Raspberry Pi RTC Module

 

Mini Real Time Clock module is designed for Raspberry Pi, but can also be used with Arduino. It plugs into the Raspberry Pi GPIO interface and you don't need to make any other connections. 

There is a battery input on the board and maintains accurate timekeeping when the device's main power is cut off. RTC keeps seconds, minutes, hours, day, date, month and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap years. The clock operates in either a 24-hour or 12-hour clock with an AM/PM indicator.