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PROM Generation question

I wanted to generate a set of .MCS files for a Xilinx XC2V3000 design, the board uses three XC18V04 PROMs in serial mode, the PROMs and the FPGA are on the same chain. I entered the prom config into Impact in File Generation mode, but my design is small (bit file is 1.5 MB in size), so the utility informed me that only one .MCS file is actually generated. Now back in JTAG mode, when I initialize the JTAG chain, it asks me to associate a file with each device, so I can put in the first MCS file into the first PROM, but what about the others? Can I just BYPASS them or do I need to do something else to make this work? I'm a bit paranoid about burning up the device, so I didn't want to try anything without asking here first. Thanks! -Jim

Reply to
jimgeorge at gmail dot com
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Yes. Put the generated MCS file into the PROM closest to the FPGA and skip the other PROMs. Should work just fine.

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-----------------------------------------------
Johan Bernspång, xjohbex@xfoix.se
Research engineer

Swedish Defence Research Agency - FOI
Division of Command & Control Systems
Department of Electronic Warfare Systems

www.foi.se

Please remove the x's in the email address if
replying to me personally.
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Reply to
Johan Bernspång

I think you must have made some other mistake. Having a small design and not using the whole FPGA does not give you a smaller configuration file. If the bit file is for a XC2V3000 then it should hold always the full

10.494.368 bits and will never fit in a single XC18V04.

You can check this in IMPACT after the PROM generation, where you see in the upper part the chain of PROMs and the target with the bit file. Go with the mouse over the single devices and a yellow window should pop up with information about the contained bits and bytes.

Are you shure you did specify a chain of 3 XC18V04 PROMs when generating the MCS-files?

Hope this helps Klaus Falser

Reply to
Klaus Falser

You should be able to upload bit files to single elements of JTAG chain. So, yes, you can skip the ones you do not need.

As someone has already mentioned, the file size is a defined number of bytes for each FGPA type.

Reply to
bobrics

=20

=20

=20

Since Johan Bernsp=E5ng said it will work by using only the first PROM I=20 have to add that my experience is limited to Spartan-3, where I have=20 seen always bit-files and MCS-files of the same (full) size. Should this be different for Virtex-2 I apologize for having given a=20 wrong information.

Best regards Klaus Falser

Reply to
Klaus Falser

Well, you are absolutely right about that. The MCS-file should be larger than one XC18V04 PROM. I should've thought about that. =)

However, if the board has more PROMs than needed for a specific device (which the board I'm using at the moment has) then it is possible to program the PROMs the way I mentioned earlier...

Sorry for the confusion..

/Johan

--
-----------------------------------------------
Johan Bernspång, xjohbex@xfoix.se
Research engineer

Swedish Defence Research Agency - FOI
Division of Command & Control Systems
Department of Electronic Warfare Systems

www.foi.se

Please remove the x's in the email address if
replying to me personally.
-----------------------------------------------
Reply to
Johan Bernspång

OK, thanks all, I found the mistake (this happens because Impact seems to maintain several "current directory" entries internally, and I was picking up a bit file for an XC2V1000)

BTW, this is out of curiosity, if I have a board with an FG676 footprint, designed to use either an XC2V3000-FG676 or an XC2V1000-FG456, and I have three XC18V04 PROMs, what should I do if I have an XC2V1000-FG456 soldered onto the board? I'm guessing Johan's suggestion may work then, but correct me if I'm wrong. Thanks!

Reply to
jimgeorge at gmail dot com

That explains... =)

Yep, that's exactly my case. I.e. you use the PROMs closest to the FPGA.

--
-----------------------------------------------
Johan Bernspång, xjohbex@xfoix.se
Research engineer

Swedish Defence Research Agency - FOI
Division of Command & Control Systems
Department of Electronic Warfare Systems

www.foi.se

Please remove the x's in the email address if
replying to me personally.
-----------------------------------------------
Reply to
Johan Bernspång

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