AVR-Chat

Is driving a stepper thru PWM then to a shift register
alright? -jay


	
		
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I'm not sure what you mean by that but i didn't see anything about 
controlling current and phase.  There are stepper controller chips 
that do all this and handle the power required.  You might go check 
out these tutorials on steppers http://209.41.165.153/stepper/  and 
then look up the following chips:  ST's L297, Allegro A3977

It shouldn't be too hard to control a stepper from a micro but you'll 
still need an H-Bridge of some ilk to drive the coils.  PWM comes 
into play when you want to drive the stepper at 5-10X its rated 
voltage.  A microcontroller + pwm is useful to support "micro" 
stepping

Phil

--- In AVR-Chat@yahoogroups.com, jay marante <jaythesis@y...> wrote:

> Is driving a stepper thru PWM then to a shift register
> alright? -jay
> 
> 
> 	
> 		
> __________________________________
> Do you Yahoo!?
> Win a $20,000 Career Makeover at Yahoo! HotJobs  
> http://hotjobs.sweepstakes.yahoo.com/careermakeover

--- In AVR-Chat@yahoogroups.com, jay marante <jaythesis@y...> wrote:
> Is driving a stepper thru PWM then to a shift register
> alright? -jay

As another poster mentioned, you can get a controller chip that does 
most or all of the work for you.  Alternatively, you can use a latch 
to provide the phase drive signals to energize the motor's coils 
through appropriate driver transistors.

The book "Easy Step'n" by David Benson describes both methods and 
gives a good background in steppers and driver circuits.

Also, I have some schematics posted of a dividing head controller 
that uses a stepper for positioning.  You can find links to them at:
http://www.kinzers.com/don/BX24/Indexer