Poor quality Xilinx boards ? Your experience ?

I just got a Digilent Spartan3E board & tried to load a bit file using webpack 9.2 IMPACT says no USB cable found. Then I tried one of the JTAG3 cables from Digilent. IMPACT can see the cable but detects too many unknown devices. I'm guessing the board is just bad from Digilent. Now I go back & recompile everything for my Avnet Virtex 4 board. Using ISE 7.2 I get the same IMPACT error. Too many unknown devices. This Avnet board was working & I have used it a few dozen times but it seems to be getting flakier and getting harder to program.

So my experience is these xilinx fpga boards are not very durable or even working when received. ( Although I am impressed with how fast they are when they do work )

My question is How long does your fpga boards last when subject to repeated configuration attempts ? How long have you used a board before you have to replace it ?

Reply to
ereader
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I have ordered 2 FPGA board by Digilent - the older S3 and newer S3e boards and a large number of smaller items like USB cables, modules, etc.

The latest experience is negative: the S3E board appear to heve the SDRAM broken somehow. Cost me several days of struggle till a frien confirmed that the same tests that fail for me pass on his board.

All other items were just fine. No complaints.

ereader wrote:

Reply to
Alex Freed

The only time I have seen the "Too many devices" dialog was when I had misconnected the JTAG cable, so I would check their first. I have used serveral Xilinx based boards from Digilent without a single problem outside of incorrect documentation.

---Matthew Hicks

Reply to
Matthew Hicks

I haven't worked with the boards you mention, but I worked on the ML505 & ML555 from Xilinx. They are very impressive, with lots of peripheral interfaces on board; DDR2, video, audio, you name it. I used it for 6 months to work on our PCIe packet based interface with a virtual FIFO using DDR2, and it proved to be very reliable. Even though it came with ES V5 part, upon request, Xilinx supplied a production part (SX50T) with the distributor loaning us another board on which we re-flowed the V5. No problem re-flowing. These are sturdy, fully functional boards. And very accessible, the

505 was around U$1400.

YMMV-

-P@

Reply to
PatC

I have seen this with older versions of ISE WebPACK, too. I was able to solve it by reducing the transfer speed. With ISE WebPACK 9.2 I never had this problem, old Digilent boards (Sparten 3 and Spartan 3E) are working fine, too.

--
Frank Buss, fb@frank-buss.de
http://www.frank-buss.de, http://www.it4-systems.de
Reply to
Frank Buss

My avnet virtex 4 board was working fine with the jtag cable. But over time, it seems to get flaky. Programming would fail. I'd have to power cycle or plug/unplug the cable to get it working again. Now it seems dead. Hope the new board I ordered works better.

Reply to
ereader

I think you hit on the problem "ereader" is having. I recall playing with the speed for our own production boards in the past. 24 Mb/s may fail, but 12 Mb/s is golden by my recollection.

I've had three development boards with no problems on any of them. I've hauled the one between home and work many times, observing reasonable handling at each location. The performance has been great.

I respect and appreciate the work Digilent does and look forward to more purchases down the road.

- John_H

Reply to
John_H

How do you reduce the speed ? I don't see any speed selection on the boards or in IMPACT.

They do offer a good value but their tech support is nonexistent and their documentation is also nonexistent.

Reply to
ereader

ereader,

The boards we have in the lab last for many, many years. My Digilent board also still works (going on 3 years).

What are you doing to them?

Electrical discharge testing?

Austin

Reply to
austin

I've spent about $1k of my own money on these boards so I am as careful with them as I can be. The boards seem mostly OK. My problems seem to be with the JTAG cables & connection. I suspect the JTAG header pins & plugs are low quality & are worn out after some number of use. Unfortunately I don't have enough test equipment to really debug the problem and I don't really want to waste my time on it either. My ethernet cables are trouble free and swapping my hard disks regularly hasn't given me any problems either. So there are cheap cabling solutions that work well. Too bad JTAG cabling & maybe software is not at the same level of reliability.

