In an ideal world, where Peter has infinite amounts of time and interest, the entire hal ecosystem could be put on the fpga. Practically, though, it is tricky to figure out exactly where the line should be drawn between servo thread modules running in the main processor and "base thread" components that run in the fpga. The fpga is parallel logic, so is well suited to encoder counters, pwm generators, and step generators. Motion planning would be a nightmare. Offset generation is in-between, as you need to connect different (arbitrary) axes, with different scaling factors. Similar to electronic gearing, but with offset as a real-time input. The fpga component would need to combine the "input" axis feedback, the "output" axis value, and a source for the cam profile (lookup table). Size of the lookup table would be an issue, as well as loading it. Specifying the profile as an equation would reduce the memory requirements, but would be arbitrarily complex. Perhaps a 3rd order polynomial would suffice. I'm sure Peter would love to implement that as well.
This would make a great EE senior project if I had lots of great students falling all over themselves to grab my project ideas. -- Ralph ________________________________________ From: Gene Heskett [[email protected]] Sent: Monday, July 13, 2020 9:33 AM To: [email protected] Subject: Re: [Emc-users] Because the hardware store was 4 miles away... On Monday 13 July 2020 12:00:19 Peter C. Wallace wrote: > On Mon, 13 Jul 2020, Ralph Stirling wrote: > > Date: Mon, 13 Jul 2020 13:15:27 +0000 > > From: Ralph Stirling <[email protected]> > > Reply-To: "Enhanced Machine Controller (EMC)" > > <[email protected]> > > To: "Enhanced Machine Controller (EMC)" > > <[email protected]> Subject: Re: [Emc-users] Because > > the hardware store was 4 miles away... > > > > Perhaps Peter could write a hostmot2 axis offset module that would > > run in the fpga. No base thread needed. > > > > -- Ralph > > Oh No, thats definately the wrong design path, the philosophy here is > to push all the hard work into someone elses domain... :-) ROTFLMAO, Peter see's right thru us. ;-) But seriously, the FPGA does seem like the ideal place for such a module. On chip com with the chosen stepgenerator removes that particular bandwidth limit. I could also see it doubleing the size of the FPGA needed so its not going to be free. I think, not knowing the first thing about writing FPGA code. :-( [...] 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 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
