Yes the faster you go the bigger the jumps. With my 1MHz clock I can only make pulses with periods that are a whole number of microseconds.
So I ask again: What is the fastest step rate you actually use with a real machine? What is needed? Do people run motors at 100,000 steps per second? What I'm guessing is that it is rare to run as high as 10K steps per second. I could be wrong, so I'm wanting to hear from people who are running real machines. To say this using MK or LinixCNC terminology what is the fastest usable "base rate"? I am using a 1 uS (or 1MHz) base rate. Is that fast enough? I looked at the data sheet that comes with the lead shine drivers and they all seem to require a pulse be high for at least 2.5 uS and then low for another 2.5 uS. This means the fastest possible period is 5 uS or 200KHz. What I'm finding is that if I use a uP like an ARM-M i'm limited to bout 1MHz base rate to go much faster I'll have to go with an FPGA and then 10MHz is reasonable. One more thing: That 10% velocity jump represents a worst case rate error of 5% but the average rate error (I think?) be only 2.5% or 1/4 of the step size. On Tue, Apr 3, 2018 at 7:46 PM, Jon Elson <el...@pico-systems.com> wrote: > On 04/02/2018 09:36 PM, Chris Albertson wrote: >> >> >> How to generate pulses with 50nS jitter? Use hardware, not software. >> The uP has 10 hardware counter/compare timers built in and you can >> program them to divide down the a 1MHz clock. > > If you have a 1 MHz clock, then you can't have any pulses with finer > resolution than 1 us. > So, a 100 KHz step pulse train will have an ~10% velocity jump to go to the > next faster or slower velocity. > > My Universal Stepper Controller has a 10 MHz clock to the step generators, > so that has 100 ns resolution. > I recommend a 300 KHz maximum step rate with it, so the next higher or lower > velocity is about a 3% jump. > > Jon > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
