I am trying to get a PIC18F2580 with some test code in it to perform and function in a breadboard. The programed CPU will work fine in my evaluation board, but when I put it in a a breadboard and connect the PIC to power/ground and put a 20 Mhz crystal it will not run as expected. We also tied the reset pin high. The weird thing about it is when I scope the crystal all I see is a DC voltage of 2.5V, with NO AC component, when I scope the crystal in my eval board I see a perfect 20Mhz sine wave. I have replaced the crystal and still results are the same. Ideas?

 

Having components that is dependant on capacitance can be a problem when being built unto a breadboard.
Breadboards have a little capacitance (usually pico Farads) which in this case can cause the capacitancy to be situated between the CLKin and CLKout (on the PIC).
Breadboards have a little capacitance (usually picoFarads).
You can also notice when building timing circuits, that the capacitor calculated in theory is not the same that you will end up on the breadboard.