ATMega2561 und UART

#include <stdio.h>

#include <avr/io.h>

#include <avr/wdt.h>

//USART

#define FOSC 16000000 //Clock speed

#define BAUD 2400

#define MYUBRR (FOSC/16/BAUD-1)

void delay_ms(unsigned int period);

void USART1_Init(unsigned int);

void USART_Transmit(unsigned char);

unsigned char USART_Receive(void);

void USART1_Init(unsigned int ubrr)

{

  /*Set baud rate*/

  UBRR1H = (unsigned char) (ubrr>>8);

  UBRR1L = (unsigned char) ubrr;

  /*Enable receiver and transmitter*/

  UCSR1B = (1<<RXEN1)|(1<<TXEN1);

  /*Set frame format: 8data, 1 stop bit */

  UCSR1C = (1<<USBS0)|(1<<UCSZ00);

}

/*USART Transmit*/

void USART_Transmit(unsigned char data)

{

  /*Wait for empty transmit buffer*/

  while(!(UCSR1A & (1<<UDRE1)));

  /*Put data into buffer, sends the data*/

  UDR1=data;

}

/*USART Receive*/

unsigned char USART_Receive(void)

{

  /*Wait for data to be reiceved*/

  while(!(UCSR1A & (1<<RXC1)));

  /*Get and return received data from buffer*/

  return (UDR1);

}

int main(void)

{

  USART1_Init(MYUBRR);

  while(1)

  {  

    USART_Transmit('a');

    delay_ms(1000);

  } 

  return 0; 

}

/*-----------------------------------------------------------------------*/

//  Enhanced delay-routine (wait) as as the standard delay routine (_delay_ms) is not able to delay

//  more than 17 ms maximum as of the used 8-bit-timer (depending on used crystal)

void delay_ms(uint16_t period)   //delay routine (milliseconds)

{

  for(unsigned int i=0; i<=period; i++)

    _delay_ms(1);

}