My Mega8 is 16MHz. Ive got a 20MHz crystal laying around. Is there a way that I can have my Mega8 use that 20MHz crystal instead of its own internal 16MHz resonator?
Oh, it's only a 20% increase. I guess that it would work with some specimens and not with others.
If yes, how do I go about setting this up?
Like if it was 16MHz.
And also, is there any sort of limit as to what Hz crystal I would be able to use?
For instance if got lucky and found like a 1GHz Crystal , could I use that?
Finding a 1GHz X-tal wouldn't take luck, but rather a very powerfull improbability field
For X-tal work on much less than half of that, a PLL with dividers has to be used, since it's impossible to grind an X-tal so thin that it would swing at that high frequencies.
... And I guess more importantly, is there a real advantage to upping the processing speed?
Any over-clocker would say yes. somewhat higher speed, but on the downside, anyone with half a deck would mumble "much higher temperatures and current consumption" as a very direct consequence.
Im guessing that I would simply be able to read in sensor data faster and make a faster decision based on that and all that right?
Read speed would depend on what your sensor can handle in quite a number of sensor apps. But you would get higher execution speed (in more than one meaning of that term
If you wanna speed up, go with a faster processor, or to start with, optimize your algos.