51單片機(jī)超聲波測距程序

1、/超聲波測距，測距范圍2cm-400cm;#include#include#define uint unsigned int#define uchar unsigned charsbit trig=P10;sbit echo=P32;sbit test=P11;/測試燈sbit dula=P26;sbit wela=P27;sbit BEEP=P23;uint timeh,timel,distance;uint ge,shi,bai,xiaoshu,flag,time;/*共陰極數(shù)碼管不帶小數(shù)點(diǎn)代碼表*/uchar code list=0x3f , 0x06 , 0x5b , 0x4f , 0

2、x66 , 0x6d ,0x7d , 0x07 , 0x7f , 0x6f , 0x77 , 0x7c ,0x39 , 0x5e , 0x79 , 0x71 ;/*共陰極數(shù)碼管帶小數(shù)點(diǎn)代碼表*/uchar code listtwo = 0xbf,0x86,0xdb,0xcf,0xe6,0xed,0xfd,0x87,0xff,0xef;/*長延時函數(shù)*/void delay(uint z)uint x,y;for(x=z;x0;x-)for(y=100;y0;y-);/*短延時函數(shù)*/void delay20us()uchar a;for(a=0;a100;a+);/*報警函數(shù)*/void be

3、er()/BEEP=0;delay(10);/*定時器初始化*/void initime0()TMOD=0x01;TH0=0;TL0=0;EA=0;ET0=0;EX0=0;/*外部中斷函數(shù)*/void estern() interrupt 0timeh=TH0;timel=TL0;beer();flag=1;/進(jìn)入中斷，標(biāo)志位就置1EX0=0;/同時關(guān)斷外部中斷和定時器 TR0=0;/*顯示函數(shù)*/void display(distance)bai=distance/1000;shi=distance%1000/100;ge=distance%100;xiaoshu=distance%10;d

4、ula=1;P0=listxiaoshu;dula=0;P0=0xff;wela=1;P0=0xf7;wela=0;delay(2);dula=1;P0=listtwoge;dula=0;P0=0xff;wela=1;P0=0xfb;wela=0;delay(2);dula=1;P0=listshi;dula=0;P0=0xff;wela=1;P0=0xfd;wela=0;delay(1);dula=1;P0=listbai;dula=0;P0=0xff;wela=1;P0=0xfe;wela=0;delay(1);/*被調(diào)用子函數(shù)*/void diaoyong()uint i;EA=0;ec

5、ho=1;/為了檢測電平的高低，首先必須拉高trig=1;delay20us();trig=0;while(echo=0);/如果進(jìn)入中斷 即接收到超聲波就向下執(zhí)行flag=0;/接收到就清除標(biāo)志位EA=1;/同時打開總中斷EX0=1;/打開外部中斷TR0=1;/開定時器TH0=0;/定時器清零TL0=0;for(i=0;i100;i+)/等待測量的結(jié)果display(distance);/用100次顯示循環(huán)來延時，解決數(shù)碼管顯示不亮問題/delay(50);/用延時函數(shù)數(shù)碼管閃爍TR0=0;/延時一段時間后關(guān)斷定時器EX0=0;/延時一段時間后關(guān)斷外部中斷if(flag=1)/如果進(jìn)入中斷，說明測距已經(jīng)測好time=timeh*256+timel;/計算測定距離，并顯示distance=time*0.1720; display(distance);if(flag=0)/如果沒有進(jìn)入中斷，距離為0，同時燈閃爍distance=0;test=!test;