write into flash memory uisng HAL_FLASH_Program STM32L0

Question

I'm trying to write some bytes of data at the specific region in the flash using HAL_FLASH_Program (uint32_t TypeProgram, uint32_t Address, uint32_t Data). But my current understanding of from HAL user manual at 19.2.7 UM1749 "Program word at a specified address" is unclear what does it mean? how can i write bytes eg: char* demo="nucleo" into memory

char* demo="nucleo";
int main(){
.
.
ScratchWrite(FLASH_SCRATCH_START, demo);
.
.
}


 uint32_t ScratchWrite(uint32_t destination, uint32_t *p_source)
{


  HAL_FLASH_Unlock();


    /* Write the buffer to the memory */
   HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD,destination, p_source );


  HAL_FLASH_Lock();

  return status;
}

Answer 1

HAL_FLASH_Program allows you to write given number of bytes under specified address. First function argument uint32_t TypeProgram controls how large the chunk you want to write is. The possibilites are:

#define FLASH_TYPEPROGRAM_BYTE        ((uint32_t)0x00U)  /*!< Program byte (8-bit) at a specified address           */
#define FLASH_TYPEPROGRAM_HALFWORD    ((uint32_t)0x01U)  /*!< Program a half-word (16-bit) at a specified address   */
#define FLASH_TYPEPROGRAM_WORD        ((uint32_t)0x02U)  /*!< Program a word (32-bit) at a specified address        */
#define FLASH_TYPEPROGRAM_DOUBLEWORD  ((uint32_t)0x03U)  /*!< Program a double word (64-bit) at a specified address */

So in case of your question, FLASH_TYPEPROGRAM_WORD writes 32-bit (4 byte) value under specified address. For example:

HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD, 0x8010000, *(uint32_t*)demo);

will write "nucl" under address 0x8010000 .

How large the chunks you want to program with HAL_FLASH_Program are is totally up to you and will affect performance if you choose small chunks ( FLASH_TYPEPROGRAM_BYTE for example) when programming large portion of flash.