51 Single chip microcomputer ultrasonic distance Measurement C program

Principle of ultrasonic testing

Program flow chart of ultrasonic distance measurement

The procedure is as follows:

Ultrasonic module Program//ultrasonic Module Program//trig = p2^0//echo = p3^2 #include <reg52.h> #define UCHAR unsigned char #define UINT u
  nsigned int//void delay (UINT Z) {uint x, y;
for (x=z;x>0;x--) for (y=110;y>0;y--);
    }//void Delay_20us () {Uchar A;
 for (a=0;a<100;a++); }//***************************************************************//Display data converter void display (UINT temp) {Uchar ge,s
    Hi,bai;
    bai=temp/100;  
    Shi= (temp%100)/10;  
    ge=temp%10;
    Wela=1;
    P0=0xf7;
    wela=0;
    Dula=1;
    P0=table[bai];
    dula=0;
    Delay (1);
    Dula=1;   p0=0x00;
    Close code dula=0;
    Wela=1;
    P0=0xef;
    wela=0;
    Dula=1;
    P0=table[shi];
    dula=0;
    Delay (1);
    Dula=1;   p0=0x00;

    Close code dula=0;
    Dula=1;
    P0=table[ge];
    dula=0;
    Wela=1;
    P0=0XDF;
    wela=0;
    Delay (1);
    Dula=1;   p0=0x00;
 Close code dula=0;
  }//*************************************************************** void Main () {UINT distance;  Test = 0;       trig=0;         First pull the low pulse input pin ea=1;    Open Total interrupt 0 tmod=0x10;           Timer 1, 16-bit working mode while (1) {ea=0;         Trig=1 of the total interruption of the shutdown;   Ultrasonic input terminal delay_20us ();         Delay 20US trig=0; Produces a 20us pulse while (echo==0); Wait for Echo echo pin to become high level succeed_flag=0; 
        Clear measure success sign ea=1;          Ex0=1;          Open external interrupt 0 th1=0;          Timer 1 Clear 0 tl1=0;          Timer 1 Clear 0 tf1=0;          Count overflow flag tr1=1;      Start Timer 1 delay (20);          Wait for the result of measurement tr1=0;          Off timer 1 ex0=0;
          Close External Interrupt 0 if (succeed_flag==1) {Time=timeh*256+timel;  distance=time*0.172;
       CM display (distance);                    } if (succeed_flag==0) {distance=0;                  No echo is clear 0 test =!test; Test Lamp Change}}}//************************************External interrupt 0, used to determine the echo level void Exter () interrupt 0//external interrupt 0 is No. 0 # {Timeh =th1;    Remove the value of the timer Timel =TL1;         Remove the value of the timer succeed_flag=1;//to the Mark Ex0=0 of the successful measurement; Off external Interrupt}//****************************************************************//Timer 1 interrupt, used as ultrasonic ranging time void timer1 ()
         Interrupt 3//{th1=0;
     tl1=0; }