And I will add.... The original Sherline controller, and probably the current one utilize a microcontroller to read the step and direction signals without any external latching. This means that the direction signal must be valid long enough for the microcontroller to notice the step signal and execute the instructions to read the direction signal before it changes.
Steve Stallings > -----Original Message----- > From: Matt Shaver [mailto:[EMAIL PROTECTED] > Sent: Monday, November 17, 2008 6:39 PM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Stepconf Sherline > > > I spoke with Steve Stallings today, and he pointed me to this thread on > the Sherline stepper drive problems some of you guys are having. I > worked on this problem in late June of 2003. > > Right before Sherline started shipping machines they tested them for > repeatability using a 3d contouring program called "heart". I've never > made one, but I think it's a tiny mold for a heart shaped widget of some > sort. Anyway, they had bad problems with losing steps and I made a bunch > of modifications to the step generating part of EMC1 including > adding .ini file parameters for step and direction pulse timing. The > things you need to know are: > > 1. EMC2 is so different from EMC1 in the step and direction pulse > generating department that comparing the code from then to now is likely > to drive you nuts! > > 2. The guy who designed the Sherline motor drives is Bryan Mumford: > http://www.bmumford.com/ > > 3. If you can contact him, he'll know what the timing requirements are. > Way back when he had this to say: > > "Here are my parameters --- the low state must last at least 10 > microseconds and the Direction state must be correct and stable for two > microseconds after that." > > I don't know if there have been revisions to the drives since then that > would have changed this, but essentially the drive steps on the falling > edge of the step pulse, so the direction bit must be stable beforehand, > and should probably be held in a stable state for the whole step pulse, > which must last a minimum of 10uS. I wouldn't change the direction > signal until after the step line has been returned to a "high resting" > state. > > Thanks, > Matt > > > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move > Developer's challenge > Build the coolest Linux based applications with Moblin SDK & win > great prizes > Grand prize is a trip for two to an Open Source event anywhere in > the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
