How to store the data at specific memory location in STM32

[MVENN.1]

how to store the data in specific memory location by using Linker script i found this one in tool how to use this one can any one tell me.

ENTRY(Reset_Handler)

/* Highest address of the user mode stack */

_estack = 0x20009000; /* end of "RAM" Ram type memory */

_Min_Heap_Size = 0x200 ; /* required amount of heap */

_Min_Stack_Size = 0x400 ; /* required amount of stack */

/* Memories definition */

MEMORY

{

 FLASH (rx) : ORIGIN = 00x88086080, LENGTH = 128K

 RAM (rwx) : ORIGIN = 0x20000000, LENGTH = 36K

}

/* Sections */

SECTIONS

{

 /* The startup code into "FLASH" Rom type memory */

 .isr_vector :

 {

  . = ALIGN(4);

  KEEP(*(.isr_vector)) /* Startup code */

  . = ALIGN(4);

 } >FLASH

 /* The program code and other data into "FLASH" Rom type memory */

 .text :

 {

  . = ALIGN(4);

  *(.text)      /* .text sections (code) */

  *(.text*)     /* .text* sections (code) */

  *(.glue_7)     /* glue arm to thumb code */

  *(.glue_7t)    /* glue thumb to arm code */

  *(.eh_frame)

  KEEP (*(.init))

  KEEP (*(.fini))

  . = ALIGN(4);

  _etext = .;    /* define a global symbols at end of code */

 } >FLASH

 /* Constant data into "FLASH" Rom type memory */

 .rodata :

 {

  . = ALIGN(4);

  *(.rodata)     /* .rodata sections (constants, strings, etc.) */

  *(.rodata*)    /* .rodata* sections (constants, strings, etc.) */

  . = ALIGN(4);

 } >FLASH

 .ARM.extab  : { 

  . = ALIGN(4);

  *(.ARM.extab* .gnu.linkonce.armextab.*)

  . = ALIGN(4);

 } >FLASH

 .ARM : {

  . = ALIGN(4);

  __exidx_start = .;

  *(.ARM.exidx*)

  __exidx_end = .;

  . = ALIGN(4);

 } >FLASH

 .preinit_array   :

 {

  . = ALIGN(4);

  PROVIDE_HIDDEN (__preinit_array_start = .);

  KEEP (*(.preinit_array*))

  PROVIDE_HIDDEN (__preinit_array_end = .);

  . = ALIGN(4);

 } >FLASH

 .init_array :

 {

  . = ALIGN(4);

  PROVIDE_HIDDEN (__init_array_start = .);

  KEEP (*(SORT(.init_array.*)))

  KEEP (*(.init_array*))

  PROVIDE_HIDDEN (__init_array_end = .);

  . = ALIGN(4);

 } >FLASH

 .fini_array :

 {

  . = ALIGN(4);

  PROVIDE_HIDDEN (__fini_array_start = .);

  KEEP (*(SORT(.fini_array.*)))

  KEEP (*(.fini_array*))

  PROVIDE_HIDDEN (__fini_array_end = .);

  . = ALIGN(4);

 } >FLASH

 /* Used by the startup to initialize data */

 _sidata = LOADADDR(.data);

 /* Initialized data sections into "RAM" Ram type memory */

 .data : 

 {

  . = ALIGN(4);

  _sdata = .;    /* create a global symbol at data start */

  *(.data)      /* .data sections */

  *(.data*)     /* .data* sections */

  . = ALIGN(4);

  _edata = .;    /* define a global symbol at data end */

 } >RAM AT> FLASH

 /* Uninitialized data section into "RAM" Ram type memory */

 . = ALIGN(4);

 .bss :

 {

  /* This is used by the startup in order to initialize the .bss section */

  _sbss = .;     /* define a global symbol at bss start */

  __bss_start__ = _sbss;

  *(.bss)

  *(.bss*)

  *(COMMON)

  . = ALIGN(4);

  _ebss = .;     /* define a global symbol at bss end */

  __bss_end__ = _ebss;

 } >RAM

 /* User_heap_stack section, used to check that there is enough "RAM" Ram type memory left */

 ._user_heap_stack :

 {

  . = ALIGN(8);

  PROVIDE ( end = . );

  PROVIDE ( _end = . );

  . = . + _Min_Heap_Size;

  . = . + _Min_Stack_Size;

  . = ALIGN(8);

 } >RAM

 /* Remove information from the compiler libraries */

 /DISCARD/ :

 {

  libc.a ( * )

  libm.a ( * )

  libgcc.a ( * )

 }

 .ARM.attributes 0 : { *(.ARM.attributes) }

[KnarfB]

You can place the variable(s) in a new section and place the section in memory, see the links below.

https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#Common-Variable-Attributes

https://ftp.gnu.org/old-gnu/Manuals/ld-2.9.1/html_chapter/ld_3.html#SEC17

For a variables like registers (MMIO) the linker script is typically ignored and a pointer cast is done instead. See CMSIS headers.

[MVENN.1]

Hi KnarfB

I'm using CMSIS header this one

#ifndef  __UNALIGNED_UINT32_WRITE

 #define __UNALIGNED_UINT32_WRITE(addr, val)  ((*((__packed uint32_t *)(addr))) = (val))

#Endif​ 

directly im calling function like __UNALIGNED_UINT32_WRITE(addr, val);

addr is ->0x88600000 and val is ->10

but memory location is showing nothing.

[KnarfB]

Are you sure that there is a RAM cell at that address? You cannot write Flash that way.

[MVENN.1]

Hi KnarfB

may i know how to write the address can you just explain.

Thanks

[KnarfB]

Pls. check the reference manual of your chip/board (don't know which) about memory map and tell us: What do you expect to find at address 0x88600000?

The line

 FLASH (rx) : ORIGIN = 00x88086080, LENGTH = 128K

looks odd. For my STM32F746NGHX_FLASH.ld:

MEMORY
{
  RAM    (xrw)    : ORIGIN = 0x20000000,   LENGTH = 320K
  FLASH   (rx)    : ORIGIN =  0x8000000,   LENGTH = 1024K
}

hth

KnarfB

[MVENN.1]

Hi KnarfB

Thanks for your answer it's working fine.