On Sunday 08 October 2017 21:01:15 Chris Albertson wrote: > Yes, you are right about the PRU's I have two Beagles here on my > desk I thought about using the PRUs but I want my code to be portable > so I avoid using them. Instead I do that kind of work with ARM > Cortex-M. This preserves the possibility to upgrade the > > There ARM M is tiny and dirt cheap and is very good for real-time > work. I have a robot with four motors and encoders and get 44,000 > interrupts per second > and much better real time latencies then from any Linux based solution > on any platform. > > My solution for robot control is a hierarchy with ARM M for the lowest > level, then > Raspberry Pi 3 connected by high speed serial. Finally the Pi 3 uses > WiFi to > connect to server class 16-core Xeon > > That said I always try to use the bigger computer for software > development if I can > usually I can at least start there until I need to test on real > hardware > > Back to machine tools - Why bother trying to save power and space. > The milling > machine already need AC mains power and weights a LOT. What does one > save by using a micro sized controller very an ATX save mainboard? > > Why can't LinuxCNC run faster on the BBB then on a 10 years old PC? > A computer is not a CPU. It has also a memory and I/O subsystem. > > Also you can't compare clocks. What mattress how mach work is done > per clock. The old PC does 2 or 4 times as much per clock and the > BBB/ So your 10 year old 1.7Ghz PC is kind of like owning a 4GHz BBB, > if such a thing could exist. Then you compare the graphic abilities > and the old PC wins by a huge amount. > > The BBB is great if you need it's small size and low power. And it's > the wrong thing to use if you don't have need to save size and power. > > I've got several project going and those running off batteries all use > ARM M and A type. > On another front, the rock64 at $44 for a 4Gb memory version, has a much faster data transfer internally than the pi-3b. So its i/o is at least 5 to 10x the pi's. Even X, with only a framebuffer like the pi's, is much snappier than on the pi's.
I did succeed in building a fully rt-preempt 4.9 kernel on it today, took about 4 hours, but I've not yet attempted to boot it as I saw some stuff go by during the build (when I wasn't checking my eyelids for leaks :) that I yet need to turn off. I think, other than fine tuning the kernel build, that convincing the hm2_rpspi driver that it should run on the rock's rk3328, arm64 quad core SoC, running at up to 1.5GHz should be the last major hurdle to making linuxcnc run on it, the sim version sure runs nice, while dancing rings around the pi. And fixing the pi's local keyboard problems that often require several reboots to get a fully working keyboard. But when it works, it works well, and old meat in the pot now has a Bartlien, SS, cut rifled, 6.5mm barrel in it, chambered for 6.5 Creedmoor, and shooting well for a hunting rifle with a bullet that looks like its doing mach3 just laying on the table. So stay tuned, folks, I think this rock64 just may be a pi killer. And its running linuxcnc straight from the x86 branch on the buildbot. Whats not to like? > On Sat, Oct 7, 2017 at 7:00 PM, John Dammeyer <jo...@autoartisans.com> > > wrote: > > Hi Chris, > > Thanks for your comments. > > > > > I don't know why people like to use these 1GHz ARM boards for > > > machine controllers. > > > I use them for projects that run on batteries but if you have AC > > > mains power available > > > go with a bigger computer. > > > > > > You can stay with Machine kit but I just don't see why so many > > > people > > > > like > > > > > the low > > > powered ARM boards. > > > > The Beagle is in a different class from the Raspberry Pi and Arduino > > modules. The dual PRU's allow it to do things that outshine the > > LinuxCNC systems from 20 years ago running on Pentium 33 size > > machines. The nice thing about them is they are small. A small > > 1GHz 32 bit PC in the tiny brick format costs into the hundreds of > > dollars. > > > > But that's also why I asked. Comparisons that I've done with a Pi3 > > and a BeagleBone Black show for normal graphics GUI and even > > compiling programs with Lazaras (Delphi Pascal) that the Beagle is > > about half the speed but then the Pi3 has a dual processor core. > > Probably still not fast enough to do the real time stuff for Linux. > > > > But it does be the question doesn't it? If Linux could run real > > time on much slower PCs 10 years ago, why can't it run on the much > > faster with more memory Beagles? > > > > Has LinuxCNC really changed that much? > > > > As I mentioned in the reply to Andy. I'm hoping to start a > > conversation with people who have used both and perhaps even Mach3. > > > > John > > > > > > > > ------------------------------------------------------------ > > ------------------ > > Check out the vibrant tech community on one of the world's most > > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
