#define F_CPU 3686400

#include <avr/io.h>
#include <util/delay.h>

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

void USART_Init( unsigned int ubrr) {

    // Baudrate einstellen
    UBRRH = (unsigned char) (ubrr>>8);
    UBRRL = (unsigned char) ubrr;

    // Receiver und Transmitter einstellen
    UCSRB = (1<<RXEN) | (1<<TXEN);

    // Frame-Format festlegen 8data, 2stop bit
    UCSRC = (1<<USBS)|(3<<UCSZ0);
}

unsigned char USART_Receive( void ) {

    // Auf empfangene Daten warten

    while ( !(UCSRA & (1<<RXC)) );

    return UDR;
}

void USART_Transmit( unsigned char data ) {

    /* Wait for empty transmit buffer */
    while ( !( UCSRA & (1<<UDRE)) );

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

char OneWire_Reset( void ) {

    char value;

    DDRB |= (1<<PB0);

    PORTB &= ~(1<<PB0);

    _delay_us(496);

    PORTB |= (1<<PB0);

    _delay_us(65);

    DDRB &= ~(1<<PB0);

    if(!(PINB & (1<<PINB0)))
        value = '1';
    else
        value = '0';

    _delay_us(424);

    return value;
}

int main (void) {

    DDRB = 0xFF;
    PORTB = 0xFF;

    USART_Init(MYUBRR);

    while(1) {

        USART_Transmit(OneWire_Reset());

        _delay_ms(2000);

    }

    return 0;
}