Hey all,
I'm in a bit of a pinch with the transceiver reference clock on the Ultrazed EV. As far as I can tell, the device is completely non-functional. This is specifically in reference to the GTH transceiver reference clock generator, IDT 8T49N241-048NLGI (U6).
I have ensured that the quad I am using is mapped to the right reference clock; I am using the clock on pins D9 and D10. I have actually tried all the available reference clocks, but to no avail. I am currently buffering the input with an IBUFDS_GTE4 before passing it to the Ultrascale transceiver wizard.
For debugging purposes, I used the ODIV2 port on the IBUFDS_GTE4, along with a BUFG_GT to bring the clock into the normal fpga fabric for testing. What I found was very strange. When hardwired to an led, the clock toggles the led variably, every 2-8 seconds. When the clock is hooked up to a counter that should roll over around 4 times a second, it never rolls over in a 60 second period.
It appears as though the clock has positive edges in an non-periodic manner, with a half-period of 2-8 seconds. This is confirmed by the fact that a two bit counter rolls over correctly after 8 of these 2-8 second half periods. All of this has been confirmed by the use of the ILA, as well. The clock signal is close to something like:
_____|‾‾‾‾‾‾|___________________|‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾|________|‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾|___________|‾‾‾‾‾‾‾‾‾‾‾‾|______________
In that it is not periodic and appears to just toggle randomly.
To me, this is never behavior that I should see from the clock, no matter what the config is. Any thoughts? I'm planning on investigating the warranty solutions, as the board is just over a month old.
