Nuvoton ARM Cortex-M0. How to put a const char string into ROM region?

Hi Dejan,

Am I sure? I look into .map file. It says, that all my consts ar placed in 0x20000.... area. RAM data. The only way to place it to ROM area is to give directive __attribute ((( etc.

Word code , or static , or ROM, or any one specific word does not work.

Plus, main problem is, that I can not add more constants now. The program fails to work. As I comment a block of constants - it works again properly.

So, I think, I am sure. I have tried all the ways I know to place the constant to where it must be - so far all in vain.

Alex.

Hi Dejan,

Am I sure? I look into .map file. It says, that all my consts ar placed in 0x20000.... area. RAM data. The only way to place it to ROM area is to give directive __attribute ((( etc.

Word code , or static , or ROM, or any one specific word does not work.

Plus, main problem is, that I can not add more constants now. The program fails to work. As I comment a block of constants - it works again properly.

So, I think, I am sure. I have tried all the ways I know to place the constant to where it must be - so far all in vain.

Alex.

Impossible, in my code it works with "const char". But I use CPP compiler. But anyway should be no problem.

If I define const char acText[]= "Hallo"; , and then look at the variable acText in the watch window, it is defined at address 0x08006678, which is clearly a code address (uVision 4.60 - ARMCC 5.0 - STM32F4).

PS: Perhaps you have some very strange project settings. Best try it first in some fresh Blinky example directly from the Keil boards folder.

Thanks! I will try. As for the project settings - it is a copy of Nuvoton's sample projects' ones. I just have copied all the settings, one by one, and whole project file.

I am also very surprised, and think, that there is some small error somewhere in my files,
so it worth to try new project. Just one string.

Alex.

Thank you b t.

I have made the project up again from the very ground, and, by means of one-by-one .h files exclusion, found a definition in old&borrowed (Microchip C32) file:

#define  const

So, when I comment it, everything works as it must.

Thank you folks. Thank you all. Best regards!
Alex.

Strange that the compiler does not give a warning in such a case. It would be generally nice, if the compiler would produce some more warnings .... (empty code, ambiguous operator order).

Not at all!

#define  const

It just means that the 'const' keyword was effectively stripped from the source code by the preprocessor.
Since 'const' was purely optional in all the cases tried, there was nothing to warn about!

eg,

const char acText[]= "Hallo";

just becomes

char acText[]= "Hallo";

and

static const acText[]= "...";

just becomes

static acText[]= "...";

and

const char txtParcer_OK[] = "ok! this is sample message ...";

just becomes

char txtParcer_OK[] = "ok! this is sample message ...";

BTW: There is nothing in the 'C' language definition that requires the compiler to put const items into read-only memory...

Yes. Stupid error, but that is it.

Thank you for the advice.

Alex.