the cap goes from wiper to ground.  I'll send you the schematic.

What value to trim the pot to?  Hmm, I think I set it at midpoint and never
mucked with it.  So I suppose I've got some headroom.

DougM

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of
Josh Koffman
Sent: Thursday, December 10, 2009 8:16 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Stepper Motor Driver

On Thu, Dec 10, 2009 at 10:55 PM, Doug Metzler <doug.metzler@gmail.com>
wrote:
> Answering both your questions Josh:
>
> For the reference voltage signal I've got a 2.2k on +5v attached to a 10k
> potentiometer that's then tied to ground. =A0So the wiper on the pot goes=
 to
> ref. =A0There's a 100n on the wiper leg as well.

Thanks for the info. Is the 100n cap in series with the wiper leg or
does it go from the wiper leg to ground? How did you decide what value
to trim it to?

> The other stepper drivers I tried were:
>
> =A0 =A0 =A0 =A0L297/298 (runs super hot, very expensive, nasty noise issu=
es)
> =A0 =A0 =A0 =A0L6228 (disaster from the get-go - could never get it to wo=
rk)
> =A0 =A0 =A0 =A0For the unipolar driver I've got an l297 driving a pair of
TA8429's.
> The initial test of these worked fine, but I haven't gone back to properly
> prove them since I'm running bipolars on the current project.

Well I'm game to try  the A3982!

Josh
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