Providing clock to micro: crystal vs oscillator

[Moriambar]

Did you find the documens linked below?

https://www.ti.com/lit/pdf/swra372&usg=AOvVaw07hrK5qhcqPR5RBU0xUJp7
http://ww1.microchip.com/downloads/en/appnotes/00826a.pdf

If you want to be pedantic about getting the right value, it's possible to calculated it.

The MCU input pin and parasitic crystal capacitances can be found on the data sheets. It's also possible to calculate the parrasitic, but as mentioned above, an approximate value is good enough for most applications.

no I did not find those, well not in the first results... thanks for the links.
Anyhow now I have a better grasp of the whole matter, thanks!