Build an FPGA programmer cable

Well, I have a similar situation. I have only worked with development platform from Xilinx, like Spartan 3E Starter kit, and now I have to work with a Xilinx FPGA which is integrated in a Sundance Board. Of course the fpga is the same but could I program it with ISE and XPS?. I think that you can use this tools for creating the bitstream, but you can not use any Xilinx tool to download this configuration. You must use another tool from the company or integrate this with some program.

But in your case, I think that you need quite a lot electronic knowledge to develop your own board. You need some interface to program the fpga, some vco to create a reference clock, some voltage regulator, etc...

My opinion is that what you try to do is a good project but I think that you are re-inventing the wheel. I hope this could help you

Best Regards Pablo

Timo Schneider wrote: [...]

Hi Timo,

It first always sounds so simple to just put together just what you need. But once you go into detail it ends up taking more than you expected.

The question will be whether you are willing to do all the electronics work necessary to get it going. The Spartan 3 has quite some voltage requirements. So just to get it going byitself will take some components. The next step is the programming. Adding some components to do the programming is one side. The other is how to get the bit stream from the PC to the components. You could use an AVR for example. With the serial port of the AVR connecting to the PC. However, if I remember right the Spartan 3 binary is quite bigger than that of the Spartan 2, so the programming process might take some time.

There is actually a way to hook up an USB interface direct to the FPGA. I have an old Spartan 2 board from digilent and they have a library that allows to download the FPGA image over their USB interface. This does not work with my Spartan 2, but it is supposed to work with the Spartan 3.

I think the USB FPGA project on sourceforge uses the same approach:

Actually, maybe that board has just what you are looking for. I think the small version also uses a X3S50.

What I like about it is, that you can even customize the USB firmware if you need so. Also the code is freely available from sourceforge.

Cheers,

Guenter

Hi!

Yes, that's what I expected. :-) Do you have some tips which problems could occour?

If it is not too complicated, I would like to do so. Learning by doing.

My first idea was too hook up the paralell port of the pc directly to the fpga-programming pins, adding resistors and a z-diode to get the voltage right. Is this completely wrong or why should I use an AVR in between the pc paralell-port and the fpga?

Mm, but this board is just as expensive as the Spartan3E Starter Kit.

Regards, Timo

Timo Schneider schrieb:

Timo,

it all depends on your skills and willingness to play around.

if you have any Xilinx FPGA then it is rather easy to make from it an devkit, some while ago I purchased some big Virtex FPGA from ebay for 49$ and made a devboard, the chip was in BGA but thats also doable with some patentience, just place the chip balls up and solder directly to the balls.

with the JTAG programming, just use series resistors that all. usually works.

so all you need to worry are the voltage regulators for the aux and core

Antti

Here is a simple schematic for the parallel cable programmer:

Hi!

Ah, thats great! And it looks easy to build. But what do I need the jtag header for? It seems the paralell port is directly connected to the fpga pins. Or is it just usefull to have a jtag header on the board so that I can use a jtag cable later on?

Regards, Timo