Interfacing AT89S51 with ultrasonic sensor and LCD

[zulnorain]

I want to make a project to measure distance using ultrasonic sensor HC-S04 and LCD to display the distance in cm. I use AT89S51, the trigger pin for ultrasonic sensor is P3.5 and the echo pin is P3.2. The echo pin is connected to P3.2 because I use interrupt so that whenever there is a HIGH it will activate timer 0 and the duration of HIGH condition (in microsecond) will be converted to cm (divided by 59). I already make sure that the ultrasonic sensor works well. The problem is the LCD always display output the same number 45. It is not varying although the distance between object and ultrasonic sensor change. Can anyone help me to solve this problem?

 

#include<REGX51.h>

#include<intrins.h>// for using _nop_() function

#define port P2

#define dataport P0 

sfr16 DPTR =0x82;

sbit trig=P3^5;

sbit rs=port^0;

sbit rw=port^1;

sbit e=port^2;

 

 

void delay(unsigned int msec)

{

int i,j;

for(i=0;i<msec;i++)

    for(j=0;j<1275;j++);

}

 

void lcd_cmd(unsigned char item) // Function to send command to LCD

{

dataport = item;

rs= 0;

rw=0;

e=1;

delay(1);

e=0;

return;

}

 

void lcd_data(unsigned char item) // Function to send data to LCD

{

dataport = item;

rs= 1;

rw=0;

e=1;

delay(1);

e=0;

return;

}

 

void lcd_data_string(unsigned char *str) // Function to send string to LCD

{

int i=0;

while(str[i]!='')

{

  lcd_data(str[i]);

  i++;

  delay(1);

}

return;

}

 

void send_pulse(void) //to generate 10 microseconds delay

{

TH0=0x00;TL0=0x00;

 trig=1;

 _nop_();_nop_();_nop_();_nop_();_nop_();

 _nop_();_nop_();_nop_();_nop_();_nop_();

 trig=0;

   

}

 

unsigned int get_range(void)

{

 int range=0;

 int s;

 send_pulse();

 while(!INT0);//         in sake of these lines you can generate a delay of 40 Milli seconds=40000 micro

    while (INT0);//         seconds

 DPH=TH0;DPL=TL0;  

 TH0=0xFF;TL0=0xFF;

 lcd_cmd(0x81);

 delay(2);

 lcd_data_string("output:");

 lcd_cmd(0x8a);

 if(DPTR<35000)

 {//actually you need to use 38000 but the sensor may not work at higher levels 

  range=DPTR/59;

  s=range/100;

  range=range%100;

  if(s!=0)

  {

  lcd_data(s+48);

  }

  else

  {

  lcd_cmd(0x06);

  s=range/10;

  range=range%10;

  lcd_data(s+48);

  lcd_data(range+48);

  lcd_data(' ');

  }

 }

 else

 {

 range=0; // indicates that there is no obstacle in front of the sensor 

 lcd_cmd(0x06);

 lcd_data(0);

 }

 return range;

}

 

void main()

{

  lcd_cmd(0x38);

  lcd_cmd(0x0c);

  delay(2);

  lcd_cmd(0x01);

  delay(2);

  lcd_cmd(0x81);

  delay(2);

  lcd_data_string("start");

  delay(20);

  TMOD=0x09;//timer0 in 16 bit mode with gate enable

  TR0=1;//timer run enabled

  TH0=0x00;TL0=0x00;

 

  P3=0x04;//setting pin P3.2 

     

 

 while(1)

 { get_range();

   delay(2);  

 }

}

 

[nidhin.k]

 

Try this code….. it will work….

 

 

#include<reg52.h>

 

#define First_Line 0x80

#define Second_Line 0xc0

#define Curser_On  0x0f

#define Curser_Off 0x0c

#define Clear_Display 0x01

#define Data_Port P0

 

sbit Lcd_rs = P2^7;

sbit Lcd_rw = P2^6;

sbit Lcd_en = P2^5;

 

sbit RX= P3^2; 

sbit TX= P3^5;

 

void Distance_Measure();

void Lcd8_Init();

void Lcd8_Command(unsigned char);

void Lcd8_Write(unsigned char,unsigned char);

void Lcd8_Display(unsigned char,const unsigned char*,unsigned int);

void Lcd8_Decimal2(unsigned char,unsigned char);

void Lcd8_Decimal3(unsigned char,unsigned char);

void Lcd8_Decimal4(unsigned char,unsigned int);

void Delay(unsigned int);

void del();  

