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JTAG cable @ 2.5 V - where?

Hi group

I'm a newbee, so please bear with me if this does not make sense.

I got a AVNet (MEMEC) Virtex 4 based developper kit based on the Virtex-4 FX12 Mini Module whoes baseboard JTAG port is documented as "a 2.5V compatible JTAG chain header". The pinout is identical to what Xilinx seems to use (14 pins etc.). The docs seem to asume that one must use the Xilinx parallel cable IV which from what I understand seems to automatically sense the voltage needs of the target and is having other nice to have features. However, due to several reasons which are beond the scope of this post, I can't simply pick up the phone and order one from a supplier last not least also because I don't know any that would carry this item here in Switzerland.

The net seems to be full of homebrew JTAG cable websites giving instructions to build you own. The question is can I use one of those? I'm a bit afraid that this will not work cause from what I understand they seem to be designed for 5V or 5V tolerant devices. What other options do I have? Any links to a schema of the Xilinx paralell cable IV or such to build my own JTAG cable running at 2.5V?

I would also not mind to shell out the needed $$$ to get that original cable if I could easily purchase it somewhere online using paypal or a credit card and get it deliverd quickly. Any ideas?

TIA

Markus

Reply to
Markus Zingg
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Markus

Our Prog2 cable(ask for narrow head version) is available in the standard 14 way 2mm connector. Cost GBP£10. It is a Cable III look-alike as most third party cables are. Schematics for Cable IV are generally not in public domain and generally not replicated by anyone as far as I know.

The only advantage of the Cable IV is the download speed.

Our shop website has those listed under programming solutions for an easy order solution.

John Adair Enterpoint Ltd. - Home of Broaddown2. The Ultimate Spartan3 Development Board.

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Reply to
John Adair

I don't see where the "Parallel Cable III look-alike" PROG2 is 2.5V compliant since the Parallel Cable III doesn't work so well from 2.5V.

I think I've gotten the III to work with a 3.3V supply for 2.5V JTAG but the IV or USB versions of the cable are certainly more robust.

Perhaps the Xilinx online store could ship to Switzerland with a simple credit card purchase.

The Parallel Cable IV doesn't include schematics but it does show what the input and output stages look like, easily replacing the simple buffers in the Parallel Cable III which does have full schematics.

- John Handwork

John Adair wrote:

Reply to
John_H

Well I did say look-alike I didn't say the same. It looks the same to the Xilinx software so it can use it without issue. Prog2 actually performs very well against the competition and works in circumstances where many others fail. We have tried several of these in compatibility testing with our own boards. Our Prog2 isn't as good as Cable IV but then it is about 1/5 th of the price when buying and we do give them away with our own development boards.

John Adair Enterpo> I don't see where the "Parallel Cable III look-alike" PROG2 is 2.5V

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Reply to
John Adair

John,

circumstances where many others fail.

is this a business secret or can you elaborate a bit on that? Using the right buffers the high level to low level translation should not be a problem anymore. Is it a question of TDO conditioning?

Best regards Ulrich Bangert

"John Adair" schrieb im Newsbeitrag news: snipped-for-privacy@i3g2000cwc.googlegroups.com... Well I did say look-alike I didn't say the same. It looks the same to the Xilinx software so it can use it without issue. Prog2 actually performs very well against the competition and works in circumstances where many others fail. We have tried several of these in compatibility testing with our own boards. Our Prog2 isn't as good as Cable IV but then it is about 1/5 th of the price when buying and we do give them away with our own development boards.

John Adair Enterpo> I don't see where the "Parallel Cable III look-alike" PROG2 is 2.5V

standard 14

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Reply to
Ulrich Bangert

Ulrich

It isn't one thing but a series of things from PCB layout through to choice of driver and decoupling. Actually as a cable our Prog1 cable does even better but it has the advantage of a Coolrunner-II CPLD and a voltage regulator built in. It is some way between what Xilinx do as Cable III and their Cable IV. At some stage we may effective take the best bits of Prog1 and Prog2 and a couple of other things we know will think will make life better and make Prog3 but that isn't until we exhaust our current Prog2 cable stock. We have a few new ideas we are trying out on our new development board Tarfessock1 which can double as a programming cable and depending if those work they may get fed back into the more general cable solutions.

Some of the problems people see in programming are actually the target board in the main and not necessarily the cable or a combination of them.

John Adair Enterpoint Ltd. - Home of Tarfessock1. The Cardbus Spartan-3E FPGA Development Board.

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Reply to
John Adair

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