Project 2 - Measuring distance of an object using ultrasonic sensor (HC-SR04)

TSE-ABINAYA INBAMANI batch 15

In this project, the implementation of code for “Measuring distance of an object using ultrasonic distance sensor (HC-SR04)

Goals:

• Measuring the distance of an object using Ultrasonic Distance Sensor (HC-SR04)
• Usage of Input Capture Mode

Key Highlights of the Project:

• Measuring the distance travelled by the wave to the object and gets bounced back from the object to sensor.
• Measuring Pulse width using Input Capture Mode

Deliverables of this project:

• The distance travelled by a wave to the object for which we want to measure the distance using Ultrasonic Distance Sensor (HC-SR04).
• Measuring Pulse width using Input Capture Mode of Timer 1

Expected Outcomes:

The students will get the Knowledge on Ultrasonic sensor (HC-SR04) to measure the distance travelled by wave to the object, the hardware connection of Atmega328p and HC-SR04 and how to use input capture mode of Timer1

/*
 * Project2.c
 *
 * Created: 28-02-2023 13:52:08
 * Author : vvima
 */ 

#include <avr/io.h>
#define F_CPU 8000000UL
#include <util/delay.h>
#include <string.h>
#include <stdlib.h>

#define LCD_Date_Dir DDRD //define LCD data port direction
#define LCD_Command_Dir DDRC //Define LCD command port direction register
#define LCD_Data_Port PORTD //Define LCD data port
#define LCD_Command_Port PORTC //
#define EN PC2 // define Enable signal pin
#define RW PC3 //Define read/write signal pin
#define RS PC4 //define register select (data reg./command reg.) signal pin

void LCD_Command(char); //lcd command write funtion
void LCD_Char(char); //lcd data write function
void LCD_Init(void); //lcd initialize function
void LCD_String(char*); //send string to lcd funtion
void LCD_String_xy(char,char,char*); //send row position and string to lcd funtion

void LCD_Command (char cmd) // lcd command write funtion
{
	LCD_Data_Port=cmd; // write command daata to lcd data port..
	LCD_Command_Port&=~((1<<RS)|(1<<RW)); //RS low (command reg.) RW low (write) 
	LCD_Command_Port|=(1<<EN); // high to low transition on EN
	_delay_ms(1);
	LCD_Command_Port&=~(1<<EN);
	_delay_ms(2); // wait little bit
	
}

void LCD_Char(char char_data) //LCD data write function
{
	LCD_Data_Port = char_data; //write data to lce data port
	LCD_Command_Port &=~(1<<RW); //RW low (write)
	LCD_Command_Port |=((1<<EN)|(1<<RS)); //RS high (data reg). high to low transis=tion on EN 
	_delay_ms(1);
	LCD_Command_Port &=~(1<<EN);
	_delay_ms(1); //wait little bit
}

void LCD_Init(void)
{
	LCD_Command_Dir|=(1<<RS)|(1<<RW)|(1<<EN); //LCD COmmand port direction as o/p
	LCD_Date_Dir =0xFF; //lcd data port direction as o/p
	
	_delay_ms(20); // lcd power up time to get things ready its always >15ms
	LCD_Command(0x38); //initialize 16*2 lcd in 8bit mode
	LCD_Command(0x0C);//display on, cursor off command
	LCD_Command(0x06);//auto increment cursor
	LCD_Command(0x01);//clear lcd command
	LCD_Command(0x80); //8 is for first line and 0 is for 0th position
}
void LCD_String(char *str) // send string to lcd fun
{
	int i;
	for (i=0;str[i]!=0;i++) //send each char of string til null
	{
		LCD_Char(str[i]);
	}
}
void LCD_String_xy(char row,char pos,char *str)
{
	if(row==1)
	LCD_Command((pos & 0x0F)|0x80); // command of 1st row and required position<16
	else if (row==2)
	LCD_Command((pos &0X0F)|0XC0); // 2ND ROW AND REQUIRED POSITION<16
	LCD_String(str); //LCD string fun
}
#define Tigger_pin PA0 // trigger pin
int timeroverflow =0;
ISR (TIMER1_OVF_vect)
{
	timeroverflow++; // TIMER OVERFLOW COUNT
}
int main(void)
{
  char string[10];
  long count;
  double distance;
  
  DDRA = 0X01; //trigger pin as output
  PORTB =0xFF; // turn on pull up
  LCD_Init();
  LCD_String_xy(1,0,"ultrasonic");
  
  //sei(); // global interrupt
  TIMSK =(1<<TOIE1);// ENABLEE TIMER1 OVERFLOW INTERRUPTS
  TCCR1A = 0; // SET ALL BIT TO ZERO NORMAL OPERATION 
  
    while (1) 
    {
		PORTA |=(1<< Tigger_pin);
		_delay_ms(10);
		PORTA &=(~(1<<Tigger_pin));
		
		TCNT1=0; //clear timer counter
		TCCR1B =0x41; //rising edge, no prescaler
		TIFR = 1<<ICF1; //clear icp flag //input capture flag
		TIFR = 1<<TOV1; //clear timer overflow flag
		
		while ((TIFR &(1<<ICF1)) == 0); // wait for rising edge
		TCNT1=0; //clear timer counter
		TCCR1B=0x01;//on falling edge,no prescaler
		TIFR=1<<ICF1; //clear icp flag (i/p capture flag
		TIFR=1<<TOV1;// clear timer overfloer flag
		timeroverflow =0; // clear timer overflow count
		
		while((TIFR &(1<<ICF1))==0); // Wait for fallling edge
		count = ICR1+(65535*timeroverflow); // take count
		// 8MHZ timer freq, sound speed=343m/s
		distance = (double) count/466.47;
		
		dtostrf(distance,2,2,string); //distance to string
		strcat (string,"cm"); //concat unit i e. cm
		LCD_String_xy(2,0,"Dist= ");
		LCD_String_xy(2,7,string); //print distance
		_delay_ms(200);
		
    }
}

OUTPUT:

• the program is loaded in atmega 32 chip.
• lcd pins are connected to the atmega32 as shown below.
• ultrasonoic sensor are connected to view the output.