STM32F103 ultrasonic serial port output data

#include "cj.h"

#include "stm32f10x.h"

#include "delay.h"

#include "usart.h"

unsigned int overcount=0;

void NVIC_Config(void)//priority setting

{

NVIC_InitTypeDef NVIC_InitStructer;

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);

NVIC_InitStructer.NVIC_IRQChannelPreemptionPriority=0;

NVIC_InitStructer.NVIC_IRQChannelSubPriority=0;

NVIC_InitStructer.NVIC_IRQChannel=TIM2_IRQn;//

NVIC_InitStructer.NVIC_IRQChannelCmd=ENABLE;

NVIC_Init(&NVIC_InitStructer);

}

void CH_SR04_Init(void) //Ultrasonic module initialization

{

GPIO_InitTypeDef GPIO_InitStructer;

TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructer;

RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOB, ENABLE);

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

GPIO_InitStructer.GPIO_Speed=GPIO_Speed_50MHz;

GPIO_InitStructer.GPIO_Mode=GPIO_Mode_Out_PP;

GPIO_InitStructer.GPIO_Pin=GPIO_Pin_8;

GPIO_Init(GPIOB, &GPIO_InitStructer); //Set PB8 as the trigger pin

GPIO_InitStructer.GPIO_Mode=GPIO_Mode_IN_FLOATING;

GPIO_InitStructer.GPIO_Pin=GPIO_Pin_9;

GPIO_Init(GPIOB,&GPIO_InitStructer); //Set PB9 as the receiving pin

TIM_DeInit(TIM2);

TIM_TimeBaseInitStructer.TIM_Period=65534;

TIM_TimeBaseInitStructer.TIM_Prescaler=71; //After pre-scaling, the value of the counter increases by one every 0.5us.

TIM_TimeBaseInitStructer.TIM_ClockDivision=TIM_CKD_DIV1;//

TIM_TimeBaseInitStructer.TIM_CounterMode=TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM2,&TIM_TimeBaseInitStructer);

    //TIM_ITConfig(TIM2,TIM_IT_Update|TIM_IT_CC1,ENABLE);//

TIM_ITConfig(TIM2,TIM_IT_Update,ENABLE);//

NVIC_Config();

TIM_Cmd(TIM2,DISABLE);//

}

float Senor_Using(void) //Distance measurement function

{

float length=0,sum=0;

u16 tim;

unsigned int i=0;

while(i!=5)

{

PBout(8)=1; //

delay_us(20); //

PBout(8)=0;

while(GPIO_ReadInputDataBit(GPIOB,GPIO_Pin_9)==RESET);

TIM_Cmd(TIM2,ENABLE);//

i+=1;

while(GPIO_ReadInputDataBit(GPIOB,GPIO_Pin_9)==SET);//

TIM_Cmd(TIM2,DISABLE);//

tim = TIM_GetCounter (TIM2); //

length=(tim+overcount*1000)/58.0;//

sum=length+sum;

TIM2->CNT=0; //

overcount=0; //

delay_ms(100);

}

length=sum/5;

return length;//

}

void TIM2_IRQHandler(void) //

{

if(TIM_GetITStatus(TIM2,TIM_IT_Update)!=RESET)

  {

TIM_ClearITPendingBit(TIM2,TIM_IT_Update);//

overcount++;

  }

}

Since it is copied and pasted, only some parts are commented. In fact, it is very simple. It is to output a high level of more than 10us as a pulse signal through a pin, and set a pin as a receiving pin. When a high level is received, the timer counts, and when a low level is detected, the count stops. Take out the value and calculate the distance through the formula. Finally, the serial port output, directly #include "stdio.h" and then use pirntf. But don't forget to configure the compiler before that. Please Baidu it yourself. It's very simple.