01-Jump

Basic Info

The stm32f103c8t6 has 64KB of flash and 20KB of SRAM

Create an APP

Configure Debug

Configure the Clock

Configure the LED

Other

Code

Once you've written it, flash it directly and see whether it runs properly: the LED blinks once per second, and it sends app is running to UART1 at the same time. Once that works, move on to the next step
The code isn't finished — you have to read to the very end!!!

Create the Boot Project

Configuration

The configuration is the same as the app above, except there's one extra button

Change the Optimization

During the boot development phase you must change the optimization to -O0, and only switch it to -O3 or whatever else once things work!!!

Getting the Binary File

Use fromelf --bin -o "$L@L.bin" "#L; after each build, a binary file is generated in the build folder

Code

#define APP_ADDRESS 0x08005000U    // Points to the location we will jump to later
void JumpToApplication(void) {
    uint32_t app_sp = *(__IO uint32_t*)APP_ADDRESS;        // Read from the specified location to check whether the SP is valid
    uint32_t app_pc = *(__IO uint32_t*)(APP_ADDRESS + 4);  // Read from the specified location to check whether the PC is valid
    // Print them out
	char data[50]="";
	HAL_UART_Transmit(&huart1,(uint8_t*)"boot start run!\r\n",sizeof("boot start run!\r\n"),1000);
	sprintf(data,"SP:0x%08X,PC:0x%08X\r\n",app_sp,app_pc);
	HAL_UART_Transmit(&huart1,(uint8_t*)data,strlen(data),1000);
    // Check whether the stack pointer is valid
    
    if((app_sp & 0x2FFE0000) == 0x20000000) {
        
        // 1. Completely "disarm" all peripherals and clear every potential interrupt source
        HAL_RCC_DeInit();
        HAL_DeInit();
        SysTick->CTRL = 0;
        SysTick->LOAD = 0;
        SysTick->VAL  = 0;

        // 2. Clear the NVIC pending flags to make sure the battlefield is absolutely clean
        for (uint32_t i = 0; i < 8; i++) {
            NVIC->ICER[i] = 0xFFFFFFFF;
            NVIC->ICPR[i] = 0xFFFFFFFF;
        }

        // 3. Redirect the interrupt vector table
        SCB->VTOR = APP_ADDRESS;

        // 4. Enable global interrupts (since the peripherals have been completely disarmed, it is absolutely safe to open the gate now, and it will save the App's HAL_Delay)
        __enable_irq();

        // 5. Danger zone: switch the stack pointer and jump directly (no local variables allowed)
        __set_MSP(*(__IO uint32_t*)APP_ADDRESS);
        ((void (*)(void)) (*(__IO uint32_t*)(APP_ADDRESS + 4)))(); 
        
    } else {
				HAL_UART_Transmit(&huart1,(uint8_t*)"[BOOT] ERROR: SP Validation FAILED!\r\n",sizeof("ERROR: SP Validation FAILED!\r\n"),1000);
    }
}