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Visitor andy.klaib
Visitor
200 Views
Registered: ‎03-18-2019

VC707 GTX Hardware Issue

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Hi,

I have two VC707 boards (one was purchased a long time ago and one was recently purchased). I also have some code that transmits an eBook over the GTX SMA connections (from the GTX Tx to the GTX Rx) and displays it on the LCD. I tested this code on the old VC707 and it works. However, this code does not work on the new VC707. The LCD displays random English characters. It seems that the GTX is aligned (since the display is showing English ASCII), but some letters are being dropped altogether. I'm not sure why.

In terms of hardware, were there any revisions made to the VC707 recently? I'm don't know why one bitstream would work on one VC707 but not the other.

 

Thanks in advance.

Andy

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Visitor andy.klaib
Visitor
76 Views
Registered: ‎03-18-2019

回复: VC707 GTX Hardware Issue

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Actually, I think I figured it out. I was using a single reset pulse derived from a button to reset both the Tx and the Rx. I changed the code so that I can reset the Tx and the Rx separately using two buttons. It appears that the Rx needs to be reset after the Tx is reset. With this change, the GTX now appears to be working correctly. Thanks again for your help in troubleshooting this problem :)

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Xilinx Employee
Xilinx Employee
181 Views
Registered: ‎07-11-2019

Re: VC707 GTX Hardware Issue

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Hello @andy.klaib 

Please check what devices each one of the boards contain because one board could have a production sample silicon while the other has an engineering sample. AR#37579 will show you how to find that information. If they are different, AR#50906 will help fix the issue. 

AR#37579: https://www.xilinx.com/support/answers/37579.html

AR#50906: https://www.xilinx.com/support/answers/50906.html

I hope this helps! 

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Xilinx Employee
Xilinx Employee
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Registered: ‎08-10-2008

回复: VC707 GTX Hardware Issue

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https://www.xilinx.com/support/answers/59753.html not much change. 

You can pull out the GTX signals for a debug, follow this: https://www.xilinx.com/support/answers/57742.html to check CDR status first. Besides, run a new-end loopback to see if same issue still occurs.

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Visitor andy.klaib
Visitor
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Registered: ‎03-18-2019

回复: VC707 GTX Hardware Issue

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Thank you both for your suggesstions. I checked the stickers on the boards and they both appear to be production silicon (they have the code 0431780 on the back). 

I pulled out the CDR status signals to some LEDs on the VC707. After a comma is sent, the RXDISPERR and RXNOTINTABLE signals go low and RXBYTEISALIGNED goes high. I also tried using the near-end PCS loopback with the same results. Any idea what else might be wrong?

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Visitor andy.klaib
Visitor
92 Views
Registered: ‎03-18-2019

回复: VC707 GTX Hardware Issue

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I just tried the near-end PMA loopback option and that actually works fine. Hmm, so the near-end PMA loopback works, but externally connecting the SMA TX and RX together didn't. Any idea why that may be? Thanks again

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Visitor andy.klaib
Visitor
77 Views
Registered: ‎03-18-2019

回复: VC707 GTX Hardware Issue

Jump to solution

Actually, I think I figured it out. I was using a single reset pulse derived from a button to reset both the Tx and the Rx. I changed the code so that I can reset the Tx and the Rx separately using two buttons. It appears that the Rx needs to be reset after the Tx is reset. With this change, the GTX now appears to be working correctly. Thanks again for your help in troubleshooting this problem :)

View solution in original post

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