#include "Wire.h"
#define DS1307_I2C_ADDRESS 0x68  // the I2C address of Tiny RTC
byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
// Convert normal decimal numbers to binary coded decimal
byte decToBcd(byte val)
{
 return ( (val/10*16) + (val%10) );
}
// Convert binary coded decimal to normal decimal numbers
byte bcdToDec(byte val)
{
 return ( (val/16*10) + (val%16) );
}
// Function to set the currnt time, change the second&minute&hour to the right time
void setDateDs1307()                
{
  second =45; 
  minute = 29;
  hour  = 13;
  dayOfWeek = 2;
  dayOfMonth =18;
  month =9;
  year= 12;
  Wire.beginTransmission(DS1307_I2C_ADDRESS);
  Wire.write(decToBcd(0));
  Wire.write(decToBcd(second));    // 0 to bit 7 starts the clock
  Wire.write(decToBcd(minute));
  Wire.write(decToBcd(hour));      // If you want 12 hour am/pm you need to set
                                  // bit 6 (also need to change readDateDs1307)
  Wire.write(decToBcd(dayOfWeek));
  Wire.write(decToBcd(dayOfMonth));
  Wire.write(decToBcd(month));
  Wire.write(decToBcd(year));
  Wire.endTransmission();
}
// Function to gets the date and time from the ds1307 and prints result
void getDateDs1307()
{
 // Reset the register pointer
 Wire.beginTransmission(DS1307_I2C_ADDRESS);
 Wire.write(decToBcd(0));
 Wire.endTransmission();
 Wire.requestFrom(DS1307_I2C_ADDRESS, 7);
 second     = bcdToDec(Wire.read() & 0x7f);
 minute     = bcdToDec(Wire.read());
 hour       = bcdToDec(Wire.read() & 0x3f);  // Need to change this if 12 hour am/pm
 dayOfWeek  = bcdToDec(Wire.read());
 dayOfMonth = bcdToDec(Wire.read());
 month      = bcdToDec(Wire.read());
 year       = bcdToDec(Wire.read());  
 Serial.print(hour, DEC);
 Serial.print(":");
 Serial.print(minute, DEC);
 Serial.print(":");
 Serial.print(second, DEC);
 Serial.print("  ");
 Serial.print(month, DEC);
 Serial.print("/");
 Serial.print(dayOfMonth, DEC);
 Serial.print("/");
 Serial.print(year,DEC);
 Serial.print("  ");
 Serial.println();
 //Serial.print("Day of week:");
}
void setup() {
 Wire.begin();
 Serial.begin(19200);
 setDateDs1307(); //Set current time;
}
void loop() 
{
 delay(2000);
 getDateDs1307();//get the time data from tiny RTC
 }