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Visitor chairo
Visitor
78 Views
Registered: ‎04-02-2019

About COMMA detect in Virtex6 GTX

 Hello. I am trying to transfer in low latency using virtex6 GTX.  

 

 In order to avoid below situations, I would like to bypass COMMA detection after BYTE is aligned. Can you suggest any solutions?

 

 There is a problem that false COMMA generated by 10 bit data being converted to COMMA are detected as COMMA under noisy environment. If a false COMMA occurs out of the correct BYTE alignment, RXBYTEISALIGNED is deasserted.

 When RXBYTEISALIGNED is deasserted and RXENPCOMMAALIGN or RXENMCOMMAALIGN is high, errors occur frequently because the BYTE alignment shifts. When RXBYTEISALIGNED is deasserted and RXENPCOMMAALIGN or RXENMCOMMAALIGN are LOW, although the cause is unknown, a phenomenon in which errors occur frequently and a phenomenon in which errors do not occur periodically occur. 

 

 I thought that RXCOMMADETUSE is appropriate and tried it.

 After BYTE was aligned, RXCOMMADETUSE was set to LOW. However, after about 10 cycles, the phenomenon that RXNOTINTABLE and RXDISPERR occur frequently occurred. Perhaps BYTE was actually misaligned.

 This solution can not be used if BYTE alignment can not be maintained when RXCOMMADETUSE is set to LOW.

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2 Replies
Moderator
Moderator
55 Views
Registered: ‎07-30-2007

Re: About COMMA detect in Virtex6 GTX

I typically use RXENMCOMMAALIGN and RXENPCOMMAALIGN to turn alignment on and off.  If your pattern is noisy enough to cause false comma's then it's noisy enough to cause the other errors you mention.  You need a less noisy environment.

Roy


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Visitor chairo
Visitor
40 Views
Registered: ‎04-02-2019

Re: About COMMA detect in Virtex6 GTX

 Thank you very much for your reply.

 

 What I would like to turn off is not realignment, but detection of COMMA.

 

 I think that false COMMA will appear with low probability, even in low noise environments.

 At that time, I would like to avoid RXBYTEISALIGNED is deasserted by detecting a false COMMA.

 Is it possible to turn off COMMA detection after BYTE alignment?

 

 When RXCOMMADETUSE was tried and the following results were obtained, the environment was noiseless.

 Isn't RXCOMMADETUSE actually used to turn off COMMA detection after BYTE alignment?

 

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 I thought that RXCOMMADETUSE is appropriate and tried it.

 After BYTE was aligned, RXCOMMADETUSE was set to LOW. However, after about 10 cycles, the phenomenon that RXNOTINTABLE and RXDISPERR occur frequently occurred. Perhaps BYTE was actually misaligned.

 This solution can not be used if BYTE alignment can not be maintained when RXCOMMADETUSE is set to LOW.

---

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