stm32驱动超声波模块

#define HCSR04_PORT   GPIOB
#define HCSR04_CLK    RCC_APB2Periph_GPIOB
#define HCSR04_TRIG   GPIO_Pin_8
#define HCSR04_ECHO   GPIO_Pin_9
#define TRIG_Send(n)  do{                \
if(n == 0)       \
GPIO_ResetBits(HCSR04_PORT,HCSR04_TRIG);\
else if(n == 1)  \
GPIO_SetBits(HCSR04_PORT,HCSR04_TRIG);  \
}while(0) 


#define ECHO_Reci     GPIO_ReadInputDataBit(GPIOB,HCSR04_ECHO)


void UltrasonicInit(void)
{


GPIO_InitTypeDef GPIO_InitStructure;
RCC_APB2PeriphClockCmd(HCSR04_CLK, ENABLE);
 
//IO初始化
GPIO_InitStructure.GPIO_Pin   = HCSR04_TRIG;       //发送电平引脚
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_Out_PP;//推挽输出
GPIO_Init(HCSR04_PORT, &GPIO_InitStructure);
GPIO_ResetBits(HCSR04_PORT,HCSR04_TRIG);
 
GPIO_InitStructure.GPIO_Pin  = HCSR04_ECHO;     //返回电平引脚
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;//浮空输入
GPIO_Init(HCSR04_PORT, &GPIO_InitStructure);  
GPIO_ResetBits(HCSR04_PORT,HCSR04_ECHO);   


TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;     //生成用于定时器设置的结构体
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM6, ENABLE);   //使能对应RCC时钟

//配置定时器基础结构体
TIM_DeInit(TIM6);
TIM_TimeBaseStructure.TIM_Period = (1000-1);          //设置在下一个更新事件装入活动的自动重装载寄存器周期的值         计数到1000为1ms
TIM_TimeBaseStructure.TIM_Prescaler =(72-1);          //设置用来作为TIMx时钟频率除数的预分频值  1M的计数频率 1US计数
TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1;//不分频
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上计数模式
TIM_TimeBaseInit(TIM6, &TIM_TimeBaseStructure);       //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位         


TIM_ClearFlag(TIM6, TIM_FLAG_Update);                 //清除更新中断，免得一打开中断立即产生中断
TIM_ITConfig(TIM6,TIM_IT_Update,ENABLE);              //打开定时器更新中断
  

NVIC_InitTypeDef NVIC_InitStructure;

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
NVIC_InitStructure.NVIC_IRQChannel = TIM6_IRQn;            //选择串口1中断
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;  //抢占式中断优先级设置为1
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;         //响应式中断优先级设置为1
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;            //使能中断
NVIC_Init(&NVIC_InitStructure);

TIM_Cmd(TIM6,DISABLE);
}


//定时器6中断服务程序
u32 msHcCount = 0;
void TIM6_IRQHandler(void)   //TIM6中断
{
if (TIM_GetITStatus(TIM6, TIM_IT_Update) != RESET)  //检查TIM3更新中断发生与否
{
TIM_ClearITPendingBit(TIM6, TIM_IT_Update);       //清除TIMx更新中断标志 
msHcCount++;
}
}


static void OpenTimerForHc()    //打开定时器
{
TIM_SetCounter(TIM6,0);      //清除计数
msHcCount = 0;
TIM_Cmd(TIM6, ENABLE);       //使能TIMx外设
}
 
static void CloseTimerForHc()  //关闭定时器
{
TIM_Cmd(TIM6, DISABLE);      //使能TIMx外设
}


//获取定时器时间
u32 GetEchoTimer(void)
{
u32 t = 0;
t = msHcCount*1000;                  //将MS转换成US
t += TIM_GetCounter(TIM6);           //得到总的US
TIM6->CNT = 0;                       //将TIM6计数寄存器的计数值清零
return t;
}


//一次获取超声波测距数据 两次测距之间需要相隔一段时间，隔断回响信号
//为了消除余震的影响，取五次数据的平均值进行加权滤波。
float Hcsr04GetLength(void )
{

u32 t = 0;
int i = 0;
float lengthTemp = 0;
float sum = 0;


while(i!=5)
{
/*发送一个20ms的脉冲*/
TRIG_Send(1);             
osDelay(20);
TRIG_Send(0);

while(ECHO_Reci == 0);     //等待接收口高电平输出(超声波发出)
OpenTimerForHc();          //打开定时器
while(ECHO_Reci == 1);     //等待超声波返回
CloseTimerForHc();         //关闭定时器
t = GetEchoTimer();        //获取时间,分辨率为1US
lengthTemp = ((float)t*17/1000.0);//cm
sum = lengthTemp + sum ;
 i = i + 1;
  }

lengthTemp = sum/5.0;
return lengthTemp;


}