I admit that I don’t know exactly what you mean with the music reference. But it looks like the image compression obfuscated some of the information on the scope screen. So I’ll try to explain.
What I set out to do was a fft on the step pulses, but apparently for $350 you can’t have a 4-channel 100mhz digital scope that also has a working fft feature. But the scope does have a nice variable intensity display that makes it possible to see the timing jitter by simply looking at adjacent pulses. So I trigger on the pulse to the left. On the image that shows three complete pulses, the time scale is 50us/div. That sample shows about a 50us step-to-step jitter. I’d guess that it’s not actually a step-step jitter, but rather servo jitter, since the fpga is responsible for step timing. This is what happens if you run a Mesa Ethernet card with a Pi4 without DPLL configured. The image that shows only the rising pulse edges is set up in a similar fashion; I focus on the pulse adjacent to the trigger and since I couldn’t see any jitter at all, so I “zoomed in” to 20ns/div. The capture shows pulse-pulse jitter of 80ns. > On Feb 3, 2022, at 5:19 AM, Peter Blodow <p.blo...@dreki.de> wrote: > Thaddaeus, > in your image0, I count 7 beats to the bar, seven, is that right? (In image1 > it is imposible to tell the pulses apart). This reminds me of the first time > I set up a stepper configuation using stepconf (in the early 2010's). I > encountered similar behaviour of the motors as you did and, after days of > fiddling around, finally detected that stepconf made a 5 beats to the bar > music. Took me quite a lot of convincing work to the programmer's community > then to get that fixed. > > Peter > > > Am 03.02.2022 um 00:54 schrieb Thaddeus Waldner: >> In case anyone is interested, here’s a scope capture of the step pulse train >> with and without the DPLL configured. >> >> >> >> >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
