Issue after bootloader on STM32F072RBT6: Stack Pointer not jumping to application address

Question

I am currently working on a project using the STM32F072RBT6 microcontroller, where I have implemented a custom bootloader to load an application program into flash memory. However, after the bootloader successfully writes the application binary, the stack pointer does not correctly jump to the application’s address, and the application fails to execute.

MCU Model: STM32F072RBT6 Bootloader

Functionality: The bootloader receives the application binary and writes it to flash memory at the designated application address.

Application Flash Address: 0x08004000

Problem: After the bootloader completes, I attempt to jump to the application by setting the stack pointer and program counter accordingly, but the application does not start. It appears that the stack pointer is not correctly set to the application's address.

Jump Code in Bootloader:

static void goto_application(void) {
    void (* app_reset_handler)(void) = (void *)(*(volatile uint32_t *) (0x08004000 + 4));

    __disable_irq();

    __set_MSP((*(volatile uint32_t *)0x08004000));

    __enable_irq();

    app_reset_handler();
}

Answer 1

You forgot about one important detail.

• you have to set the VTOR register to set the vector table to application one.

Also if the application is run from the bootloader it should enable interrupts itself. Otherwise you will have a gray area when interrupts are enabled and call handlers from the the new vector table - but the app did not have time to initialize itself.

Side note:

void (* app_reset_handler)(void) = (void (*)(void))(0x08004000 + 4));