基于STM32的hc-sr04超声波测距模块的代码

以下是基于STM32的hc-sr04超声波测距模块的代码，使用的是HAL库：

#include "stm32f1xx_hal.h"

#define TRIG_Pin GPIO_PIN_0
#define TRIG_GPIO_Port GPIOB
#define ECHO_Pin GPIO_PIN_1
#define ECHO_GPIO_Port GPIOB

TIM_HandleTypeDef htim3;

void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_TIM3_Init(void);

int main(void)
{
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_TIM3_Init();

  while (1)
  {
    // 发送一个10us的高电平脉冲
    HAL_GPIO_WritePin(TRIG_GPIO_Port, TRIG_Pin, GPIO_PIN_SET);
    HAL_Delay(10);
    HAL_GPIO_WritePin(TRIG_GPIO_Port, TRIG_Pin, GPIO_PIN_RESET);

    // 等待接收到高电平
    while (!HAL_GPIO_ReadPin(ECHO_GPIO_Port, ECHO_Pin));

    // 启动定时器3
    HAL_TIM_Base_Start(&htim3);

    // 等待接收到低电平
    while (HAL_GPIO_ReadPin(ECHO_GPIO_Port, ECHO_Pin));

    // 停止定时器3
    HAL_TIM_Base_Stop(&htim3);

    // 计算距离并输出
    uint16_t pulseWidth = __HAL_TIM_GET_COUNTER(&htim3);
    float distance = pulseWidth * 0.017f;
    printf("Distance: %.2f cm\n", distance);

    HAL_Delay(500);
  }
}

void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct;
  RCC_ClkInitTypeDef RCC_ClkInitStruct;

  __HAL_RCC_PWR_CLK_ENABLE();
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
  RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
}

static void MX_TIM3_Init(void)
{
  TIM_ClockConfigTypeDef sClockSourceConfig;
  TIM_MasterConfigTypeDef sMasterConfig;

  htim3.Instance = TIM3;
  htim3.Init.Prescaler = 0;
  htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim3.Init.Period = 0xFFFF;
  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();
  }

  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim3, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }
}

static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct;

  __HAL_RCC_GPIOB_CLK_ENABLE();

  GPIO_InitStruct.Pin = TRIG_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(TRIG_GPIO_Port, &GPIO_InitStruct);

  GPIO_InitStruct.Pin = ECHO_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_PULLDOWN;
  HAL_GPIO_Init(ECHO_GPIO_Port, &GPIO_InitStruct);
}

需要注意的是，在使用HAL库的时候，需要在工程中添加相应的库文件，并在代码中包含相应的头文件。同时，还需要对时钟进行初始化，以确保定时器能够正常工作。