Direction setup - Used wrong or error in doc?

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25 May 2011 21:47 #10077 by kreature
Here's a pic of a quick test btw.
I see with these timings that the narrow timings I enter are not really that important as the system uses much longer timings regardless.
(Again used to running at ns accuracys...)



Notice the zoom on the middle there where the dir pin changes.
There are two step pulses very close to this point and that is fine as they both uphold the timings I enter.
However, is it correct to suddently execute two steps this fast after eachother, even though opposite directions they should be linked to the velocity timing?
Interesting, although not what I was originally looking for.

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26 May 2011 13:32 #10091 by PCW
This is expected behavior, 2 pulses can be arbitrarily close (but obey timing) across reversals. This has to do with the fact that EMC has higher internal resolution than the step size (EMC uses floating point positions) so if a reversal position is just past a point 1/2 way between steps you can get a very close back and forward step pair.
This is the most accurate thing to do as far as step generation is concerned (that is an up down counter run from this signal would b as close as possible to EMC's commanded position). I suppose it might be less than desirable for non uStep drives but I dont really know.

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26 May 2011 16:00 #10094 by kreature
Thanks. I see.
I adjusted timing somewhat and it seems to be dependant on the velocity vs the timing. One can actually avoid it, making very neat sequences obaying my double-step time for reversal thought.

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