#ifndef F_CPU

/* In the new version of the WinAVR/Mfile Makefile guideline One can defined F_CPU in the Makefile, a repeated 

   definition here would lead to a compiler warning . therefore "prevention" through    #ifndef/#endif

   This "Prevention" can lead to Debugger, if AVRStudio use a another, not the hardware fitting Clock rate: 

   Then the    following definition doesn't use, but instead the default value (1 MHz?) of AVRStudio - hence 

   the Output of a warning if F_CPU yet does not define:*/ 

#warning "F_CPU was not defined yet, now make up with 3686400"

#define F_CPU 3686400L // Systemtakt in Hz - define as  long>> Without errors in the computation 

#endif

#define BAUD 9600L

#define UBRR_VAL ((F_CPU+BAUD * 8)/(BAUD*16)-1)     //clever round

#define BAUD_REAL (F_CPU/(16*(UBRR_VAL+1)))         //real baud rate

#define BAUD_ERROR ((BAUD_REAL*1000)/BAUD-1000)     //Error per thousand

#if ((BAUD_ERROR>10)||(BAUD_ERROR<-10))

#error Systematic error in the baud rate more than 1% and thus too high!

#endif

#include <avr/io.h>

#include <stdlib.h>

#include <inttypes.h>

#include <util/delay.h>

void USART_Init(void) 

{

  UBRRH = (unsigned char)(UBRR_VAL>>8);  // Set baud rate

  UBRRL = (unsigned char)UBRR_VAL;

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

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

}//end USART_Init()

void USART_Putc(unsigned char c)

{

  while (!(UCSRA & (1<<UDRE))); // Do nothing until data have been transmited 

  UDR = c;                // Put data into Buffer, sends the data

  _delay_ms(10);   

}//end USART_Putc()

void USART_Puts (char *string)

{

    while( *string != '\0' )  //as long as *string != '\0' so unlike the "stringer end-character"

    {  

        USART_Putc(*string);

        string++;

    }

}//end USART_Puts()

int main(void) 

{

  USART_Init();

  USART_Puts("\r\n");

  while(1) 

  {

    USART_Puts("Hey !!!!");  

  }

   return 0;                     

} //end main()