On Saturday 12 June 2021 19:24:49 Leonardo Marsaglia wrote: > Hello guys, > > As some of you know, I'm finishing a CNC router and I'm about to > purchase all the control hardware. I know Gene, John, and several > people here are running LCNC on the PI with success but I would like > to know how much of a pain in the ass is to get it running well with a > 7i76E for controlling the router. > > I'm trying to decide wheter I purchase Rpi 4b or I use a normal PC as > I've been doing with all the other machines. I really like the idea of > using something as portable and small as the Rpi but I don't want to > purchase one just to test right now... I do have a Rpi3 with Octoprint > on the ender but I don't know if that's a good candidate to test LCNC.
I may be the first, or nearly so, to use a pi to run LCNC. Ethernet interfaces didn't seem to fill the bill because I wanted to use the only hardware ethernet it had as a normal network connection, so the interface chosen at the time was the 7i90HD which could be driven by a parport, or by SPI. Since the pi didn't then have a parport, it was SPI. I don't use the radio, but thats a different story/subject. But LCNC didn't have an SPI interface, so a swedish prof wrote rpspi.ko and gave it to us. The pi3 could run my lathe rather nicely, but it did keep it pretty busy, so when I wrote the hal stuff to add two more encoder dials so I could drive it by hand too, and given that the dials were only 100 ppr, I added a 200hz thread to hal and put all that stuff in it. But first I had to build a quasi-realtime kernel, which presented me with a problem, the pi folks would not help me install it. So I grabbed what the pi needed. organized it in a tarball, that if unpacked to a u-sd card with raspbian already installed, put everything the pi needed to run this kernel: 4.19.71-rt24-v7l+ #1 SMP PREEMPT RT Thu Feb 6 07:09:18 EST 2020 armv7l Which is all in one slightly less than 30 megabyte tarball. Its not perfect, but plenty close enough for me until I tried to cut some lathe pawns out of air while browseing the evening news with firefox on the rpi3. I could hear a stutter now and then. That started out with a raspian jessie install, then stretch and now the same kernel is running raspian buster on a 2 gig pi4. Still booting from the u-sd card, but with the pi4, its not dragging its tongue at all, I can browse the net while cutting pawns out of air & never hear a single stutter from the steppers. I have a 240G SSD on a usb3 cable adapter, moved as much of the stuff as I could off the u-sd to another 120G SSD on the other usb3 port, and am building master or master-gtk3 at least daily and installing it, on that same u-sd card, for over a year now. I check github for fresh commits 4x a day so I'm tracking the buildbot with maybe a days lag maximum. The only thing I spent extra money on was a trio of 7i42TA's to protect and buffer the 7i90's 3 volt gpio stuff, I had some noise get backed into the 7i90 and blew some pins on the first 3 7i90's. I redid all the grounds onto one BIG star setup, which got rid of the noise at the same time I added the 7i42TA's, whose terminals made the interfaceing enough easier that I don't regret the cost. And I recently changed the motors driving that 75 yo Sheldon, for 3 phase stepper driven servo's. Much quieter, moves like Casper the ghost now, and twice as fast. These have a fault output that I use to kill motion as instantly as it can get stopped. Has not tripped while doing a job, but I can position it to hit a chuck jaw at cutting speed, and jog it into the jaw without damaging the chip in the tool, or making a mark on the jaw, so I'd guess its working as intended. My $0.02. > What do you guys think? > > Thanks as always and I hope you're all doing well :) > > _______________________________________________ > 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
