STM32学习日记_keysking之输入捕获与超声波模块

超声波测距

输入捕获

原理

测定时器输入引脚（TIMx_CHx）上的边沿信号（如上升沿、下降沿或双边沿）来实现。

当边沿信号发生跳变时，定时器当前的计数器值（TIMx_CNT）会被锁存到对应的捕获/比较寄存器（TIMx_CCRx）中，从而完成一次捕获。

             

功能

1. 输入捕获模式：可以配置为上升沿捕获、下降沿捕获或双边沿捕获，以适应不同的信号测量需求。
2. 多通道支持：每个高级定时器和通用定时器都配备了多个输入捕获通道（通常为4个），允许同时监测多个输入信号。
3. PWM输入模式：在PWM输入模式下，可以同时测量信号的频率和占空比，提供更全面的信号分析。
4. 主从触发模式：结合主从触发模式，可以实现硬件全自动测量，简化编程和调试过程

超声波测距仪工程代码示例

main.c

/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "i2c.h"
#include "tim.h"
#include "gpio.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <stdio.h>
#include "oled.h"

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* 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 */
int upEdge = 0;
int downEdge = 0;
float s = 0;

void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim){
	if (htim == &htim1 && htim->Channel == HAL_TIM_ACTIVE_CHANNEL_4){
		upEdge = HAL_TIM_ReadCapturedValue(htim, TIM_CHANNEL_3);
		downEdge = HAL_TIM_ReadCapturedValue(htim, TIM_CHANNEL_4);
		s = ((downEdge - upEdge) * 0.034) / 2;
	}
}

/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
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_I2C1_Init();
  MX_TIM1_Init();
  /* USER CODE BEGIN 2 */
  HAL_Delay(20);
  OLED_Init();

  HAL_TIM_Base_Start(&htim1);
  HAL_TIM_IC_Start(&htim1, TIM_CHANNEL_3);
  HAL_TIM_IC_Start_IT(&htim1, TIM_CHANNEL_4);

  char message[20] = "";
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
	  HAL_GPIO_WritePin(Trig_GPIO_Port,Trig_Pin, GPIO_PIN_SET);
	  HAL_Delay(1);
	  HAL_GPIO_WritePin(Trig_GPIO_Port,Trig_Pin, GPIO_PIN_RESET);
	  __HAL_TIM_SET_COUNTER(&htim1,0);
	  HAL_Delay(300);

	  OLED_NewFrame();
	  sprintf(message, "S: %.2f",s);
	  OLED_PrintString(0, 0, message, &font16x16, OLED_COLOR_NORMAL);
	  OLED_ShowFrame();

	  HAL_Delay(500);
	/* USER CODE END WHILE */

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