#include <Wire.h>

int clockAddress = 0x68;  // This is the I2C address
int command = 0;  // This is the command char, in ascii form, sent from the serial port     
long previousMillis = 0;  // will store last time Temp was updated
byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
byte test; 

// 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) );
}

// 1) Sets the date and time on the ds1307
// 2) Starts the clock
// 3) Sets hour mode to 24 hour clock
// Assumes you're passing in valid numbers, 
// Probably need to put in checks for valid numbers.
void setDateDs1307()                
{
  // Use of (byte) type casting and ascii math to achieve result.  
  second = (byte) ((Serial.read() - 48) * 10 + (Serial.read() - 48)); 
  minute = (byte) ((Serial.read() - 48) *10 +  (Serial.read() - 48));
  hour  = (byte) ((Serial.read() - 48) *10 +  (Serial.read() - 48));
  dayOfWeek = (byte) (Serial.read() - 48);
  dayOfMonth = (byte) ((Serial.read() - 48) *10 +  (Serial.read() - 48));
  month = (byte) ((Serial.read() - 48) *10 +  (Serial.read() - 48));
  year= (byte) ((Serial.read() - 48) *10 +  (Serial.read() - 48));
  Wire.beginTransmission(clockAddress);
  Wire.write(byte(0x00));
  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();
}

// Gets the date and time from the ds1307 and prints result
void getDateDs1307() {
  // Reset the register pointer
  Wire.beginTransmission(clockAddress);
  Wire.write(byte(0x00));
  Wire.endTransmission();

  Wire.requestFrom(clockAddress, 7);

  // A few of these need masks because certain bits are control bits
  second     = bcdToDec(Wire.read() & 0x7f);
  minute     = bcdToDec(Wire.read());
  
  // Need to change this if 12 hour am/pm
  hour       = bcdToDec(Wire.read() & 0x3f);  
  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);

}


void setup() {
  Wire.begin();
  Serial.begin(57600);
}

void loop() {
  if (Serial.available()) {  // Look for char in serial que and process if found
    command = Serial.read();
    if (command == 84) {      //If command = "T" Set Date
      setDateDs1307();
      getDateDs1307();
      Serial.println(" ");
    }
    else if (command == 81) {  //If command = "Q" RTC1307 Memory Functions
      delay(100);     
      if (Serial.available()) {
        command = Serial.read(); 
        
        // If command = "1" RTC1307 Initialize Memory - All Data will be set to 255 (0xff).  
        // Therefore 255 or 0 will be an invalid value.  
        if (command == 49) { 
          
          // 255 will be the init value and 0 will be cosidered an error that 
          // occurs when the RTC is in Battery mode. 
          Wire.beginTransmission(clockAddress);
          
          // Set the register pointer to be just past the date/time registers.
          Wire.write(byte(0x08));  
          for (int i = 1; i <= 27; i++) {
            Wire.write(byte(0xff));
            delay(100);
          }   
          Wire.endTransmission();
          getDateDs1307();
          Serial.println(": RTC1307 Initialized Memory");
        }
        else if (command == 50) {      //If command = "2" RTC1307 Memory Dump
          getDateDs1307();
          Serial.println(": RTC 1307 Dump Begin");
          Wire.beginTransmission(clockAddress);
          Wire.write(byte(0x00));
          Wire.endTransmission();
          Wire.requestFrom(clockAddress, 64);
          for (int i = 1; i <= 64; i++) {
            test = Wire.read();
            Serial.print(i);
            Serial.print(":");
            Serial.println(test, DEC);
          }
          Serial.println(" RTC1307 Dump end");
        } 
      }  
    }
    Serial.print("Command: ");
    Serial.println(command);  // Echo command CHAR in ascii that was sent
  }

  command = 0;  // reset command                  
  delay(100);
}