If you haven’t used I2C on your Raspberry Pi yet, it probably means that the I2C communication is not activated. To learn more about gpio headers: Raspberry Pi pinout guide | Arduino Uno pinout guide.

To make it simple, in this scenario the Raspberry Pi will impose 3.3V, which is not a problem for the Arduino pins. If the Raspberry Pi is configured as a master and the Arduino as a slave on the I2C bus, then you can connect the SDA and SCL pins directly. But in this specific case we can avoid using one. Usually you’d have to use a level converter between 3.3V and 5V. You should really pay attention when you connect 2 pins between those boards. You are learning how to use the combo Raspberry Pi + Arduino to build your own projects?Ĭheck out Raspberry Pi and Arduino and learn step by step. Important note: the Raspberry Pi 4 (and earlier) is running under 3.3V, and the Arduino Uno is running under 5V!

Connect the SCL (I2C clock) of the Pi (pin 3) to the Arduino SCL.

Connect the SDA (I2C data) of the Pi (pin 2) to the Arduino SDA.

Link the GND of the Raspberry Pi to the GND of the Arduino.

Make sure the Raspberry Pi detects the Arduino board on the I2C bus.

Raspberry Pi I2C master program with WiringPi.

Arduino wire library choose bus