beylerrrr şuan kuzen yanımda uyuyorr off off

#include<avr/io.h>
5. include<avr/interrupt.h>
6. include<util/delay.h>

7. define MYUBRR 51
8. define FIFO 8
volatile unsigned char string[FIFO];
volatile unsigned char sayici=0;
volatile unsigned char sayici2=0;

void USART_Init(int ubrr);
unsigned char USART_Receive( void );
void USART_Transmit( unsigned char data );

ISR(USART_RXC_vect){

PORTA=0xff;
_delay_ms(500);
PORTA=0x00;

}

int main( void )
{
unsigned char a;

DDRA=0xff;

USART_Init( MYUBRR );

sei();

while(1){
a=USART_Receive();
USART_Transmit(a);
}
}

void USART_Init(int ubrr)
{

/* Set baud rate */
UBRRH = 0;
UBRRL = ubrr;

UCSRA = 0;

/* Enable receiver and transmitter */
UCSRB = (1<<RXEN)|(1<<TXEN)|( 1<<RXCIE);

/* Set frame format: 8data, 1 stop bit */
UCSRC = (1<<URSEL)|(1<<UCSZ0)|(1<<UCSZ1);
}

void USART_Transmit( unsigned char data )
{
/* Wait for empty transmit buffer */
while ( !( UCSRA & (1<<UDRE)) );

/* Put data into buffer, sends the data */
UDR = data;
}

unsigned char USART_Receive( void )
{
/* Wait for data to be received */
while ( !(UCSRA & (1<<RXC)) );

/* Get and return received data from buffer */
return UDR;
}