Writing to flash memory on stm32f746 discovery

[andy0105]

Hello all 

I'm trying to write to the flash memory on an STM32F746 discovery board. 

This is the code so far, just a test to write a single word..

#define FLASH_USER_START_ADDR 0x080c0000
int Flash_Write(void)
{
    HAL_StatusTypeDef status;
    uint32_t address = FLASH_USER_START_ADDR; // Start address for writing

    // 1. Unlock the Flash memory
    HAL_FLASH_Unlock();
    printf("memory unlocked\n");

     __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_EOP | FLASH_FLAG_OPERR | FLASH_FLAG_WRPERR | FLASH_FLAG_PGAERR ); //| FLASH_FLAG_PGSERR );
     FLASH_Erase_Sector(FLASH_SECTOR_7, VOLTAGE_RANGE_3);

    // 2. Erase the required flash sector
    FLASH_EraseInitTypeDef eraseInitStruct;
    uint32_t sectorError = 0;

    eraseInitStruct.TypeErase = FLASH_TYPEERASE_SECTORS;
    eraseInitStruct.VoltageRange = FLASH_VOLTAGE_RANGE_3;  // Voltage range 2.7 to 3.6V
    eraseInitStruct.Sector = 7;                             // Change sector as per the location
    eraseInitStruct.NbSectors = 1;                         // Erasing 1 sector

    printf("erasing .\n");

    status = HAL_FLASHEx_Erase(&eraseInitStruct, &sectorError);

    if (status != HAL_OK)
    {
        // Error occurred while erasing
        HAL_FLASH_Lock();
        return(-1);
    }


    status = HAL_FLASH_Program((uint32_t)  FLASH_TYPEPROGRAM_WORD, 0x080c0000, (uint32_t) 0x00000123);


    return(0);
}

The erasing part works. If I add a memory lock and return after the memory erase the code runs ok and I can use the cube programmer to write a few numbers at 080c0000 and then see it has been erased

Adding the line to write causes a crash with this output.... 

memory unlocked
erasing .

++ MbedOS Fault Handler ++

FaultType: HardFault

Context:
R 0: 080C0000
R 1: 00000123
R 2: 40023C10
R 3: 00000201
R 4: 00000123
R 5: 080C0000
R 6: 00000000
R 7: 00000002
R 8: 200064A4
R 9: 00000000
R 10: 00000000
R 11: 00000000
R 12: 200064C0
SP : 20005550
LR : 080037E3
PC : 080024A8
xPSR : 81000000
PSP : 200054E8
MSP : 2004FFD0
CPUID: 410FC271
HFSR : 40000000
MMFSR: 00000082
BFSR : 00000000
UFSR : 00000000
DFSR : 0000000B
AFSR : 00000000
MMFAR: 080C0000
Mode : Thread
Priv : Privileged
Stack: PSP

-- MbedOS Fault Handler --

++ MbedOS Error Info ++
Error Status: 0x80FF013D Code: 317 Module: 255
Error Message: Fault exception
Location: 0x80024A8
Error Value: 0x20005A34
Current Thread: main Id: 0x20005DD8 Entry: 0x800B009 StackSize: 0x1000 StackMem: 0x200045A0 SP: 0x20005550
For more info, visit: https://mbed.com/s/error?error=0x80FF013D&tgt=DISCO_F746NG
-- MbedOS Error Info --

 You can see the printf() messages memory unlocked and erasing, then the crash ..

[SofLit · Accepted solution]

Hello @andy0105 ,

Better to refer to this example (FLASH_EraseProgram) provided in STM32CubeF7 under the path: 

https://github.com/STMicroelectronics/STM32CubeF7/tree/master/Projects/STM32746G-Discovery/Examples/FLASH/FLASH_EraseProgram