NVSMSP432_HWAttrs Struct Reference

NVSMSP432 attributes. More...

#include <NVSMSP432.h>

Data Fields
void *	regionBase
size_t	regionSize

Detailed Description

NVSMSP432 attributes.

The 'regionBase' field must point to the base address of the region to be managed.

The regionSize must be an integer multiple of the flash sector size. For most MSP432 devices, the flash sector size is 4096 bytes. The NVSMSP432 driver will determine the device's actual sector size by reading internal system configuration registers.

Care must be taken to ensure that the linker does not unintentionally place application content (e.g., code/data) in the flash regions.

For CCS and IAR tools, defining and reserving flash memory regions can be done entirely within the ti_drivers_config.c file. For GCC, additional content is required in the application's linker command file to achieve the same result.

The example below defines a char array 'flashBuf' and uses CCS and IAR compiler pragmas to place 'flashBuf' at a specific address within the flash memory.

For GCC, the 'flashBuf' array is placed into a named linker section. Corresponding linker commands are added to the application's linker command file to place the section at a specific flash memory address. The section placement command is carefully chosen to only RESERVE space for the 'flashBuf' array, and not to actually initialize it during the application load process, thus preserving the content of flash.

The 'regionBase' fields of the two HWAttrs region instances are initialized to point to the base address of 'flashBuf' and to some offset from the base of the char array.

The linker command syntax is carefully chosen to only RESERVE space for the char array and not to actually initialize it during application load.

 #define SECTORSIZE 0x1000
 #define FLASH_REGION_BASE 0x3b000

 //
 // Reserve flash sectors for NVS driver use
 // by placing an uninitialized byte array
 // at the desired flash address.
 //
 #if defined(__TI_COMPILER_VERSION__)

 //
 //  Place uninitialized array at FLASH_REGION_BASE
 //
 #pragma LOCATION(flashBuf, FLASH_REGION_BASE);
 #pragma NOINIT(flashBuf);
 char flashBuf[SECTORSIZE * 4];

 #elif defined(__IAR_SYSTEMS_ICC__)

 //
 //  Place uninitialized array at FLASH_REGION_BASE
 //
 __no_init char flashBuf[SECTORSIZE * 4] @ FLASH_REGION_BASE;

 #elif defined(__GNUC__)

 //
 //  Place the flash buffers in the .nvs section created in the gcc linker file.
 //  The .nvs section enforces alignment on a sector boundary but may
 //  be placed anywhere in flash memory.  If desired the .nvs section can be set
 //  to a fixed address by changing the following in the gcc linker file:

.nvs (FIXED_FLASH_ADDR) (NOLOAD) : AT (FIXED_FLASH_ADDR) {
     *(.nvs)
} > REGION_TEXT

 __attribute__ ((section (".nvs")))
 char flashBuf[SECTORSIZE * 4];

 #endif

 NVSMSP432_HWAttrs nvsMSP432HWAttrs[2] = {
     //
     // region 0 is 1 flash sector in length.
     //
     {
         .regionBase = (void *)flashBuf,
         .regionSize = SECTORSIZE,
     },
     //
     // region 1 is 3 flash sectors in length.
     //
     {
         .regionBase = (void *)(flashBuf + SECTORSIZE),
         .regionSize = SECTORSIZE*3,
     }
 };

 Example GCC linker command file content reserves flash space
 but does not initialize it:

 MEMORY
 {
     MAIN_FLASH (RX) : ORIGIN = 0x00000000, LENGTH = 0x00040000
     INFO_FLASH (RX) : ORIGIN = 0x00200000, LENGTH = 0x00004000
     SRAM_CODE  (RWX): ORIGIN = 0x01000000, LENGTH = 0x00010000
     SRAM_DATA  (RW) : ORIGIN = 0x20000000, LENGTH = 0x00010000
 }

 .nvs (0x3b000) (NOLOAD) : AT (0x3b000) {
     KEEP (*(.nvs))
 } > NVS

Field Documentation

regionBase

void* NVSMSP432_HWAttrs::regionBase

Base address of flash region

regionSize

size_t NVSMSP432_HWAttrs::regionSize

The size of the region in bytes

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The documentation for this struct was generated from the following file:

• NVSMSP432.h