[En-Nut-Discussion] SAM9260-EK getting started

[steve]

Hi,

  Further to my problems getting the expected performance from the
  9260 processor it seems the limiting factor is bus speed to the
  external SDRAMs (notwithstanding the lack of clarity over whether
  or not the caches are actually doing anything).  Given that the
  max bus speed is 100MHz plus the necessary latencies in SDRAM
  accesses this results in a best-case net performance NO BETTER
  than a 48MHz ARM7!

  It would therefore seem that the only hope of achieving any
  improvement on this would be if best use could be made of the
  8Kbytes internal fast ram.  Does anyone know of any mechanism
  to persuade the compiler/linker to place critical bits of code
  / data and perhaps the stack in internal SRAM?

  Thanks a lot.

Cheers,
Steve.


At 14:01 13/07/2008, you wrote:
>steve wrote:
> >
> >   If I program the webradio application into dataflash on my 9260-EK,
> >   (along with the Atmel bootloader) then it works.  Programming directly
> >   into SDRAM @ 0x20000000 it fails.  Clearly there's something in that
> >   bootloader that makes all the difference, does this make any sense?
>
>Indeed, there may be a missing initialization in the SAM-BA ROM or the
>Webradio, which is provided by the boot loader. Unfortunately I haven't
>had the time to test all this here. At least I do have the same board
>revision 1.0.
>
> >
> >   I now have another problem - my LJG JPEG decompression application
> >   runs slightly _SLOWER_ on the 9260-EK (CPU clk 90.3MHz) than on my old
> >   SAM7X-EK (CPU clock at 48MHz).  I moved to ARM9 specifically to get
> >   more speed, does anyone have any idea why?
>
>I had a discussion with Atmel about similar experiences with the MP3
>fixed point software decoder used in the webradio. They later changed
>the SDRAM initialization (SAM-BA script and bootloader) and performance
>increased. It was still slower than expected, but significantly faster
>than the SAM7X. In case you are using an old SAM-BA Tool or boot loader...
>
>Harald
>
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