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Visitor kehaworth
Visitor
10,501 Views
Registered: ‎05-29-2014

ZC706 to ZC706

Hello,

 

I'm attempting to hook up one ZC706 board to another to test interfaces while I wait for my real boards to show up. I can program each ZC706 without problems, but as soon as I hook up them together via FMC-FMC cable to the LPC connectors, the Hardware Manager no longer finds any target devices.  I'm using Vivado 2014.2.

 

From previous posts, I know that the U31/U32 JTAG bypass switches route the TDI/TDO though the connector, and presumably out to the other board. Perhaps there is some sort of contention when this happens. When I get my real board, I can route TDO to TDI which will (hopefully) solve the problem. 

 

But for now, has anyone tried this with two ZC706 boards and found a solution to this problem?

 

Thanks.

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5 Replies
Xilinx Employee
Xilinx Employee
10,491 Views
Registered: ‎01-03-2008

Re: ZC706 to ZC706

It is going to depend on what the FMC-to-FMC cable does with the PRSNT_M2C_B and TCK/TMS/TDI/TDO connections.

 

If the TCK and TMS pins aren't no connects in the cable it will create contention and/or signal integrity problems. 

If the PRSNT_M2C_B is grounded in the cable and TDI is not looped back to TDO at each connector then the chain will be broken.

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Visitor kehaworth
Visitor
10,484 Views
Registered: ‎05-29-2014

Re: ZC706 to ZC706

Mcgett:

 

Thanks for your response. The FMC-FMC cable is the one Xilinx recommends (Samtec 153151 custom flex jumper). I haven't been able to find any information other than it doesn't connect the power pins, so I assume it connects all others.

 

 

To summarize what I think is the issue, I'm going to call the ZC706 boards A and B:

 

  • If I turn on board A, but not board B, the TDI to TDO is not looped back on board B, so I have a broken chain.

 

  • If I turn on both boards, there is contention with TCK and TMS. 

 

What I need is to be able to bypass the LPC, force a loopback of TDI to TDO on a ZC706 board, or effectively turn off the JTAG in one of the boards. I'd really prefer to bypass the LPC.

 

I'm hoping I'm not only one who has tried using this Xilinx-recommended jumper to tie together two boards. Do you have any ideas as to a workaround?

 

Kari

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Xilinx Employee
Xilinx Employee
10,471 Views
Registered: ‎01-03-2008

Re: ZC706 to ZC706

I wasn't aware that Xilinx made any recommendations for this cable.  Can you point me to where this recommendation is made?

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Visitor kehaworth
Visitor
10,460 Views
Registered: ‎05-29-2014

Re: ZC706 to ZC706

http://www.xilinx.com/products/boards_kits/fmc.htm

 

It's down near the bottom: FMC-to-FMC cable. There are several flavors of it, including ones meant to link boards to mezzanine cards, but the one I have links LPC to LPC or HPC to HPC. 

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Participant amistad
Participant
6,340 Views
Registered: ‎09-28-2012

Re: ZC706 to ZC706

Please refer the p.8 in the attachment XAPP1160. 

Xilinx does recommend the FMC-HPC 2 FMC-HPC cable for use in the AXI chip2chip example. 

And it cause the problems for downloading by JTAG chain. 

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