Store constant variables in Flash

[Mohammad A]

Posted on May 31, 2017 at 20:54

I am trying to figure out how to store a constant variable (a constant string of chars) on flash, so it does not occupy valuable blocks of RAM to store a const. In AVR there was something called PROGMEM, but here I can't find any similar method to do so.

How can I store a constant array of chars in the Flash memory?

#variable #flash #ram

[Tesla DeLorean]

Posted on May 31, 2017 at 21:38

static const unsigned char foo[] = { 0x01, 0x02, 0x03, 0x04 };

[Mohammad A]

Posted on May 31, 2017 at 22:16

shouldn't I only use const without static keyword? because when I use const without static, I can find my variable inside map file in .rodata and stored inside FLASH section

 .rodata 0x08003be4 0x8 Src/main.o
 0x08003be4 constvar�?�?

but when I add static keyword, I can't find constvar in the map file.

Actually what does static do here if only adding const makes the variable to be stored in the flash section?

[Danish1]

Posted on May 31, 2017 at 22:24

static (in that context) just means that the data isn't visible outside that file. I guess as a consequence it won't show in the map file.

[Viktor POHORELY]

Posted on June 07, 2017 at 18:16

One example from Keil project to force array at given address. You could force it similary to generic address as well.

variable_t volatile array_storage[NUMBER_OF_RECORDS] __attribute__((at(FLASH_ADDRESS))) = {