Saving some data in RAM between Reboots.

[Marius CO]

Hello,

I am trying to add s RAM section at the end of the RAM to save

some data (states) between warm reboots, when the watchdog kicks due some

wiring problems (i2c).

I changed the ld file as:

• I reduced the stack -2k
• I reduced ram -2k
• I created a RAMAUX and afferent section.

/* LD file ... */
/* _estack = 0x20028000;   --  taken out */
_estack = 0x20027800;        /*  new stack - 2K */
 
//...
MEMORY
{
RAM   (xrw)     : ORIGIN  = 0x20000000,  LENGTH = 158K    /* was 160  now is - 2K */
FLASH (rx)      : ORIGIN  = 0x8000000,   LENGTH = 512K
AUXRAM (rx)     : ORIGIN  = 0x1FFFF800,  LENGTH = 0x800    /* use 2 K */
}
 
/// then later on at the end.
 
      .my_ram : {
		KEEP(*(.my_ram))
	} > AUXRAM
 
  /* Remove information from the standard libraries */
 
 

The program wont start.

I hangs in the startup file here:

The start hang here. Anything else I am missing.

The intend is to access it in C like

uint32_t ram_end __attribute__((section (".my_ram"))) ;
 
static void* __attribute__((optimize("O0"))) 	_ram_storage(void)
{
	void* ptr = (void*)&ram_end;
	return ptr;
}

Thank you,

... addon

sometime this pops up from atolic

[Clive1 (HNL)]

The AUXRAM can't be below 0x20000000, you're recovering from the END of memory

The Stack moves downward, so the base for both stack and auxram should be 0x20027800

[KnarfB · Accepted solution]

something like

/* Highest address of the user mode stack */
_estack = ORIGIN(RAM) + LENGTH(RAM);	/* end of "RAM" Ram type memory */
 
_Min_Heap_Size = 0x200 ;	/* required amount of heap  */
_Min_Stack_Size = 0x400 ;	/* required amount of stack */
 
AUXLEN = 2K;
 
/* Memories definition */
MEMORY
{
  RAM	(xrw)	: ORIGIN = 0x20000000,	             LENGTH = 160K-AUXLEN
  AUX   (xrw)   : ORIGIN = ORIGIN(RAM) + LENGTH(RAM) LENGTH = AUXLEN
  FLASH	(rx)	: ORIGIN = 0x8000000,	             LENGTH = 512K
}

[Marius CO]

RESOLVED !

Many thanks.

This solved my problem.

... and the elegance of the provided code. Thank you again.