> From: Les Newell [mailto:[email protected]] > > Since very slow PCs with limited memory could do this as well as the slower > PRU processors on the BBB, I'd venture a guess that if a Pi4 can't do at least > 50kHz stepping while also doing trajectory planning and screen updates there > is something really 'off' with LinuxCNC. > [SNIP] > > Maybe too many hardware abstraction layers? > Remember LinuxCNC is designed to be a versatile, highly customizable and > modular machine controller. It's original name Enhanced Machine Control > reflects this. You can use it to run anything from a simple X,Y desktop > engraver to a huge 5 axis monster with a complex tool changer or a robot > arm. It was never intended to be optimized, tweaked and streamlined to > wring out every last drop of performance for one task. You can have > performance or you can have versatility. You can't have both.
Thank you Les. That was a very comprehensive reply and I appreciate the time you took to write it. I want the performance, not the versatility. And it appears that this performance is only possible by offloading from LinuxCNC to MESA or PICO or whatever. Which is why I bought the MESA 7i92H instead of just complaining about the speed of the parallel port. Since I know very little about rebuilding Linux systems in general it's unlikely at this point that I could spend any time doing even what Gene has done rebuilding the system to run on a Pi. What he says is a totally foreign language to me. But I am perplexed that if LinuxCNC is so modular why MachineKit for the Beagle was forked rather than maintained as part of LinuxCNC. Perhaps the word modular is overused in this case? After all the goal of running a RPi4 must be to have a really low cost small processor but it does require a MESA if you want stepping pulses over 10kHz. If the BBB doesn’t need a MESA card then the overall cost does end up being lower. And it gets away with that by using the PRUs then that's a good thing. But it seems that the BBB and LinuxCNC into MachineKit were more like an exercise to see if it could be done rather than a desire to make a smaller more modular LinuxCNC engine. All I remember is there was a discussion and some lamenting that the fork for MachineKit wasn't maintained. Or that it couldn't be maintained. I think partly I don't understand the difference between the current LinuxCNC and the MachineKit LinuxCNC. What does make them so different that a newer version of LinuxCNC with bugs removed can't be used? Since the Beagle has an Ethernet port could I use it to run the MESA? Or does that once again require long strings of LinuxOS upgrade knowledge since the for LinuxCNC need a precompiled (for BBB) hostmot2 driver? loadrt hostmot2 loadrt hm2_eth board_ip="192.168.1.121" config=" num_encoders=0 num_pwmgens=0 num_stepgens=5" setp hm2_7i92.0.watchdog.timeout_ns 5000000 etc... Again, thanks for your very thoughtful reply. John Dammeyer _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
