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. So the wiper on the pot goes to ref. There's a 100n on the wiper leg as well. The other stepper drivers I tried were: L297/298 (runs super hot, very expensive, nasty noise issues) L6228 (disaster from the get-go - could never get it to work) For 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. DougM -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of Josh Koffman Sent: Thursday, December 10, 2009 2:09 PM To: Microcontroller discussion list - Public. Subject: Re: [EE] Stepper Motor Driver On Thu, Dec 10, 2009 at 12:01 AM, Josh Koffman wrote: > I only had enough time to get halfway through the datasheet tonight > but looks good so far. Thanks for the tip! Just out of curiousity, > which others have you tried and what didn't you like about them? Doug, I've been looking through the datasheet. The only part I'm tripping up on is the reference voltage signal. It seems to want something between 0 and 4V. What did you use and how did you generate it? I'm guessing that once you pick a Vref calculating out the sense resistors is pretty straightforward. Thanks! Josh -- A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist