On Fri, 2011-04-08 at 06:06 -0400, V G wrote:
> Hi all,
>=20
> I'm seriously considering getting myself a Papilio. This question is pure=
ly
> out of curiosity. The $50 version has a Spartan 3E FPGA chip with 250K
> gates.
>=20
> What can I do with 250K gates?=20

Alot.

> How many 8 bit CPU cores can I fit on there,
> for example? How about an ARM 32 bit core? How many gates (approximately)=
 do
> these cores take?

No idea. And any number I'd give you would be completely useless.

A "gate" isn't the same across FPGA families (or any other sort of
digital logic). The reason is there are no "gates" on FPGAs, just LUTs,
registered elements (flops/latches) and SRAM (both distributed and block
I believe in that FPGA). How many gates a bunch of LUTs is equivalent
too depends one what kind of logic you put into it.

The answer is: download the Xilinx webpack (free to download and use for
the smaller parts), target the FPGA you want, and compile the core
you've got. The tool will tell you how much of the FPGA you're using,
and use that to gauge what size part you need (if you start getting
tight there are tool options you can use to optimize for size or speed,
but you just want a rough number for the moment).


> The Spartan 3E series seem to be pretty cool (and cheap) chips.=20

Spartan 3s are pretty full featured, they share the architecture of I
believe the Virtex 2 Pros, so alot of features in those parts are
available to you.

> I checked
> out other chips on Xilinx's and Altera's site and they seem to have some
> seriously high end stuff on there. Just out of curiosity, how much would =
a
> really high end FPGA cost?

Can't give you specific pricing, but if you're targeting the largest
parts you start reaching the $10k mark, per device.

TTYL

--=20
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