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I need to feed a 320MHz LVPECL clock into an FPGA for a design which then allows me to have a synchronous 4 bit counter following for my lower frequencies (like Flashy). Is the Xylo-EM board able to add an external LVPECL crystal oscillator somewhere on the board? (I've currently got a 7mm x 5mm SMT part).
Thanks,
Teddy

Xylo-EM can't take an LVPECL signal directly.
Also 320MHz is very fast, might be a problem with a regular LVCMOS signal too.

From Altera web site: "Cyclone II devices support
the LVPECL input standard at the clock input pins only", so I guess my question becomes, are the clock input pins brought out to pads on the Xylo-EM board. I could jumper the signals directly from a second board that holds the 320MHz xtal. LVCMOS will just not support above about 160MHz.

Ok, I guess I was wrong.
Does Cyclone-II support LVPECL at 320MHz?

From Chapter 5 "DC Characteristics and Timing Specifications" of the Cyclone II data sheet, max input speed for LVPECL based clock is 402MHz.

You can find the list of the pins available in chapter 39.3 of Xylo-EM's doc.
Pins 88, 89 and 93 on CONIO1 might be used as clocks.

That might work, though I'll have to reroute the Flashy to some alternate pins for 88,89. One last question I hope, from Altera:

"When Cyclone II dedicated clock input pins are configured for the LVDS or LVPECL I/O standard for input operations, the differential buffer is powered by VCCINT, not VCCIO"

On the Xylo-EM these are pins 50,62,124,131.
Are these pins tied to a supply, or not connected by any chance?

Thanks
Teddy

VCCINT are connected to 1.2V on Xylo-EM (which is required by the Cyclone-II family).