The I2C or “I squared C” bus is a simple way to transfer data between different integrated circuits, boards or sensors in your Arduino project. I2C stands for “Inter-Integrated Circuit”. One of the great things about I2C is that it only requires two connections to your Arduino, SDA (data) and SCL (clock), and you can easily connect multiple devices to the bus. If you want to learn more about the I2C bus checkout this tutorial from tronixstuff, or this tutorial from How To Mechatronics.
One of our products that uses an I2C interface is our RELAY8: 8-channel relay driver shield.
You can drive up to 8 relays from your Arduino using just 2 I/O pins with this shield. It communicates with your board using I2C, so you can even stack several shields together to drive 16, 24, or more outputs! Includes back-EMF protection and works with a wide range of relays. Perfect for home automation projects! For more information and to order, click here.