set_RTC_Clock.ino

///////////////////////////////////////////
 // RTC data and time setter              //
 //                                       //
 // This sample program allows the user   //
 // to set the date and time of an RTC    //
 // using I2C.                            //
 //                                       //
 // Codes by:                             //
 // eGizmo Mechatronix Central            //
 // Taft, Manila, Philippines             //
 // http://www.egizmo.com                 //
 // April 15, 2013                        //
 ///////////////////////////////////////////

 #include <Wire.h>
 const int DS1307 = 0x68; // Address of DS1307 see data sheets
 const char* days[] =
 {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
 const char* months[] =
 {"January", "February", "March", "April", "May", "June", "July", "August","September", "October", "November", "December"};
  
 // Initializes all values: 
 byte second = 0;
 byte minute = 0;
 byte hour = 0;
 byte weekday = 0;
 byte monthday = 0;
 byte month = 0;
 byte year = 0;

 void setup() {
   Wire.begin();
   Serial.begin(9600);
   delay(2000); // This delay allows the MCU to read the current date and time.
  
   Serial.print("The current date and time is: ");
   printTime();
   Serial.println("Please change to newline ending the settings on the lower right of the Serial Monitor");
   Serial.println("Would you like to set the date and time now? Y/N");
  
   while (!Serial.available()) delay(10);
   if (Serial.read() == 'y' || Serial.read() == 'Y')
  
   // This set of functions allows the user to change the date and time
   {
     Serial.read();
     setTime();
     Serial.print("The current date and time is now: ");
     printTime();
   }
  
  
   Serial.println("Thank you.");
 }

 // Continuous function for converting bytes to decimals and vice versa
 void loop() {
 }
 byte decToBcd(byte val) {
   return ((val/10*16) + (val%10));
 }
 byte bcdToDec(byte val) {
   return ((val/16*10) + (val%16));
 }


 // This set of codes is allows input of data
 void setTime() {
   Serial.print("Please enter the current year, 00-99. - ");
   year = readByte();
   Serial.println(year);
   Serial.print("Please enter the current month, 1-12. - ");
   month = readByte();
   Serial.println(months[month-1]);
   Serial.print("Please enter the current day of the month, 1-31. - ");
   monthday = readByte();
   Serial.println(monthday);
   Serial.println("Please enter the current day of the week, 1-7.");
   Serial.print("1 Sun | 2 Mon | 3 Tues | 4 Weds | 5 Thu | 6 Fri | 7 Sat - ");
   weekday = readByte();
   Serial.println(days[weekday-1]);
   Serial.print("Please enter the current hour in 24hr format, 0-23. - ");
   hour = readByte();
   Serial.println(hour);
   Serial.print("Please enter the current minute, 0-59. - ");
   minute = readByte();
   Serial.println(minute);
   second = 0;
   Serial.println("The data has been entered.");
  
   // The following codes transmits the data to the RTC
   Wire.beginTransmission(DS1307);
   Wire.write(byte(0));
   Wire.write(decToBcd(second));
   Wire.write(decToBcd(minute));
   Wire.write(decToBcd(hour));
   Wire.write(decToBcd(weekday));
   Wire.write(decToBcd(monthday));
   Wire.write(decToBcd(month));
   Wire.write(decToBcd(year));
   Wire.write(byte(0));
   Wire.endTransmission();
   // Ends transmission of data
 }


 byte readByte() {
   while (!Serial.available()) delay(10);
   byte reading = 0;
   byte incomingByte = Serial.read();
   while (incomingByte != '\n') {
     if (incomingByte >= '0' && incomingByte <= '9')
       reading = reading * 10 + (incomingByte - '0');
     else;
     incomingByte = Serial.read();
   }
   Serial.flush();
   return reading;
 }


 void printTime() {
   char buffer[3];
   const char* AMPM = 0;
   readTime();
   Serial.print(days[weekday-1]);
   Serial.print(" ");
   Serial.print(months[month-1]);
   Serial.print(" ");
   Serial.print(monthday);
   Serial.print(", 20");
   Serial.print(year);
   Serial.print(" ");
   if (hour > 12) {
     hour -= 12;
     AMPM = " PM";
   }
   else AMPM = " AM";
   Serial.print(hour);
   Serial.print(":");
   sprintf(buffer, "%02d", minute);
   Serial.print(buffer);
   Serial.println(AMPM);
 }


 void readTime() {
   Wire.beginTransmission(DS1307);
   Wire.write(byte(0));
   Wire.endTransmission();
   Wire.requestFrom(DS1307, 7);
   second = bcdToDec(Wire.read());
   minute = bcdToDec(Wire.read());
   hour = bcdToDec(Wire.read());
   weekday = bcdToDec(Wire.read());
   monthday = bcdToDec(Wire.read());
   month = bcdToDec(Wire.read());
   year = bcdToDec(Wire.read());
 }