Ultrasonic principle is simple and accurate, and it is widely used. Below is a digital tube program written by myself. The display part needs to be modified. What I write is that I am using a Huijing development board, a common cathode digital tube.
//Ultrasonic module program
//Trig = P2^0
//Echo = P3^2
#include
#define uchar unsigned char
#define uint unsigned int
unsigned char code table []={0x3f, 0x06, 0x5b, 0x4f, 0x66,
0x6d, 0x7d, 0x07, 0x7f, 0x6f}; //0-9 code table
uint time = 0;
uint TImeH = 0;
uint TImeL = 0;
uint succeed_flag;
sbit dula=P2^0; //Latch control of segment selection signal
sbit wela=P2^1; //Latch control of bit selection signal
sbit Trig = P2^2;
sbit Echo = P3^2;
//
void delay (uint z)
{
uint x, y;
for(x=z;x》0;x--)
for(y=125;y》0;y--);
}
//
void delay_20us()
{
uchar a;
for(a=0;a《100;a++);
}
//************************************************ ***************
//Display data conversion program
void display (uint temp)
{
uchar qian, ge, shi, bai;
qian = temp/1000;
bai=temp/100%10;
shi=temp%100/10;
ge=temp%10;
wela=1;
//P0=0xf7;
P0 = 0xfe;
wela=0;
dula=1;
P0=tableï¼»qianï¼½;
dula=0;
delay(5);
wela=1;
//P0=0xf7;
P0 = 0xfd;
wela=0;
dula=1;
P0=table[bai];
dula=0;
delay(5);
dula=1;
P0=0x00; //Close position code
dula=0;
wela=1;
//P0=0xef;
P0 = 0xfb;
wela=0;
dula=1;
P0=table [shi];
dula=0;
delay(5);
dula=1;
P0=0x00; //Close position code
dula=0;
dula=1;
P0=tableï¼»geï¼½;
dula=0;
wela=1;
//P0=0xdf;
P0 = 0xf7;
wela=0;
delay(5);
dula=1;
P0=0x00; //Close position code
dula=0;
}
//************************************************ ***************
void main()
{
uint distance;
uint test =0;
Trig=0; //First pull down the pulse input pin
EA=1; //Open the total interrupt 0
TMOD=0x10; //Timer 1, 16-bit working mode
while(1)
{
EA=0; //Close the total interrupt
Trig=1; //Ultrasonic input terminal
delay_20us(); //delay 20us
Trig=0; //Generate a 20us pulse
while (Echo==0); //Wait for the Echo echo pin to go high
succeed_flag=0; //Clear the measurement success flag
EA=1;
EX0=1; //Open external interrupt 0
TH1=0; //Timer 1 is cleared
TL1=0; //Timer 1 is cleared
TF1=0; //Counting overflow flag
TR1=1; //Start timer 1
delay(20); //Waiting for the measurement result
TR1=0; //Close 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; //clear if there is no echo
test =! test; //Test light change
}
}
}
//************************************************ ***************
//External interrupt 0, used to judge the echo level
void exter() interrupt 0 // External interrupt 0 is number 0
{
timeH =TH1; //Remove the timer value
timeL =TL1; //Remove the value of the timer
succeed_flag=1;//To the flag of successful measurement
EX0=0; //Close the external interrupt
}
//************************************************ ****************
//Timer 1 is interrupted, used for ultrasonic ranging timing
void timer1() interrupt 3 //
{
TH1=0;
TL1=0;
}
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