-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 7/20/2012 9:11 AM, Kent A. Reed wrote: > On a more serious note, as has been discussed on the two emc mail > lists, the road to ARM is littered with ideas but so far we have > little result. > > The nicely done miniEMC2 project by Sergey Kaydalov is the most > complete effort I know of. It employed the higher-latency Xenomi > code rather than RTAI. Inquiring minds want to know more about the > possibility of porting this code or something like it to boards > like the RPi or BB and about the resulting performance attainable. > I wish I could have tackled this already but I've got too many > family issues at the moment.
I'm planning on trying to use the PREEMPT_RT version of LinuxCNC with my Pi when it comes in, but I'm not sure what sort of latencies to expect. On conventional PC hardware, I've gotten decent latency jitter with modern systems, but not yet down to the RTAI levels. On older hardware latency with PREEMPT_RT is much worse, particularly on single-core systems (although I don't yet know if this is due to not having two cores to schedule between or because all my single-core systems are pretty ancient). I'm also hoping on the Arm it might be possible to use the fast IRQ and read/write the I/O pins in an ISR which may allow the servo thread to run with much higher jitter. > Then there's the problem of gluing these boards to our CNC hardware > about which I yield to Jon. My current plan is to bit-bang GPIO pins based on code from the parallel port driver, but adding a bit of electronics would probably make things much easier. I'll evaluate that option once I see where I get with software stepgen. - -- Charles Steinkuehler [email protected] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAlAJa6IACgkQLywbqEHdNFyNjwCfTVchMrwrcmA2RZ78hoYM0OEa zn0AoOyTZa74B1MnFaDOL2HqUxG5LwOH =Dmby -----END PGP SIGNATURE----- ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
