On Tue, Jun 17, 2008 at 2:39 PM, Olin Lathrop wrote: > I guess you missed the point that a ceramic resonator is *easier* than a > canned oscillator. You hook it up and you're done. I've seen canned > oscillators cause trouble in circuits, usually because someone didn't pay > attention to bypassing and high frequency loop currents. In other words, > canned oscillators are more advanced and require more expertise to get > right. They look easy, but they're really not. They are not for beginners. Fair enough, but my experience differs. I spent the majority of the time on my first PIC project for hire some years back tinkering with a crystal oscillator circuit that wouldn't start reliably. This was with an SMT PCB layout and traces about .2" long and much experimentation with cap values. I've since had projects that worked fine with crystals of course, but I've also never had a problem with a canned osc and neither has any of the dozens of people I've seen use them in projects. Lucky I guess. > > On the other hand, I don't remember having a problem with a PIC crystal > oscillator. My experience is that they just work. If you want to use a > junkbox crystal that you can't identify to find the datasheet, just use 22pF > caps. The frequency might be a little off, but it will oscillate. > > I don't use ceramic resonators much, but the ones with the built in load > caps are the easiest of all. Connect the end leads to the PIC pins and the > center lead to ground and you're all done. > > No matter what you chose, you still have to set up the PIC oscillator mode, > that's a wash. For 20MHz on a 16F887 there is no doubt this needs to be HS > for a crystal or resonator. > > > ******************************************************************** > Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products > (978) 742-9014. Gold level PIC consultants since 2000. > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist