超声波测距51单片机C语言源程序

#include<reg52.H> #include<INTRINS.H> #define uchar unsigned char #define uint unsigned int sbit lcdrs=P2^5; sbit lcdrw=P2^6; sbit lcden=P2^7; sbit P20=P2^0; sbit P21=P2^1; bit flag; uchar const table[]= "LENTH: mm "; uchar const table1[]=" "; uchar const table2[]="OUT OF RANGE!!! "; float l; uchar num,ge,shi,bai,qian,wan; uint distance,t,i; void send(void); void delay(uint z); //延时z毫秒 void init(); void write_com(uint com); void write_date(uint date); void main() { init(); TMOD=0x01; TH0=0; TL0=0; IT0=1; ET0=1; EA=1; // PX0=1; flag=1; // TR0=1; while(1) { if(flag) { // TR0=1; send(); TH0=0; TL0=0; TR0=1; //定时器0开始计时 i=150; while(i) { _nop_(); i--; } _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); EX0=1; //允许INT0中断 } } } void delay(uint z) //延时z毫秒 { uint x,y; for(x=z;x>0;x--) for(y=110;y>0;y--); } void init() //1602初始化 { write_com(0x38); write_com(0x01); write_com(0x0c); write_com(0x06); write_com(0x80); for(i=0;i<16;i++) { write_date(table[i]); } write_com(0x80+0x40); for(i=0;i<15;i++) { write_date(table1[i]); } } void write_com(uint com) //1602写指令 { lcdrs=0; lcdrw=0; P0=com; delay(5); lcden=1; delay(5); lcden=0; } void write_date(uint date) //1602写数据 { lcdrs=1; lcdrw=0; P0=date; delay(5); lcden=1; delay(5); lcden=0; } void int_0() interrupt 0 //外部中断0服务函数 { //定时器1停止 TR0=0; //定时器0停止 flag=1; t=(TH0*256+TL0)/2; //单程传播时间 l=0.344*t; distance=l; wan=distance/10000; qian=distance%10000/1000; bai=distance%1000/100; shi=distance%100/10; ge=distance%10; write_com(0x80+0x06); write_date(0x30+wan); write_date(0x30+qian); write_date(0x30+bai); write_date(0x30+shi); write_date(0x30+ge); } void timer0() interrupt 1 //定时器0中断服务函数 { write_com(0x80+0x40); for(i=0;i<16;i++) { write_date(table2[i]); } P21=~P21; TR0=0; flag=1; } void send(void) //P20口发送40KHZ方波 {flag=0; i=25; while(i) { P20=1; _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); _nop_(); P20=0; _nop_(); _nop_(); _nop_(); _nop_(); i--; } }