12-06-2017 11:16 PM
I used IBERT CORE on KC705 (xc7k325tffg900)which id the FPGA kintex 7, to debug the GTX transceiver on display port.
I connected two display ports by cable to make loopback，so I can transfer signal from display port1 to display port2.
I want to see the BER through theses two display ports by using eye scan plots.
Here is my setted parameters on GUI.
I found that I can get the link succeed when I chose the loopback model as Near-End PMA/PCS,either PRBS or Fast/Slow Clk via TX and RX Pattern.
But,when I chose loopback model as None ，there is no link unless I select the TX and RX Pattern as Fast/Slow Clk.
Who can tell me why PRBS can not do(but clk can) the link when I chose loopback model as None,even I connected 2 display ports by cable?
12-13-2017 07:43 AM
It looks like you have a link but with cable loopback you are probably overdriving the equalization. Uncheck the DFE checkbox which will switch you to LPM equalization. Also try lower amplitudes. If this is not ac coupled it could be a problem?
12-13-2017 08:24 PM
Thanks for your reply.
I have unchecked the DFE and it still doesn't work.
What do you mean by lower amplitudes?Is it the TX Diff swing voltage?I changed it for several values, but no effect.
And as you said ac coupled ,how can I set this?
I've tried another board with ARTIX-7(xc7a200tffg1156),I met the same problems.
Do you have any ideas ?