11-03-2009 02:57 AM
I understand that the development board from xilinx provide Jtag to the FPGA using iMpact.
However, i realized that another development board from Opal Kelly uses only USB interface to load up the FPGA.
Is there any advantage of one over the other?
And also if i were to use USB to load the FPGA, do i use iMpact as well?
Thanks in advance
11-03-2009 05:53 AM
You'll probably need to get more information from OpalKelly on how they do it,
but in general you need to add some USB hardware to the board in order to
load the FPGA. Many people use a Cypress EZ-USB chip for example. This may
make sense for hobby or eval boards where each board is intended to be uploaded
regularly and the cost of the USB on-board hardware is usually less than a
Xilinx programming cable. It's not generally done for embedded products that
are only programmed at the factory because the factory would only need one
Xilinx cable (or some other PROM / Flash programming equipment) and the
extra cost of the USB parts would be multiplied by a lot of boards.
Unless I'm mistaken, boards like the OpalKelly you saw with built-in USB
use proprietary software rather than impact for loading. How you decide to
build your own board obviously depends on the intended use and whether
you needed USB functionality for some other reason as well.
11-03-2009 05:24 PM
I am currently designing an embedded controller for a power module, which requires high frequency switching.
is there any recommendation on which method i should adopt for loading of the FPGA?
What are the pros and cons of each method?
Also, i understand that i would need a PROM to be interfaced with the FPGA if i want it to function in a certain way when it boots up.
Is ther any particular PROM that can be recommended for such purpose?
and how should i go about loading the PROM, if i wish to use the tools in ISE webpack?
11-04-2009 05:49 AM
The PROM depends on the FPGA choice. For larger FPGA's it is usually cheapest to use a standard SPI
Flash part. Check the device you're considering to see if this method of configuration is supported. For
smaller FPGA's the PlatformFlash series XCFxxS parts are usually a win for simplicity and ease of
programming using the impact tools and a standard Xilinx programming cable. The Configuration
User Guide for your FPGA family shows the circuit diagram for this. Basically the PlatformFlash
parts include a flash memory and logic to emulate the older 17xxx series serial configuration PROMs
as well as a JTAG interface for prgramming the part in-circuit. You can place the PlatformFlash in
the same JTAG chain as the FPGA giving you the ability to hook up your cable and either program
the FPGA directly or program the flash for power-on configuration. I would suggest using a standard
14-pin 2mm header pinned out to accept the ribbon cable from the Parallel Cable IV or USB cables.
This reduces the time to program from the .1" header and flyiong leads approach.
11-04-2009 03:40 PM
If i were to be using a Virtex family FPGA, e.g. Virtex 5 or 6, which is the recommended PROM to use?
and for connection, i just have to follow the schematics given in data sheet to make sure the PROM is in the JTAG chain?