Ok... My understanding was that I could connect the clock to a pin in the Arduino, assuming the signal would be changing from HIGH to LOW or vice versa, so attaching an interrupt on HIGH, LOW or CHANGE would work for me to act upon a new pulse. If the clock is at 15 MHz, I assume I would get that event triggered every 1/15M sec.
Considering your comments about the AC voltage.. I get that instead of Xv to 0v it will go from Xv to -Xv.. so I do not know how I can mange that in the Arduino. Also I see that it will not produce any rising edge event. Correct? How could then I use it, or if a crystal doesn't fit at all for that purpose, how could I get such a signal tracked in the Arduino? Is there any kind of "known" circuit that can produce such event at a predefined frequency?
Thank you for the help!