基于stm32f103c8t6超声波测距代码

以下是基于stm32f103c8t6超声波测距的代码：

#include "stm32f10x.h"

#define HCSR04_TRIG_PIN GPIO_Pin_0 // 超声波触发引脚
#define HCSR04_ECHO_PIN GPIO_Pin_1 // 超声波回声引脚

void delay_us(uint32_t time);

int main(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
  TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
  TIM_ICInitTypeDef TIM_ICInitStructure;
  uint16_t prescalerValue = 0;
  float distance = 0;
 
  /* Enable peripheral clocks --------------------------------------------------*/
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
 
  /* Configure GPIO -----------------------------------------------------------*/
  GPIO_InitStructure.GPIO_Pin = HCSR04_TRIG_PIN;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
 
  GPIO_InitStructure.GPIO_Pin = HCSR04_ECHO_PIN;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
 
  /* TIM3 configuration ------------------------------------------------------*/
  TIM_DeInit(TIM3);
  prescalerValue = (uint16_t) (SystemCoreClock / 1000000) - 1;
  TIM_TimeBaseStructure.TIM_Period = 65535;
  TIM_TimeBaseStructure.TIM_Prescaler = prescalerValue;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
 
  TIM_ICStructInit(&TIM_ICInitStructure);
  TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;
  TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
  TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
  TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
  TIM_ICInitStructure.TIM_ICFilter = 0x0;
  TIM_ICInit(TIM3, &TIM_ICInitStructure);
 
  /* TIM enable counter ------------------------------------------------------*/
  TIM_Cmd(TIM3, ENABLE);
 
  while (1)
  {
    /* 发送一个10us的高电平脉冲 */
    GPIO_SetBits(GPIOA, HCSR04_TRIG_PIN);
    delay_us(10);
    GPIO_ResetBits(GPIOA, HCSR04_TRIG_PIN);
 
    /* 等待回声引脚变为高电平 */
    while (GPIO_ReadInputDataBit(GPIOA, HCSR04_ECHO_PIN) == RESET);
 
    /* 开始计时 */
    TIM_SetCounter(TIM3, 0);
 
    /* 等待回声引脚变为低电平 */
    while (GPIO_ReadInputDataBit(GPIOA, HCSR04_ECHO_PIN) != RESET);
 
    /* 停止计时 */
    distance = (float) TIM_GetCounter(TIM3) / 58.0;
  }
}

/**
 * 延时函数，精度为1us
 */
void delay_us(uint32_t time)
{
  uint32_t i = 0;
  for (i = 0; i < time * 8; i++);
}

该代码使用了STM32的定时器TIM3和超声波测距模块，通过发送10us的高电平脉冲触发超声波测距模块，然后等待回声引脚变为高电平，开始计时，直到回声引脚变为低电平，停止计时。最后，通过计算计时器的数值得到距离。需要注意的是，该代码的距离单位为厘米。