Am 14.01.2014 um 19:33 schrieb Charles Steinkuehler <[email protected]>:
> On 1/14/2014 12:21 PM, Bas de Bruijn wrote: >> Yes, the BeagleBone Black, >> the PRU is hat 10us step length and 1us step time. The PRU code cannot cause an "unexpected realtime delay", since this is a message generated by the motion component. Since missing steps have no way to find their way back into HAL except if you are running a stepper servo loop with encoders (which you likely dont), this cannot be the source either. The logic for "unexpected realtime delay" is here: https://github.com/mhaberler/linuxcnc/blob/unified-build-candidate-3/src/emc/motion/control.c#L249 What motion does is: - observes its invocation interval over a window of samples, - once the window is filled with samples, start checking: - compare the current invocation time to all samples - if the current interval is longer than 1.2 of any of the samples then generate an "unexpected realtime delay" message. What you want to do is investigate the functions on the servo thread. see the 'show thread' and 'show param' commands http://www.linuxcnc.org/docs/devel/html/hal/tutorial.html, in particular the '.time' and '.tmax' values, which might give a hint which thread function takes too long. It might be worth looking at motion execution times, see the PARAMETERS section of http://www.linuxcnc.org/docs/devel/html/man/man9/motion.9.html. - Michael >> The servo task period, in nano sec is 1000000. >> When i run a latency test i get a jitter of approximately 56000 to 60000 ns >> max Jitter >> >> I’ll disable the screensaver to check. > > The latency you report is typical for the BeagleBone. The "unexpected > realtime delay" is something I see occasionally on my systems. I > haven't fully dug into the cause, but it seems like something in > LinuxCNC has hard-coded jitter numbers and doesn't like the BeagleBone > (which has higher IRQ jitter than a typical x86 system). I've never had > it cause issues, however, and it is not correlated with a spike in > latency as measured by either the LinuxCNC latency-test or the xenomai > latency utility. > > I also run with the screen saver and display power management enabled on > my BeagleBone and have not had any issues with "missed steps". > > I suggest you review the current setting on your stepper drivers, > cooling on the stepper drivers, the mechanical system (make sure > everything moves freely and can't bind), and review your machine setup. > > I did have to dial my acceleration down to around 2400 mm/s/s to avoid > missing steps with some Slic3r generated infill gcode, but that had > nothing to do with the BeagleBone, my steppers and drivers just weren't > up to the task when running off 12V. > > -- > Charles Steinkuehler > [email protected] > > ------------------------------------------------------------------------------ > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > Learn Why More Businesses Are Choosing CenturyLink Cloud For > Critical Workloads, Development Environments & Everything In Between. > Get a Quote or Start a Free Trial Today. > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk_______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ CenturyLink Cloud: The Leader in Enterprise Cloud Services. Learn Why More Businesses Are Choosing CenturyLink Cloud For Critical Workloads, Development Environments & Everything In Between. Get a Quote or Start a Free Trial Today. http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
