> > 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?
My experiance with robotic motion control says “no, it can’t”. But that is Ok because today no one would design tasks like encoder reading or BLDC motor comutation into the Linux-based computer. We can buy a Raspberry Pi Pico for $5 that can do 20 million encoder transitions per second and program it using either Arduino IDE or (better) in micro-python. Today what people do is “close the loop” in the microcontroller and the Linux app only has to send the (time-tagged) target trajectory points, PIOD constants, and so on. The thing about the Pi is not that the CPU is too slow but the communications bus is very limited. This is mostly fixed on the Pi5 but still the Pi does not have a 16-lane PCIe bus and there is no way to install a high-end GPU. The only connection is the GPIO pins and those are not “high bandwidth”. I think the Pi5 would be good for Linux CNC if you used an Ethernet-connected Mesa card. The Pi5 has much better networking than did the pi4. ARM is of course the future. Apple moved from Intel to ARM and the rest of the PC industry is trying to follow. At some point to change-over will be complete. Buit it should not matter. Today we should be controlling our machines via standard interfaces such as Ethernet or Thunderbolt (USB 3/4) or other high speed ports found on every computer. > > 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 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
