STM32H7 HAL_FLASHEx_Erase returns HAL_OK but something extrange is happening

[DCajigal]

I am trying to build an iap that reads a .bin file from a uSD card and loads it into the flash memory, but something is happening with the erase function. If i run this bootloader and the flash is empty everything works just fine. However, if the flash is not empty, the HAL_FLASHEx_Erase returns HAL_OK but then, when trying to write it crashes. If i stop the program just before the write function and go to the STM32CubeProgrammer in order to watch if the flash has been erased, if returns a "Error: Data read failed" message".

The erase function:

uint32_t FLASH_STM_M7_Erase (uint32_t StartSector)
{
  uint32_t UserStartSector;
  uint32_t SectorError;
  FLASH_EraseInitTypeDef pEraseInit;
 
  /* Unlock the Flash to enable the flash control register access *************/
  HAL_FLASH_Unlock();
  FLASH_STM_M7_Init();
 
  /* Get the sector where start the user flash area */
  UserStartSector = GetSector(APPLICATION_ADDRESS);
 
  pEraseInit.TypeErase = FLASH_TYPEERASE_SECTORS;
  pEraseInit.Sector = UserStartSector;
  pEraseInit.NbSectors = 8 - UserStartSector;
  pEraseInit.VoltageRange = FLASH_VOLTAGE_RANGE_3;
 
  if (APPLICATION_ADDRESS < ADDR_FLASH_SECTOR_0_BANK2)
  {
    pEraseInit.Banks = FLASH_BANK_1;
    if (HAL_FLASHEx_Erase(&pEraseInit, &SectorError) != HAL_OK)
    {
      /* Error occurred while sector erase */
      return (1);
    }
 
    /* Mass erase of second bank */
    pEraseInit.TypeErase = FLASH_TYPEERASE_MASSERASE;
    pEraseInit.Banks = FLASH_BANK_2;
    if (HAL_FLASHEx_Erase(&pEraseInit, &SectorError) != HAL_OK)
    {
      /* Error occurred while sector erase */
      return (1);
    }
  }
  else
  {
    pEraseInit.TypeErase = FLASH_TYPEERASE_SECTORS;
    pEraseInit.Banks = FLASH_BANK_2;
    if (HAL_FLASHEx_Erase(&pEraseInit, &SectorError) != HAL_OK)
    {
      /* Error occurred while sector erase */
      return (1);
    }
  }
  HAL_FLASH_Lock();
  return (0);
}

#define APPLICATION_ADDRESS				   (uint32_t)0x08020000
/////////////////////////////////////////////////////////////////////////////////////////////
 
if (finfno.fsize < (FLASH_SIZE - IAP_SIZE)) {
/* Erase necessary page to download image */
	if (FLASH_STM_M7_Erase(APPLICATION_ADDRESS) != 0) {
		state = BOOT_ERROR;
		break;
	}
	TSC_SetTimer(bootloader_time, BOOTLOADER_TIMEOUT, s);
	state = WRITE_FLASH;
	break;
} else {

[TDK]

What sectors are you erasing? Is a watchdog event happening? Does it work correctly if you step through the code, and if not, where and how does it fail?

[DCajigal]

I am really sorry for the late answer, i could not try it anymore until now. I am erasing the whole memory starting from the address 0x08020000 and it is not happening a watchdog event.

The erase function returns HAL_OK but then the write function crashes when trying to write something, like it would happen if the memory had not been erased before. If i step through the code the result is the same...

Thanks for the help

[DCajigal]

Maybe i have missed something but in the end it seems that the problem was in the flash initialization. I had this:

	HAL_FLASH_Unlock();
 
	  __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_EOP | FLASH_FLAG_OPERR | FLASH_FLAG_WRPERR | FLASH_FLAG_PGSERR | FLASH_FLAG_WRPERR);
 
	HAL_FLASH_Lock();

and then i commented the "HAL_FLASH_Unlock();" and "HAL_FLASH_Lock();" lines and everything started to work as it should.

[Piranha]

Take a note that by default FLASH is configured as a write-through memory. Because of that, after erase completes one typically must do cache invalidation on the erased sectors. If that is not done, cache can contain old data.