Thanks Charles, I understand. I'll stick with the 20us period and get the other numbers right to remove all error messages. After that if time allows and I want to go further I'll investigate the pru_busy pin. Bas
> On 1 jan. 2014, at 21:54, Charles Steinkuehler <[email protected]> > wrote: > >> On 1/1/2014 9:24 AM, Bas de Bruijn wrote: >> Hi, >> >> I got my Delta Type printer moving with the Machinekit image from Charles >> and compiled with the lineardeltakins from Jeff Epler. Thank you guys for >> the wonderful work, Also a big thanks to Michael and Bas for getting me up >> to speed. I’m not yet ready to compile the ubc3+ja4 branch, but that’s just >> a matter of time now that I’m plunging more and more into Linux and LinuxCNC. >> >> Here’s little video of my printer writing “LinuxCNC" on a piece of paper. >> http://youtu.be/G2oQGTJH4Vc >> >> Now as I’m going froward I want to correctly set up my stepper motors. I >> checked the step time, step space, direction and hold. I’m wondering if my >> calculations are right regarding the setup of the stepping. >> >> When powering the motors in LinuxCNC I get the messages >> "stepgen.0/1/2.maxvel is too big for current step timing & position-scale, >> clipping to max possible". >> Sometimes I get a joint following error. So I did some reading on the >> LinuxCNC wike >> >> Am I going in the right direction if I calculate: >> STEPLEN + STEPSPACE (each 1000ns for my stepsticks acc. >> http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Latency-Test) = 2us >> SCALE = 64 steps per mm (16x micro stepping) >> STEPGEN_MAX_VEL = 2us with 64 steps per mm thus gives (1/2us)/64 = 7812.5 >> >> and that means my MAX_VELOCITY can never be higher than STEPGEN_MAX_VEL? > > The default PRU task period is 10 uS, so the maximum step rate is 20 uS > (10 uS high and 10 uS low). The 1000 nS times for STEPLEN and STEPSPACE > are *MINIMUM* times, the actual time taken will be the smallest integer > number of PRU task periods that is at least as long as each timeout. > >> When I run latency-test I get approx 60.000 ns jitter. But these are for >> software stepping, and the PRU on beagle bone takes care of the stepping if >> i read correctly. >> >> Now reading http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Following_Error where >> do I set the BASE_PERIOD. >> Is that the SERVO_PERIOD in the .ini file? > > The PRU task period is set using the pru_period= parameter when loading > the module (default is 10,000 nS or 10 uS if not specified). If you > want to reduce this value, make sure you leave enough overhead for the > worst-case timing path through the PRU code. You can monitor the PRU > active and idle time using the pru_busy_pin (defaults to enabled on PRU > direct output 0). The PRU busy pin *MUST* be a PRU direct I/O, and you > have to setup pin muxing to send the PRU bit to the I/O pin. By default > the LCD/HDMI signals is using the PRU I/O bit 0, so you either need to > move this signal to another pin, disable (or override) the HDMI pin > multiplexing for PRU I/O 0, or just shorten the PRU task period and hope > for the best (not recommended). > > -- > Charles Steinkuehler > [email protected] > > ------------------------------------------------------------------------------ > Rapidly troubleshoot problems before they affect your business. Most IT > organizations don't have a clear picture of how application performance > affects their revenue. With AppDynamics, you get 100% visibility into your > Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! > http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Rapidly troubleshoot problems before they affect your business. Most IT organizations don't have a clear picture of how application performance affects their revenue. With AppDynamics, you get 100% visibility into your Java,.NET, & PHP application. Start your 15-day FREE TRIAL of AppDynamics Pro! http://pubads.g.doubleclick.net/gampad/clk?id=84349831&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
