#include <avr/io.h> 


#define BAUD 9600
#define MYUBRR F_CPU/16/BAUD-1

//This function is used to initialize the USART
//at a given UBRR value
void USARTInit(unsigned int ubrr)
{

   //Set Baud rate

    UBRR0H = (ubrr>>8);
    UBRR0L = ubrr;




   //Enable The receiver and transmitter
 UCSR0B = (1<<RXEN0)|(1<<TXEN0);
 // Set fram format: 8data 2stopBit
 UCSR0C = (1<<USBS0)|(3<<UCSZ00);


}


//This function is used to read the available data
//from USART. This function will wait untill data is
//available.
unsigned char USARTReadChar( void )
{
   //Wait untill a data is available

   while(!(UCSR0A & (1<<RXC0)))
   {
      //Do nothing
   }

   //Now USART has got data from host
   //and is available is buffer

   return UDR0;
}


//This fuction writes the given "data" to
//the USART which then transmit it via TX line
void USARTWriteChar(unsigned char data)
{
   //Wait untill the transmitter is ready

   while(!(UCSR0A & (1<<UDRE0)))
   {
      //Do nothing
          PORTD ^= 1 << PINB2;

   }

   //Now write the data to USART buffer

   UDR0 = data;
}

int main(void)
{
DDRB |= 1 << PINB2;

   //Varriable Declaration
   char data;


   USARTInit(MYUBRR);   

  //Loop forever
	
	USARTWriteChar('>');

   while(1)
   {
      //Read data
       data = USARTReadChar();

      /* Now send the same data but but surround it in
      square bracket. For example if user sent 'a' our
      system will echo back '[a]'.

      */

      //USARTWriteChar('[');
      USARTWriteChar(data);
      //USARTWriteChar(']');

  }
}

 So, das ist der Code