On Thursday 09 January 2020 07:54:10 andy pugh wrote: > I have just sorted out a problem on the forum where a user had > activated doublestep on a pin by setting step_spaced to zero, but had > then made a copy/paste error such that the reset function wasn't > activated on that pin. > > Why is it that the driver uses step_space = 0 to activate doublestep, > rather than using reset = 1 ? > > It seems like using the reset flag would be a more robust way to do it > and would avoid the problem seen here (at the expense of the peak step > rate being halved, and with the step = 1, space = 0 config the step > length would aways be exactly one base period.
Because the ideal is to polarize the signals so the narrow on pulse is a logic zero, pulling the - input to the driver to ground while the + input is connected to the + rail of the 5 volt logic supply. You get better drive into the driver input that way when it pulls down to turn "on". While there are exceptions, most drivers only need a 3 microsecond pulse to call it a step. Using the parport on a D-525-MW mobo, I don't recall ever needing more than 5 u-secs. With base thread rates of 27 u-secs being pretty much the limit of that board, giving up the reset and making a step pulse that long costs too much in rapids, often putting the top g0 speed too near peak resonance and easy stalls, and that in my experience puts you below 10 ipm for g0 speed. Thats too much like watching oil based paint dry. So while I've not waded thru the source code, thats what I see on the scope, or I change it until that is what I see on the scope. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
