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

#include <avr/io.h>
#define F_CPU 16000000ul
#include <util/delay.h>
#include <avr/interrupt.h>
#include <string.h>
#include <stdlib.h>


#define lcd_data_dir DDRD         
#define lcd_command_dir DDRC      
#define lcd_data_port PORTD       
#define lcd_command_port PORTC      
#define EN PC2                      
#define RW PC3                       
#define RS PC4                      

void lcd_command(char);                     
void lcd_char(char);                        
void lcd_init(void);                         
void lcd_string(char*);                   
void lcd_string_xy (char,char,char*);          

void lcd_command (char cmd)                    
{
	lcd_data_port = cmd;                          
	lcd_command_port&=~((1<<RS)|(1<<RW));                   
	lcd_command_port|= (1<<EN);                         
	_delay_ms(1);
	lcd_command_port&=~(1<<EN);
	_delay_ms(2);                                   
	
}
void lcd_char(char char_data)                     
{
	lcd_data_port= char_data;                       
	lcd_command_port&=~(1<<RW);                     
	lcd_command_port|=((1<<EN)|(1<<RS));            
	_delay_ms(1);
	lcd_command_port&=~(1<<EN);
	_delay_ms(1);
}
void lcd_init(void)                               
{
	lcd_command_dir|= (1<<RS)|(1<<RW)|(1<<EN);              
	lcd_data_dir = 0xff;                                     
	
	_delay_ms(20);                            
	lcd_command(0x38);                        
	lcd_command(0x0C);                      
	lcd_command(0x06);                      
	lcd_command(0x01);                      
	lcd_command(0x80);                     
}
void lcd_string(char *str)             

	int i;
	for(i=0;str[i]!=0;i++)            
	{
		lcd_char (str[i]);               
	}
	
}
void lcd_string_xy(char row,char pos,char *str)             
{
	if (row == 1)
	lcd_command((pos & 0x0f)|0x80);
	else if (row == 2)
	lcd_command((pos & 0x0f)|(0xC0));
	lcd_string(str);                        
}
#define trigger_pin PA0                     
int TimerOverFlow = 0;
ISR(TIMER1_OVF_vect)
{
	TimerOverFlow++;                      
}
int main (void)
{
	char string[10];
	long count;
	double distance;
	
	DDRA = 0x01;                           
	PORTB = 0xff;                         
	
	lcd_init();
	lcd_string_xy(1,0,"ultrasonic");
	
	sei();                                
	TIMSK = (1<< TOIE1);                 
	TCCR1A = 0;                           
	
	while(1)
	{
		PORTA |= (1<< trigger_pin);
		_delay_ms(10);
		PORTA &=(~(1<< trigger_pin));
		
		TCNT1 = 0;                             
		TCCR1B = 0x41;                          
		TIFR = 1<<ICF1;                           
		TIFR = 1<<TOV1;                          
		
		
		while ((TIFR & (1<<ICF1)) == 0);                
		TCNT1 = 0;                                     
		TCCR1B = 0x01;                                 
		TIFR = 1<<ICF1;                               
		TIFR = 1<<TOV1;                                
		TimerOverFlow = 0;                               
		
		while ((TIFR & (1<< ICF1))== 0);                         
		count = ICR1 +(65535 * TimerOverFlow);              
		distance = (double)count/466.47;
		
		dtostrf(distance,2,2,string);                      
		strcat(string,"cm");                             
		lcd_string_xy(2,0,"dist= ");
		lcd_string_xy(2,7,string);                     
		_delay_ms(200);
	}
}