Tiny RTC

Arduino Tiny RTC I2C Real Time Clock Pinout
PIN	Description	Comment
BAT	Battery voltage	To monitor the battery voltage, or not connected
GND	Ground	Ground
VCC	5V supply	Power the module and charge the battery
SDA	I2C data	I2C data for the RTC
SCL	I2C clock	I2C clock for the RTC
DS	DS18B20 Temp. Sensor output	One wire inteface
SQ	Square wave output	Normally not used

The I2C wires "SDA" and "SCL" are the data line and clock line, they should be connected to the corresponding pins depending on the Arduino board.

Board	I2C / TWI pins
Uno, Ethernet	A4 (SDA), A5 (SCL)
Mega2560	20 (SDA), 21 (SCL)
Leonardo	2 (SDA), 3 (SCL)
Due	20 (SDA), 21 (SCL), SDA1, SCL1

Arduino LCD 1602