ds3231test.c

#include <bcm2835.h>  
#include <stdio.h>
#include <unistd.h>

//regaddr,seconds,minutes,hours,weekdays,days,months,yeas
char  buf[]={0x00,0x00,0x43,0x15,0x05,0x01,0x03,0x19};
char  *str[]  ={"SUN","Mon","Tues","Wed","Thur","Fri","Sat"};
void pcf8563SetTime(uint8_t * buf)
{
    bcm2835_i2c_write(buf,8);
}

void pcf8563ReadTime(uint8_t * buf) 
{   
    buf[0] = 0x00;  
    bcm2835_i2c_write_read_rs(buf ,1, buf,7);  
} 

int main(int argc, char **argv)
{
    if (!bcm2835_init())
    {
	printf("bcm2835_init failed. Are you running as root??\n");
	return 1;
    }
    
    if (!bcm2835_i2c_begin(2))
    {
	printf("bcm2835_i2c_begin failed. Are you running as root??\n");
	return 1;
    }
      
    bcm2835_i2c_setSlaveAddress(0x68);  
    bcm2835_i2c_set_baudrate(10000);  
    printf("DS3231 Test Program ...\n\n"); 
   	
    //pcf8563SetTime(buf); 
    while(1)  
    {  
       	pcf8563ReadTime(buf);
	buf[0] = buf[0]&0x7F; //sec
	buf[1] = buf[1]&0x7F; //min
	buf[2] = buf[2]&0x3F; //hour
	buf[3] = buf[3]&0x07; //week
	buf[4] = buf[4]&0x3F; //day
	buf[5] = buf[5]&0x1F; //mouth
	//year/month/day
	printf("20%02x-%02x-%02x ",buf[6],buf[5],buf[4]);
	////hour:minute/second
	printf("%02x:%02x:%02x ",buf[2],buf[1],buf[0]);
	////weekday
	printf("%s\n",str[(unsigned char)buf[3]]);
	bcm2835_delay(1000); 
    }  

    bcm2835_i2c_end(2);  
    bcm2835_close();  
      
    return 0;  
}