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Big endian and Little endian ?

asterix
Associate II
Posted on January 09, 2008 at 18:05

Big endian and Little endian ?

5 REPLIES 5
asterix
Associate II
Posted on May 17, 2011 at 12:20

Hi Folks,

I am tearing my hair out on this one and hoping someone can help :

is STM32 ( Cortex-M3) Little or Big endian and how we can change it at both processor level and in keil or IAR compiler options ? :-?

Thanks , Magigimix

edware
Associate III
Posted on May 17, 2011 at 12:20

Hi Magigimix,

Here's a quote from the Arm M3 Cortex Technical Reference Manual:

Quote:

The processor can access data words in memory in little-endian format or big-endian format. It always accesses code in little-endian format.

Note

Little-endian is the default memory format for ARM processors.

...

The processor contains a configuration pin, BIGEND, that enables you to select either the little-endian or BE-8 big-endian format. This configuration pin is sampled on reset.

You cannot change endianness when out of reset.

I hope you still have some hair left!

Regards

edware

sjo
Associate II
Posted on May 17, 2011 at 12:20

No you cannot change the endianess, it is little endian only.

The BIGEND is an internal setting to the cortex die.

Cheers

Spen

asterix
Associate II
Posted on May 17, 2011 at 12:20

Dear edware,

Thanks so much , I still have some 🙂 last night.

back to your answer and to conclude : I can change at reset the data endianess only, but how ? I can not see any pin called BIGEND. Thx again.

kind regards, Magigimix

"some hair left" is the reason I thumbed it up. :D