超声波测距HC-SR04测得的距离不变，急，求指正！！谢谢！！-第2页回答

1楼-- · 2019-07-16 10:57

代码看起来没有问题啊，但是计算距离的公式有点不明白，贴上我的试试看

/**
  ******************************************************************************
  * @file Ultrasound.c
  * @author  xjg
  * @version V1.0
  * @date 2017-4-26
  * @brief 超声波模块控制函数接口
  ******************************************************************************
  * @attention
  *
  * 实验平台:STM32F103CB
  *
  ******************************************************************************
  */

#include "Ultrasound.h"
extern u8 overcnt;
float RespondTime = 0;
float SubTimeCnt = 0,Distance = 0,Predistance = 0;
u8 js;
static void NVIC_Configuration(void)
{
  NVIC_InitTypeDef NVIC_InitStructure;

  /* 嵌套向量中断控制器组选择 */
  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);

  /* 配置USART为中断源 */
  NVIC_InitStructure.NVIC_IRQChannel = ULTRISOUND_ECHO_EXTI_IRQ;
  /* 抢断优先级*/
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  /* 子优先级 */
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
  /* 使能中断 */
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  /* 初始化配置NVIC */
  NVIC_Init(&NVIC_InitStructure);
}

static void ULTRISOUND_TRIG_ECHO_GPIO_INIT(void)
{

/*定义一个GPIO_InitTypeDef类型的结构体*/
GPIO_InitTypeDef GPIO_InitStructure;

/*开启LED相关的GPIO外设时钟*/
RCC_APB2PeriphClockCmd( ULTRISOUND_TRIG_GPIO_CLK|ULTRISOUND_ECHO_GPIO_CLK , ENABLE);


/*设置引脚速率为50MHz */
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

/*设置引脚模式为推挽输出*/
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
/*选择要控制的GPIO引脚*/
GPIO_InitStructure.GPIO_Pin = ULTRISOUND_TRIG_GPIO_PIN;
/*调用库函数，初始化TRIG*/
GPIO_Init(ULTRISOUND_TRIG_GPIO_PORT, &GPIO_InitStructure);

/*设置引脚模式为浮空输入*/
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
/*选择要控制的GPIO引脚*/
GPIO_InitStructure.GPIO_Pin = ULTRISOUND_ECHO_GPIO_PIN;
/*调用库函数，初始化ECHO*/
GPIO_Init(ULTRISOUND_ECHO_GPIO_PORT, &GPIO_InitStructure);

GPIO_EXTILineConfig(ULTRISOUND_ECHO_EXTI_PORTSOURCE,ULTRISOUND_ECHO_EXTI_PINSOURCE);

}
static void ULTRISOUND_TECHO_EXTI_INIT(void)
{
// EXTI_InitTypeDef EXTI_InitSturct;
//
// RCC_APB2PeriphClockCmd( RCC_APB2Periph_AFIO , ENABLE);
//
// EXTI_InitSturct.EXTI_Line = ULTRISOUND_ECHO_EXTI_Line;
//
// EXTI_InitSturct.EXTI_LineCmd = ENABLE;
//
// EXTI_InitSturct.EXTI_Mode = EXTI_Mode_Interrupt;
//
// EXTI_InitSturct.EXTI_Trigger = EXTI_Trigger_Rising_Falling;//EXTI_Trigger_Rising_Falling;
//
// EXTI_Init(&EXTI_InitSturct);
//
// EXTI_ClearITPendingBit(ULTRISOUND_ECHO_EXTI_Line);
//
//
//
// GPIO_InitTypeDef GPIO_InitStructure;
EXTI_InitTypeDef EXTI_InitStructure;

  EXTI_InitStructure.EXTI_Line = ULTRISOUND_ECHO_EXTI_LINE;

/* EXTI为中断模式 */
  EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
/* 上升沿中断 */
  EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising_Falling;
  /* 使能中断 */
  EXTI_InitStructure.EXTI_LineCmd = ENABLE;

  EXTI_Init(&EXTI_InitStructure);

}

static void ULTRISOUND_TIM_INIT()
{
//定义基本定时器，比较输出定时器结构体
TIM_TimeBaseInitTypeDef TIM_TimeBaseInitSturct;

//初始化定时器的时钟
RCC_APB1PeriphClockCmd(ULTRISOUND_TIM_CLK,ENABLE);

TIM_DeInit(ULTRISOUND_TIM);
//配置基本定时器
TIM_TimeBaseInitSturct.TIM_ClockDivision = TIM_CKD_DIV1;

TIM_TimeBaseInitSturct.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInitSturct.TIM_Period = 0xffff;

TIM_TimeBaseInitSturct.TIM_Prescaler = 72-1;

TIM_TimeBaseInit(ULTRISOUND_TIM,&TIM_TimeBaseInitSturct);

TIM_SetCounter(ULTRISOUND_TIM,0);

}

void ULTRISOUND_INIT(void)
{

ULTRISOUND_TRIG_ECHO_GPIO_INIT();

ULTRISOUND_TECHO_EXTI_INIT();

NVIC_Configuration();

ULTRISOUND_TIM_INIT();

}
void Get_Distance(void)
{
u16 subcnt;

subcnt = TIM_GetCounter(ULTRISOUND_TIM);

printf("subcnt=%d ",subcnt);

TIM_SetCounter(ULTRISOUND_TIM,0);

RespondTime = (overcnt*0xffff+subcnt)*0.000001;
// RespondTime = SubTimeCnt*0.000001;

Distance = (RespondTime*314)/2*100;

if(js < 1)
{
Predistance = Distance;

js++;

return;

}
else
{
if(Predistance > Distance)
{
Distance = Predistance;
}

js = 0;

}
// Distance = subcnt/58;
overcnt = 0;

printf("Distance=%2.f ",Distance);

// SubTimeCnt = 0;

}

void ULTRISOUND_ECHO_IRQHandler(void)
{
// if(EXTI_GetITStatus(ULTRISOUND_ECHO_EXTI_Line) == SET)
// {
// printf(" *********ccccccccccccccc*********** ");
OSIntEnter();
if((ULTRISOUND_ECHO_GPIO_PORT->IDR & ULTRISOUND_ECHO_GPIO_PIN) == 0)
{

TIM_Cmd(ULTRISOUND_TIM,DISABLE);
// printf("停止计数 ");
// EHO_START_CNT_FLAG = 0;

Get_Distance();
}
else
{

TIM_Cmd(ULTRISOUND_TIM,ENABLE);//开始计数
// printf("开始计数 ");
// EHO_START_CNT_FLAG = 1;

}

// }
EXTI_ClearITPendingBit(ULTRISOUND_ECHO_EXTI_LINE);
OSIntExit();

}
void ULTRISOUND_TIM_IRQHandl(void)
{
OSIntEnter();
if(TIM_GetITStatus(ULTRISOUND_TIM,TIM_IT_Update)!=RESET)

  {
TIM_ClearITPendingBit(ULTRISOUND_TIM,TIM_IT_Update);
//清除中断标志
overcnt++;

  }
OSIntExit();

}