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Re: [Xylo-SDR] RFC - Motherboard

Altera's FPGA's Cyclone II chips are dirt cheap, something special like a 100 MHz A/D would require one up close, but $13 qty one is not unreasonable for a demanding task, and that is way cheaper than the A/D chip itself. Actually this would simplify things considerably.
We either have the high speed stuff on the FPGA board, or plan on having more than one FPGA so we need to get over it and move on. 


At 08:21 PM 1/24/2006, you wrote:


On 1/24/06, Eric Ellison <ecellison@comcast.net> wrote:

> The buss stuff really all
> started to unravel when Phil_C said he needed an FPGA on the Radio board due 
> to the probable lack of capability of the buss to carry the A/D and other
> high speed sigs to and from the Lionheart. Bill ­ KD5TFD and I sort of said
> the same thing Saturday:  "If we can't leverage the Lionheart for all buss
> mounted FPGA projects now and in the future, what is the point of the buss?" 
>

Gosh, this is really getting tiring...  Really, please get away from
the idea that a FPGA or CPLD is some special kind of magic thing... It
is just a chip that can replace a board full of other logic chips.
People don't think twice when we are using the Wolfson/TI ADC and
another TI ADC/DAC on the same board.  And people happily put two
Analog Devices DDS chips on a board to get a quadrature LO...  But God
forbid if I mention using more than one FPGA ;-)

> Cecil suggested a .100 pin header  to which we would attach a twisted pair
> to a single pair block going from board to board. It is a good idea for a
> couple of pairs of pins, but if we need 16 pair or probably more, it is a
> little impractical, but do-able.

We only need a couple of high speed lines, not 16.

Phil C
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Cecil Bayona
KD5NWA
www.qrpradio.com
"I fail to see why doing the same thing over and over and getting the same results every time is insanity: I've almost proved it isn't; only a few more tests now and I'm sure results will differ this time ... " 

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