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little step-u — Parallax Forums

little step-u

ArchiverArchiver Posts: 46,084
edited 2002-07-30 00:06 in General Discussion
I'm running a stepper motor with the little step-u, never done that before,
and I notice the motor is getting really hot. I assume that it isn't
supposed to do that but I'm not sure what I'm doing wrong, any ideas?

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2002-05-01 00:28
    Maybe the current is not set right?? That a possibility?? I might be
    able to make more specific recommendations if I had a schematic.

    Leroy

    raoul vaneigem wrote:
    >
    > I'm running a stepper motor with the little step-u, never done that before,
    > and I notice the motor is getting really hot. I assume that it isn't
    > supposed to do that but I'm not sure what I'm doing wrong, any ideas?
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
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    of the message will be ignored.
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  • ArchiverArchiver Posts: 46,084
    edited 2002-05-01 00:32
    Raoul,

    It sounds like the motor is always activate even when not in use. If
    so, consider adding a relay to turn off the motor power until you need
    it. You can activate a solid state relay to do this with one stamp pin.

    Dennis

    Original Message
    From: raoul vaneigem [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=njxFowKc4LwgeI-3SC93tqd3_L9X1VLQz0r8j9z6ju7MT_zJqYKoe_yDotQEDg3Kfvdi656o2nA]raoul@c...[/url
    Sent: Tuesday, April 30, 2002 3:19 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Re: little step-u


    I'm running a stepper motor with the little step-u, never done that
    before,
    and I notice the motor is getting really hot. I assume that it isn't
    supposed to do that but I'm not sure what I'm doing wrong, any ideas?


    To UNSUBSCRIBE, just send mail to:
    basicstamps-unsubscribe@yahoogroups.com
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    and Body of the message will be ignored.


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  • ArchiverArchiver Posts: 46,084
    edited 2002-05-01 00:32
    Stepper motors naturally run extremely hot, I dont believe you have anything to
    worry about. But I would consider not braking the stepper motor any more than
    needed.
    Jim Gorbet
    raoul vaneigem <raoul@c...> wrote: I'm running a stepper motor with the
    little step-u, never done that before,
    and I notice the motor is getting really hot. I assume that it isn't
    supposed to do that but I'm not sure what I'm doing wrong, any ideas?


    To UNSUBSCRIBE, just send mail to:
    basicstamps-unsubscribe@yahoogroups.com
    from the same email address that you subscribed. Text in the Subject and Body of
    the message will be ignored.


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    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2002-05-01 00:35
    If I remember right you can serout a command to the little step-u to denergize
    the coils.
    Leroy Hall <leroy@f...> wrote: Maybe the current is not set right?? That a
    possibility?? I might be
    able to make more specific recommendations if I had a schematic.

    Leroy

    raoul vaneigem wrote:
    >
    > I'm running a stepper motor with the little step-u, never done that before,
    > and I notice the motor is getting really hot. I assume that it isn't
    > supposed to do that but I'm not sure what I'm doing wrong, any ideas?
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the Subject and Body
    of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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    Do You Yahoo!?
    Yahoo! Health - your guide to health and wellness

    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2002-05-01 01:16
    Raoul,
    You should have a resistor in series with the power supply lead (s) to the
    motor. Actually, the motors are rated to run VERY hot.
    You can also run the stepper controller in bi-level mode. Use an
    opto-isolator and a mosfet and a power resistor. Limit the current to the
    motor with an appropriate power resistor so that you have the holding
    current you want. When you are ready to step, have the stamp send an
    output high to the opto-isolator. The opto-isolator will be configured to
    turn on the mosfet, which is shunting the current limiting resistor. When
    you are done stepping, turn the opto-isolator off. Actually, real bi-level
    controlling raises the voltage to the motor until the current in the
    windings has reached a fixed level and then returns it to a lower voltage.
    That's probably more than you want to do :-)
    If you haven't done so, you may want to check out
    http://www.wirz.com/stepper/index.html. Wirz gives a lot of helpful info on
    steppers and their controllers.
    Mike


    At 03:18 PM 4/30/2002 -0700, you wrote:
    >I'm running a stepper motor with the little step-u, never done that before,
    >and I notice the motor is getting really hot. I assume that it isn't
    >supposed to do that but I'm not sure what I'm doing wrong, any ideas?
    >
    >
    >To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    >from the same email address that you subscribed. Text in the Subject and
    >Body of the message will be ignored.
    >
    >
    >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

    _________________________________
    Mike Walsh
    walsh@i...


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2002-06-04 13:15
    Hi Andrew,

    You *can* control more than one motor with a controller, however....

    1) you cannot control them both at the same time
    2) they must be matched, volts,amps etc
    3) you risk loosing steps.

    Obviously, #1 is self evident. on an X and Y axis, you cannot use
    one signal to step one motor 17 steps while it is stepping the other
    3 steps.

