Jon Elson wrote: > Sebastian Kuzminsky wrote: >> Yeah something's not right there, 190 us is way too long. >> >> >> Hm, these numbers come from 'halcmd show param hm2_7i43.*.time', which I >> thought was in nanoseconds, but looking at hal_lib.c I see that it's in >> CPU clock cycles. Is that intentional? >> >> In hal_lib.c's thread_task(), it calls rtapi_get_clocks() instead of >> rtapi_get_time(). >> >> <http://cvs.linuxcnc.org/cvs/emc2/src/hal/hal_lib.c?rev=1.59> >> >> >> Mine's a 2.6 GHz CPU, so 190 cycles is about 74 microseconds. With the >> 50% margin we've been working with that's 3 KHz, which is a little better. >> > Ahh, I measure this stuff with a logic analyzer. But, those > numbers seem much more reasonable! (Darn, thought I had a > competitive advantage, he he!)
Just to keep the record straight, that 74 us number is high too - it includes 30 or so microseconds of a higher-priority thread sampling all the gpios (in addition to the servo thread doing it). The actual frequency, once I figured out how to measure it properly, is right at 5 KHz. >> Each EPP cycle takes right around 1 us on my test system. >> > I can get down to about 800 ns with mo-bo parport, and 640 or so > with a PCI parport. I get quite a bit of jitter on my on-board parport. Uploading 128 KB of firmware goes anywhere from 850 KBps to 1.1 MBps. Contention on the PCI bus maybe? There's a wifi card and a bunch of other stuff there. I have a plug-in PCI parport card, but I haven't gotten it to work yet... -- Sebastian Kuzminsky Cryogenic travel has improved since then... I woke screaming in a translucent box. “There, there,” said the box. “Everything will be all right. Have some coffee.” -- Ken Macleod, "Who's afraid of Wolf 359" <http://outofthiseos.typepad.com/blog/files/KenMacleodWhosAfraidofWolf359.htm> ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
