HC-SR04 ultrasonic module 51+PIC microcontroller routine

The microcontroller source program is as follows:

//Crystal oscillator = 8M

//MCU=STC10F04XE

//P0.0-P0.6 common anode digital tube pin

//Trig = P1^0

//Echo = P3^2

#include //Include a 52 standard kernel header file

#define uchar unsigned char //define for easy use

#define uint unsigned int

#define ulong unsigned long

//***********************************************

sfr CLK_DIV = 0x97; //Defined for STC microcontroller, system clock division

                     //Set the address definition for the IO port of the STC microcontroller

sfr P0M1 = 0X93;

sfr P0M0 = 0X94;

sfr P1M1 = 0X91;

sfr P1M0 = 0X92;

sfr P2M1 = 0X95;

sfr P2M0 = 0X96;

//***********************************************

sbit Trig = P1^0; //Generate pulse pin

sbit Echo = P3^2; //Echo pin

sbit test = P1^1; //test pin

uchar code SEG7[10]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90}; //digital tube 0-9

uint distance[4]; //Distance measurement receiving buffer

uchar ge,shi,bai,temp,flag,outcomeH,outcomeL,i; //Custom register

bit succeed_flag; //Measurement success flag

//********Function declaration

void conversion(uint temp_data);

void delay_20us();

//void pai_xu();

void main(void) // Main program

{ uint distance_data,a,b;

   uchar CONT_1;   

   CLK_DIV=0X03; //The system clock is 1/8 crystal oscillator (pdf-45 pages) 

     P0M1 = 0; //Set the io port to push-pull output

     P1M1 = 0;

     P2M1 = 0;

     P0M0 = 0XFF;

     P1M0 = 0XFF;

     P2M0 = 0XFF;

   i=0;

   flag=0;

        test =0;

        Trig=0; //First pull the pulse input pin low

        TMOD=0x11; //Timer 0, timer 1, 16-bit working mode

        TR0=1; //Start timer 0

   IT0=0; //Change from high level to low level, triggering external interrupt

        ET0=1; //Enable timer 0 interrupt

//ET1=1; //Enable timer 1 interrupt

        EX0=0; //Disable external interrupt

        EA=1; //Open interrupt 0        

while(1) //Program loop

        {

  EA=0;

             Trig=1;

        delay_20us();

        Trig=0; //Generate a 20us pulse at the Trig pin  

        while(Echo==0); //Wait for the Echo pin to become high

             succeed_flag=0; //Clear measurement success flag

             EX0=1; //Open external interrupt

                   TH1=0; //Timer 1 cleared

        TL1=0; //Timer 1 cleared

             TF1=0; //

        TR1=1; //Start timer 1

   EA=1;

      while(TH1 < 30); //Wait for the measurement result, period 65.535 milliseconds (can be implemented by interruption)  

                  TR1=0; //Turn off timer 1

        EX0=0; //Disable external interrupt

    if(succeed_flag==1)

             {         

                   distance_data=outcomeH; //High 8 bits of the measurement result

           distance_data<<=8; //Put in the high 8 bits of 16 bits

                     distance_data=distance_data|outcomeL; //Merge with the lower 8 bits to form 16-bit result data

            distance_data*=12; //Because the timer defaults to 12 division

           distance_data/=58; //microseconds divided by 58 equals centimeters

         } //Why is divided by 58 equal to centimeters, Y meters = (X seconds * 344) / 2

                                                               // X seconds = (2*Y meters)/344 ==》X seconds = 0.0058*Y meters ==》Centimeters = microseconds/58 

    if(succeed_flag==0)

                   {

            distance_data=0; //clear if no echo

                           test = !test; //Test light changes

           }

     /// distance[i]=distance_data; //Put the measurement result data into the buffer

     /// i++;

            /// if(i==3)

          /// {

          /// distance_data=(distance[0]+distance[1]+distance[2]+distance[3])/4;

     /// pai_xu();

     /// distance_data = distance[1];

           a=distance_data;

       if(b==a) CONT_1=0;

       if(b!=a) CONT_1++;

       if(CONT_1>=3)

                   { CONT_1=0;

                          b=a;

                          conversion(b);

                        }       

          /// i=0;

          /// }             

         }

}

//*******************************************************************

//External interrupt 0, used to determine the echo level

INTO_() interrupt 0 // External interrupt is number 0

{    

     outcomeH =TH1; //Get the timer value

     outcomeL =TL1; //Get the timer value

     succeed_flag=1; //Flag of successful measurement

     EX0=0; //Disable external interrupt

  }

//****************************************************************

//Timer 0 interrupt, used for display

timer0() interrupt 1 // Timer 0 interrupt is number 1

   {

         TH0=0xfd; //Write timer 0 initial value

         TL0=0x77;                 

         switch(flag)   

      {case 0x00:P0=ge; P2=0xfd;flag++;break;

            case 0x01:P0=shi;P2=0xfe;flag++;break;

            case 0x02:P0=bai;P2=0xfb;flag=0;break;

      }

   }

//********************************************************************

/*

//Timer 1 interrupt, used for ultrasonic ranging timing

timer1() interrupt 3 // Timer 0 interrupt is number 1

    {

TH1=0;

TL1=0;

     }

*/

//**********************************************************************

//Display data conversion program

void conversion(uint temp_data)  

{  

    uchar ge_data,shi_data,bai_data;

    bai_data=temp_data/100;

    temp_data=temp_data%100; //Remainder operation

    shi_data=temp_data/10;

    temp_data=temp_data%10; //Remainder operation

    ge_data=temp_data;

    bai_data=SEG7[bai_data];

    shi_data=SEG7[shi_data];

    ge_data =SEG7[ge_data];

    EA=0;

    bai = bai_data;

    shi = shi_data;

    ge = ge_data; 

         EA=1;

}

//**********************************************************************

void delay_20us()

{ uchar bt ;

    for(bt=0;bt<100;bt++);

}

/*

void pai_xu()

  { uint t;

  if (distance[0]>distance[1])

    {t=distance[0];distance[0]=distance[1];distance[1]=t;} /*Exchange values

  if(distance[0]>distance[2])

    {t=distance[2];distance[2]=distance[0];distance[0]=t;} /*Exchange values

  if(distance[1]>distance[2])

    {t=distance[1];distance[1]=distance[2];distance[2]=t;} /*Exchange values         

    }

*/