On Jul 28, 2011, at 7:03 PM, DJ Delorie wrote: > >> Or 4000-series CMOS logic. Nice thing about 4000 series in this >> application is that it can operate on unregulated 12V. > > I thought of that, but a linear regulator just for the pic would be > cheap, and you get debounce, multi-input state machines, and a > watchdog for no extra cost...
Simple state machines and debounce are easy with MSI, too, and you don't need a software development setup. Arguably easier to debug a simple MSI circuit than a program. > > Even if I ran a 4000 right on the 12v, I wouldn't count on that 12v to > be very clean if it has motors running off it. Electrically braking a > motor with an H-bridge can spike the power rails. 4000 series is extremely resistant to noise on the power rails. I've run it off raw stepper motor power, no problem. I think that's really its remaining niche: slow logic running on noisy raw power. > > And a pic + regulator (sot-26 + sot-323) is probably going to be > smaller than the equivalent 4000-series chips anyway. If you use a 12V H-bridge you need level translation, too. That's sometimes annoyingly expensive in one way or another. > > But of course, there are zillions of ways of doing it, it's up to the > designer to pick what's best for their needs. Agreed. John Doty Noqsi Aerospace, Ltd. http://www.noqsi.com/ j...@noqsi.com _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
