FileX boot record, ensuring data persistence

I am currently developing on a custom board based on the STM32U5 microcontroller with the MX25UM512 NOR flash memory.

I am following the example provided by the STM32CubeU5 SDK. The example works correctly when I first run it (so data is written correctly). However, upon subsequent runs following a reset, the previously written data seems to vanish, as a new "STM32.TXT" file is created without FX_ALREADY_CREATED

After conducting a thorough investigation, I discovered that the fx_media_format overwrites the boot record during each invocation. To avoid this I modified the example code as follow.

void fx_app_thread_entry(ULONG thread_input)
 {

  UINT nor_ospi_status = FX_SUCCESS;

/* USER CODE BEGIN fx_app_thread_entry 0*/
      ULONG bytes_read;
      ULONG available_space_pre;
      ULONG available_space_post;
      CHAR read_buffer[32];
      CHAR data[] = "This is FileX working on STM32";

      //printf("FileX/LevelX NOR OCTO-SPI Application Start.\n");

      /* Print the absolute size of the NOR chip*/
      //printf("Total NOR Flash Chip size is: %lu bytes.\n", (unsigned long)LX_STM32_OSPI_FLASH_SIZE);

/* USER CODE END fx_app_thread_entry 0*/

  /* Open the OCTO-SPI NOR driver */

 nor_ospi_status =  fx_media_open(&nor_ospi_flash_disk, FX_NOR_OSPI_VOLUME_NAME, fx_stm32_levelx_nor_driver, (VOID *)LX_NOR_OSPI_DRIVER_ID, (VOID *) fx_nor_ospi_media_memory, sizeof(fx_nor_ospi_media_memory));

/* Check the media open nor_ospi_status */
  if (nor_ospi_status != FX_SUCCESS)
  {
    /* USER CODE BEGIN OCTO-SPI NOR open error */

        nor_ospi_status =  fx_media_format(&nor_ospi_flash_disk,                                                           // nor_ospi_flash_disk pointer
                                           fx_stm32_levelx_nor_driver,                                                     // Driver entry
                                           (VOID *)LX_NOR_OSPI_DRIVER_ID,                                                  // Device info pointer
                                           (UCHAR *) fx_nor_ospi_media_memory,                                             // Media buffer pointer
                                           sizeof(fx_nor_ospi_media_memory),                                               // Media buffer size
                                           FX_NOR_OSPI_VOLUME_NAME,                                                        // Volume Name
                                           1,                                                     // Number of FATs
                                           32,                                                                             // Directory Entries
                                           0,                                                     // Hidden sectors
                                           (LX_STM32_OSPI_FLASH_SIZE - LX_STM32_OSPI_SECTOR_SIZE)/ FX_NOR_OSPI_SECTOR_SIZE,// Total sectors
                                           FX_NOR_OSPI_SECTOR_SIZE,                                                        // Sector size
                                           8,                                                                              // Sectors per cluster
                                           1,                                                                              // Heads
                                           1);                                                                             // Sectors per track

        if (nor_ospi_status != FX_SUCCESS)
        {
          while(1);
        }

        nor_ospi_status =  fx_media_open(&nor_ospi_flash_disk, FX_NOR_OSPI_VOLUME_NAME, fx_stm32_levelx_nor_driver, (VOID *)LX_NOR_OSPI_DRIVER_ID, (VOID *) fx_nor_ospi_media_memory, sizeof(fx_nor_ospi_media_memory));
        if (nor_ospi_status != FX_SUCCESS)
        {
            while(1);
        }
    /* USER CODE END OCTO-SPI NOR open error */
  }

/* USER CODE BEGIN fx_app_thread_entry 1*/

    /* Get the available usable space */
    nor_ospi_status =  fx_media_space_available(&nor_ospi_flash_disk, &available_space_pre);
......
...
.

This code, previously checks if media can be opened without problems, if not formatting is executed than re-opened.

However, data is not maintained, which I think is because the boot record isn't updated after file creation. So, after a reset, when sector 0 is read, the STM32.TXT file is gone.

I am not sure why this is happening. I would appreciate any help you can provide.

STMicroelectronics / STM32CubeU5

FileX boot record, ensuring data persistence #39