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Posted by Adman on March 28, 2008, 6:43 pm
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Hi all... I'm a software guy trying to learn the ropes of electronics.
I have the goal of controlling a stepper motor using my PC parallel
port to create +5v control signals. Shouldn't be that hard, right?
My understanding of 5-wire stepper motors is that there will be one
common power wire, and four other wires coming out. Attach the power
wire to the power source, and attach the other wires to ground (using
some logic to connect the right ones to ground at the right time), and
you're all set.
I bought a unipolar stepper motor... the first one listed on this
page:
http://www.futurlec.com/StepperMotors.shtml
One thing I noticed is that the spec sheet lists that it has a "drive
circuit".
Some more investigation led me here:
http://www.eminebea.com/content/html/en/engineering/motors/pm_motor/selection_pm/drivecircuit.shtml
Since I bought a unipolar stepper, I think the first schematic on the
page applies. I'm not quite sure how to read it. It appears that
what I want to do is attach my parallel port data pins DIRECTLY to the
bases of each of the transistors (which is what the four non-power
wires coming out of the motor will be).
If that's the case, it looks like I use my parallel port control
signals to activate each transistor according to activate the internal
electromagnets in the proper order. Being a smart software guy, I can
handle that. When I do that, the power will go through the coils,
through the transistors, and into the little black boxes.
What are those little black boxes? Some sort of internal ground?
Sorry for the newbish questions, but every description of a unipolar
stepper motor seems to imply that I need to build or buy my own drive
circuitry. So the idea that this one might come with its own already
built right in is throwing me for a loop.
If someone could confirm my suspicions, or point me in the right
direction, I'd appreciate it.
Also, I don't actually have the motor in my hand yet. It's being
shipped. I'm just trying to get things figured out before it gets
here. :)
Thanks!
Adman
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Posted by on March 28, 2008, 8:20 pm
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On Fri, 28 Mar 2008, Adman wrote:
> Date: Fri, 28 Mar 2008 15:43:24 -0700 (PDT)
> Newsgroups: comp.robotics.misc
> Subject: Driving stepper motors / schematic comprehension help
>
> Hi all... I'm a software guy trying to learn the ropes of electronics.
>
> I have the goal of controlling a stepper motor using my PC parallel
> port to create +5v control signals. Shouldn't be that hard, right?
>
> My understanding of 5-wire stepper motors is that there will be one
> common power wire, and four other wires coming out. Attach the power
> wire to the power source, and attach the other wires to ground (using
> some logic to connect the right ones to ground at the right time), and
> you're all set.
>
> I bought a unipolar stepper motor... the first one listed on this
> page:
>
> http://www.futurlec.com/StepperMotors.shtml
>
> One thing I noticed is that the spec sheet lists that it has a "drive
> circuit".
>
> Some more investigation led me here:
>
>
http://www.eminebea.com/content/html/en/engineering/motors/pm_motor/selection_pm/drivecircuit.shtml
>
> Since I bought a unipolar stepper, I think the first schematic on the
> page applies. I'm not quite sure how to read it. It appears that
> what I want to do is attach my parallel port data pins DIRECTLY to the
> bases of each of the transistors (which is what the four non-power
> wires coming out of the motor will be).
>
> If that's the case, it looks like I use my parallel port control
> signals to activate each transistor according to activate the internal
> electromagnets in the proper order. Being a smart software guy, I can
> handle that. When I do that, the power will go through the coils,
> through the transistors, and into the little black boxes.
>
> What are those little black boxes? Some sort of internal ground?
>
> Sorry for the newbish questions, but every description of a unipolar
> stepper motor seems to imply that I need to build or buy my own drive
> circuitry. So the idea that this one might come with its own already
> built right in is throwing me for a loop.
>
> If someone could confirm my suspicions, or point me in the right
> direction, I'd appreciate it.
>
> Also, I don't actually have the motor in my hand yet. It's being
> shipped. I'm just trying to get things figured out before it gets
> here. :)
>
> Thanks!
> Adman
>
See if this kids course doesn't help:
http://www.taomc.com/bits2bots/index.htm
I believe they used BASIC print commands to move their stepper ...
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Posted by Adman on March 28, 2008, 9:00 pm
Please log in for more thread options > See if this kids course doesn't help:
>
> http://www.taomc.com/bits2bots/index.htm
>
> I believe they used BASIC print commands to move their stepper ...
Thanks for your response! That site looks really helpful. I'll check
it out.
You didn't actually read my post, did you? The site you referenced
specifically uses a ready-made IC to convert signals to drive the
stepper motor. My question is, given the stepper motor that I bought,
do I need to use a similar chip myself. Or does the schematic
described in the following link:
http://www.eminebea.com/content/html/en/engineering/motors/pm_motor/selection_pm/drivecircuit.shtml
... prove sufficient.
Thanks again!
Adam
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Posted by on March 28, 2008, 11:46 pm
Please log in for more thread options > =A0When I do that, the power will go through the coils,
> through the transistors, and into the little black boxes.
>
> What are those little black boxes? =A0Some sort of internal ground?
>
NPN transistors (NOT POINTING N)
-+-
base is +, collector and emitter are -
so, a small positive voltage on base (the flat line sticking
to the left)
causes voltage to flow from the emitter (the lead with the
arrow that is NOT POINTING IN) to the base
this biases the transistor, and will allow collector current
to flow through the emitter...
so, small positive voltage on base (control) ends up giving
your stepper motor GROUND (negative)
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Posted by Adman on March 29, 2008, 1:22 am
Please log in for more thread options > so, small positive voltage on base (control) ends up giving
> your stepper motor GROUND (negative)
Gotcha... I guess I expected "ground" to be a wire coming out of the
whole system. It appears from the schematic that there is some sort
sort of "internal ground".
That is, if I apply a control signal to the base of one of the
transistors, the current flows from the source, through the coil,
through the transistor, and into the internal ground... ?
I think we're on the same page. thanks so much for your reply!
Adman
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> Newsgroups: comp.robotics.misc
> Subject: Driving stepper motors / schematic comprehension help
>
> Hi all... I'm a software guy trying to learn the ropes of electronics.
>
> I have the goal of controlling a stepper motor using my PC parallel
> port to create +5v control signals. Shouldn't be that hard, right?
>
> My understanding of 5-wire stepper motors is that there will be one
> common power wire, and four other wires coming out. Attach the power
> wire to the power source, and attach the other wires to ground (using
> some logic to connect the right ones to ground at the right time), and
> you're all set.
>
> I bought a unipolar stepper motor... the first one listed on this
> page:
>
> http://www.futurlec.com/StepperMotors.shtml
>
> One thing I noticed is that the spec sheet lists that it has a "drive
> circuit".
>
> Some more investigation led me here:
>
>