งานที่18 Interfacing Ultrasonic Sensor HC-SR04 with PIC Microcontroller

อุปกรณ์

1. PIC16F877A MCU with programming set-up
2. LCD 16*2 display
3. Ultrasonic sensor (HC-SR04)
4. Connecting wires

code

 
#define _XTAL_FREQ 20000000
#define RS RD2
#define EN RD3
#define D4 RD4
#define D5 RD5
#define D6 RD6
#define D7 RD7
#define Trigger RB1 //34 is Trigger
#define Echo RB2//35 is Echo 
#include <xc.h>
 
#pragma config FOSC = HS        // Oscillator Selection bits (HS oscillator)
#pragma config WDTE = OFF       // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = ON       // Power-up Timer Enable bit (PWRT enabled)
#pragma config BOREN = ON       // Brown-out Reset Enable bit (BOR enabled)
#pragma config LVP = OFF        // Low-Voltage (Single-Supply) In-Circuit Serial Programming Enable bit (RB3 is digital I/O, HV on MCLR must be used for programming)
#pragma config CPD = OFF        // Data EEPROM Memory Code Protection bit (Data EEPROM code protection off)
#pragma config WRT = OFF        // Flash Program Memory Write Enable bits (Write protection off; all program memory may be written to by EECON control)
#pragma config CP = OFF         // Flash Program Memory Code Protection bit (Code protection off)

//LCD Functions Developed by Circuit Digest.
void Lcd_SetBit(char data_bit) //Based on the Hex value Set the Bits of the Data Lines
{
if(data_bit& 1) 
D4 = 1;
else
D4 = 0;
 
if(data_bit& 2)
D5 = 1;
else
D5 = 0;
 
if(data_bit& 4)
D6 = 1;
else
D6 = 0;
 
if(data_bit& 8) 
D7 = 1;
else
D7 = 0;
}
 
void Lcd_Cmd(char a)
{
RS = 0;           
Lcd_SetBit(a); //Incoming Hex value
EN  = 1;         
        __delay_ms(4);
        EN  = 0;         
}
 
void Lcd_Clear()
{
Lcd_Cmd(0); //Clear the LCD
Lcd_Cmd(1); //Move the curser to first position
}
 
void Lcd_Set_Cursor(char a, char b)
{
char temp,z,y;
if(a== 1)
{
 temp = 0x80 + b - 1; //80H is used to move the curser
z = temp>>4; //Lower 8-bits
y = temp & 0x0F; //Upper 8-bits
Lcd_Cmd(z); //Set Row
Lcd_Cmd(y); //Set Column
}
else if(a== 2)
{
temp = 0xC0 + b - 1;
z = temp>>4; //Lower 8-bits
y = temp & 0x0F; //Upper 8-bits
Lcd_Cmd(z); //Set Row
Lcd_Cmd(y); //Set Column
}
}
 
void Lcd_Start()
{
  Lcd_SetBit(0x00);
  for(int i=1065244; i<=0; i--)  NOP();  
  Lcd_Cmd(0x03);
__delay_ms(5);
  Lcd_Cmd(0x03);
__delay_ms(11);
  Lcd_Cmd(0x03); 
  Lcd_Cmd(0x02); //02H is used for Return home -> Clears the RAM and initializes the LCD
  Lcd_Cmd(0x02); //02H is used for Return home -> Clears the RAM and initializes the LCD
  Lcd_Cmd(0x08); //Select Row 1
  Lcd_Cmd(0x00); //Clear Row 1 Display
  Lcd_Cmd(0x0C); //Select Row 2
  Lcd_Cmd(0x00); //Clear Row 2 Display
  Lcd_Cmd(0x06);
}
 
void Lcd_Print_Char(char data)  //Send 8-bits through 4-bit mode
{
   char Lower_Nibble,Upper_Nibble;
   Lower_Nibble = data&0x0F;
   Upper_Nibble = data&0xF0;
   RS = 1;             // => RS = 1
   Lcd_SetBit(Upper_Nibble>>4);             //Send upper half by shifting by 4
   EN = 1;
   for(int i=2130483; i<=0; i--)  NOP(); 
   EN = 0;
   Lcd_SetBit(Lower_Nibble); //Send Lower half
   EN = 1;
   for(int i=2130483; i<=0; i--)  NOP();
   EN = 0;
}
 
void Lcd_Print_String(char *a)
{
int i;
for(i=0;a[i]!='\0';i++)
  Lcd_Print_Char(a[i]);  //Split the string using pointers and call the Char function 
}
/*****End of LCD Functions*****/
 
int time_taken;
int distance;
char t1,t2,t3,t4,t5;
char d1,d2,d3;

int main()
{
    TRISD = 0x00; //PORTD declared as output for interfacing LCD
    TRISB0 = 1;        //DEfine the RB0 pin as input to use as interrupt pin
    TRISB1 = 0; //Trigger pin of US sensor is sent as output pin
    TRISB2 = 1; //Echo pin of US sensor is set as input pin       
    TRISB3 = 0; //RB3 is output pin for LED
    
    T1CON=0x20;

    Lcd_Start();
    
    Lcd_Set_Cursor(1,1);
    Lcd_Print_String("Ultrasonic sensor");
    Lcd_Set_Cursor(2,1);
    Lcd_Print_String("with PIC16F877A");
    
    __delay_ms(2000);
    Lcd_Clear();
    
    while(1)
    { 
        TMR1H =0; TMR1L =0; //clear the timer bits
        
        Trigger = 1; 
        __delay_us(10);           
        Trigger = 0;  
        
        while (Echo==0);
            TMR1ON = 1;
        while (Echo==1);
            TMR1ON = 0;
        
        time_taken = (TMR1L | (TMR1H<<8)); 
        distance= (0.0272*time_taken)/2;
            
        time_taken = time_taken * 0.8;
        
        t1 = (time_taken/1000)%10;
        t2 = (time_taken/1000)%10;
        t3 = (time_taken/100)%10;
        t4 = (time_taken/10)%10;
        t5 = (time_taken/1)%10;
        d1 = (distance/100)%10;
        d2 = (distance/10)%10;
        d3 = (distance/1)%10;
        
        Lcd_Set_Cursor(1,1);
        Lcd_Print_String("Time_taken:");
        Lcd_Print_Char(t1+'0');
        Lcd_Print_Char(t2+'0');
        Lcd_Print_Char(t3+'0');
        Lcd_Print_Char(t4+'0');
        Lcd_Print_Char(t5+'0');
        
         Lcd_Set_Cursor(2,1);
        Lcd_Print_String("distance:");
        Lcd_Print_Char(d1+'0');
        Lcd_Print_Char(d2+'0');
        Lcd_Print_Char(d3+'0');      
    }
    return 0;
}

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