Placing variables in dedicated part of memory.

[SSmit.13]

Hi

  I'm using a STM32L433 in a battery application, and running in Stop mode. I want to keep some variables in RAM2 so their values are not lost when the processor is woken up.

I managed to get it working as follows. I created a block in the linker file called ".Permanent_buffer ", then initialised a block of memory to fit in it, see below at bottom.

I will have a few variables working this way, and wondering if there is a way I can assign the start all variables in RAM2, for example ( I havent a clue how to do this, just to show what I mean):

#define .Permanent_buffer

int PermA=1; //will keep value on STOP 

long PermB=2; //will keep value on STOP 

#endif

int TempA=3; //will loose value on STOP

long TempB=4; //will loose value on STOP 

This way it would save me adding __attribute__((section(".Permanent_buffer"))) one each variables. Is there a way to do this?

Many thanks

Scott

Code I have working.......

typedef struct{

long sig;

long date;

long time;

short int hum;

short int temp;

}Results;

char PermanentBuff[sizeof(Results)*500] __attribute__((section(".Permanent_buffer")));

Results *ResPtr=(Results *)&PermanentBuff[0];

Linker file:

.Permanent_buffer :

{

KEEP(*(.Permanent_buffer))

} >RAM2

[Johi]

See

https://stackoverflow.com/questions/44443619/how-to-write-read-to-flash-on-stm32f4-cortex-m4/44855815#44855815 

And you can still use a

#define perm __attribute__((section(".user_data")))

If you want to get rid of the __atrribute__ blablabla 🙂

Best regards,

Johi.

[SSmit.13]

Hi Johi

  The link doesnt go anywhere, can you please check the web site?

Best Regards

Scott

[Johi]

https://stackoverflow.com/questions/44443619/how-to-write-read-to-flash-on-stm32f4-cortex-m4 

[TDK]

You can't do this unless you also modify the startup script to initialize those values, or initialize them somewhere else in your code.