    #2 should be obvious. Since a stepper performs well at 10 to 20
    times it's rated voltage, a small change in motor spec can be a big
    change in performance.

    A stepper drive with limiting resistor will offer a slight solution
    as you can just use the proper resistor for each motor. A chopper
    driver will be MUCH more efficient and a stepper driven with a
    chopper will deliver much more power. However, you need to handle
    the motor generated voltage when you remove power and it is still
    spinning.

    Lastly, anyone playing with a stepper for the first time gets a kick
    out of the simple way to testing which leads are which. one can
    rotate a stepper easily by hand, until you connect any two leads on
    the same circuit. This is just taking a stepper and shorting the
    motor's own wires, no external stuff. As soon as there is a proper
    pair shorted, the motor locks up.

    Then there is the holding power from the drive itself. If your
    plotter has any force on one axis while the other is moving, it may
    move the un-powered axis. you can short any pair of leads from the
    un-driven motor and get a little holding torque, but you cannot use
    the controller to hold the motor.

    This may be OK on your plotter app, but on a machine tool it could
    lead to real problems.

    Those three ought to make you re-think the idea. We all have had
    that idea to try to save a few bucks, save a few output pins, reduce
    size....

    And one other problem is speed. you need to select a channel, drive
    it, change to another channel, drive it.... imagine trying to draw a
    curve, one step at a time... up, over, up, over... you will find the
    time to do so unbearable.

    Like I said, you CAN use one, however.....

    Dave




    --- In basicstamps@y..., "manwithapipe" <manwithapipe@y...> wrote:
    > Just a quick newbie question regarding the little step-u...
    > Is it pretty much a 1:1 ratio to # of little step-u's to # of
    stepper
    > motors? Or is there a clever way to wire up a little step-u to run
    > more than one stepper motor independently. The reason why I ask is
    > because I am designing something that operates similar to a plotter
    > and need to know if one step-u can run both x and y. Thanks!
    >
    > Andrew
  • ArchiverArchiver Posts: 46,084
    edited 2002-07-29 20:05
    Iam trying to get a read back from a little step-u stepper controller purchesed
    from parallax to a basicstamp2 there directions are not to clear to me.
    the controller has a serin and a serout pin I hooked pin10 of stamp2 to serin
    oncontroller hooked pin 11 to serout on controller .This is there instruction{U}
    SHOW STATUS,RETURNS[noparse][[/noparse]POSITION,SPEED,RAMP}
    there is no example for this particular code all oter code has an example so I
    tried this.
    baud con 396 '2400 baud
    cpos var word
    serout 10,baud,[noparse][[/noparse]"{Q}"] 'SET POS REGISTER TO 0
    GOSUB CKBUSY
    SEROUT 10,BAUD,[noparse][[/noparse]"{U}"] 'OUTPUT DATA FOR STATUS
    SERIN 11,BAUD,CPOS 'READ DATA
    THE Q COMMAND WORS FINE AND THE SPEED AND DIRECTION COMMANDS WORK FINE I AM NOT
    SURE ON HOW TO WRITE THE SERIN AND WHAT KIND OF VAR I CAN USE.ANY INFO WOULD BE
    HEPPFUL
    THANKS MAX


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2002-07-30 00:06

    Original Message
    From: "max powell" <mpowell@t...>
    To: <basicstamps@yahoogroups.com>
    Sent: Monday, July 29, 2002 12:05 PM
    Subject: [noparse][[/noparse]basicstamps] little step-u


    > Iam trying to get a read back from a little step-u stepper controller
    purchesed from parallax to a basicstamp2 there directions are not to clear
    to me.
    > the controller has a serin and a serout pin I hooked pin10 of stamp2 to
    serin oncontroller hooked pin 11 to serout on controller .This is there
    instruction{U} SHOW STATUS,RETURNS[noparse][[/noparse]POSITION,SPEED,RAMP]
    > there is no example for this particular code all other code has an example
    so I tried this.
    > baud con 396 '2400 baud
    > cpos var word
    > serout 10,baud,[noparse][[/noparse]"{Q}"] 'SET POS REGISTER TO 0
    > GOSUB CKBUSY
    > SEROUT 10,BAUD,[noparse][[/noparse]"{U}"] 'OUTPUT DATA FOR STATUS
    > SERIN 11,BAUD,CPOS 'READ DATA
    > THE Q COMMAND WORKS FINE AND THE SPEED AND DIRECTION COMMANDS WORK FINE I
    AM NOT SURE ON HOW TO WRITE THE SERIN AND WHAT KIND OF VAR. I CAN USE.ANY
    INFO WOULD BE HELP FULL
    >


    THANKS MAX
    >
    >
    > [noparse][[/noparse]Non-text portions of this message have been removed]
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the Subject and
    Body of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
    >
    >
    >
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