Fixup overflow in main

[AjRj14]

Hi,

I'm trying to place a variable  in an absolute flash location. Target is S12ZVM and I'm using codewarrior. 

For this, I modified the .prm file as below:

In “SEGMENTS” defined “ROM_VAR_SPACE” (I selected small part of FLASH);

Then in “PLACEMENT” told linker, ROM_VAR data must be placed to ROM_VAR_SPACE.

Then in main.c ,

When I am trying to access the buffer[0] from main function, I am getting the below error.

But I am able to access buffer[1]. No issues are occurring at that time. Could you please tell me why this is happening.

I have attached my .prm and main.c.

[StanoA]

Hi AjRj14,

This is caused by internal CodeWarrior compiler – it wants to optimize the organization of the code in FLASH.

If the CONST_SEG is used the compiler can’t optimize this section and musts write the constant (your variable in fact) into FLASH to specified place.

I have tested the next format how to set-up this feature:

------------------------------------------

SEGMENTS  /* Here all RAM/ROM areas of the device are listed. Used in PLACEMENT below. */

      RAM           = READ_WRITE  0x001000 TO 0x001FFF;

      ROM           = READ_ONLY   0xFF8000 TO 0xFFFCFF;

      MY_ROM_VAR_SPACE = READ_ONLY    0xFFFD00 TO 0xFFFDFF;

END

PLACEMENT /* here all predefined and user segments are placed into the SEGMENTS defined above. */

      _PRESTART,              /* Used in HIWARE format: jump to _Startup at the code start */

      STARTUP,                /* startup data structures */

      ROM_VAR,                /* constant variables */

      STRINGS,                /* string literals */

      NON_BANKED,             /* runtime routines which must not be banked */

      DEFAULT_ROM,

      COPY              INTO  ROM;

      MY_ROM_VAR              INTO  MY_ROM_VAR_SPACE;

      DEFAULT_RAM             /* all variables, the default RAM location */

                        INTO  RAM;

END

-------------------------------

And in main.c:

----------------------------------

/* MODULE main */

/* Including needed modules to compile this module/procedure */

#include "Cpu.h"

#include "Events.h"

/* Include shared modules, which are used for whole project */

#include "PE_Types.h"

#include "PE_Error.h"

#include "PE_Const.h"

#include "IO_Map.h"

/* User includes (#include below this line is not maintained by Processor Expert) */

volatile dword my_Variable;

/* Write your local variable definition here */

#pragma CONST_SEG MY_ROM_VAR

      const volatile dword ROM_Volatile = {0x12341234};

#pragma CONST_SEG DEFAULT

void main(void)

{

/*** Processor Expert internal initialization. DON'T REMOVE THIS CODE!!! ***/

  PE_low_level_init();

  /*** End of Processor Expert internal initialization.                    ***/

  /* Write your code here */

  /* For example: for(;;) { } */

  /*** Don't write any code pass this line, or it will be deleted during code generation. ***/

  /*** RTOS startup code. Macro PEX_RTOS_START is defined by the RTOS component. DON'T MODIFY THIS CODE!!! ***/

  #ifdef PEX_RTOS_START

    PEX_RTOS_START();                  /* Startup of the selected RTOS. Macro is defined by the RTOS component. */

  #endif

  /*** End of RTOS startup code.  ***/

  /*** Processor Expert end of main routine. DON'T MODIFY THIS CODE!!! ***/

    my_Variable = ROM_Volatile;

  for(;;){}

  /*** Processor Expert end of main routine. DON'T WRITE CODE BELOW!!! ***/

} /*** End of main routine. DO NOT MODIFY THIS TEXT!!! ***/

/* END main */

-------------------------------

The changes are implemented in the PE example project – the yellow marked rows.

Please use it as example for your settings.

I hope it could help you.

Best Regards,

Stano.