51單片機超聲波測距程序

1、/超聲波測距，測距范圍2cm-400cm;#in clude<reg52.h>#i ncludevi ntri ns.h>#defi ne uint un sig ned int#defi ne uchar un sig ned charsbit trig=P1A0;sbit echo二卩3八2;sbit test二PM1；/ 測試燈sbit dula=P2A6;sbit wela=P2A7;sbit BEEP二卩2八3;uint timeh,timel,dista nee;uint ge,shi,bai,xiaoshu,flag,time;/*共陰極數(shù)碼管不帶小數(shù)點代碼表*

2、/uchar code list=0x3f , 0x06,0x5 b , 0x4f ,0x66,0x6d ,0x7d , 0x07 ,0x7f , 0x6f , 0x77,0x7 c ,0x39,0x5e , 0x79,0x71 ;/*共陰極數(shù)碼管帶小數(shù)點代碼表*/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;x>0;x-) for(y=100;y>0;y-);/*短延時函數(shù)*/void delay

3、20us()uchar a;for(a=0;a<100;a+);/*報警函數(shù)*/void beer()/ BEEP=0;delay(10);/*定時器初始化*/ void in itimeO()TMOD=0x01;THO=O;TLO=O;EA=O;ET0=0;EXO=O;/*外部中斷函數(shù)*/void estern() in terrupt 0timeh=TH0;timel=TL0;beer();II進入中斷，標(biāo)志位就置1/同時關(guān)斷外部中斷和定時器flag=1;EX0=0;TR0=0;/*顯示函數(shù)*/void display(dista nee)bai=dista nce/1000;shi

4、二dista nce%1000/100;ge二dista nce%100; xiaoshu二dista nce%10; dula=1;PO=listxiaoshu;dula=0;PO=Oxff;wela=1;P0=0xf7;wela=0;delay(2);dula=1;PO=listtwoge;dula=0;P0=0xff;wela=1;P0=0xfb;wela=0;delay(2);dula=1;P0=listshi;dula=0;PO=Oxff; wela=1; PO=Oxfd; wela=0; delay(1); dula=1; PO=listbai; dula=0;P0=0xff; w

5、ela=1;P0=0xfe; wela=0; delay(1);/*被調(diào)用子函數(shù)*/void diao yon g()uint i;/為了檢測電平的高低，首先必須拉EA=0;echo=1;trig=1;delay20us();trig=O;while(echo=0);/如果進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THO=O;/定時器清零TLO=O;for(i=0;i<100;i+)/等待測量的結(jié)果display(dista nee); /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)/如果進入中斷，說明測距已經(jīng)測好time二timeh*256+timel;計算測定距離，并顯示dista nee二time*0.1720;display(dista nee);if(flag=O)/如果沒有進入中斷，距離為 0,同時燈閃爍dista nce=0;test二!test;