Tiny RTC I2C

http://tiptopboards.free.fr/arduino_forum/viewtopic.php?t=5&p=5

https://breadboardtronics.wordpress.com/2013/08/27/at24c32-eeprom-and-arduino/

https://github.com/Naguissa/uRTCLib support du DS1307 ET de l'EEPROM AT24CP