05-24-2011 08:02 PM
I am using a HiTech Global Virtex-6 PCIe board, with a LX365T-P1759-3 chip. I have 16 differential inputs all going in to IBUFDS and then in to ISERDES. All of the 16 ISERDES blocks are the same... but when I hook up a logical zero to all of them, I get all zeroes out.. except for one pin, which gets a 1. When I hook up logical one.. I get all 1's out.. except one zero. The same pin.
I have looked at the pinout.. and I have it set to the differential pair of AV23 and AU22 ... and the positive and negative rails are connected right.... I GUESS I could just swap the p and n inputs.. but that doesn't tell me what the problem is. Any ideas?
05-25-2011 07:01 AM
The documents all say you are OK, but the actual board implementation may be a different story. Did you ring out the traces to the FPGA balls to see if they are correct?
05-25-2011 11:49 AM
I guess the answer is , it could be a bug.
being practical, it is easy to flip in the code, and it does not add delay to the signal.