Hi Jon, With respect to high speed encoder interface using the PRU on the Beagle I may have misunderstood the comment from Charles from the second link below. I'm thinking a 6000 RPM spindle with a 1000 line encoder detecting in quadrature. That's tracking 24KHz which has a period of 41.667uS so I guess the PRU can probably count that as long as it isn't doing to many other things in that same 10uS interrupt.
Here's what I've found so far to a posting I did back in 2015. https://groups.google.com/forum/#!searchin/machinekit/Beaglebone$20machineki t$20lathe$20spindle%7Csort:relevance/machinekit/6klZrJH_2ZA/kDVr-6LgFgAJ 1. A reply from Jeff Pollard on which pins on the Xylotex 26 pin header to use for the QEP along with instructions to not use the "A HOME/LIMIT" switch on the DB-25 for homing and instead remove a filter capacitor so the index pulse can be read. How to configure the Xylotex .ini file is not explained. Past that the other link from 15JUN15: https://groups.google.com/forum/#!searchin/machinekit/Beaglebone$20machineki t$20lathe$20spindle%7Csort:relevance/machinekit/OvkMCwhhpjY/O0y1sl8y8OcJ 1. A comment from Charles which is what has led me to think the QEP for spindle isn't possible on the Beagle yet. But that was more than 2 years ago. "You can implement slow user-interface style encoder inputs on the ARM in the servo thread (1 mS period) using the software encoder input and GPIO pins. The PRU encoders will run at the PRU period (10 uS by default) and must use direct PRU input pins. The hardware encoders obviously need to use the specific pins for the channel(s) used. If you need more higher performance encoders, it's possible to dedicate one of the PRUs to do just encoder inputs, but that software has yet to be written (pull requests greatly appreciated!). :) Charles Steinkuehler" > -----Original Message----- > From: Jon Elson [mailto:[email protected]] > Sent: October-14-17 7:55 PM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] MachineKit on the BeagleBone Black > > On 10/14/2017 03:14 PM, John Dammeyer wrote: > > I'll see if I can find that link. From what I remember it's specific PRU > > code for the Beagle that needs to be written for the Lathe part and that was > > never done. > > > > > But, there is NO specific PRU code for a lathe. What you > need are steps (assuming a step/dir motor interface), > some digital I/O to control the spindle, and at least one > encoder counter with direction. The generic PRU code > built by Charles Steinkuehler can provide this, if the hal > command line asks it to do so. > > Once you have a spindle encoder, you can do lathe threading > operation. > > Now, one other item might be an analog output to control > spindle speed. You can always integrate a PWM output, which > the PRU can provide, to get this. > > Jon > > ---------------------------------------------------------------------------- -- > 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 ------------------------------------------------------------------------------ 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
