Saving Date and Time using a DS1307

The arduino has no time information. First I wanted to use NTP, but one HTTP client (the one sending the sensor data to the server) is enough difficulty for this problem. A friend of mine build a board similar to this setup: .

For initializing and reading the date/time information I use the code from .

Now I have date/time information for writing the sensor data to the SD card in the future.