#include <avr/io.h>
#include <avr/interrupt.h>
#define F_CPU 12000000
#include <util/delay.h>
#define BAUD 9600
#define UBRR_VAL F_CPU/16/BAUD-1

void delay_ms(int delay) {
        int i;
        for (i=0;i<=delay;i++) {
                _delay_ms(1);
        }
}

void init_uart(unsigned int ubrr) {
        UBRRH = (unsigned char)(ubrr>>8);
        UBRRL = (unsigned char)(ubrr);
        UCSRB |= (1<<RXEN);
        UCSRB |= (1<<TXEN);
        UCSRB |= (1<<RXCIE);
        UCSRC = (1<<URSEL)|(1<<USBS)|(3<<UCSZ0);
}

void send_char(unsigned char data) {
        while (!(UCSRA & (1<<UDRE)));
        UDR = data;
}

void send_string(char *data) {
        while (*data) {
                send_char(*data);
                data++;
        }
}
ISR(USART_RXC_vect) {
        send_string("Interrrupt!!!");
}

int main(void) {
        init_uart(UBRR_VAL);
        DDRC |= (1<<PC5);
        sei();
        while (1) {
                PORTC &= (!(1<<PC5));
                delay_ms(1000);
                send_string("Hallo");
                send_char(0x0A);
                PORTC |= (1<<PC5);
                delay_ms(1000);
        }
        return 1;
}