Hi Chris, Simply put, many PICs have an analog comparator, plus a settable voltage divider inside that lets you choose a voltage to compare against. And this voltage can be routed to an I/O pin. You get 4 bits or 16 voltage levels you can set. Presto, cheap DAC! I finally had a chance to code something up and make a few waves on a 'scope. Now I realize I can't post pictures here, so I'll have to devise a plan B. Meanwhile, I'll think about connecting it up as a state analyzer, per Joe's idea. On Fri, Apr 19, 2013 at 2:36 PM, Chris Roper wrote: > "since some PICs have an "unadvertised" 4-bit D/A" > > I had not herd of that, I think a Google search is in order, combined wit= h > Joe's tip that could be a very useful tool. > any pointer would help, but I don't want to derail the thread as the topi= c > is getting interesting. > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .