USB to Parallel Adapter for Xilinx JTAG

[banjo]

xilinx usb jtag

The simple circuit for connecting a parallel port to the Xilinx JTAG programmer is readily available on the web and works fine. However, my laptop does not have a parallel port. I tried a couple of "Port Replicators" but these use a chipset that does not allow any bi-directional operation.

I stumbled across one adapter that uses the MOSCHIP, MCS7705. From the datasheet for the chip, it seems fully capable of being used as a bi-directional port. However, I am having lots of problems getting Windows XP to load the proper drivers.

1. Is anyone familar with this adapter?

2. Has anyone gotten it to work for direct accesses to the LPT port for programmers like the Xilinx? If so, can you tell us the tricks? Can you report what version of driver you are using?

Again, while this device shows promise, I have not gotten it to work yet. The manual for the device states that it will work with scanners that run in SPP mode. (The port replicators that failed for me all say that scanners are not supported.)
This device seems to be available on the web. Below is a URL .

**broken link removed**

Thanks.

----- Steve

 

[dainis]

xilinx jtag usb

**broken link removed**

 

[echo47]

usb2lpt

banjo, how about abandoning LPT and using USB? The Platform Cable USB is a little expensive, but it works great for me:
**broken link removed**
Or do you have special JTAG software that only talks to LPT devices?

dainis, that looks like a pretty clever device. I'll bet it's slow, though. Does anyone know for sure?

 

[banjo]

usb jtag xilinx

Thanks for the leads. I have contacted the designer of USB2LPT. First, let me say that I have the utmost regard for his work. I think he has done a fine job. There are a couple of issues with his device. First, I am running XP and some XP machines have problems with his drivers. Secondly, he is building these devices by hand and therefore availability is low. Considering the costs involved in hand building small quantities, his price is very low. He is probably selling these at close to cost.
He would rather I would clone my own device(s) from his info on the web. (Should you wish to do that, please email the author as he wants to issue serial numbers for the EEPROM.)

The Xilinx solution is a possibility, but the prices I was quoted are huge. I may need to outfit a couple of laptops, so any price differential adds up quick. Also, I have several programmers for microcontrollers that only run from an LPT port. If I can get an LPT port working via USB, I can support these programmers from my laptop as well.

With regard to the MOSCHIP device, I do not seem to have gotten a good install on several XP boxes. My laptop will not run the device at all. Two XP desktops install the device, but its own internal loopback test fails. However, on a Win2K desktop, I did get it to install and pass the internal loopback test. Unfortunately, the WIN2K box does not have the IMPACT software installed, so I cannot test JTAG yet.

I will probably keep trying for the remainder of the week on the MOSCHIP device. If I cannot make any headway, I will probably buy a USB2LPT and hope I do not run into the WIN XP issue.

P.S. Yes, USB2LPT is slow. If you dig through his web-page, he mentions this fact and gives some numbers. However, I use JTAG only for programming. Since, loading new bits files does not happen that often for me even when prototyping, the speed issue is not a big deal.

 

[echo47]

usb to parallel jtag

A month ago I bought a Xilinx Platform Cable USB for $149 US, but now it's $199 US. Ouch!

Digilent sells their JTAG-USB cable for only $38 US, but you must use Digilent's "Adept" software instead of iMPACT. I haven't tried it.
http://www.digilentinc.com/Products/Catalog.cfm?Nav2=Cables&Cat=Cable

When I use iMPACT 9.1i to configure the Virtex-5 SX50T (2.4 megabyte bitstream) on my Xilinx ML-506 board:
- Xilinx Platform Cable USB: 5.8 seconds
- Xilinx Parallel Cable IV: 5.7 seconds
- Clone Parallel Cable III: 85.5 seconds

The Parallel Cable III is slow because it bit-bangs the JTAG signals.
Hopefully the additional USB2LPT slowdown is less severe than the 100x worst-case scenario.

 

[banjo]

usb xilinx jtag

Well after testing the MOSCHIP device on Windows 2000, I found that its existing drivers do not support direct port register accesses. Therefore, I could not get either the Xilinx Impact or the XESS software to work with the adapter. The Windows 2000 machine I was using had an existing LPT1 on the motherboard, so I was able to verify all the cables and assemblies were good before starting the test.

The USB2LPT seems to include an emulation program that forms a software wedge which traps and redirects the register IO accesses that are meant for the USB printer port. The drivers for the MOSCHIP device apparently contain no software wedge.

I have ordered one of the USB2LPT converters from Henrik. Hopefully it will work with my XP laptop. While the Digilent JTAG cable is slightly less expensive and faster, it would not support other existing boards. For example the XESS line of FPGA development boards contain a DB25 LPT port connecter right on the board. These boards cannot be programmed by JTAG and must connect to a parallel port.

 

[tcwong3]

usb2lpt jtag

Hello,

I brought a piece of JTAG-USB cable from Digilent.

I launched the ExPort of Adept Software Suite. I managed to initialized the chain and it showed my device (XC9536) on the screen. My problem is that, when I clicked BROWSE button to open file, I couldn’t find SVF file in my CPLD project folder that generated under Xilinx’s ISE Webpack.

I added JED file to Configuration file column, but the Program function in the manu is still disabled.

What are the differences between JED & SVF files? How can I generate SVF from ISE Webpack?

 

[banjo]

usb parallel jtag

I have never used SVF files. I suspect that these are internal files created by the Digilent tool. When you close the app does it ask if you want to save the SVF file. The reason I suspect this is that Xilinx has something similar, the CDF file. I never use these and always just load the JED directly.

Did you try clicking in the little box next to your chip to select it? These tools are constructed to talk to several parts in the JTAG chain. Therefore, you have to indicate which device in the chain you are trying to address. The tools will put all other devices in pass-through mode. This step is redundant when the chain contains only one device, but I think you have to check the box next to the device picture.

Will the device do blank check? If this is also grayed out, then it is another clue that the programmer does not know that the device is selected.

 

[echo47]

jtag xilinx usb

Browse iMPACT Help for a section named "Generating an SVF, XSVF or STAPL File". I've never tried it.

This may be useful too:
"SVF and XSVF File Formats for Xilinx Devices"
https://www.xilinx.com/bvdocs/appnotes/xapp503.pdf

 

[banjo]

xilinx jtag usb cable

Echo47 is correct. Impact can generate SVF files. Now that I have had some sleep, my memory is returning.

I used SVF files a few months ago for an in-field CPLD upgrade. Xilinx has published some microcontroller code that uses an SVF input for its input to bit-bang the JTAG. Our software department did a direct port of that code and therefore required that I supply CPLDs in that format for the upgrade. From within Impact, you can choose the SVF conversion from the "Output" pull-down menu. As I recall, I just followed the GUI prompts and all was fine. In fact, the process was so easy it took me awhile to even remember having to do it. All I did was load the JED file into Impact and then Output the SVF format.