AVR Freaks

#include 
#include 

#define F_CPU 1000000UL

volatile unsigned char RDY, timp1, timp2;
long int data1, data2;

void init (void) {

	DDRC = 0x00;      // PORTC is input
	DDRB = 0xFF;       // PORTB is output
	DDRA = 0xFF;         // PORTA is output

	PORTA = 0x00;
	PORTB = 0x00;

	RDY = 0x00;

	MCUCR |= 0x03;  // set up interrupt (0x03 shows rising edge interrupt)
	GICR |= 0x40; //enable pin INT0 for use
	sei(); //interrupt enable
}

ISR (INT0_vect) {  //interrupt function with its vector
    RDY = 0xFF;     //if there's input, interrupt happends and set flag high
    cli();
}

int main (void) {

    int k, i;

    init();

	while (1) {

        if (RDY == 0xFF) {      //if interrupt flag is set high, start taking data

            timp1 = 0x00;
            timp2 = 0x00;
            data1 = 0x00;
            data2 = 0x00;

            TCCR1B |= (1 << CS10); // Set up timer

            while (TCNT1 <= 2304) //reset ADCs - 6conversion cycles
            {
                PORTB |= 0x02;  //SCLK high for 2304
            }

            PORTB &= ~0x02;  // then SCLK is set low

            TCNT1 = 0; // Reset timer value

            while (TCNT1 <= 40) {}  //waste at least 36CLK for DRDY mode

            for (i=2; i>=0; i--)  //long char takes 3 bytes data - 24bits
            {

                for (k=7; k>=0; k--) {  //int takes 8bits data - 1byte

                    timp1 |= (PINC0 << k);  //variables to store 8bits data
                    timp2 |= (PINC2 << k);

                    PORTB |= 0x02;  //toggle SCLK
                    PORTB &= ~0x02;
                }

                data1 |= timp1 << (i*8);    //atfer taking 8bits data, shift bytes in data1
                data2 |= timp2 << (i*8);

                PORTA = data1;      //bytes of data is shifted out through PORTA for observation
                PORTA = data2;

            }

            RDY = 0x00;
            sei();
        }
    }
	return(0);
}