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From: pes on 29 Apr 2010 11:05
Hi,

I' m new to FPGA and I want to design a board with a Xilinx Spartan6
FPGA and 4GB of RAM.
Is it realistic to have a such quantity of RAM on a board? I suppose
that there are design constraints to do it, is it easier to do it with
DDR2 than DDR3 or others?
The Spartan6 integrated memory controller only treats 16bits bus, I
suppose I can' t use easily DIMM memory?

How to proceed to do it the simplest possible? Any documents?

Thank you for me clarify.

christophe
From: Nico Coesel on 30 Apr 2010 08:50
pes <dontspamme(a)thanks.com> wrote:

>Hi,
>
>I' m new to FPGA and I want to design a board with a Xilinx Spartan6
>FPGA and 4GB of RAM.
>Is it realistic to have a such quantity of RAM on a board? I suppose
>that there are design constraints to do it, is it easier to do it with
>DDR2 than DDR3 or others?
>The Spartan6 integrated memory controller only treats 16bits bus, I
>suppose I can' t use easily DIMM memory?

I think you can if your design goals are realistic. A 125MHz DDR2
interface (250Mbit/s) should be feasible but you should be willing to
roll your own DDR2 controller. A couple of years ago I created a
design in which a standard PC style DDR dimm module is shared between
two Spartan3 (speed grade 4) FPGAs. One FPGA contains the DDR
controller the other is just a slave. BTW I've started to convert this
design to DDR2.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico(a)nctdevpuntnl (punt=.)
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