Reply to
ereader

ereader,

OK, so you are a serious user, and you seem to be having more than your fair share of problems.

Given the header pins, and socket are gold plated copper, it takes one hell of a lot of wear to remove the gold, and then, you still have copper.

It would also take a great deal of bending and tugging to crack solder, bend pins, etc.

In addition to checking on the speed settings of the cable/software, I would also ask if you have a ground loop. Is the board also connected to something else? Perhaps you are controlling something, or interfacing with something? If the two systems share the same ground, it may be that they are both "grounded" to separate electrical system feeds.

Austin

Reply to
austin

Open the Impact tool (I have 9.2.03i). Go to the Output menu tab. Select the "Cable Setup..." menu item. The dialog box that pops up includes a Xilinx USB Cable radio button and, when selected, has "Max Speed" and "Select Speed" settings available.

When I choose the "Max Speed" I still end up with my original 6 MHz setting that I had when I opened Impact. If your speed is 24 MHz or you want to try different speeds, go to the "Select Speed" setting [and press the OK button to get the available speeds] and dial that speed back.

I've noticed the marginal JTAG chain behavior when I'm in a non-Xilinx application hooking up through the same Digilent USB connection that implements the Xilinx USB Cable on the demo board. In that other application, 24 MHz is the default and the results on our production boards are often spotty with the TCLK termination schemes we've used. Dialing the speed down to 12 MHz or 6 MHz can eliminate the problem.

Good luck getting a stable connection,

- John_H

Reply to
John_H

The board is just by itself. No complicated setup. I am suspicious of the Digilent jtag cable connector. It's just shrink wrapped header. Probably a very cheap header. There are many different types of xilinx download cables from $12 to $200. That right there suggest the xilinx download solutions are not well thought out. Why should such an essential & basic function have so many variations ? It should be just plug & go with nothing to adjust or check.

Reply to
ereader

Thanks for the tip.

Reply to
ereader

ereader,

Parallel port to JTAG, or USB to JTAG cable from Digilent?

I understand you think these cables are garbage, but the general consensus on this board is that the hardware is just fine.

The only issues I have heard complaints about are the software drivers for USB cables from anyone. Seems the variations of hardware, and operating systems for supporting USB have added additional headaches.

Austin

Reply to
austin

Parallel to JTAG.

I'm glad to hear the positive impressions of digilent cables & boards. That means maybe it's just a sw problem & I don't have to buy new boards.

Reply to
ereader

You said you were using a parallel cable to JTAG interface?

A similar thing applies ; the Parallel Cable 4 (and clones) are quite fussy in high speed modes, about the settings on the parallel port, and often don't work at all on laptops.

But there is a low speed mode (Parallel Cable 3 compatibility mode) about 200kbits/second. It auto-selects that on my system. At

200kbits/second, things take a while .... but at least they are reliable.

- Brian

Reply to
Brian Drummond

I am using the parallel cable III but unfortunately it doesn't work at all on my new Digilent Spartan3E board and has started to quit working on my Avnet Virtex 4 boards. My boards are falling apart despite low (& careful ) usage. Thus my complaint.

Reply to
ereader

Reply to
John_H

Well shoot. It's quite possibly just a voltage issue. The JTAG interface is quite probably a 2.5V interface which isn't very compatible with the LPT port. Before I purchased the much better Xilinx USB Platform Cable (similar in interface to the Parallel IV) I hooked up the VCC of my Parallel-III to 3.3V such that the I/O to the

2.5V JTAG chain was good and the 5V LPT logic was still happy. The buffers in the Parallel-III don't provide good LPT voltages when powered by 2.5V.

I highly suggest making the big purchase and getting a Xilinx USB cable. The headaches are significantly fewer! But for the moment, strap VCC for the cable to 3.3V.

(and sorry, folks, for the empty response I just accidentally posted)

Reply to
John_H

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