-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 7/20/2012 5:37 PM, Karl Schmidt wrote: > On 07/20/2012 11:47 AM, Jon Elson wrote: >> Charles Steinkuehler wrote: >>> My current plan is to bit-bang GPIO pins based on code from the >>> parallel port driver, but adding a bit of electronics would >>> probably make things much easier. > > What would the "bit of electronics" look like? Most of the single > chip uP have hardware pulse generators built in that could easily > generate the stepper pulses without jitter. Those chips are under > $1 these days... > > Lattice now has a 1000 logic cell FPGA with built in configuration > ROM and lots of other goodies for less than $2 .. (twice that in > single quantities from digikey ) there is enough room to put a > softcore CPU to talk to the controlling system etc..
Yeah, I've been helping Tim (a mutual friend) write some VHDL code for the Lattice parts, which look pretty sweet. I'd probably use some form of programmable FPGA/CPLD under $10 or so, and right now the Lattice Ice parts are looking like the best bang for the buck. Having even a little bit of real hardware makes stepgen and encoder monitoring a lot simpler than bit-banging in SW. Plus most of the micro-controllers don't have real (or very many) encoder inputs, and can run out of timers fairly quick. There's still level translation, isolation, and protection to deal with, but that can be scaled to the task (ie: I'd put a lot more money into protecting I/O headed to mains-driven servos than a RepRap powered from the same 12V supply as my CPU). > If I have this pictured correctly - the controlling Linuxemc system > would run the outer servo loop - and the hardware would generate > the pulses for steppers? > > Hardware cost is no longer an issue. ...as long as I can get it to work. If not, you'll have to wait until the atom class chips get down to the Raspberry Pi pricing level. :) - -- Charles Steinkuehler [email protected] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAlAJ7i8ACgkQLywbqEHdNFxiSgCffU9l2ydzcRafQuEutFzQUl1J ZZoAoOoeOQgNyqoh+rx3C7RLY0LBLNNy =4tHo -----END PGP SIGNATURE----- ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
