DS1307 RTC module

Product info
This moduel is based on DS1307 RTC chip. There are two types of chip, genuine Dallas DS1307 or HGSEMI DS1307. The module communicates via I2C bus. The CR2032 battery NOT included!
Pin header
Pin header is NOT installed (unsoldered) by default.
Arduino and DS1307 module connection
Arduino - DS1307
5V - Vcc
GND - GND
A5 - SCL
A4 - SDA
Do not connect SQW pin!
Download Arduino UNO and Nano sample code here.
Prices
DS1307 module with genuine Dallas DS1307 chip: €5.6
DS1307 module with HGSEMI DS1307 chip: €2.8