 

unsigned char i,inch1,inch2,result,obj_distance,rept,sec,j,a=0,c=0,kc,cu=0xc0,l,e[20],num[20],n,v[20];

unsigned long int count=0,count1=0;

 

void main()

{

 

EA=1;

ET0=1;

TMOD=0x01;

TH0=TL0=0x00;

TR0=1;

relay2=0;

Lcd8_Init();Delay(65000); 

    Lcd8_Display(0x80,”Ultrasonic      “,16);

Lcd8_Display(0xc0,”                “,16);

Delay(65000);Delay(65000);

Lcd8_Display(0xC0,”Distance:       “,16);

 

while(1)

{

 

Distance_Measure();

 

}

}

 

 

void Distance_Measure()

{

count=count1=0;

TH0=0x00;TL0=0x00; 

TR0=0;

for(i=0;i<10;i++)         

{

TX=0;           

Delay(1000);

TX=1;           

Delay(10);

TX=0;   

while(RX==0);

TR0=1; 

while(RX==1);

TR0=0;

count=TH0<<8;      

count=count|TL0;    

TH0=TL0=0x00; 

count1=count1+count;

Delay(5000);        

}

count=count1/10;

inch1=count%10000/1000;

inch2=count%1000/100;

result=(inch1*10)+inch2;

 

obj_distance=result-2;  

Lcd8_Decimal3(0XCb,obj_distance); 

 

}

 

void Lcd8_Init()

{

Lcd8_Command(0x38); //to select function set

Lcd8_Command(0x06); //entry mode set

Lcd8_Command(0x0c); //display on

Lcd8_Command(0x01); //clear display

}

 

void Lcd8_Command(unsigned char com)

{

Data_Port=com;

Lcd_en=1;

Lcd_rs=Lcd_rw=0;

Delay(125);

Lcd_en=0;

Delay(125);

}

 

void Lcd8_Write(unsigned char com,unsigned char lr)

{

Lcd8_Command(com);

 

Data_Port=lr; // Data 

Lcd_en=Lcd_rs=1;

Lcd_rw=0;

Delay(125);

Lcd_en=0;

Delay(125);

}

 

void Lcd8_Display(unsigned char com,const unsigned char *word,unsigned int n)

{

unsigned char Lcd_i;

 

for(Lcd_i=0;Lcd_i<n;Lcd_i++)

{ 

Lcd8_Write(com+Lcd_i,word[Lcd_i]);

  }

}

 

void Lcd8_Decimal2(unsigned char com,unsigned char val)

{

unsigned int Lcd_hr,Lcd_t,Lcd_o;

 

Lcd_hr=val%100;

Lcd_t=Lcd_hr/10;

Lcd_o=Lcd_hr%10;

 

Lcd8_Write(com,Lcd_t+0x30);

Lcd8_Write(com+1,Lcd_o+0x30);

}

 

 

void Lcd8_Decimal3(unsigned char com,unsigned char val)

{

unsigned int Lcd_h,Lcd_hr,Lcd_t,Lcd_o;

 

Lcd_h=val/100;

Lcd_hr=val%100;

Lcd_t=Lcd_hr/10;

Lcd_o=Lcd_hr%10;

 

Lcd8_Write(com,Lcd_h+0x30);

Lcd8_Write(com+1,Lcd_t+0x30);

Lcd8_Write(com+2,Lcd_o+0x30);

}

 

 

 

void Delay(unsigned int del)

{

while(del–);

}

 

 

[AJISH ALFRED]

I suspect the working of this function.

 

void send_pulse(void) //to generate 10 microseconds delay

{

TH0=0x00;TL0=0x00;

 trig=1;

 _nop_();_nop_();_nop_();_nop_();_nop_();

 _nop_();_nop_();_nop_();_nop_();_nop_();

 trig=0;

   

}

How can you make sure that this code will generate exactly 10 microsecond delay? It depends on your crystal frequency and how your compiler compiles the code.

Suggest you use a timer for that also

[zulnorain]

hey ,

nidhin.k can you please explain the code ?? and in what units the range is displayed(cm/m)

[nidhin.k]

hai zulnorain…..

 

 

    in that program, i just high low the transitter pin and waiting for the  recieve high low pulse.

during that time i will on the timer and counter for calulating the receieve timing. the values in TH0 and TL0 will give the exact timing.

 

after some calculation it will convert it to inch.

 

 

u can check and caliber it into cm….

