Hi there!

I'm on my first standalone pcb with a "plain" atmega. I found much about how to hook up the crystal to the AVR.

But two questions remain:

In the datasheet of the atmega is stated that XTAL1 is "input" and XTAL2 is "output". But do I see this right, the crystal oscillator doesn't have something like an input and output, the pins are the same?

I found the formula for choosing the capacitors. It is C = 2CL - (CP+CI), and that I should assume that CP+CI equals 5. So with this calculation, I get 35pf for the capacitors. So in this application I'm not sure if I should choose 33pf oder 39pf. If they were resistors, it would be clear, always choose the greater value. But for the capacitors I have no idea. And last, can my capacitor be too high voltage? Or is this value just a maximum and that I should try not to have a too large piece?

Thank you!