Lots of platform solutions today. I just found a very affordable FPGA card. Cheap enough to experiment with and if it don't work out no loss newegg.com/Product/Product.aspx?Item=9SIADD... <https://www.newegg.com/Product/Product.aspx?Item=9SIADD85RA5820&cm_re=fpga-_-9SIADD85RA5820-_-Product>
New thing like this falling under the $20 price point make up for the loss of things like PRUs on current ARM chips. On Fri, Oct 13, 2017 at 10:26 PM, Frederic RIBLE <[email protected]> wrote: > On 2017-10-14 00:21, andy pugh wrote: > > I lost track of Machinekit a while ago. Do they have any >> encoder-counting facility in the PRU? >> >> If they have then the rest is just config. (editing text files...) >> > > Yes, Machinekit has nice PRU encoder facility with eQEP: high-speed > quadrature + index. > That is a strong feature of BBB. FPGA like encoder performances, without > the cost of the FPGA. > I am using it for synchronized motion on my EMCO-120P lathe with a 1024ppr > encoder and a Furaday cap. > I have wired a custom electronics to handle the differential outputs of > the encoder. > Should work to synchronize Z, even when moving the spindle manually. > My machine is WIP, so not yet tested with real chips! > See https://youtu.be/zVUMC1mdQKg?t=23m26s > > PRU micro-code encoder is also available, but with lower pulse rate. I am > using it for MPG. > Also, I am using the PRU micro-code to manage the stepgen: high pulse rate > can be achieved without impact on CPU load. > > Encoder electrical wiring as below: > P8.12: SPINDLE A > P8.11: SPINDLE B > P8.16: SPINDLE INDEX > > Here is the portion of my hal config file: > > loadrt hal_arm335xQEP encoders=eQEP0,eQEP2 > > # Spindle encoder > > addf eqep.update servo-thread > > setp eQEP2.position-scale 4096 > setp eQEP2.min-speed-estimate 0.2 > setp eQEP2.capture-prescaler 5 # can measure down to 50 Hz pulses / 20 rpm > setp eQEP2.counter-mode 0 # Quadrature mode > setp eQEP2.invert-B 1 > > net spindle-position eQEP2.position => motion.spindle-revs > net spindle-velocity eQEP2.velocity => motion.spindle-speed-in > net spindle-index-enable eQEP2.index-enable <=> motion.spindle-index-enable > > Frederic > http://cnc.f1oat.org > > > > ------------------------------------------------------------ > ------------------ > 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
