shaking stepper

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Hi everyone! I am trying to build something that requires a stepper motor and I can't get it work... iti keep shaking left and right very little. I have the program written in AVR studio 4

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Does the motor have 4 wires or 6 wires? Can you rig the program to step when you hit a key? Tell us the pattern you put out on the outputs for the 4 steps. If we cant figure out the problem from this info, we will have to actually look atthe program. (Yikes. Might be embarrassing)

Imagecraft compiler user

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It could be driven incorrectly (wrong circuit or voltage). The motor could be connected incorrectly (wires swapped). Drive and connection may be correct but driving it much too fast can also cause that to happen.

Jim

 

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Steppers usually have to be ramped up slowly, as otherwise a single step pulse can't overcome the inertia and they won't start turning. The same goes for slowing them down to a stop - if you just stop the pulses dead they'll overshoot and lose position. If you spin up the shaft with your fingers, does it continue turning? If you temporarily slow down the pulse rate by some large factor - say 16 or 128, which can be done easily with the timer prescaler - will it turn then?

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I have 4 wires on my motor and a white wire witch i supossed to be the comon ground. I have tried several things like starting 2 coils at the same time, but with no results. My motor makes only one step and back from where it started.

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Your motor seems to be a bipolar stepper. There's no "common ground" on this type of motors, and you need to use H-bridges to switch the current flow on the two motor phases.

How are you "starting" the coils? Apart from the explanations above that talk about the step frequency, maybe you're not producing the right sequence. Try google or the Atmel's application note about building an AVR-based stepper controller to know more about this if needed.

...
[Edit]
Opps! I didn't see the big

Quote:
"AND" a white...
In this case, though I don't remember the name of the exact type of motor, I think is something like "bifiliar unipolar motor". Nevertheless, please tell us how are you driving it electronically and the step frequency you're using.
[/Edit]

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Can you read ohms from the white to each other wire? Good. Find the pairs that have exactly twice this value. That's the two pairs that go to the 4 output mosfets/buffers/drivers. White goes to 5V or 12V or whatever.

Imagecraft compiler user

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At the attachment file there is a program for stepper motor.
SO, You can check your circuit.
It would be better to sent your circuit for checking.

Attachment(s): 

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bobgardner wrote:
Can you read ohms from the white to each other wire?

Already did that and I found that by mesuring the resistence betwint the wite wire and the ohters I have the same value witch is 1/2 the value obtained by conectig 2 of any wires except the wite one... I will try to rewrite the program again after looking on the example posted here. I use an 90s1200 controler

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If power consumption isn't a concern, you can use single ended mosfet drivers. I built such a controller yesterday with a tiny2313. On my motor, the two coils are on mosfet drivers on data bits 7-5 and 6-4. A logic 0 on a pin causes 12v to be sent to the motor, a logic 1 causes the pin to be grounded. I can run the motor using the following byte sequence on portB:

0x80
0x40
0x20
0x10

Note that since there is no common ground, both 0x00 and 0xF0 put the motor at rest since there's no voltage difference between the pins. 0x00 is easier on the mosfets though.

Oops, old thread, sorry!