Crystals question

[primal65]

In the schematics it has 3 of the 12mhz and 2 of the 16mhz. It appears, if I"m reading it right there's only one spot for each crystal on the PCB. Do you combine these? How does this work?

Thanks guys

[dmitri]

I don't get what "3 of the 12mhz and 2 of the 16mhz" crystals you are talking about.
In the schematic there is one crystal for PIC18F2550 which can be 4/8/12/16/20MHz (usually 12MHz) and one crystal for Atmega which can be 12/16/20MHz (for Atmega644 it is better to use 20MHz).

[primal65]

You're right. On the schmatic it does say that, but on the components pdf showing the layout it has the x3 and x2 over the crystals. And it has 3 and 2 listed in the number of crystals to buy in the parts list.

Wait, actually it is on the schematic as well.

[dmitri]

Xn is a usual way to denote crystals. It is like Rn for resistors or Cn for capacitors.

[primal65]

Haha. See I thought that, but then I didn't see an x1, only an x2 and x3, and on the parts list it said 2 and 3 of each so I was confused. Now I realize they were just the crystal numbers. I'm a noob, so I have to know precisely what I"m doing. Thanks for bearing with me.

Regard, Primal