STM32: Flash erase and read and write operations

• Application platform: STM32F030F4P6

• ST official library: STM32Cube_FW_F0_V1.9.0

background knowledge

• For most MCUs and microcontrollers (ARM, x86), the address space is in bytes, which means that one address is one byte.

• Flash memory has a characteristic that it can only write 0, not 1. So if there is data at the original address, it means that some bits are 0, and these bits are equivalent to invalid. So you must make sure they are all 1 before writing, and you can only erase them. In addition, each time you erase, you must erase a 4K sector, which is determined by the characteristics of flash.

• The internal oscillator must be turned on before operating the Flash. 

Introduction to Flash storage of STM32F030F4P6

STM32F030F4P6 hardware configuration: FLASH (16KB) RAM (4KB) 
(contains 4 sectors, 1 sector contains 4 pages, each page has 1Kbyte space) 
Users can program and erase Flash.

Main Flash memory programming 
The main Flash memory can be programmed 16 bits at a time. 
Flash memory erase 
The Flash memory can be erased page by page or completely (Mass Erase). 

STM32F030F4P6 Flash read and write reference code (HAL library)

/* Base address of the Flash sectors */

#define ADDR_FLASH_PAGE_0     ((uint32_t)0x08000000) /* Base @ of Page 0, 1 Kbyte */

#define ADDR_FLASH_PAGE_1     ((uint32_t)0x08000400) /* Base @ of Page 1, 1 Kbyte */

#define ADDR_FLASH_PAGE_2     ((uint32_t)0x08000800) /* Base @ of Page 2, 1 Kbyte */

#define ADDR_FLASH_PAGE_3     ((uint32_t)0x08000C00) /* Base @ of Page 3, 1 Kbyte */

#define ADDR_FLASH_PAGE_4     ((uint32_t)0x08001000) /* Base @ of Page 4, 1 Kbyte */

#define ADDR_FLASH_PAGE_5     ((uint32_t)0x08001400) /* Base @ of Page 5, 1 Kbyte */

#define ADDR_FLASH_PAGE_6     ((uint32_t)0x08001800) /* Base @ of Page 6, 1 Kbyte */

#define ADDR_FLASH_PAGE_7     ((uint32_t)0x08001C00) /* Base @ of Page 7, 1 Kbyte */

#define ADDR_FLASH_PAGE_8     ((uint32_t)0x08002000) /* Base @ of Page 8, 1 Kbyte */

#define ADDR_FLASH_PAGE_9     ((uint32_t)0x08002400) /* Base @ of Page 9, 1 Kbyte */

#define ADDR_FLASH_PAGE_10    ((uint32_t)0x08002800) /* Base @ of Page 10, 1 Kbyte */

#define ADDR_FLASH_PAGE_11    ((uint32_t)0x08002C00) /* Base @ of Page 11, 1 Kbyte */

#define ADDR_FLASH_PAGE_12    ((uint32_t)0x08003000) /* Base @ of Page 12, 1 Kbyte */

#define ADDR_FLASH_PAGE_13    ((uint32_t)0x08003400) /* Base @ of Page 13, 1 Kbyte */

#define ADDR_FLASH_PAGE_14    ((uint32_t)0x08003800) /* Base @ of Page 14, 1 Kbyte */

#define ADDR_FLASH_PAGE_15    ((uint32_t)0x08003C00) /* Base @ of Page 15, 1 Kbyte */

/* Private define ------------------------------------------------------------*/

#define FLASH_USER_START_ADDR   ADDR_FLASH_PAGE_15          /* Start @ of user Flash area */

#define FLASH_USER_END_ADDR     ADDR_FLASH_PAGE_15 + FLASH_PAGE_SIZE   /* End @ of user Flash area */

#define DATA_32                 ((uint32_t)0x12345678)

/*Variable used for Erase procedure*/

static FLASH_EraseInitTypeDef EraseInitStruct;

uint32_t Address = 0;

/**

  * @brief  Main program

  * @param  None

  * @retval None

  */

int main(void)

{

    /* STM32F0xx HAL library initialization:

         - Configure the Flash prefetch

         - Systick timer is configured by default as source of time base, but user

           can eventually implement his proper time base source (a general purpose

           timer for example or other time source), keeping in mind that Time base

           duration should be kept 1ms since PPP_TIMEOUT_VALUEs are defined and

           handled in milliseconds basis.

         - Low Level Initialization

       */

    HAL_Init();

    /* Configure the system clock to 48 MHz */

    SystemClock_Config();

    /* Unlock the Flash to enable the flash control register access *************/

    HAL_FLASH_Unlock();

    /* Erase the user Flash area

      (area defined by FLASH_USER_START_ADDR and FLASH_USER_END_ADDR) ***********/

    /* Fill EraseInit structure*/

    EraseInitStruct.TypeErase = FLASH_TYPEERASE_PAGES;

    EraseInitStruct.PageAddress = FLASH_USER_START_ADDR;

    EraseInitStruct.NbPages = (FLASH_USER_END_ADDR - FLASH_USER_START_ADDR) / FLASH_PAGE_SIZE;

    if (HAL_FLASHEx_Erase(&EraseInitStruct, &PageError) != HAL_OK)

    {

        /*

          Error occurred while page erase.

          User can add here some code to deal with this error.

          PageError will contain the faulty page and then to know the code error on this page,

          user can call function 'HAL_FLASH_GetError()'

        */

        /* Infinite loop */

        while (1)

        {

            /* User doing something here */

        }

    }

    /* Program the user Flash area word by word

      (area defined by FLASH_USER_START_ADDR and FLASH_USER_END_ADDR) ***********/

    Address = FLASH_USER_START_ADDR;

    while (Address < FLASH_USER_END_ADDR)

    {

        if (HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD, Address, DATA_32) == HAL_OK)

        {

            Address = Address + 4;

        }

        else

        {

            /* Error occurred while writing data in Flash memory.

               User can add here some code to deal with this error */

            while (1)

            {

                /* User doing something here */

            }

        }

    }

    /* Lock the Flash to disable the flash control register access (recommended

       to protect the FLASH memory against possible unwanted operation) *********/

    HAL_FLASH_Lock();

    /* Check if the programmed data is OK

        MemoryProgramStatus = 0: data programmed correctly

        MemoryProgramStatus != 0: number of words not programmed correctly ******/

    Address = FLASH_USER_START_ADDR;

    MemoryProgramStatus = 0x0;

    while (Address < FLASH_USER_END_ADDR)

    {

        data32 = *(__IO uint32_t *)Address;

        if (data32 != DATA_32)

        {

            MemoryProgramStatus++;

        }

        Address = Address + 4;

    }

    /*Check if there is an issue to program data*/

    if (MemoryProgramStatus == 0)

    {

        /* User doing something here */

    }

    else

    {

        while (1)

        {

            /* User doing something here */

        }

    }

    /* Infinite loop */

    while (1)

    {

    }

}