FPGA JTAG selection - Page 1
Forum section: electronics / projects

author: MattHollands
author_rank: Frequent Contributor
timestamp: October 09, 2015, 06:48:58 am
content: 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 thishttp://www.digilentinc.com/Products/Detail.cfm?NavPath=2,395,523&Prod=JTAG-USBdo?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

author: tggzzz
author_rank: Super Contributor
timestamp: October 09, 2015, 07:58:36 am
content: Quote from: MattHollands on October 09, 2015, 06:48:58 amYes, they do. Seehereandhere.Let us know whatelseyou need to know.

author: Someone
author_rank: Super Contributor
timestamp: October 09, 2015, 08:42:06 am
content: 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.

author: cat87
author_rank: Regular Contributor
timestamp: October 09, 2015, 11:31:04 am
content: 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.

author: nctnico
author_rank: Super Contributor
timestamp: October 09, 2015, 11:47:31 am
content: No brainer:http://www.ebay.com/itm/Xilinx-Platform-USB-Download-Cable-Jtag-Programmer-for-FPGA-CPLD-C-Mod-XC2C64A-/181100412793

author: bingo600
author_rank: Super Contributor
timestamp: October 09, 2015, 11:59:52 am
content: 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

author: Neilm
author_rank: Super Contributor
timestamp: October 09, 2015, 03:48:06 pm
content: I have been using a Digilent JTAG programmer. It works nicely with my Spartan 6, but refuses to programme the CPLDs on the board.

author: MattHollands
author_rank: Frequent Contributor
timestamp: October 09, 2015, 10:13:41 pm
content: @tggzzzNeither 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@SomeoneThe boards actually came with a parallel port jtag. I'll try getting a usb-parallel port adapter and see if that works. Thanks.@everyone elseOtherwise 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 goesThanks guys

author: TerminalJack505
author_rank: Super Contributor
timestamp: October 10, 2015, 01:10:19 am
content: I've got one of the Xilinx Platform Cable clones as well and have had good luck with it. (Seethis postfor 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.

author: stevenhoneyman
author_rank: Regular Contributor
timestamp: October 10, 2015, 09:30:05 am
content: 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.

author: Korken
author_rank: Regular Contributor
timestamp: October 10, 2015, 10:02:37 am
content: 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?