Using this address, master selects a particular slave for data transmission (send or receive) and the selected slave responds according to request. I made an extensive tutorial on basics of I 2C Communication. For more information on that, visit “ Basics of I2C Communication”. I2C in ArduinoĪrduino supports I2C Communication. If you take a look at the pinout of Arduino UNO from the tutorial “ ARDUINO UNO PINOUT”, Analog Input pins A4 and A5 have an alternative function of I2C.

The A4 pin acts as SDA while the A5 pin acts as SCL.

In R3 of original Arduino UNO, there are two more pins near Digital IO Pin 13 (near the USB socket), dedicated to SDA and SCL. If you are using any other board then the following table will be useful to you as it describes the I2C pins on all the popular Arduino boards.ĪTmega328P Microcontroller used in Arduino UNO and Nano supports I2C Data Transfer speeds up to 400 kHz. To demonstrate the working of I2C in Arduino, let us build a small circuit. In this demo, I connected two Arduino UNO boards to communicate over I2C Bus.

To make things interesting and actually see the communication, I added a couple of LEDs and Potentiometers (one set for each UNO Board). The potentiometers are connected to respective Analog Input pins (A0) and the LEDs are connected to a Digital IO Pin with PWM (Pin 9). One UNO board is configured as I2C Bus Master and the other UNO is configured as a Slave device.

Attiny88 wire library