[zulnorain]

nidhin.k thanx for the code buddy its working fine….now if i want to introduce leds and buzzer in it how will that be done?

for example 4 red leds (P0^0 to P0^3) glow when distance is <= 20 inches and buzzer (P1.3) is sound…if distance > 20

4 green leds glow(p0.4 to p0.7)

 

please help…

[nidhin.k]

hai zulorain….

 

 

u just edit that code…

 

 

sbit red1=P0^0;

sbit red2=P0^1;

sbit red3=P0^2;

sbit red3=P0^3;

 

sbit green1=P0^4;

sbit green2=P0^5;

sbit green3=P0^6;

sbit green4=P0^7;

sbit buzzer=P1^3;

 

 

 

if(obj_distance<20){red1=red2=red3=red4=1;green1=green2=green3=green4=0;buzzer=1;}

else{red1=red2=red3=red4=0;green1=green2=green3=green4=1;buzzer=0;}

 

the conditional statements are placed in while condition.

[zulnorain]

hey nidhin.k,

 

if i introduce dc motor (with L293D ic) in this project how can i control motor speed using ultrasonic sensor.?

so at a certain say (40 inches) motor speed reduces and at 20 inches motor stops.?

[nidhin.k]

hai zulnorain….

 

 

u can control the speed of a DC motor… by using PWM signal…. 

 

try… and if any problem occur.. post here….

 

all the best…..

 

 

 

[zulnorain]

hey nidhin.k can you explain this section of the code:

 

void Distance_Measure()

{

count=count1=0;

TH0=0x00;TL0=0x00; 

TR0=0;

for(i=0;i<10;i++)         

{

TX=0;           

Delay(1000);

TX=1;           

Delay(10);

TX=0;   

while(RX==0);

TR0=1; 

while(RX==1);

TR0=0;

count=TH0<<8;      

count=count|TL0;    

TH0=TL0=0x00; 

count1=count1+count;

Delay(5000);        

}

count=count1/10;

inch1=count%10000/1000;

inch2=count%1000/100;

result=(inch1*10)+inch2;

 

obj_distance=result-2;  

Lcd8_Decimal3(0XCb,obj_distance); 

 

}

[B V RAjeswararao]

can u help me the ultrasonic code using serial communication

 

[rohit pandey]

^{nidhin i need ur help in making a similar project but i dont have to display it i just have to convert the range into vibration like maximum range gives minimum vibrations and min range gives maximum vibration using pwm can you provide somthing on the it will be highly appriciable i am using 6 volt dc motor using maimum 5 volt range as entier circuit will be powered by a 9 volt battry and i am using hc sr04 ultrasonic range module and atmel 89s51 as processor please help as i am new to c programming and dont know how to do all this thanks in advance}

[rohit pandey]

and the cicuit diagram if possible for you or zulhoriz please provide the schematics for connection of sensor to micro and to dc motor thnx in advance

[rohit pandey]

 

#include<REGX51.h>

#include<intrins.h>// for using _nop_() function

sfr16 DPTR =0x82;

sbit trig=P3^1;

void send_pulse(void) //to generate 10 microseconds delay

{

TH0=0x00;TL0=0x00; 

 trig=1;

 _nop_();_nop_();_nop_();_nop_();_nop_();

 _nop_();_nop_();_nop_();_nop_();_nop_();

 trig=0;

    

} 

 

unsigned char get_range(void) 

{

 unsigned char range;

 send_pulse();

    while(!INT0);//         in sake of these lines you can generate a delay of 40 Milli seconds=40000 micro 

    while (INT0);//         seconds

 DPH=TH0;DPL=TL0; 

 TH0=0xFF;TL0=0xFF;

 if(DPTR<35000)//actually you need to use 38000 but the sensor may not work at higher levels 

  range=DPTR/59;

  else

  range=0; // indicates that there is no obstacle in front of the sensor 

  return range; 

}

void main()

{

  TMOD=0x09;//timer0 in 16 bit mode with gate enable

  TR0=1;//timer run enabled

  TH0=0x00;TL0=0x00;

 

 P1=0xff;

  P3|=0x04;//setting pin P3.2    

         

}

 

this is my code please help me in howing distance on led as above mentioned led code it is giving me errors please patch them into this 

[Hussein]

hello Mr Zulnorain,,, 
or his helpful friend,,

can someone email me or paste the last edited full code for ultrasonic with leds and motor ??
 

i really appreciate it @@ thanks so much
Hussein-Yemen
 

 

[Author]

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