蓝桥杯单片机超声波模块

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这个超声波模块的工作原理很简单，传感器像两个喇叭一样的东西，一个是负责发送超声波的，另一个负责接收超声波，根据发出到接收的时间间隔就可以算出距离了。

s = v*t/2

初中物理知识哦。

就不多说了直接上代码

main.c

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#include "common.h"

char sonic_counter = 0;
extern char smgbuf[8];

void main()
{
	int distance;
	init();
	while(1)
	{
		if(sonic_counter >= 40)//每隔一定的时间测量一次，必须要加否则测的数据不正确
		{
			distance = measure_distance();
			sonic_counter = 0;
		}
		smgbuf[5] = distance/100;
		smgbuf[6] = distance%100/10;
		smgbuf[7] = distance%10;
	}
}

void timer2() interrupt 12//定时器2（52单片机多出来的一个定时器）
{
	sonic_counter++;
	display();
}

common.h

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#ifndef _COMMON_H_
#define _COMMON_H_

#include <reg52.h>
#include <intrins.h>
#include "sonic.h"

sfr AUXR = 0x8e;
sfr IE2 = 0xaf;
sfr T2H = 0xd6;
sfr T2L = 0xd7;

void select_channel(char channel);
void init();
void init_timer();
void display();

#endif

common.c

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#include "common.h"

unsigned char smgw[8] = {0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80};
unsigned char smgd[] = {0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F,0x00};
char smgbuf[8],num = 0;

void select_channel(char channel)
{
	switch(channel)
	{
		case 4: P2 = P2&0x1f|0x80; break;
		case 5: P2 = P2&0x1f|0xa0; break;
		case 6: P2 = P2&0x1f|0xc0; break;
		case 7: P2 = P2&0x1f|0xe0; break;
	}
}

void init()
{
	char i;
	for(i = 0;i<8;i++)
		smgbuf[i] = 10;
	
	P0 = 0xff;
	select_channel(4);
	P2&= 0x1f;
	
	P0 = 0x00;
	select_channel(5);
	P2&= 0x1f;
	
	init_timer();
}

void init_timer()
{
	AUXR = AUXR&0x33|0x10;//定时器2的配置
	IE2 = 0x04;
	T2H = 0xf8;
	T2L = 0x2f;
	EA = 1;
	
	TMOD = 0x01;//定时器1的配置，用于计算发送和接收之间的时间间隔
	TH1 = 0;
	TL1 = 0;
	TR1 = 0;
}

void display()
{
	num++;
	if(num >= 8)
		num = 0;
	
	P0 = 0xff;
	select_channel(7);
	P2&= 0x1f;
	
	P0 = 0x00;
	select_channel(6);
	P0 = smgw[num];
	P2&= 0x1f;
	
	P0 = 0xff;
	select_channel(7);
	P0 = ~smgd[smgbuf[num]];
	P2&= 0x1f;
}

sonic.h

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#ifndef _SONIC_H_
#define _SONIC_H_

#include "common.h"

#define somenop {_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();_nop_();};

//可以参照原理图
sbit tx = P1^0;//发送波传感器的引脚
sbit rx = P1^1;//接收波传感器的引脚

void send_wave();
int measure_distance();

#endif

sonic.c

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#include "sonic.h"

void send_wave()//发送超声波
{
	char i;
	for(i = 0;i<8;i++)//发送一组超声波
	{
		tx = 1;
		somenop;somenop;somenop;somenop;somenop;somenop;somenop;somenop;
		tx = 0;
		somenop;somenop;somenop;somenop;somenop;somenop;somenop;somenop;
	}
	TR1 = 1;//定时器1开始计时
}

int measure_distance()//计算、测量距离
{
	int distance;
	send_wave();//先发送
	while(rx == 1&&TF1 == 0);//等待接收完毕或者定时器1溢出
	TR1 = 0;//定时器1停止计时
	if(rx == 0&&TF1 == 0)//正常量程之内
	{
		distance = ((TH1<<8)+TL1)*0.017;//计算距离
		TH1 = 0;
		TL1 = 0;
	}
	else 
	{
		distance = 999;//超出量程
		TF1 = 0;
		TH1 = 0;
		TL1 = 0;
	}
	
	return distance;
}