spartan3 starter kit.

a really stupid question.... so general purpose ports/pins. where are they on the spartan 3 starter kit? so i read that i can just use the jtag pins.. but that doesnt seem like many pins to toggle/twiddle. im used to programming on avr mega 128. where all the ports are obvious. what i sort of think is that i can use any pins on the board as general io? are there some pins that are faster ? i just want to connect it to some DACs. so im thinking ill need at least 20 pins. so i should be using the expansion slots?

thanks peter

Reply to
zhangweidai
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look in your documentation!

there are TONS of ports on this thing.

You define what signal goes to what pin within the ISE...

Start the Project Navigator, go to HELP go to TUTORIALS go to ISE QUICKSTART

it will open a PDF. It takes about an hour to work through the tutorial, and explains how to set output and input pins on the example 4 bit counter circuit.

Rich

Reply to
aiiadict

If you can't find the schematics on the Xilinx web site, you can get them from:

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The main problem I see is that there is only one ground pin on each of the 40 pin connectors.

How fast a DAC to you need? Digilent has a board with a (slow) bit serial DAC.

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Reply to
Hal Murray

that was really simple!!!!

thanks, Peter

Reply to
zhangweidai

Hi Hal, An SI work-around for driving long ribbon cables is to drive every other pin low. Bummer if you need all the I/O! Cheers, Syms.

Reply to
Symon

Here's another way : The ground is the nearest to the solder side of the inner planes so it's possible to dremel down to it & add more grounds..

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Reply to
Mike Harrison

Mike, You butcher! VG! I wonder if there's a lesson here for the prototype board product guys. After all, these boards are often bodged up for proof-of-concept projects. Put a ring of exposed ground all the way around the edge of the board to help SI design. Carefully stiched to the gnd plane, of course. What about it, Mr. Adair? Cheers, Syms.

Reply to
Symon

One neat feature of his Raggedstone 1 board is the provision of solder-bridges to reassign IOs to ground.

Reply to
Mike Harrison

Oh we have done better than that on some of the RF boards we have done for customers. How about exposed earth bond(0V) both side and mounting screw holes every 20mm.

On a simpler note you might what we have done on Hollybush1 but you will have to wait until DATE to see it.

John Adair Enterpoint Ltd. - Home of Hollybush1. The PC104+ Spartan-3 Development Board.

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Reply to
John Adair

"John Adair" wrote in message news: snipped-for-privacy@doris.uk.clara.net...

Hi John, Trouble is, _every_ board with a modern FPGA on it is an 'RF' board these days!! Cheers, Syms.

Reply to
Symon

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