Quote Originally Posted by rossfree View Post
I never got an answer to this question.

I would like to share the crystal of a 16f876 with a 16f88. By the thread above, I tie osc2 from the 16f876 to osc1 on the 16f88. What about the second osc2 input on the 16f88. Do I leave that pin hanging or tie it to something?


Thank you,

Ross
For one thing, OSC2 is usually Fosc/4 (i.e. 10mhz in = 2.5mhz out), so depending on how you have it set up, the one PIC will run 1/4 the speed of the other PIC. In any case, you try it with it hanging; it doesn't work, try a weak pull up, that doesn't work, try a weak pull up, etc. and so on and so on...

If it was me (and I've done this before), I'd get yourself one of those 4 pin oscillators, run the clock output of that into something like a 7404, tie a couple of the inputs together, and use the individual outputs to drive the seperate clocks of the PICs, which are set to external clock or HS mode. Simply put, the 7404 is used as a buffer to keep the 2 inputs from messing with each other.
Or, use a 7404 as part of a crystal oscillator circuit and take the output and run it into a couple of other inputs as suggested above.