On Wednesday, February 2, 2022 5:21:34 PM EST Peter C. Wallace wrote: > On Wed, 2 Feb 2022, Thaddeus Waldner wrote: > > Date: Wed, 2 Feb 2022 15:45:16 -0600 > > From: Thaddeus Waldner <thadw...@gmail.com> > > Reply-To: "Enhanced Machine Controller (EMC)" > > > > <emc-users@lists.sourceforge.net> > > > > To: "Enhanced Machine Controller (EMC)" > > <emc-users@lists.sourceforge.net> Subject: Re: [Emc-users] Stepper > > PID > > > >> > I suspect that you are not using the DPLL, or that it is not setup properly. For a RPI4 I would suggest these settings: > > setp hm2_7i76e.0.dpll.01.timer-us -200 > > set hm2_7i76e.0.stepgen.timer-number 1 > > > > These should reduce the stepgenb position sampling jitter to a > > fraction of 1 usec. > > > >Thank you, Peter. I will check and see what the configuration looks > >like later when I get home. Is there any documentation on how this > >works? Also, what are the implications of increasing the dpll timer > >period? If I can get away with 2ms > >servo loop, should I set this to 400us? > > No, the DPLL sample time setting is determined by jitter > statistics (average delay shifts = delay baseline drift), > not thread period. > > If you change this value you should add it to the PID loops > FF2 parameter. This will compensate for the added delay between > the position read and velocity write. For -200 usec you would use > an added FF2 value of 0.0002 (PID values are scaled in seconds) > > Peter Wallace > Mesa Electronics > Hhmm, and if there's no PID's in your config cuz you are using the new 3 phase stepper/servo's? These have encoders on the motors that don't get fed to LCNC, only back to the driver, and among other things, the drivers use the error they do detect to determine how much current is needed by the motor to get there. Motors run 50C cooler.
Thank you Peter. 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, 1940) 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-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
