发觉用新版（V6.9.1）的它生成代码，会有问题。可能是 BUG。具体如下：

一个简单的点灯程序，用 Keil MDK 5.38a（compiler version 6）编译。

如果在变量前，不加上关键字“volatile”，是不会闪灯的。

V6.8.1 也同样，但好象如果你的工程是在旧版本中，慢慢升一步步上来的，不会有事，如果是新建的就出问题。

大家可以试试？

main.c 中

extern volatile uint32_t u32LedFlashTimeAdd;/* USER CODE END PTD *//* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD *//* USER CODE END PD *//* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM *//* USER CODE END PM *//* Private variables ---------------------------------------------------------*//* USER CODE BEGIN PV *//* USER CODE END PV *//* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP *//* USER CODE END PFP *//* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 *//* USER CODE END 0 *//*** @brief  The application entry point.* @retval int*/
int main(void)
{/* USER CODE BEGIN 1 */u32LedFlashTimeAdd = 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 */MX_GPIO_Init();/* USER CODE BEGIN 2 *//* USER CODE END 2 *//* Infinite loop *//* USER CODE BEGIN WHILE */while (1){//HAL_Delay(1);if(u32LedFlashTimeAdd > 5000){u32LedFlashTimeAdd = 0;HAL_GPIO_TogglePin(Led_Flash_GPIO_Port,Led_Flash_Pin);}/* USER CODE END WHILE *//* USER CODE BEGIN 3 */}/* USER CODE END 3 */
}

stm32g0xx_it.c 中

volatile uint32_t u32LedFlashTimeAdd;//...void SysTick_Handler(void)
{/* USER CODE BEGIN SysTick_IRQn 0 */u32LedFlashTimeAdd++;/* USER CODE END SysTick_IRQn 0 */HAL_IncTick();/* USER CODE BEGIN SysTick_IRQn 1 *//* USER CODE END SysTick_IRQn 1 */
}