stm32控制超声波模块最大距离就显示168cm,用例程代码255多，搞不明白

ID:751817 · 发表于 2020-7-6 23:17

#include "hc_sr04.h"

float Distance;

void hcgpio_init(void)
{
      GPIO_InitTypeDef       gpio_struct;
      NVIC_InitTypeDef       nvic_struct;
      EXTI_InitTypeDef       exti_struct;

      RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC | RCC_APB2Periph_GPIOA |
                              RCC_APB2Periph_AFIO, ENABLE);

      gpio_struct.GPIO_Pin          =    GPIO_Pin_0;
      gpio_struct.GPIO_Mode          =    GPIO_Mode_Out_PP;
      gpio_struct.GPIO_Speed       =    GPIO_Speed_50MHz;
      GPIO_Init(GPIOC,&gpio_struct);

      gpio_struct.GPIO_Pin          =    GPIO_Pin_1;
      gpio_struct.GPIO_Mode          =    GPIO_Mode_IPD;
      gpio_struct.GPIO_Speed       =    GPIO_Speed_50MHz;
      GPIO_Init(GPIOC,&gpio_struct);

      GPIO_EXTILineConfig(GPIO_PortSourceGPIOC,GPIO_PinSource1);

      exti_struct.EXTI_Line          =    EXTI_Line1;
      exti_struct.EXTI_Mode          =    EXTI_Mode_Interrupt;
      exti_struct.EXTI_Trigger       =    EXTI_Trigger_Rising;
      exti_struct.EXTI_LineCmd       =    ENABLE;
      EXTI_Init(&exti_struct);

      nvic_struct.NVIC_IRQChannel    =    EXTI1_IRQn;
      nvic_struct.NVIC_IRQChannelCmd  =    ENABLE;
      nvic_struct.NVIC_IRQChannelPreemptionPriority =    2;
      nvic_struct.NVIC_IRQChannelSubPriority       =    2;
      NVIC_Init(&nvic_struct);

}

void EXTI1_IRQHandler(void)
{
      delay_us(10);

      if(EXTI_GetITStatus(EXTI_Line1) !=RESET)
      {
            TIM_SetCounter(TIM2,0);
TIM_Cmd(TIM2,ENABLE);

while(GPIO_ReadInputDataBit(GPIOC,GPIO_Pin_1));  //μè′yμíμçÆ½

TIM_Cmd(TIM2,DISABLE);

Distance=TIM_GetCounter(TIM2)*340/200.0;

if(Distance>0)
{
printf("Distance:%f cm\r\n",Distance);
}

EXTI_ClearITPendingBit(EXTI_Line1);

      }
}

void hc_sr04(void)
{
      GPIO_SetBits(GPIOC,GPIO_Pin_0);
      delay_us(20);
      GPIO_ResetBits(GPIOC,GPIO_Pin_0);

}

#include "hc_time.h"

void hctime_init(void)
{
      TIM_TimeBaseInitTypeDef       time_struct;
      NVIC_InitTypeDef             nvic_struct;

      RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2 ,ENABLE);

      time_struct.TIM_Period       =    5000;
      time_struct.TIM_Prescaler    =    7199;
      time_struct.TIM_CounterMode    =    TIM_CounterMode_Up;
      time_struct.TIM_ClockDivision =    0;
      //tim2
      TIM_TimeBaseInit(TIM2,&time_struct);

TIM_ITConfig(TIM2,TIM_IT_Update,ENABLE);
TIM_ITConfig(TIM2,TIM_IT_Trigger,ENABLE);

      nvic_struct.NVIC_IRQChannel    =    TIM2_IRQn;
      nvic_struct.NVIC_IRQChannelCmd  =    ENABLE;
      nvic_struct.NVIC_IRQChannelPreemptionPriority =  1;
      nvic_struct.NVIC_IRQChannelSubPriority       =  0;

      NVIC_Init(&nvic_struct);
}

void TIM2_IRQHandler(void)
{
      if(TIM_GetITStatus(TIM2,TIM_IT_Update) != RESET)
      {
            TIM_ClearITPendingBit(TIM2,TIM_IT_Update);
      }

}

ID:476215 · 发表于 2020-7-7 00:12

是不是超声波模块信号多次反射了，可以降低超声波的发射频率试一下；还有一种可能是你计时的定时器出了问题，对比这查看下

ID:764088 · 发表于 2020-7-7 10:33

这个例程有这些毛病：接收反馈回波，中断处理开头就延时，处理内用过杂，过多，甚至打印。
本来超声波模块是通过发送波及回波间隔，来测试距离的，

ID:751817 · 发表于 2020-7-7 10:58

qee654 发表于 2020-7-7 00:12
是不是超声波模块信号多次反射了，可以降低超声波的发射频率试一下；还有一种可能是你计时的定时器出了问题 ...

频率减低了，也不行；定时器的问题不清楚

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