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Topic: Stepper Motor + BigEasyDriver + AccelStepper (Read 4458 times) previous topic - next topic

GS88

Hi!

I'm in the process to learn something about controlling and programming for stepper motor.

I'm looking for this: http://www.sparkfun.com/products/10846 with driver: http://www.sparkfun.com/products/10735

What I would like to know is:
- do someone have used both with AccelStepper library?
- how do I connect BigEasyDriver to arduino for microstep control?
- anyone know about example with this type of configuration?

Any other hints and helps are welcome.

Regards.

MarkT

Just connect step and dir lines (and ground!) and the controller does the rest (defaulting to 1/16th steps).
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GS88

Thank you Mark!

So I don't have to connect M1, M2, M3 of the BigEasyDriver to arduino for getting micro stepping work?

Just Dir and Step? Can I use AccelStepper library for this?

Regards.

MarkT

The documentation says that with only dir/step the default is 1/16th micro steps.  You can configure it if more lines are connected of course.
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marzetti

Yes, the AccelStepper library does support step/direction control. Be aware, though, that it has an upper limit of how many steps/sec it can generate which means using the default 1/16 setting you will have very slow motor speeds. No problem though, you can pull M1,M2, and M3 low according to the chart in the datasheet (all of them pulled low gives you full steps).

GS88

Thank you very much!

Now I'm understanding much more than yesterday :)

So without M1,M2,M3 connected I only have 1/16 step increment. This mean very slow movement I think.

At this time I'm out of pin in my arduino 2009 based project. Could I use a shift register like 74HC595N to controlling both Step/Dir and step increment (M1,M2,M3)?

Regards.

GS88

More on microstep.

If I don't use microstep a complete rotation is something similar to rotate(400) - in a 400 step motor. With the easy driver is something like rotate(6400).

So, what's the difference between the two? Does the rotate(400) is more fast or they're simply equal and the only change is in the number of step I've to use for a complete rotation?

Hope to be clear...

Thank's.

marzetti

First question: No, I would not use a shift register for step and direction. You may not have to control the step mode pins with software. In most applications these would be set in hardware.
Second question: Most stepper motors are 200 steps/rev. 1/2 stepping mode gives you 400, 1/4 gives you 800, etc. It is very much like shifting gears in a car. Full stepping gives you the most speed, microstepping gives you more resolution and smoother motion. Beyond 1/8 stepping there is no real resolution gain, however, because the motor cannot accurately position itself that finely. You will get smoother motion however.
Hope that answers your questions.

marzetti

Another thought-
You don't describe the nature of your project but I would encourage you to determine all the physical requirements before sizing your motor, choosing step mode, etc. There is a lot of good info on these issues here: http://www.geckodrive.com/ark-2/support.html.

GS88

Thank you very much Yankee. Very clear.

The project involves a sort of micro rail for moving a microscope.

Other commercial application uses this one: http://www.sparkfun.com/products/10846


MarkT


First question: No, I would not use a shift register for step and direction. You may not have to control the step mode pins with software. In most applications these would be set in hardware.
Second question: Most stepper motors are 200 steps/rev. 1/2 stepping mode gives you 400, 1/4 gives you 800, etc. It is very much like shifting gears in a car. Full stepping gives you the most speed, microstepping gives you more resolution and smoother motion. Beyond 1/8 stepping there is no real resolution gain, however, because the motor cannot accurately position itself that finely. You will get smoother motion however.
Hope that answers your questions.


Smoother running probably means somewhat higher speeds since resonances are much reduced with microstepping.  Certainly will run more quietly.
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