BasicMicro - Forums

Hi
I am trying to figure out how to spin or use stepper motors. I tried the program from the library in Studio but the motor just jerks sporadically, spun a bit, etc. I tried mixing up the lines (coding) but could not find the right combo. I know very little about steppers and have no documentation on this one. It is a AStrosyn 17pm series but cannot find the spec sheet online. Probably out of a printer or something I scrapped years ago. I used an ohm meter to figure out the 6 leads and they are 2 centertapped coils and it bumps on 12-24 volts but that is as far as I got.

Any pointers? Is there any particular sequence that one can reason out the correct pulse sequence? Can I move such a device with 4 mosfets and a single sided supply?

Cheers,

Sounds liek you have a uni-polar motor. The 2 center tap leads are your common power. The 4 other leads are the 4 pins from the driver chip which is being controlled by the processor. Do not try running a stepper directly off the I/O pins of the processor. There isn't even close to enough sinking capability unless its a super tiny stepper with no load. You have to use a driver chip of some find.

I've run Nema17 motors(probably what that is) with a Mosfet driver board. Its pretty simple. Figuring out which wires to put where is also fairly simple. There are only 16 combinations and IIRC only 8 are unique as far as the stepper are concerned.

Pin combinations example:

1 2 3 4
2 3 4 1
3 4 1 2
4 1 2 3
etc...

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Basic Micro - Robotic Technology Evolved

I am driving power Mosfets (http://pdf1.alldatasheet.com/datasheet- ... F820A.html) with a Nano8. I initially used the program mentioned above but then tried just turning the various P0-P3 in different combinations.

Now I am back on the bench and the motor is an Astrosyn PJJQ159ZB-A.

So that is correct and I just have to find the right combination? I will keep playing.

Thanks

I am able to get motor to spin but very jumpy and ocassionally, jumps a couple of steps backwards, then continuous on. It is like 20 steps forward, couple back, 18 forward, few back, cannot see a rhythm or particular sequence.

This is the code I am using, It is what I figure is the simplest form to drive a motor but am I off base? I have been switching the sections around but have not been able to find the right combo. (kind of like the lottery, have not found that combo either... )

Just means you aren't stepping in the correct sequence.

You should have 4 steps. You should set all 4 pins each step.

eg:


Now just change the pin constants until you get the right order.

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Basic Micro - Robotic Technology Evolved

Ohhh, I did not realize that more than one pin was enabled at a time.

I only ever put one winding on at a time sooo

Thanks Nathan and I will give it a shot.

Report back later

There are stepping patterns that only use one winding at a time but it cuts the torque way down(by about 1/3 IIRC).

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Basic Micro - Robotic Technology Evolved

That worked out better, although I do not think I have the perfect pattern yet. I did get continuous rotation but it faltered after a few rotations and became erratic. This could be a result of the Mosfets heating up too as they are not heatsinked.

With a pause = 0, the motor just sits and whines. With a pause of ~2-3, it is not too fast. Is this a function of the Nano 8 being a slower controller? ie 4 MHz I think? I expected a much faster rotation with a short pause.

I set up a For Next loop to see how many pulses for a complete revolution but haven't fine tuned it yet. Looks like around 60.

Different stepper motors can go at different speeds. You very well could need to slow yours down so it doesn't mis-step.

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Basic Micro - Robotic Technology Evolved

I know this may be a bit late, but have you considered using a :looks around to see if anyone is watching: Pololu A4988? Easily breadboarded and will support motors up to 1A w/o heatsink, 2A with. I've tinkered with it for speeding up execution time on nano's. What I'd really like is a way to send a number of steps and get an irq back when those steps have completed. wink wink, nudge nudge BM.

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Studio 2.0.0.16 on Win 7 Home x64 updated daily - Original Roboclaw 5A V1.3.9
Mostly a Nano40 for prototyping, but I have others in my bins

Don't forget acceleration/deceleration ramps. You can't expect a stepper to "jump" into motion.

Alan KM6VV

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