Paja

DS1307 Real time clock can tell time to Arduino. You can turn off Arduino as a small button battery is attached to the DS1307. Once you  set the right time on the DS1307, it can keep ticking up to 7 years.

The components you need:

• Realtime clock  DS1307  x 1
• Clock Crystal 32.768 kHz
• Battery Holder CR20xx  for a button cell
• Button cell  (Lithium Battery) 3V Ø 20 x 2,5 mm
• Arduino
• Arduino Software v1.0 (the example code  doesn’t work if it’s before v1.0)

 Arduino code