A lot of breakout boards use Inter-Integrate Circuit (I2C) to communicate with the host microcontroller. This is a nice general purpose communication bus that only requires two pins for the data transmission. When using breakouts that include STEMMA or STEMMA QT connectors, usage is essentially plug-and-play.

However, sometimes things just don't seem to work for some reason. When that happens, the best initial troubleshooting step is to do an I2C scan. This is a simple "Hey! Who's out there?" sort of sanity check.

In this guide, we show how to perform an I2C scan on various platforms and provide some guidance on how to use the results to aid in troubleshooting.