STM32H7 - Write float value into flash memory permanently

[yaxsomo]

Hello Everyone,

 

I'm trying to write a float value into my STM32H743VIT6 flash memory, bit it jumps straight to the HardFaultHandler and I cannot understand why...

 

 

Here's the two functions:  

 

HAL_StatusTypeDef Store_AltitudeMax(float altitude)
{
 HAL_StatusTypeDef status;
 uint32_t FirstSector, NbOfSectors, SectorError;
 FLASH_EraseInitTypeDef EraseInitStruct;

 // Ensure data is written in a full 32-byte Flash word
 uint64_t FlashWord[4] = { 0xFFFFFFFFFFFFFFFF, 0xFFFFFFFFFFFFFFFF,
 0xFFFFFFFFFFFFFFFF, 0xFFFFFFFFFFFFFFFF };

 memcpy(&FlashWord[0], &altitude, sizeof(float));

 // Unlock Flash
 status = HAL_FLASH_Unlock();
 if (status != HAL_OK)
 {
 return status;
 }

 // Get the sector of ALTITUDE_MAX_ADDRESS
 FirstSector = GetSector(ALTITUDE_MAX_ADDRESS);
 NbOfSectors = 1; // Only erase 1 sector

 // Configure Erase Structure
 EraseInitStruct.TypeErase = FLASH_TYPEERASE_SECTORS;
 EraseInitStruct.VoltageRange = VOLTAGE_RANGE;
 EraseInitStruct.Banks = FLASH_BANK;
 EraseInitStruct.Sector = FirstSector;
 EraseInitStruct.NbSectors = NbOfSectors;

 // Erase Flash Sector
 if (HAL_FLASHEx_Erase(&EraseInitStruct, &SectorError) != HAL_OK)
 {
 HAL_FLASH_Lock();
 return HAL_ERROR;
 }

 // Program the Flash word (32 bytes)
 status = HAL_FLASH_Program(FLASH_TYPEPROGRAM_FLASHWORD, ALTITUDE_MAX_ADDRESS, (uint32_t)FlashWord);

 // Lock Flash after programming
 HAL_FLASH_Lock();
 return status;
}

float Retrieve_AltitudeMax(void)
{
 float altitude = 0.0f;
 uint64_t FlashWord[4];

 // Read from Flash (direct memory access)
 memcpy(FlashWord, (uint64_t*)ALTITUDE_MAX_ADDRESS, sizeof(FlashWord));

 // Extract stored float value
 memcpy(&altitude, &FlashWord[0], sizeof(float));

 return altitude;
}

 

 

And the test snippet : 

 

 HAL_StatusTypeDef ret = Store_AltitudeMax(768);

 if(ret != HAL_OK) {
	 printf("Something went wrong with the storage of the variable! \r\n");
 } else {
	 HAL_Delay(3000);

	 float value = Retrieve_AltitudeMax();

	 printf("Altitude retrieved: %d \r\n", (int)value);
 }

 

 

Can anyone tell me what's going on here ?

[TDK]

What is the value of ALTITUDE_MAX_ADDRESS? It needs to be 256-bit aligned.

Step through the code, which line does it go to a hard fault?

/**
 * @brief Program a flash word at a specified address
 * @PAram TypeProgram Indicate the way to program at a specified address.
 * This parameter can be a value of @ref FLASH_Type_Program
 * @PAram FlashAddress specifies the address to be programmed.
 * This parameter shall be aligned to the Flash word:
 * - 256 bits for STM32H74x/5X devices (8x 32bits words)
 * - 128 bits for STM32H7Ax/BX devices (4x 32bits words)
 * - 256 bits for STM32H72x/3X devices (8x 32bits words)
 * @PAram DataAddress specifies the address of data to be programmed.
 * This parameter shall be 32-bit aligned
 *
 * @retval HAL_StatusTypeDef HAL Status
 */
HAL_StatusTypeDef HAL_FLASH_Program(uint32_t TypeProgram, uint32_t FlashAddress, uint32_t DataAddress)

 

[yaxsomo]

Hello TDK,

Finally I found the solution.

Actually, the Both functions seems good.

the 3 defines that i created during the issue were the following : 

 

 

#define ALTITUDE_MAX_ADDRESS 0x081E0000U 
#define FLASH_BANK FLASH_BANK_1
#define VOLTAGE_RANGE FLASH_VOLTAGE_RANGE_3

 

 

The HardFaultHandler issue occurred during the Retrieve_AltitudeMax function.

I just changed the FLASH_BANK value to FLASH_BANK_2 and it solved the issue. Can you tell me if the two functions are optimized or if i can do better? 

Maybe it's not a smart question, but why this change solved the issue ? And why on this particular H7 model, there's not really explicit informations on the flash addresses on the datasheet? Does this apply on all H7 MCUs?

[TDK]

The reference manual is the best source of information. It will have the memory map and flash layout. The datasheet is secondary.

STM32H742, STM32H743/753 and STM32H750 Value line advanced Arm®-based 32-bit MCUs - Reference manual

[yaxsomo]

That's why I couldn't find the information on the datasheet!! 

Thank you so much!