stm32超声波测距程序

单片机用的是STM32F103VC系列，超声波是淘宝买的一个模块，只有5个引脚，用起来很方便。

用的时候只需要其中4个脚，VCC,GND,TRIG,ECHO。 TRIG接PA8,OUT_PP模式；ECHO接PA9,IN_FLOATING模式。

#include "stm32f10x_heads.h"

#include "HelloRobot.h"

#include "display.h"

void Tim2_Init(void);

void TIM2_IRQHandler(void)

{

if(GPIO_ReadInputDataBit(GPIOE,GPIO_Pin_12)==0)

GPIO_SetBits(GPIOE,GPIO_Pin_12);

else

GPIO_ResetBits(GPIOE,GPIO_Pin_12);

TIM_ClearFlag(TIM2, TIM_FLAG_Update);

}

int main(void)

{

u16 count;

float length;

BSP_Init();

Tim2_Init();//定时器初始化函数

LCM_Init();

delay_nms(5);

GPIO_ResetBits(GPIOA,GPIO_Pin_8);

Display_List_Char(1,0,"distance:"); //PA8:Trig PA0:Echo

while (1)

{

GPIO_SetBits(GPIOA,GPIO_Pin_8);

delay_nus(20);//拉高超过10us，发射超声波

GPIO_ResetBits(GPIOA,GPIO_Pin_8);

TIM2->CNT=0;//计数器清0

while(GPIO_ReadInputDataBit(GPIOA,GPIO_Pin_9)==0);//等待ECHO脚高电平

TIM_Cmd(TIM2, ENABLE);// TIM2 enable counter [允许tim2计数]

while((GPIO_ReadInputDataBit(GPIOA,GPIO_Pin_9)==1)&&(TIM2->CNTARR-10));

TIM_Cmd(TIM2, DISABLE);

count=TIM2->CNT;//ECHO脚低电平后读取计数器的值，从而算出往返时间

length=count/58.0;

Display_List_Char(1,9," ");

Display_List_Float(1,9,length);

delay_nms(200);

}

}

void Tim2_Init(void)

{

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

TIM_DeInit(TIM2);//复位TIM2定时器

TIM_TimeBaseStructure.TIM_Period = 49999;

TIM_TimeBaseStructure.TIM_Prescaler = 71;

TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM2, & TIM_TimeBaseStructure);

TIM_ClearFlag(TIM2, TIM_FLAG_Update);

TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);

}