Tom's Life Bits

Each I2C device has an address. The DS1307 chip address is 0x68.

The Ram on the device starts at address 0x08. The first 7 locations are the RTC.

To get to the start of RAM, use the following code:

   Wire.beginTransmission(DS1307_ADDRESS);   
   Wire.send(8);	
   Wire.endTransmission();

This will set the I2C address to 0x68, the DS1307 Address.
The second line sets the register index to 8, the start of RAM.
The third line, Wire.endTransmission(); , transmits the sequence.

Subsequent reads from the chip will start at 8. For example, to read 4 bytes from the chip:

   Wire.requestFrom(DS1307_ADDRESS, 4);

This will put the 4 bytes into the receive buffer. To fetch the bytes:

   while(Wire.available())    // slave may send less than requested
   { 
    byte c = Wire.receive(); // receive a byte as character
    Serial.print(c, HEX);         // print the character
    Serial.print(" ");
   }