AVR UART Datei senden und Empfanfangen

//

// Datei uart.c

// MCU: Atmega16

//

#include <avr/io.h>

// CHECK F_CPU WITH HARDWARE OSZILLATOR SETTING !!!!

#define F_CPU 1000000UL

#define UART_BAUD 9600

void uart_init(void);

unsigned char uart_getc(void);

int uart_putc(unsigned char c);

void uart_puts (char *s);

int main(void)

{

   unsigned char c;

   uart_init();

   uart_puts("hello world!\r\n\r\n");

   while(1)

   {

      // Poll

      c = uart_getc();

      // Funny conversion

      if (c >= 'a' && c <= 'z')

         c += 'A' - 'a';

      else if (c >= 'A' && c <= 'Z')

         c += 'a' - 'A';

      // Echo

      uart_putc(c);

   }

   return 0;

}

void uart_init(void)

{

    UCSRB |= (1<<TXEN) |(1<<RXEN);  // tx/rx enable

    UCSRC |= (1<<URSEL)|(3<<UCSZ0); // Asynchron 8N1

#if F_CPU < 2000000UL && defined(U2X)

    UCSRA |= (1<<U2X);   /* improve baud rate error by using 2x clk */

    UBRRL = (F_CPU / (8UL * UART_BAUD)) - 1;

#else

    UBRRL = (F_CPU / (16UL * UART_BAUD)) - 1;

#endif

}

int uart_putc(unsigned char c)

{

    while (!(UCSRA & (1<<UDRE)))  /* warten bis Senden moeglich */

    {

    }

    UDR = c;                      /* sende Zeichen */

    return 0;

}

void uart_puts (char *s)

{

    while (*s)

    {   /* so lange *s != '\0' also ungleich dem "String-Endezeichen" */

        uart_putc(*s);

        s++;

    }

}

unsigned char uart_getc(void)

{

    while (!(UCSRA & (1<<RXC)))   // warten bis Zeichen verfuegbar

        ;

    return UDR;        // Zeichen aus UDR an Aufrufer zurueckgeben

}