positivelydoped23:
Hi!
I am confused regarding the load capacitance of the crystal to be used.
Some forums say 18 pf would be a good choice, but I do not understand how they arrive at that conlusion.
I do understand that the caps we use along with the crystal are 22 pf each in series, so they form a capacitance of 11 pf effectively.
So if I am using two 22 pf caps, which amounts to 11 pf capacitance, then what would be the right load capacitance of the crystal.
This seems really critical because I am using I2C to communicate to my sensor.
HELP PLEASE!!!
Internal pin capacitance of the clock pins of the AVR chip is also added to form the total capacitance loading amount for the crystal. The 'exact' proper total load capacitance is determined by the crystal manufacture and is listed in a datasheet for the crystal. Being off some will only effect the frequency generated a very small amount. So don't sweat it, it won't effect your ability to use I2C modules.
Lefty