Grove – High Precision RTC

Key Features

Provides year, month, day, weekday, hours, minutes, and seconds based on a 32.768 kHz quartz crystal
Clock operating voltage: 0.9 V to 5.5 V
Low current: typical less than 1.2 uA at VDD = 3.3 V and Tamb = 25 degree C
Up to 400 kHz two-line I 2 C-bus interface (at VDD = 1.8 V to 5.5 V)
Programmable clock output for peripheral devices (32.768 kHz, 16.384 kHz, 8.192 kHz, 4.096 kHz, 2.048 kHz, 1.024 kHz, and 1 Hz)
Selectable integrated oscillator load capacitors for CL = 7 pF or CL = 12.5 pF
Minute and half minute interrupt
Internal Power-On Reset (POR)
Programmable offset register for frequency adjustment
Compatible platform: Arduino, BeagleBone Green, BeagleBone Green Wireless etc.

Resources
Wiki