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Hardware connection BasicStamp and Little Step U — Parallax Forums

Hardware connection BasicStamp and Little Step U

J.WeJ.We Posts: 15
edited 2005-07-15 08:24 in BASIC Stamp
When I connect my LSU(Little step U from Parallax)·to my BSsx I need a separate power supply for the LSU to drive the stepper motor. My stepper motor needs 12Volts and thats ok, but what about common GND?·I cant get my·motor to move.. My BSsx is currently on the board of education, do I have to·connect the boards GND to the GND on the extern power supply?

Hoping for reply
Best regards//jw

Comments

  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-07-14 12:07
    JW -

    Yes, connect the two grounds together so they become one common ground.

    Regards,

    Bruce Bates
  • J.WeJ.We Posts: 15
    edited 2005-07-14 14:04
    Ok, Thanks. Maybe you ore someone else can help me thou some more, this is the first time I use this type of controller and I really need some assistance. Thanks in advance.

    My motor still don’t move.. I can’t quite figer out how to connect the wires. I have a stepper motor (pdf: http://www.elfa.se/pdf/54/05450739.pdf). The motor has six cables, incl. two·commons, they are marked: 1,2,3,4 +com1, com2. (See pdf)·

    The Little step U has six inputs for motor: A,B,C,D CTAC and CTBD. (http://www.parallax.com/dl/docs/prod/motors/littlestepuman.pdf)

    I have now connected them as follows: A=1, B=2, C=3, D=4, CTBD=COM2, CTAC=COM1.

    I have tried to run·the simple program below, just to see if the stepper works, but nothing happens.
    I can’t see any other way to connect·the wires and·I really can’t see what is wrong, any ideas? Any other way to make a test?

    '{$STAMP BS2sx}
    baud··· CON· 396
    INPUT· 12····· ' Busy input
    DEBUG "Move Relative backward", CR
    SEROUT 10,baud,[noparse][[/noparse]"{E-200}"]······· ' Go backward 200 steps
    GOSUB CheckBusy··········· ' Wait till it gets there
    PAUSE 500
    DEBUG "Move Relative forward", CR
    SEROUT 10,baud,[noparse][[/noparse]"{E200}"]······· ' Go forward 200 steps
    GOSUB CheckBusy··········· ' Wait till it gets there
    PAUSE 500
    CheckBusy:
    PAUSE 10
    CB_loop:
    IF IN12 = 1 THEN CB_loop····· 'Wait till not busy
    PAUSE 1
    RETURN

    Please do anyone have any ideas what to do?
    Regards//JW
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-07-14 14:27
    JW -

    The Little Step U controller is intended for use with UNIPOLAR stepper motors. Based on what I see in the motor documentation you supplied, that looks like a BIPOLAR stepper motor. Therein lies the problem. All is not lost, however!

    I believe a BIPOLAR motor such as yours can be externally re-wired to operate in UNIPOLAR mode. Unfortunately, I'm not the best person to advise you on that re-wiring. There are others on this forum who are stepper motor "experts" and I'm sure they'll chime in with suggestions as to how this can be done. I'm sure you'll have this up and running in no time.

    Regards,

    Bruce Bates
  • J.WeJ.We Posts: 15
    edited 2005-07-14 14:38
    Thank you Bruce.
    Yes, I bought this motor because it was possible to run it both Bipolar and unipolar. I thought that this was the "unipolar way".. ·
    But ok, I will try to re-write my question so the stepper motor "experts" answers.
    Thank you for your support!
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-07-14 14:45
    JW -

    I honestly only looked at the stepper motor schematic and glanced at the Step U documentation, when I said what I did. I don't have a printer, pad and paper handy to extrapolate your wiring (as noted) to the indicated wiring in the schematic, or the examples in the Little Step U documentation - sorry. Your wiring may be correct, but having someone more knowledgable look at it, is proabably still the best course of action.

    Regards,

    Bruce Bates
  • kelvin jameskelvin james Posts: 531
    edited 2005-07-14 16:00
    A common mistake is happening here, the baud rate in the example code for the stepu is written for a bs2, since you are using the bs2sx, it is different. The correct value would be 1021 as shown in the baud table in the serial out section of the pbasic help. Assuming you have everything wired properly, the motor documentation looks pretty good, that change should get you going. And you should also declare your input and output pins in your program, like input 10 and output 11, as an example. I just use the seperate supply ground for the motor, not a common with the BOE, it's up to you what you want to do. If you have any other questions about operation, I can probably help out.

    kelvin
  • J.WeJ.We Posts: 15
    edited 2005-07-15 08:24
    ..as simple as that! Its now running!

    Next time I will check the numbers more careful..

    THANK YOU! //JW
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