1.CUBEMAX配置

测量PA6，PA7输出的占空比，只需要把主要的配置，配置为A6口就行，A7口黄色表示配置不正确，不用管。

 2.软件代码

TIME.c中找到TIM3的初始化，在后面初始化A7口
void MX_TIM3_Init_PA7(void)
{

  /* USER CODE BEGIN TIM3_Init 0 */

  /* USER CODE END TIM3_Init 0 */

  TIM_ClockConfigTypeDef sClockSourceConfig = {0};
  TIM_SlaveConfigTypeDef sSlaveConfig = {0};
  TIM_MasterConfigTypeDef sMasterConfig = {0};
  TIM_IC_InitTypeDef sConfigIC = {0};

  /* USER CODE BEGIN TIM3_Init 1 */

  /* USER CODE END TIM3_Init 1 */
  htim3.Instance = TIM3;
  htim3.Init.Prescaler = 80-1;
  htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim3.Init.Period = 65535;
  htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim3.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
  if (HAL_TIM_Base_Init(&htim3) != HAL_OK)
  {
    Error_Handler();
  }
  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  if (HAL_TIM_ConfigClockSource(&htim3, &sClockSourceConfig) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_TIM_IC_Init(&htim3) != HAL_OK)
  {
    Error_Handler();
  }
  sSlaveConfig.SlaveMode = TIM_SLAVEMODE_RESET;
  sSlaveConfig.InputTrigger = TIM_TS_TI2FP2;//第一个地方
  sSlaveConfig.TriggerPolarity = TIM_INPUTCHANNELPOLARITY_RISING;
  sSlaveConfig.TriggerFilter = 0;
  if (HAL_TIM_SlaveConfigSynchro(&htim3, &sSlaveConfig) != HAL_OK)
  {
    Error_Handler();
  }
  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim3, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }
  sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_FALLING;//第二个地方
  sConfigIC.ICSelection = TIM_ICSELECTION_INDIRECTTI;//第三个地方
  sConfigIC.ICPrescaler = TIM_ICPSC_DIV1;
  sConfigIC.ICFilter = 0;
  if (HAL_TIM_IC_ConfigChannel(&htim3, &sConfigIC, TIM_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }
  sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_RISING;//第四个地方
  sConfigIC.ICSelection = TIM_ICSELECTION_DIRECTTI;//第五个地方
  if (HAL_TIM_IC_ConfigChannel(&htim3, &sConfigIC, TIM_CHANNEL_2) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN TIM3_Init 2 */

  /* USER CODE END TIM3_Init 2 */

}

循环函数中
static uint32_t time10ms;
	static uint8_t time3_sta=0;
	if(uwTick-time10ms>10)
	{
	time10ms=uwTick;
	if(time3_sta==0)//PA6
	{
	 duty1=(HAL_TIM_ReadCapturedValue(&htim3,TIM_CHANNEL_2)+1)*100.0f/(HAL_TIM_ReadCapturedValue(&htim3,TIM_CHANNEL_1)+1);
	  MX_TIM3_Init_PA7();
	 HAL_TIM_IC_Start(&htim3,TIM_CHANNEL_1);
	 HAL_TIM_IC_Start(&htim3,TIM_CHANNEL_2);
	}
	if(time3_sta==1)//PA7
	{
	 duty2=(HAL_TIM_ReadCapturedValue(&htim3,TIM_CHANNEL_1)+1)*100.0f/(HAL_TIM_ReadCapturedValue(&htim3,TIM_CHANNEL_2)+1);
	 MX_TIM3_Init();
	 HAL_TIM_IC_Start(&htim3,TIM_CHANNEL_1);
	 HAL_TIM_IC_Start(&htim3,TIM_CHANNEL_2);
	}
	time3_sta=!time3_sta;
	}