Mike8748

#include <avr/interrupt.h>typedef struct { 	unsigned char second;	unsigned char minute;	unsigned char hour;                                     	unsigned char date;       	unsigned char month;	unsigned int year;     	unsigned char changed;} time_t;time_t time={0,0,12,1,1,2007};char not_leap(void)      //check for leap year{    if (!(time.year%100)) return (char)(time.year%400);    			     else return (char)(time.year%4);}         SIGNAL(SIG_OVERFLOW2) //overflow interrupt vector{     if (++time.second==60)        //keep track of time, date, month, and year    {        time.second=0;        if (++time.minute==60)         {            time.minute=0;            if (++time.hour==24)            {                time.hour=0;                if (++time.date==32)                {                    time.month++;                    time.date=1;                }                else if (time.date==31)                 {                                        if ((time.month==4) || (time.month==6) || (time.month==9) || (time.month==11))                     {                        time.month++;                        time.date=1;                    }                }                else if (time.date==30)                {                    if(time.month==2)                    {                       time.month++;                       time.date=1;                    }                }                              else if (time.date==29)                 {                    if((time.month==2) && (not_leap()))                    {                        time.month++;                        time.date=1;                    }                                }                                          if (time.month==13)                {                    time.month=1;                    time.year++;                }            }        }    }  	time.changed=1;}   void RTC_init(void){		TIMSK2 = 0;             // disable OCIE2A and TOIE2	ASSR = (1<<AS2);        // select asynchronous operation of Timer2	TCNT2 = 0;              // clear TCNT2A	TCCR2B = (1<<CS22) | (1<<CS20);             // select precaler: 32.768 kHz / 128 = 1 sec between each overflow	while(ASSR & (0x01 | 0x04));       // wait for TCN2UB and TCR2UB to be cleared	TIFR2 = 0xFF;           // clear interrupt-flags	TIMSK2 = (1<<TOIE2);    // enable Timer2 overflow interrupt}int main(void){RTC_init();sei();while(1) { }