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cmicrocontroller

Read content of a specific address from flash memory STM32F1

I need to read the content of a specific address from the FLASH memory of a STM32F1 microcontroller. Each address contains 32 bits, so I would like to know if I can do the following:

uint32_t addr = 0X0801F000;
read_value = (*((uint32*)(addr)));

or should I do something like this:

uint32_t addr = 0X0801F000;
read_value = *(unsigned char *)addr;  // this in a loop since char is 8 bits?
Solution

  • It can be written it like this (but see below for a beeter idea):

    uint32_t *addr = 0X0801F000;
uint32_t read_value = *addr;

    If you cast addr as an unsigned char * like you do in your second example, then, when you dereference the unsigned char pointer, you get an unsigned char:

    uint32_t* addr = 0X0801F000;
unsigned char read_value = *(unsigned char *)addr;

    So that's not what you want because then you only read one character. Then, there is one other thing you should remember, you need volatile if you want the compiler to read the memory address every single time you dereference the pointer. Otherwise, the compile could skip that if it already knows that the value is. Then you would have to write it like this:

    volatile uint32_t *addr = 0X0801F000;
uint32_t read_value = *addr;

    Or if you put it all on one line (like you did in your comment):

    uint32_t read_value = (*((volatile uint32_t*)(0x0801F000)));