Preloading SDRAM?

Hi,
I have to initialise an SDRAM with an LUT (48MB). I have the LUT in
.dat format. Is there anyway I can do this with the Xilinx ISE tool? I
can do writes continuously but I'd like to know how to access the file
in the first place. I read somewhere that I need a different IDE for
it..that too only for RAM blocks. what does that mean?

I am new to this field so if this question has been asked before please
do point me in the right direction (I've done a good search already).

Thanks

Subhasri krishnan wrote:
> Hi,
> I have to initialise an SDRAM with an LUT (48MB). I have the LUT in
> .dat format. Is there anyway I can do this with the Xilinx ISE tool? I
> can do writes continuously but I'd like to know how to access the file
> in the first place. I read somewhere that I need a different IDE for
> it..that too only for RAM blocks. what does that mean?
>
> I am new to this field so if this question has been asked before please
> do point me in the right direction (I've done a good search already).
>
> Thanks

I think you're confusing build-time and run-time tools.  ISE
lets you build your FPGA project into code that can be loaded in
the FPGA including any internal (distributed or block RAM) memory
initialization.

External memory needs to be loaded at run time by the FPGA.  File
access for this depends on how your system is connected to the
computer containing the file.  There are probably tools for this
if you're using one of the development boards and the embedded
processor design kit.  Perhaps this (EDK) is the "different IDE"
you're referring to?

Yes I understand that the external memory needs to loaded through the
FPGA. I am not using any development boards but I am using a chip that
has been designed to work as a special purpose processor. I was
wondering on how to access the 48MB data and convert it into bitstream
to be loaded into the FPGA through the JTAG port. Please do suggest
some way I can do this.

I know that Xilinx has a SystemACE format for tasks such as this, but
it may require you to use an embedded processor.  It is impossible,
though, to convert your LUT data into a bitstream as the FPGA can't
store that much data.

Subhasri krishnan schrieb:
> Hi,
> I have to initialise an SDRAM with an LUT (48MB). I have the LUT in
> .dat format. Is there anyway I can do this with the Xilinx ISE tool? I
> can do writes continuously but I'd like to know how to access the file
> in the first place. I read somewhere that I need a different IDE for
> it..that too only for RAM blocks. what does that mean?
> 
> I am new to this field so if this question has been asked before please
> do point me in the right direction (I've done a good search already).
> 
> Thanks
> 
Hi,
I see two possible solutions to your problem:
1) if the Data can be calculated (e.g. a sine-table) then the algorithm 
can be placed in the fpga and calculate the SDRAM contents once before 
the rest of the system starts.

2)Use a Flash memory (on board, or SD-Card, MMC-Card etc.) where your 
data is stored. Transfer this data to the SDRAM by some FPGA_logic 
before the rest of your system starts.

It is most unlikely to put this ammount of data into a bitfile, but like 
Stephen Craven posted before, there is a system ACE chip that supports 
the second solution, so your own effort will be minimized. This chip is 
intended as a booting solution for operating systems (e.g. to load a 
linux kernel after FPGA-configuration)

have a nice synthesis

   Eilert

On 29 Sep 2005 08:15:37 -0700, "Stephen Craven" <scraven@vt.edu> wrote:

>I know that Xilinx has a SystemACE format for tasks such as this, but
>it may require you to use an embedded processor.  It is impossible,
>though, to convert your LUT data into a bitstream as the FPGA can't
>store that much data.

..but the data could be combined into whatever storage device is supplying the FPGA bitstream, then
accessed by the FPGA once configured. SystemAce or parallel flash would seem appropriate for this
amount of data.

"Subhasri krishnan" <subhasri.krishnan@gmail.com> schrieb im Newsbeitrag
news:1128003125.870713.34210@z14g2000cwz.googlegroups.com...
> Hi,
> I have to initialise an SDRAM with an LUT (48MB). I have the LUT in
> .dat format. Is there anyway I can do this with the Xilinx ISE tool? I
> can do writes continuously but I'd like to know how to access the file
> in the first place. I read somewhere that I need a different IDE for
> it..that too only for RAM blocks. what does that mean?
>
> I am new to this field so if this question has been asked before please
> do point me in the right direction (I've done a good search already).
>
> Thanks
>

www.xess.com

they have an application that preloads an SDRAM connected to FPGA with
binary image.
That sdram content can be later used by the FPGA real application that needs
it, the SDRAM goes into self refresh and maintains its content when CLK is
stopped. Xess has I think all source code needed for this kind of applciatio
available for downloads

Antti

Subhasri krishnan <subhasri.krishnan@gmail.com> wrote:

> I have to initialise an SDRAM with an LUT (48MB). I have the LUT in

This should be possible with XMD (a Xilinx-Tool). At least I've seen
a JPEG-example uploading the jpeg to sdram by issueing a few commands
in a gui-wrapped terminal (iirc XMD).

Perhaps this may help you, if not I could ask the one showing me
this jpeg-example for detailed information.


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