Real-time Clock (RTC) for Arduino
Grove real-time clock (RTC) for Arduino. Includes DS1307 chip. Communicates via I2C. Requires BR1225/CR1225 battery (included). Includes 20cm Grove cable. No soldering required (assuming you have an Arduino with a Grove shield). The clock/calendar provides seconds, minutes, hours, day, month, and year. Includes 56-byte, battery-backed, nonvolatile (NV)RAM for data storage. Sample code available at ManyLabs.org.