Minimum circuit to get Spartan-3 running

design

get

methods

You would think that the simplest approach is to take the schematic that comes with the starter / eval boards and start removing the parts you don't need. That being said, I have never seen an eval board that was designed with minimizing component count or board space as a goal. Most often the design expands to fill the available PC board real-estate.

So in reality a better place to start is with a design for a commercial product rather than an evaluation board. The problem is getting access to the schematic for such boards.

The problem with designing a "minimum" board with a programmable component is that the design will depend on what you expect to put into the program of the component. In the case of the FPGA this means power supply current, I/O voltages, and decoupling in addition to other components. You could make some estimates for maximum requirements based on the I/O pin count, the I/O standards, and frequencies you intend to use. For Xilinx parts look at the "user guide" rather than the data sheet for useful information on board design and layout. Also look at the power estimator to get a handle on power supply requirements.

Good luck, Gabor

Gabor,

Thanks for the ideas... I was originally not thinking deep enough and planning on just getting the chip running, then breaking out the IOs to headers. Of course that doesn't take into account what IO type I would then want to use and any possible level converters. I guess that's why there's a market for demo boards, afterall.

thanks, Josh

You can define a simple design, like

Verilog exampl

module top(led, button)

output led

input button

assign led = button

endmodul

Then, you need to specify a constraint file, telling the P&R wher

what FPGA pins to use for 'button' and for 'led'

This is a very basic

Hi, The B5-X300 Spartan2E board takes the approach of bringing the the FPGA I/Os out to headers.

Not much else on the board, except power supply, a header programmable oscillator (1 to 100MHz), one test LED, and one test pushbutton switch. It is a board that you can build into equipment, rather than just use for demo. Best regards,

Tony Burch BurchED, Making FPGA Prototyping Easy,

BurchED FPGA boards...

• Largest number of accessible I/O pins.

• Widest selection of expansion modules.

• Fast and economical prototyping of professional designs.

• Ideal for advanced-student projects.

has about as minimal of a board you can get.. Might be worth looking at for your ideas of where to start