Hi!
I want to use 2 firmware on the same microcontroller, one is written at 0x8000000 with ram starting at 0x20000000. The other is flashed at 0x8040000 with ram starting at 0x20010000.
The first firmware should use the second as a function. So i allocated a function pointer, like in a common bootloader, and used the function. The function execute, because the led switches on, but it does not return to the caller firmware after execution. These are the 2 main of the projects, that are all the executed code:
Caller program:
int main(void)
{
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
char var = 0;
char* pvar = &var;
char** ppvar = &pvar;
uint32_t JumpAddress = *(__IO uint32_t*)(SYSMEM_ADDRESS + 4);
int (*run)(int len, char** v) = (void*) JumpAddress;
while (1)
{
//__set_MSP(*(__IO uint32_t*)SYSMEM_ADDRESS);
run(1, ppvar);
//SCB->VTOR = SYSMEM_ADDRESS;
HAL_Delay(1000);
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}
Called program:
int main(int len, char** var)
{
/* USER CODE BEGIN 1 */
//SCB->VTOR = 0x08020000;
GPIOD->BSRR = LED_RED_Pin|LED_BLUE_Pin;
(**var) +=1;
//__set_MSP(*(__IO uint32_t*)0x08000000);
GPIOD->BSRR = (LED_GREEN_Pin|LED_ORANGE_Pin|LED_RED_Pin|LED_BLUE_Pin);
return 0;
/* USER CODE END 1 */
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
// HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
//SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
// while (1)
// {
// /* USER CODE END WHILE */
//
// /* USER CODE BEGIN 3 */
// }
/* USER CODE END 3 */
}
I tryed to run the called firmware from debugger and after the return 0 in line 9 it returns in the reset handler, in particular in the third line:
/* Call the application's entry point.*/
bl main
bx lr
I think that is normal if i launch the second firmware without the first one, it returns in the reset handler, but looking at the disassebly flash address with the debugger, it is the same address that goes into when i call the second firmware from the first one.
I think it is a bit strange because if i call a function, when it returns, it should have the return address and so it should return in the address that called it. Do you know what am i doing wrong?
PS: all the code is generated from CubeMX (STM32F401VC), the only modified files are the main.c and the flash.ld, only for start address and size of the flash and ram. I tryed execute the code changing the stack pointer and VTOR register and without changing them (you can see the commented lines).
Thank you in advance
