Stm32f4内存跳跃

Question

I am working with the stm32f4 Discovery board and I am trying to jump to a section of flash where I will begin executing another program there.The variable ApplicationAddress is 0x08008000. When my code hits this section, the PC goes to 0x0000000 and the system freezes. I am not sure exactly what is going on. Thank you for your time. My code to jump is shown below.

    NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x8000);  
    JumpAddress = *(__IO uint32_t*) (ApplicationAddress + 4);
    Jump_To_Application = (pFunction) JumpAddress;
    /* Initialize user application's Stack Pointer */
    __set_MSP(*(__IO uint32_t*) ApplicationAddress);
    Jump_To_Application();

Answer 1

Presumably the bit of code that you posted int he question is actually using the MSP stack, so when you execute:

__set_MSP(*(__IO uint32_t*) ApplicationAddress);

that stack gets thrown away and if the Jump_To_Application variable is a local variable (which might have been on the stack if it's a local variable - especially if you're running a non-optimized/debug build) might suddenly be garbage.

to solve this problem, I've used:

void LoadStackAndGo( void* sp, void* entry)
{
    __asm (
        "mov sp, r0 \n"
        "mov pc, r1 \n"
    );
}

which should be easily adaptable to whatever toolchain you're using.

Answer 2

I had the exact same problem, however my solution:

__set_MSP (*(__IO uint32_t*)ApplicationAddress);

__set_PSP (*(__IO uint32_t*)ApplicationAddress);

and declare the function pointer as static...

static Function jumpToApplication = (Function) * (__IO uint32_t*)(ApplicationAddress + 4);