Hello.

I just started looking at Picoblaze.  Has anyone completed a Picoblaze
and DDR RAM implementation?  Or does anyone have any strong opinions on
this issue.  My main goal is to store program data on RAM and access it
with Picoblaze. I see OpenCores has a DDR/SDRAM controller...

Thanks for your constructive ideas.

How big a RAM do you need? PicoBlaze is usually a
small 8-bit
controller that only uses BlockRAM.
Peter Alfke, Xilinx
==========
karrelsj wrote:
> Hello.
>
> I just started looking at Picoblaze.  Has anyone completed a Picoblaze
> and DDR RAM implementation?  Or does anyone have any strong opinions on
> this issue.  My main goal is to store program data on RAM and access it
> with Picoblaze. I see OpenCores has a DDR/SDRAM controller...
> 
> Thanks for your constructive ideas.

karrelsj schrieb:
> Hello.
> 
> I just started looking at Picoblaze.  Has anyone completed a Picoblaze
> and DDR RAM implementation?  Or does anyone have any strong opinions on
> this issue.  My main goal is to store program data on RAM and access it
> with Picoblaze. I see OpenCores has a DDR/SDRAM controller...
> 
> Thanks for your constructive ideas.

I guess this is the wrong combination. Picoblaze is just a small 8 bit 
Micro, with only 256/1024 (Spartan-2/Spartan-3) words of instruction 
space directly addressable. If you need mor program space,

a) use two or more picoblaze, the are small
b) use bank switching to access multiple banks of BRAM

Regards
Falk

karrelsj wrote:
> Hello.
> 
> I just started looking at Picoblaze.  Has anyone completed a Picoblaze
> and DDR RAM implementation?  Or does anyone have any strong opinions on
> this issue.  My main goal is to store program data on RAM and access it
> with Picoblaze. I see OpenCores has a DDR/SDRAM controller...
> 
> Thanks for your constructive ideas.

  Do you mean a large data-space in DDR, and that the PicoBlaze runs from
Block Ram in the FPGA ?
  That would be do-able, and you could add features like the Serial FLASH
devices have, which is auto-inc of Rd/Wr address, for continual access.
( that saves a lot of address thrashing )

  If you needed more code, two bock RAMS, with reload-flip support in
the FPGA, would allow the DDR behave like a HardDisk (from
the code perspective).

What split and sizes do you need for Code/data ?

-jg

Thanks for everyones comments.  Anyone have any
suggestions on getting
started monkeying around with RAM controllers?  I didn't have picoblaze
in mind for a specific task, rather just playing around getting my feet
wet.  I would like to work with a basic setup to start out.  Load
program data from RAM, and then advance into modifying a controller to
decrypt data as it brings it it.

Anyone have any good starting points to "ease" me into this world.
Implementing a RAM controller tutorial...

Thanks


Jim Granville wrote:
> karrelsj wrote:
> > Hello.
> >
> > I just started looking at Picoblaze.  Has anyone completed a Picoblaze
> > and DDR RAM implementation?  Or does anyone have any strong opinions on
> > this issue.  My main goal is to store program data on RAM and access it
> > with Picoblaze. I see OpenCores has a DDR/SDRAM controller...
> >
> > Thanks for your constructive ideas.
>
>   Do you mean a large data-space in DDR, and that the PicoBlaze runs from
> Block Ram in the FPGA ?
>   That would be do-able, and you could add features like the Serial FLASH
> devices have, which is auto-inc of Rd/Wr address, for continual access.
> ( that saves a lot of address thrashing )
>
>   If you needed more code, two bock RAMS, with reload-flip support in
> the FPGA, would allow the DDR behave like a HardDisk (from
> the code perspective).
> 
> What split and sizes do you need for Code/data ?
> 
> -jg