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Visitor
Visitor
10,000 Views
Registered: ‎04-03-2009

can PCIE x1 endpoint core into the PCIe x4 card ?

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When I create PCIE x4 endpoint core into the PCIe x4 card, Link(x4) is OK.

But when I create PCIE x1 endpoint core into the PCIe x4 card, Link is failure.

Can not  link at  x1?

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Xilinx Employee
Xilinx Employee
12,206 Views
Registered: ‎04-06-2010

Re: can PCIE x1 endpoint core into the PCIe x4 card ?

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Some chipsets have problems with what you're explaining.

This is why some people use an interposer or tape off the unused lanes.  

This is not an issue with all chipsets.

View solution in original post

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Xilinx Employee
Xilinx Employee
12,207 Views
Registered: ‎04-06-2010

Re: can PCIE x1 endpoint core into the PCIe x4 card ?

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Some chipsets have problems with what you're explaining.

This is why some people use an interposer or tape off the unused lanes.  

This is not an issue with all chipsets.

View solution in original post

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Xilinx Employee
Xilinx Employee
9,920 Views
Registered: ‎02-01-2010

Re: can PCIE x1 endpoint core into the PCIe x4 card ?

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you can try taping off the upper lanes on your card to see if that helps.

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Visitor
Visitor
9,895 Views
Registered: ‎04-03-2009

Re: can PCIE x1 endpoint core into the PCIe x4 card ?

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Thanks for tip.

Make a try.

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Adventurer
Adventurer
9,854 Views
Registered: ‎11-06-2007

Re: can PCIE x1 endpoint core into the PCIe x4 card ?

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Did you switch the presence detect strap from X4 to X1?

 

Bruce

 

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Visitor
Visitor
9,753 Views
Registered: ‎04-03-2009

Re: can PCIE x1 endpoint core into the PCIe x4 card ?

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Taping off the upper(unused) lanes is USEFUL.

Thanks everone for help  !

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Explorer
Explorer
9,428 Views
Registered: ‎05-15-2009

Re: can PCIE x1 endpoint core into the PCIe x4 card ?

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Why is taping the lanes necessary if the boards have a lane configuration switch (such as J42 on the ML605) from where you can switch to x8, x4 or x1 ?

 

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Explorer
Explorer
9,370 Views
Registered: ‎05-15-2009

Re: can PCIE x1 endpoint core into the PCIe x4 card ?

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Ok now i understand what the J42 does on the ML605 and yes, taping the lanes above pin B19 and A19 (inclusive) to B/A42 allowed my board to be detected by windows XP x64. I used the PCIe Bridge core, it is now working and data is exchanged between the PC and the board in a using a x8 PCIe slot on the motherboard.

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Explorer
Explorer
9,305 Views
Registered: ‎03-26-2010

Re: can PCIE x1 endpoint core into the PCIe x4 card ?

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Pardon my ignorance, folks, but when you say "tape off" unused root PCIe lanes, what do you mean exactly?

 

I have a x4 PCIe root and an x1 PCIe endpoint, and I'd like them to talk to one another. Should I terminate the unused x4 lanes, or does "tape off" imply something else?

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Xilinx Employee
Xilinx Employee
9,301 Views
Registered: ‎08-07-2007

Re: can PCIE x1 endpoint core into the PCIe x4 card ?

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Hi,

 

It means to actually tape them off using something like scotch tape - maybe not Duct Tape in this case ...to sticky :).

 

If you use the CEM specification you can identify the pins that are only used for x1 and if you tape off the other pins, it will isolate the x4 channels. 

 

-John

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Explorer
Explorer
2,810 Views
Registered: ‎03-26-2010

Re: can PCIE x1 endpoint core into the PCIe x4 card ?

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Aah, ok, so in my case - I'm making a custom x1 PCIe card - I can just leave the other 3 lanes floating?

 

I take it the tape option was to simply not put a load on a connector, such that Windows/Host OS would get confused?

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