Todd, ROFL First of all I agree with you that likely the current crop of processors is more than fast enough. And with 4 cores it's likely that the Pi3 which I run with the MESA 7i92 should be fast enough. Although it's odd that when it boots LinuxCNC it also tells me one core isn't functional. Maybe that's the one chosen to be an I/O processor?
Back when the BeagleBone Black (BBB) was still running MachineKit they made use of the co-processors to do the actual bit banging and handle high speed quadrature encoders. MACH2 on an early Pentium had no trouble, because of direct access to the hardware, creating step/dir pulses but I have no idea if the 1PPR for lathes was only because of lack inexpensive quadrature encoders or computer speed. I can do 20kHz step rates on a PIC18F series for my ELS but that processor didn't have a quadrature decoder nor enough interrupt inputs to properly decode hi-res encoders. Not to mention that when I developed the ELS the cost of an encoder was more than the entire kit so a 1PPR solution was often also the only solution. Now we can get PIC32's that have built in quadrature encoders and more than enough speed to do fairly high step/dir signals plus PWM just like the BBB has. The far east supplies quadrature with index for $25. But can a Pi3/4/5 handle a 1000 line encoder in quadrature mode? If not then it's the same smoke and mirrors used with the Arduino based Electronic Gearing pretending to be an ELS but having a spindle limit of 1800 RPM or so. So you are right, the ARM family is likely more than fast enough for trajectory planning and graphical user interface but can it handle the low end hardware? John > -----Original Message----- > From: Todd Zuercher via Emc-users [mailto:emc-users@lists.sourceforge.net] > Sent: August 27, 2024 12:50 PM > To: Enhanced Machine Controller (EMC) > Cc: Todd Zuercher > Subject: Re: [Emc-users] LinuxCNC 2.9.3 has been released > > I have no experience with the Pi. But I've been of the opinion that computer > horse power has not been a real issue for Linuxcnc for a very long time. A > pc's real time latency generally has (or used to have) little to do with how > fast the computer actually is. It is more about the whole of the computer's > architecture. Back in the day we were running EMC2 on pcs with Pentium III > and Pentium 4 cpus with respectable latency and adequate speeds. Even a > Pi3 is probably at least as fast or a faster pc than most of those old dinosaurs. > > As long as a computer has enough processing power and resources to > comfortably meet the host operating systems requirements, it will be fast > enough to run Linuxcnc, so long as it can also reliably meet the real-time > latency requirements. Or at least that was the case with older RTAI kernels. > The newer Preempt-RT ones do seem to be more reliant on processing power > to get decent latency. I believe that may be because it is more of a patch > within the kernel vs RTAI which is more on the outside. > > Now to my uninformed mind it appears to me that ARM cpus would have a > strike or two against them when it comes to real time. (But I have no idea if > that is actually true or just my own personal misconception.) My thoughts > being that an ARM cpu operates in more of an indeterminant manor than a > CISC one. True ARMs are used all the time for real real-time applications, but > those are generally using a dedicated real-time os to do singular tasks, not > trying to do real time within a threaded PC environment. If this isn't the > case would someone more familiar with the inner workings of computers > please set me straight. > > All that said, Pi3s have already been proven to work at least marginally, Pi4s > to work adequately, and Pi5s???, but there's no evidence to expect less than > the Pi4. > > What was the question again? And why did I type all this? I'm just going to > click send rather than delete, to try to justify my wasting of time. > > Todd Zuercher > P. Graham Dunn Inc. > 630 Henry Street > Dalton, Ohio 44618 > Phone: (330)828-2105ext. 2031 > > -----Original Message----- > From: John Dammeyer <jo...@autoartisans.com> > Sent: Tuesday, August 27, 2024 12:38 PM > To: 'Enhanced Machine Controller (EMC)' <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] LinuxCNC 2.9.3 has been released > > [EXTERNAL EMAIL] Be sure links are safe. > > I've read a posting on another forum where the author states he's running > LinuxCNC with a Raspberry Pi using the Pi4 (and now Pi5) I/O pins configured > to duplicate the PC parallel port. With the quad core processor on the Pi is it > now fast enough to duplicate a PC with a parallel port or is the guy full of BS? > John > > > -----Original Message----- > > From: Chris Albertson [mailto:albertson.ch...@gmail.com] > > Sent: July 13, 2024 11:40 AM > > To: Enhanced Machine Controller (EMC) > > Subject: Re: [Emc-users] LinuxCNC 2.9.3 has been released > > > > If the old Lenovo PC has ahard drive, or better yet an SSD inside,then > > it will run much better then the Pi4 that is runniong off an SD card. > > Those cards a re very slow. > > > > If you want to upgrade the hardware replace th mechanical hard drive > > in the PC with a SATA SSD. If it already has an SSD, then you are > > good already > > > > > On Jul 13, 2024, at 11:24 AM, John Dammeyer > <jo...@autoartisans.com> > > wrote: > > > > > > > > > > > >> From: andy pugh [mailto:bodge...@gmail.com] > > >> > > >> On Sat, 13 Jul 2024 at 19:00, John Dammeyer > > >> <jo...@autoartisans.com> > > >> wrote: > > >>> > > >>> Hi Andy, > > >>> On my workbench for playing around I'm running 2.8.4 on a Pi4 with > > >>> an > > LCD > > >> touch screen and the MESA 7i92H. How easy to update that? > > >> > > >> The best thing to do with a Pi is probably to make a new SD card > > >> from the LinuxCNC image, then copy your existing config across > > >> (probably easiest to put the linuxcnc folder on a USB stick then > > >> swap SD cards) Then you can always go back to the old, working, SD > > >> card if there is a problem. > > >> > > > > > > Thanks. That's what I figured. > > > What about the 2.8.1 PC? Better to replace it? I picked it up > > > surplus for > > about $75 a number of years ago. I have a second one as a spare. > > > John > > > > > > > > > > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://li/ > > > sts.sourceforge.net%2Flists%2Flistinfo%2Femc- > users&data=05%7C02%7Cto > > > > ddz%40pgrahamdunn.com%7C4a116847897741b4963608dcc6b6d4c4%7C5 > 758544c5 > > > > 73f47cebee96c3e0806fb43%7C0%7C0%7C638603735784920972%7CUnkno > wn%7CTWF > > > > pbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXV > CI > > > > 6Mn0%3D%7C0%7C%7C%7C&sdata=fj%2FKIo6UJD7KW3xxD2WCJ%2BPLkh6 > ZxRoVLUlYs > > > vkv%2FIc%3D&reserved=0 > > > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://list/ > > s.sourceforge.net%2Flists%2Flistinfo%2Femc- > users&data=05%7C02%7Ctoddz% > > > 40pgrahamdunn.com%7C4a116847897741b4963608dcc6b6d4c4%7C57585 > 44c573f47c > > > ebee96c3e0806fb43%7C0%7C0%7C638603735784932012%7CUnknown%7 > CTWFpbGZsb3d > > > 8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0% > 3D%7C > > > 0%7C%7C%7C&sdata=CD%2FxKbSxVj%2BQX7cSM8JceD%2BG%2FQAKCzYmq > a5aM3QKAWo%3 > > D&reserved=0 > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
