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typo
PostPosted: May 15, 2008 - 11:19 AM
Newbie


Joined: Mar 26, 2008
Posts: 15


Can anyone advise me on simple methods wiring a ATmega8 to drive a low cost commercial Microstepping Driver.

I'm a total novice here but I've had some very modest success with a first project using salvaged unipolar motors and a ULN2003s, but when it came to bipolar motors I got intimidated over H-briges and Allegro/Sanken circuits and bought a very cheap microstepping driver. (with limited documentation attached)

It uses pulse and direction via a 5V opto coupling. Am I right in thinking that I could simply connect the lines to the chip and toggle ports to sink the lines? (330 Ohm resistors are shown series)If so would I need do something about noise suppression? (3microsecond pulse sensitivity)However, if I use PWM I'm guessing I would need some kind of transistor interface or another Darlington array. I don't think the voltage would work for the ULN2003. Is there a suitable alternative or a better way of doing this?

Since I need to move up from batteries to a 30v Bench power supply (for 12v motors) the smoke risk has increaded dramatically. If only for the sake of my dining room table, could someone advise me here.

Thanks,

Dave
 
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UNiXWHoRe
PostPosted: May 15, 2008 - 03:49 PM
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Joined: Nov 03, 2006
Posts: 1120


Quote:

If only for the sake of my dining room table, could someone advise me here.


Get a bench... Wink
 
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typo
PostPosted: May 15, 2008 - 04:35 PM
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Joined: Mar 26, 2008
Posts: 15


The sad thing is I have the bench, and a serviceable shed/workshop, I just can't get in it for the 10 years worth of accumulated clutter my wife's keeping for "when our son leaves home". ... but that's for a different forum.

Dave
 
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bobgardner
PostPosted: May 15, 2008 - 06:10 PM
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Joined: Sep 04, 2002
Posts: 23451
Location: Orlando Florida

When you turn it on the first time, make sure the current limit is down in the 100ma level instead of the 3A level. Welcome to AVRfreaks.

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typo
PostPosted: May 15, 2008 - 08:52 PM
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Joined: Mar 26, 2008
Posts: 15


In the deep end! I've tried just toggling a port ... and it seems to work. At least no pyrotechnics yet!

Is it really all I need to do? Surely I risk damaging the chip, particularly if I drive multiple motors? Sorry to be so dumb.

Dave
 
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JohanEkdahl
PostPosted: May 15, 2008 - 09:59 PM
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Joined: Mar 27, 2002
Posts: 21351
Location: Lund, Sweden

typo!

Where did you buy those MSD415's? What did you pay?
 
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typo
PostPosted: May 15, 2008 - 10:16 PM
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Joined: Mar 26, 2008
Posts: 15


JohanEkdahl,

I got them from these guys:
http://www.motioncontrolproducts.co.uk/
@ 21.50 + tax

I've seen them with other labels on other UK sites at a similar price. Not looked internationally.

Dave
 
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