AT91RM9200 and RTEMS

Jay Monkman jtm-list-rtems at
Wed Apr 28 18:05:43 UTC 2004

On Wed, Apr 28, 2004 at 01:48:23PM +0200, Ole Hansen wrote:
> The ARM920T - core used in AT91RM9200 seems to have 2 instruction-sets.
> ...
> Which one is used to build RTEMS/compile application for RTEMS ?????

The ARM support in RTEMS doesn't work with the thumb instruction
set. So, unless you want to add thumb support, you'll have to use the
ARM instruction set. Thumb is really only useful if you have tight
memory requirements or a narrow memory bus.

> Anybody know the performance difference running from 32-bit SDRAM or 16-bit SRAM ???

It depends on the clock rates of the busses, SDRAM latency, and your
application. Calculate the bandwidth of each configuration an you'll
have most of your answer. A 16 bit SRAM at 200 MHz will be faster than
a 32 bit SDRAM at 60 MHz.

I have an AT91RM9200 BSP (for the Cogent CSB337) that will hopefully
get into the RTEMS development branch soon. You can get an older
version of the source at (It's based
on a 4.6.0 prerelease.)

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