STM32F303VET6 Jump to Bootloader

DNA-) · ‎2026-03-16

Hello,

As part of a new project, I'd like to use DFU mode for programming my STM32F303VET6.

I have a button that controls BOOT0. If the button is pressed during the microcontroller reset, there's no problem; I successfully enter DFU mode and can reprogram without any issues.

I'd like to be able to perform this step without any physical intervention on the board, but rather by creating a 'jump' from my application to the internal ST Bootloader.

My board is connected to the PC via a CDC connection. Using HyperTerminal, I send a command that calls a JumptoBootloader function.

My function is as follows:

void JumpToBootloader(void)
{
    // 1. Stop USB peripheral
    RCC->APB1ENR &= ~RCC_APB1ENR_USBEN;   // Disable USB clock
    RCC->APB1RSTR |=  RCC_APB1RSTR_USBRST; // Reset USB
    RCC->APB1RSTR &= ~RCC_APB1RSTR_USBRST;

    // 2. Put USB pins (PA11/PA12) in analog mode
    RCC->AHBENR |= RCC_AHBENR_GPIOAEN;
    GPIOA->MODER |= (3U << (11 * 2)) | (3U << (12 * 2)); // Analog mode

    // 3. Disable all interrupts
    __disable_irq();
    for (int i = 0; i < 8; i++)
        NVIC->ICER[i] = 0xFFFFFFFF;

    // 4. Stop SysTick
    SysTick->CTRL = 0;
    SysTick->LOAD = 0;
    SysTick->VAL  = 0;

    // 5. Reset clock configuration
    HAL_RCC_DeInit();

    __DSB();

    // 6. Set MSP to bootloader's initial stack pointer
    uint32_t bootloader_addr = 0x1FFF0000; // System Memory for STM32F303
    uint32_t msp = *(volatile uint32_t *)bootloader_addr;
    __set_MSP(msp);

    // 7. Optional: set vector table offset
    SCB->VTOR = bootloader_addr;

    // 8. Jump to bootloader reset handler
    void (*bootloader)(void);
    bootloader = (void (*)(void)) (*(volatile uint32_t *)(bootloader_addr + 4));
    bootloader();
}

Unfortunately, I can't debug it. All I know is that the card seems to be malfunctioning; the USB connection is no longer recognized, and no device is visible in Windows Device Manager after unplugging and replugging the USB cable.

Do you have any ideas?