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Registered: ‎06-07-2011

Virtex5 GTP loopback doesn't meet the real

Hi :

      I'm using the V5LX50T GTP to implement a custom data transfer.I met a strange problem.

      I generated a 2G 16 bit  core with 100MHz clk. The Near-End PMA Loopback test was successed , in my design, I sent two K code before sending data, one of the two is a comma ,in the loopback mode, the rxcommadet signal is 10ns and the rxcharisk is 20ns which is correct, but when I connected a real optical fiber, there is a 20ns  rxcommadet signal ,but no signal on rxcharisk and rxdata

      I also generated a 1G 8bit core with the same clk, this time data transfer works fine both on loopback mode and normal mode, but the  rxcommadet and  rxcharisk are both 20 ns.

      I have no idea how to explain these, anyone can help ?

      Thank you very much in advance.

 

     

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