1. 接线图：

2. 

2 :实验目的：

利用pwm实现呼吸灯。

关键PWM定时器设置：

代码部分：

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();
  MX_TIM2_Init();
  /* USER CODE BEGIN 2 */
  // start timer2 pwm
  HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_1); // start pwm on channel 1 of timer 2

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
  // for breath led, change duty cycle of pwm, from 0 to 100% and back to 0
    for (int i = 0; i < 500; i++)
    {
      __HAL_TIM_SET_COMPARE(&htim2, TIM_CHANNEL_1, i);  // set duty cycle of pwm
      HAL_Delay(10);
    }
    //delay 500ms
    HAL_Delay(200);

    for (int i = 500; i > 0; i--)
    {
      __HAL_TIM_SET_COMPARE(&htim2, TIM_CHANNEL_1, i);  // set duty cycle of pwm
      HAL_Delay(10);
    }
    //delay 200ms
    HAL_Delay(200);

    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

1. ps:pwm说明：

输出比较、CNT、CRR的概念：

pwm概念：