Gene Heskett wrote: >On Friday 20 November 2009, Chris Knowlton wrote: > > >>OK, I found the data sheets on the chip and I also found a couple of app >>notes, which helped a bit, now I need some translation of the EMC tags >>please >> >>Step Time: I assume this means the pulse width from rising edge to falling >>edge? >> >> >Or better, from falling edge to rising edge, there is more giddy up on a >logic zero than in a logic one, so a logic zero is generally considered the >active state. > > While this is good advice for most electronics, keep in mind that the software step generator generates positive steps. The step is assumed to occur on the rising edge of the stepgen output, and that is the edge that the direction changes are timed from. If the driver board actually needs an active low signal, then the step output needs to be inverted (which is a checkbox on the port setup page if you're using stepconf)
>>Step Space: I assume this is the smallest spacing between pulses that >>should be sent? >> >> >Something like that, and usually that is a lot faster than emc can send them >anyway. > > Stepspace is the setting you use to tell the step generator the minimum "off" time needed between steps. >>Direction Hold: I assume that this is the amount of time the direction >>signal has to stay high to make the direction change? >> >> >This one isn't clear to me. > > Not quite. This is the amount of time that the direction line has to be held in the same state after a step has been issued. Some drivers may need some time to sample the DIR line after a step arrives. In addition, some drives with input step multipliers needed the DIR line to be high until all the "multiplied" steps were issued (some early Geckos are in this category). The step multiplier would clock off 2, 5, or 10 steps for every one that came in, but it didn't latch the direction line - that was a straight feed-through to the internal electronics. If you changed the DIR line while the extra steps were being generated, some of them would go the wrong direction. >>Direction Setup: I have no idea what this is. >> >> >Time a direction signal must be valid before a step should be sent. Maybe.. > > This is the amount of time after the direction line has been changed before the next step can be output. Note that there is a complete stepgen timing diagram in the EMC2 manual which shows all of these parameters, and there is also additional information on the wiki, particularly here: <http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?TweakingSoftwareStepGeneration> - Steve ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
