by support »
Hello,
The only thing that I could suggesting is check what happens with the LEDs. But it seems like the board doesn't have any.
Do Trenz offer any reference designs with PCIe? If so, are they detected by the computer?
If they have a working example, definitely compare pinouts etc.
Anyhow, there's no reason in the world why it would work on one FPGA part and not the other. When things like this happen, I speculate that it wasn't supposed to work on either. For example, if the reference clock that is used for the PCIe bus is the one provided by the board and not by the PCIe finger, it may work with some luck, even though it shouldn't. Or if the reference clock pin is wired to just some random pin, but it somehow picks up the clock with crosstalk.
Another thing I suggest looking at is lane reversal. Refer to the KC705's schematics on which transceiver is connected to which PCIe finger position, and make sure you have it the same. It's a confusing business. I don't see why an issue like this would cause the problem you're facing, but when weird things happen, check everything.
Also, I suppose you adopted the design for KC705, and modified it into a x4 design...? If that's done incorrectly, things might be unstable, so moving to another device can reveal the problem. Preferably use the PCIe bundle forZC706 to begin with, because that board has x4 lanes as well.
Regards,
Eli