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Voyager
Voyager
1,483 Views
Registered: ‎05-30-2017

Artix 7 xc7a200 receive HD-SDI using GTP and 100MHz PCIe ref clock

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Hello I'm working with Vivado 2018.2 and Artix 7 xc7a200tfbg484-2. On my board I have only one reference mgt clock that is 100MHz PCIe clock. With this I can recover SD-SDI using DRU but i would want to know if is there a way to receive HD-SDI 1,485Gb/s using this clock. Looking at 7 series FPGA tranceiver wizard it seems that this not possibile. Infact selecting  1,485Gb/s as line rate it is possibile to select various values ​​of reference clock but 100MHz is not present. Is there a way to do what I want or it is impossible? Thank you.

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Xilinx Employee
Xilinx Employee
1,666 Views
Registered: ‎08-02-2011

Re: Artix 7 xc7a200 receive HD-SDI using GTP and 100MHz PCIe ref clock

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To add to what Dr Smith is alluding to here...

 

while it is technically possible to route a fabric clock to the GT refclk, you should never do this. It might work okay for test/prototype on an empty design, but as the design fills up and there is more core switching noise causing excess jitter in the clock and things start to break down.

 

SDI has very specific refclk requirements that must be met. If you only need some subset of the standards supported (or only need Rx), you can get by with only 1 refclk instead of 2, but the freq is set to 74.25 or 148.5 MHz (with a second required for the 74.25/1.001 and 148.5/1.001). Refer to relevant xapps/user guides.

https://www.xilinx.com/support/documentation/application_notes/xapp1097-smpte-sdi-a7-gtp.pdf

www.xilinx.com
7 Replies
Scholar drjohnsmith
Scholar
1,468 Views
Registered: ‎07-09-2009

Re: Artix 7 xc7a200 receive HD-SDI using GTP and 100MHz PCIe ref clock

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If the tool wont let you select it, Im 99.( % certain your out of luck 

 

Its the limitation of the multiplier thats used to generate the internal clock, it can "only" do n/m , and only over a certain range of frequencies and integers,

 

You might be able to take the 100 into one pll on the fpga, generate say 125 MHz from that( or what ever frequency you need ) , an d feed that into the refclk you need

    but its a long shot, jitter build up , routing etc

 

<== If this was helpful, please feel free to give Kudos, and close if it answers your question ==>
Voyager
Voyager
1,433 Views
Registered: ‎05-30-2017

Re: Artix 7 xc7a200 receive HD-SDI using GTP and 100MHz PCIe ref clock

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Thanks for the quick reply. So maybe I could feed mgt PLL using not ref clock but an internally generated clock but probably this clock could not have the required specifications and so I have to do same test to see if it could work. Isn't it? Thank you.   

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Scholar drjohnsmith
Scholar
1,420 Views
Registered: ‎07-09-2009

Re: Artix 7 xc7a200 receive HD-SDI using GTP and 100MHz PCIe ref clock

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Yep you will need to experiment, 

 

but I'd say its low chance of success, 

 

please let us know how it goes,

 

<== If this was helpful, please feel free to give Kudos, and close if it answers your question ==>
Xilinx Employee
Xilinx Employee
1,667 Views
Registered: ‎08-02-2011

Re: Artix 7 xc7a200 receive HD-SDI using GTP and 100MHz PCIe ref clock

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To add to what Dr Smith is alluding to here...

 

while it is technically possible to route a fabric clock to the GT refclk, you should never do this. It might work okay for test/prototype on an empty design, but as the design fills up and there is more core switching noise causing excess jitter in the clock and things start to break down.

 

SDI has very specific refclk requirements that must be met. If you only need some subset of the standards supported (or only need Rx), you can get by with only 1 refclk instead of 2, but the freq is set to 74.25 or 148.5 MHz (with a second required for the 74.25/1.001 and 148.5/1.001). Refer to relevant xapps/user guides.

https://www.xilinx.com/support/documentation/application_notes/xapp1097-smpte-sdi-a7-gtp.pdf

www.xilinx.com
Voyager
Voyager
1,399 Views
Registered: ‎05-30-2017

Re: Artix 7 xc7a200 receive HD-SDI using GTP and 100MHz PCIe ref clock

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Thanks for the help. I'll try to see what happens and than I'll let you know.

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Moderator
Moderator
1,311 Views
Registered: ‎11-09-2015

Re: Artix 7 xc7a200 receive HD-SDI using GTP and 100MHz PCIe ref clock

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HI @pierlum,

 

I believe your question has been answered by @drjohnsmith and @bwiec. Could you kindly close the topic by marking on of their reply as accepted solution (click on accept as solution below the topic while logged in).

 

Thanks and Regards,


Florent
Product Application Engineer - Xilinx Technical Support EMEA
**~ Don't forget to reply, give kudos, and accept as solution.~**
Voyager
Voyager
1,305 Views
Registered: ‎05-30-2017

Re: Artix 7 xc7a200 receive HD-SDI using GTP and 100MHz PCIe ref clock

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Thanks for the help. I have to do other things so I left this project pending. If I'll complete it in the future I'll let you now. Thanks for the help.