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Can Virtex 7 transceiver Quad work with two sources?

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Visitor
Posts: 9
Registered: ‎11-08-2017

Can Virtex 7 transceiver Quad work with two sources?

I have Virtex 7 Transceiver Quad connected to two different sources:

 

2 channels connected to one silicon and 2 other channels to another silicon.

In this setup only one pair locks on data, and the other is failing. 

Is it a known limitation? Or is it a matter of configuration? 

If I use separate Quad to connect with second silicon, but the reference clock is the same, will it work?

 

Thank you,

Vladimir

Scholar
Posts: 1,148
Registered: ‎02-24-2014

Re: Can Virtex 7 transceiver Quad work with two sources?

This is not a limitation, but probably a configuration problem.   What are the data rates you are trying to capture for each of the sources?   are they different by more than 1000 ppm?    You may need to have a separate reference clock for each data source you are trying to capture.

Don't forget to close a thread when possible by accepting a post as a solution.
Moderator
Posts: 134
Registered: ‎05-02-2017

Re: Can Virtex 7 transceiver Quad work with two sources?

hi @vyudovich,

 

I believe your looking to know are there any limitation on configuration which your using .

 

there are no limitation , can you let us know what is clocking structure your using and also the what is issue your facing on the board .

 

Chandra

 

  

Visitor
Posts: 9
Registered: ‎11-08-2017

Re: Can Virtex 7 transceiver Quad work with two sources?

Hi Chandra,

 

Refclock is fed through QPLL (GTXE_COMMON) and fed to all 4 channels. 

Recovered RX clock from channel 0 is used via PLL as RXUSRCLK. RX buffer is enabled and the clock source is RXCLKOUT.

 

Two channels are connected to one external source, and lock well. Two other channels are connected to another source and can't lock.

 

Thanks,

Vladimir.

Visitor
Posts: 9
Registered: ‎11-08-2017

Re: Can Virtex 7 transceiver Quad work with two sources?

Hi  @csattar

 

Did you have a chance to look at this issue?

 

thank you,

Vladimir.

Moderator
Posts: 477
Registered: ‎07-30-2007

Re: Can Virtex 7 transceiver Quad work with two sources?

[ Edited ]

You need to look at the frequency of the input and the output of the clocks driving the RX buffers.  When the RXUSRCLK is derived from a different source than what is driving the RX inputs for the channel it will cause the RX buffer to overflow or underflow.  If you are driving inputs into the quad that are based on different reference clocks on the far end you will need to either use 2 different RXUSRCLKs, derived from the inputs (RXOUTCLK) of each of the far end silicon devices, or use a protocol that has clock correction. 

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Xilinx Employee
Posts: 413
Registered: ‎08-07-2007

回复: Can Virtex 7 transceiver Quad work with two sources?

hi @vyudovich

 

are Virtex-7, Silicon 1 and Silicon 2 sharing the same clock source oscillator?

 

Thanks,

Boris

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