Using the AUX RAM as RAM

If your application does not use the Sensor Controller, you can use this memory as RAM for your application. However, access to this memory is significantly slower than access to the SRAM. This may lead to increased power consumption and slower program execution.

In order to use the AUX RAM with you application, follow these steps (CCS is first described, then IAR).

1. Make a new define in the linker command file predefines: In CCS; Project -> Properties -> ARM Linker -> Advanced Options -> Command File Preprocessing. In IAR; Options -> Linker -> Config. Add AUX_AS_RAM=1.

2. The linker command/configuration files are somewhat different from CCS to IAR. The instructions for altering the linker configuration file in IAR follows the CCS specific explanations.

• In the linker command file cc26xx_app.cmd, define the AUX_RAM memory area:

  #ifdef AUX_AS_RAM
  #define AUX_RAM_BASE            0x400E0000
  #define AUX_RAM_SIZE            0x800
  #endif /* AUX_AS_RAM */
  

• Create a AUX_RAM memory section in MEMORY{}

#ifdef AUX_AS_RAM
AUX_RAM (RWX) : origin = AUX_RAM_BASE, length = AUX_RAM_SIZE
#endif /* AUX_AS_RAM */

• Add sections of memory or code to AUX_RAM in SECTIONS{}

  Listing 68. Move object files into AUX_RAM. Example from simple_peripheral (cc26xx_app.cmd).

  #ifdef AUX_AS_RAM
    reorganized_into_auxram
    {
      simple_peripheral.obj(.data)
      devinfoservice.obj(.data)
      simple_gatt_profile.obj(.data)
      icall.obj(.data)
      board.obj(.bss)
      } > AUX_RAM
  #endif/* AUX_AS_RAM */
  

The .obj files are listed in the FlashROM folder of the app project. They are also listed with size in the .map file. A detailed description of the linker command file and memory sections is given in the wiki article Linker Command File Primer.

If you want more control over what is stored in AUX_RAM, individual variables can be stored there with the #pragma DATA_SECTION command. Please note that this is only possible for global variables.

Listing 69. Move the global display handle variable into a new AUX RAM section called my_section.

// Display Interface
#pragma DATA_SECTION(dispHandle, "my_section")
Display_Handle dispHandle = NULL;

You can find my_section in the map-file. Here you will find the names of the objects included in my_section. In this case, the object is simple_peripheral.obj (my_section).

Listing 70. In the linker command file (cc26xx_app.cmd), add the section to AUX_RAM.

#ifdef AUX_AS_RAM
  reorganized_into_auxram
  {
    simple_peripheral.obj(my_section)
  } > AUX_RAM
#endif /* AUX_AS_RAM */

Important

When making alterations only to the linker command file, please make sure to press Rebuild, not just Build. (CCS will not recognize that you have made changes to the project before you press Rebuild.)

3. For IAR, open the linker configuration file cc26xx_app.icf. Under Memory Definitions, add

////////////////////////////////////////////////////////////////////////////////
// AUX_RAM
//
if ( isdefinedsymbol(AUX_AS_RAM) )
{
  define symbol AUX_RAM_START        = 0x400E0000;
  define symbol AUX_RAM_SIZE         = 0x800;
  define symbol AUX_RAM_END          = AUX_RAM_START + AUX_RAM_SIZE;
}

• Under Memory Regions, add

  if ( isdefinedsymbol(AUX_AS_RAM) )
  {
    define region AUX_RAM               = mem:[from AUX_RAM_START to AUX_RAM_END];
  }
  

• Under Memory Placement, add

  Listing 71. Move object files into AUX_RAM. Example from simple_peripheral (cc26xx_app.icf).

  if ( isdefinedsymbol(AUX_AS_RAM) )
  {
    // AUX_RAM
    define block AUXDATA { section .data object simple_peripheral.o,
                           section .data object devinfoservice.o,
                           section .data object simple_gatt_profile,
                           section .data object icall.o,
                           section .data object board.o};
    place in AUX_RAM { block AUXDATA };
  }
  

The .o-files are listed in the .map file. For more information on the linker configuration file, please see IAR C/C++ Development Guide.

If you want more control over what is stored in AUX_RAM, individual variables can be stored there with the #pragma location command. Please note that this is only possible for global variables.

Listing 72. Move the global display handle variable into a new Cache RAM section called my_section.

// Display Interface
#pragma location="my_section"
Display_Handle dispHandle = NULL;

You can find my_section in the map-file. Here you will find the names of the objects included in my_section. In this case, the object is simple_peripheral.o (my_section).

Listing 73. In the linker configuration file (cc26xx_app.cmd), add the section to AUX_RAM.

if ( isdefinedsymbol(AUX_AS_RAM) )
{
  // AUX_RAM
  define block AUXDATA { section my_section object simple_peripheral.o };
  place in AUX_RAM { block AUXDATA };
}