anyone can help me?



    Hi,

    I'm not sure of the queston, but can take a stab at it anyway.

    First, I missed how many motors you want/need to run.

    A DC motor can be switched ON or OFF so it runs at full speed, or it
    can be controlled with a variable speed/variable voltage.

    The ON/OFF is easy as it can be one transistor per motor for single
    direction, or 4 to make an H-bridge (but uses 2 output pins)

    Variable speed is more complicated, but if you use pwm out on a pin,
    and can run the transistors in the analogue range you can control the
    motor speed.

    Multiple motors can be run from one signal, but they would run
    exactly the same (direction or speed)

    Can you describe your project in a little more detail ? or, at least
    your needs and quantities for the motors ?

    As you multiplex outputs, you need to use serial comm and that can
    slow signals down.

    For machine control, I would not recomend serial comm unless the data
    speed is higher than the machine speed.

    For an art project, it may not be a problem.

    Dave









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