bitcount = 0x00;
data = 0x00;
ISR(INT0_vect)
{
        /*
        if(bit_is_set(PIND, KBD_DATA_PIN))
                send_character('1');
        else
                send_character('0');
        */
        if(bitcount > 0 && bitcount < 9)
        {
                if(bit_is_set(PIND, KBD_DATA_PIN)) // Button pressed
                {
                        data |= (0x01 << (bitcount - 1));
                }
        }

        if(++bitcount == 11)
        {
                char string[10];
                sprintf(string, "%02X", data);
                send_string(string);
                data = 0x00;
                bitcount = 0x00;
        }
}