On Monday 16 October 2017 11:28:40 Nicklas Karlsson wrote: > > > I have been thinking about FPGA for a communication switch, it > > > would be possible to get perfect timings. Then ordinary micro > > > controllers could be used for implementing the hardware, the > > > approach is similar to the new devices with so called Cortex-M-* > > > PRUs but by using SPI, UART or maybe CAN it is possible to build > > > more modular and add an insulation barrier. > > > > > > The new devices with PRU may be a cheaaper solution for machines > > > built in very large series. A modular architecture there different > > > special hardware drivers could be combined is a better solution > > > then building a lot of different mashines. > > > > The Cortex M Costs about $1 or some of them even less. You can buy > > a complete system on a PCB with connectors. For under $3 shipping > > included. If you need to make something like a switch or control a > > few motors these work well. I have several of them. I am using > > them for motion controller. > > Yes I know it very well and also have a few of them. > > > In terms of "compute power" They are an order of magnitude above an > > Arduino. But not even close to a Pi 3 or BBB. > > This is good enough for one motor probably with plenty margin. > > > ... > > I'm using one of the boards liked to below to control two motors > > using PID. I have two PIP loops running and the optical encoder is > > sending about 11,000 interrupts per second for each motor. I run > > the PIP loops and get commands over a serial ... > > Similar as I do. > > > I would not go with an FPGA unless you need very high speed where > > signals are in the teen's of megahertz at least, up to GHz. The > > FPGA is much harder to program them an ARM Cortex-M. > > > > If I were building a machine tool controller from scratch I'd run > > much of it on a small computer under Linux then I'd get as many of > > these Cortex-M chips as required. Each could handle between 2 and 6 > > axis. > > There I am heading. The FPGA could give me as many serial > communication ports as needed with perfect communication period. > Second option is to add a Ethercat slave device on each device. > > This sounds appetizing. Lets say you've installed LCNC on a rock64. Now the rock64 has a 5 Gigabaud usb3 port, and hubs for usb3 stuff are showing up, which would allow to have something besides the currently mounted 1Tb seagate usb3 backup disk. With a hub, and I found them as wide as 13 ports just last week, how hard would it be to make one of these things with a usb3 interface, just plugging in enough for the number of axises the machine has?
I just bought another of the dells I am using on the bigger mill, might be here by the end of the week, but I've also got two rock64's, which have more than enough housepower to run this stuff. With the usb2 bottleneck in the i/o gone, the rock64 is many times faster than a pi3b and its running my big lathe very well once a reboot, sometimes several, has managed to find the local keyboard and mouse 100% of the time. But interfacing to the real world of a 7i90 I've not been able to do because the hm2_rpspi.ko driver is loaded with code to make sure its running on a pi. I am attempting to excise those checks, because rock64 claims to be pi compatible in its gpio, but have not been successful enough to even crash the rock64. So there is your "what if" for the week. :) > Regards Nicklas Karlsson > > ---------------------------------------------------------------------- >-------- 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
