Author Topic: FPGA JTAG selection  (Read 5015 times)

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Offline MattHollandsTopic starter

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FPGA JTAG selection
« on: October 09, 2015, 06:48:58 am »
Hi! Today I managed to get my hands on some Digilent D2SB boards (spartan 2), and some VIRTEX-II based boards. Both of these boards need to be programmed using Xilinx ISE 10.1 software, but now I need to get a JTAG-usb cable to connect them.

I don't know much about JTAG. Are all jtag cables the same? Or do I need something specific? My budget is $60ish.

Would something like this http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,395,523&Prod=JTAG-USB do?

Or can I get anything cheaper? I just want to be able to program these FPGAs, nothing more.

If anyone has any experience that'd be awesome :)
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Offline tggzzz

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Re: FPGA JTAG selection
« Reply #1 on: October 09, 2015, 07:58:36 am »
If anyone has any experience that'd be awesome :)

Yes, they do. See here and here.

Let us know what else you need to know.
« Last Edit: October 09, 2015, 08:28:08 am by tggzzz »
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Offline Someone

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Re: FPGA JTAG selection
« Reply #2 on: October 09, 2015, 08:42:06 am »
The diligent USB cables have been quite unreliable, though not as bad as the clone JTAG pods direct from china. With those old devices and your small budget it might be best to accept the slow speeds and stick with a parallel port cable.
 

Offline cat87

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Re: FPGA JTAG selection
« Reply #3 on: October 09, 2015, 11:31:04 am »
If you'll buy a knock off, be sure it's not the absolute cheapest possible. Personally, I;d recommend some gear from Xilinx (no, they do not fit into your 60$ budget) or something from Segger. No, not all cables are the same. For example, I've had issues with an original JTAG programmer from Xilinx with a Xilinx II FPGA. The cable was a bit too long and I couldn't communicate with the device at all, except at very low baud rates. I shortened the cable to about 5 centimeters and that let me flash at max baud rate.

But if you're going to buy a cheap one, make sure it  at least mentions the fact that it supports JTAG programming for your specific device.

Offline nctnico

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Offline bingo600

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Re: FPGA JTAG selection
« Reply #5 on: October 09, 2015, 11:59:52 am »
I've had nice experiences with two *bay clones (approx. $35) , like the ones ntnico links to.

I'd NOT recommend a Parport Jtag, as you might have a hard time finding a PC with a ParPort.

/Bingo

 

Offline Neilm

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Re: FPGA JTAG selection
« Reply #6 on: October 09, 2015, 03:48:06 pm »
I have been using a Digilent JTAG programmer. It works nicely with my Spartan 6, but refuses to programme the CPLDs on the board.
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Offline MattHollandsTopic starter

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Re: FPGA JTAG selection
« Reply #7 on: October 09, 2015, 10:13:41 pm »
@tggzzz
Neither of those links answer my question. I'm well aware that there are cheap jtag cables. But my question was whether any cable would do, or if I had to get something specific. "Are all jtag cables the same? Or do I need something specific?" - Me

@Someone
The boards actually came with a parallel port jtag. I'll try getting a usb-parallel port adapter and see if that works. Thanks.

@everyone else
Otherwise tt looks like most people reckon a $35 ebay clone is a good idea for the budget so I'll get one of those and see how it goes :) Thanks guys
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Offline TerminalJack505

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Re: FPGA JTAG selection
« Reply #8 on: October 10, 2015, 01:10:19 am »
I've got one of the Xilinx Platform Cable clones as well and have had good luck with it.  (See this post for a teardown.)  It uses the Xilinx drivers and works with Xilinx's Impact software. 

I'm not so sure the Digilent cable you linked to will work with the Xilinx Impact software.  You might have to use Digilent's software to program CPLDs/FPGAs.
 

Offline stevenhoneyman

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Re: FPGA JTAG selection
« Reply #9 on: October 10, 2015, 09:30:05 am »
The cables are all mostly the same. Sure, some will have faster throughput, adapt to your target voltage, input protection, etc... and the cheaper ones won't.

The main (and most important difference) is down to which cable your software supports. If you're set on Xilinx (for example), it's probably a bad idea to choose an Altera Blaster clone.
FT2232H-based cables are the most generic/universally supported that I've seen.
 

Offline Korken

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Re: FPGA JTAG selection
« Reply #10 on: October 10, 2015, 10:02:37 am »
I have used the Digilent Inc. programmers (HS2, HS3 and the older JTAG-USB) over my entire FPGA learning-curve and they have worked a treat.
From Spartan-3, Spartan-6 to Artix, Kintex and Zynq (must use the HS3 for Zynq if you want to reset the PS) and no problems so far. :)
Impact seem to support them without hassle.

Has anyone had problem with these?
 


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