AVR Freaks

I think changing it to ! fixed it , timer1 was always stopped as this condition was always true that's why i get one digit and then a bunch of garbage values.

i've also tried commenting more and making spaces in my code , i actually found it hard to read my own code sometimes, have also added new line character and detect null character and this is new code and its working thanks all.

#define F_CPU 8000000UL 
 #define TRIGGER 6
 #define ECHO 2
#include <util/delay.h> 
#include <avr/interrupt.h>
#include <avr/io.h>
#include <stdlib.h>
volatile uint16_t travel_time;
volatile unsigned char count =0xff;
volatile unsigned char rising_edge=0x00;
volatile unsigned char wave_sent=0x00;




void start_timer1(void);
void send_wave(void);




ISR(INT0_vect){
	rising_edge=0xff;
	
}

int main(void)

{
	char to_monitor[8];
	
   MCUCSR|=(1<<JTD);                        //disable JTAG >>Free PORTC
   MCUCSR|=(1<<JTD);                        // ....................    
   
   
   PORTD&=~(1<<TRIGGER);                    //TRIGGER PIN OUTPUT .... initial LOW
   DDRD|=(1<<TRIGGER);
   
   DDRD&=~(1<<ECHO);                        //ECHO pin input .... No pullup
   PORTD&=~(1<<ECHO);
   
   
   GICR=(1<<INT0);                            //Enable external interrupt INT0 ;;;; rising edge
   MCUCR=(0b11<<ISC00);
   
   
   UBRRL=51;                //      9600 baud rate
   UCSRB|=(1<<TXEN);          //      UART Transmit enable
   UCSRC=(0b11<<UCSZ0)|(1<<URSEL);             //8 bit data
   sei();
	
   
   
   while(1){
	   
	   
	   if(!wave_sent){
		   send_wave();
		   wave_sent=0xff;
	   }
	   
	   
	   
	   
	   if(rising_edge){
		   
		   
		   start_timer1(); 
		                                                   
		   while(1){
			  if(!(PIND&(1<<ECHO))){                         // POLL echo pin for low
				                                         
				  travel_time=TCNT1;
				  itoa(travel_time,to_monitor,10);
				  TCCR1B=0X00;
				  
				  
				  for(count=0;count<=7;++count){
					  if(to_monitor[count]==0){                                    //transmit timer1 values via UART
						  break;
					  }
					  
					  
					  UDR=to_monitor[count];
					  _delay_ms(100);
					  
					  }
					  UDR='\n';
					   _delay_ms(100);
					  
				   break;
		   }
		   
		   }
	   
	   
rising_edge=0x00;  
                                           //reset wave_sent ;;; rising_edge flags
wave_sent=0x00;	 
  
}

   }
   
}