# How to Scan and Detect I2C Addresses

## Overview

![I2C](https://cdn-learn.adafruit.com/assets/assets/000/044/476/medium640/sensors_i2cdemo_bb.png?1501383863)

A **lot** of breakout boards use [Inter-Integrate Circuit (I2C)](https://en.wikipedia.org/wiki/I%C2%B2C) 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](https://learn.adafruit.com/introducing-adafruit-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.

- [Next Page](https://learn.adafruit.com/scanning-i2c-addresses/i2c-basics.md)

## Featured Products

### TCA9548A I2C Multiplexer

[TCA9548A I2C Multiplexer](https://www.adafruit.com/product/2717)
You just found the perfect I2C sensor, and you want to wire up two or three or more of them to your Arduino when you realize "Uh oh, this chip has a fixed I2C address, and from what I know about I2C, you cannot have two devices with the same address on the same SDA/SCL pins!" Are you...

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[Related Guides to the Product](https://learn.adafruit.com/products/2717/guides)
### Adafruit TCA4307 Hot-Swap I2C Buffer with Stuck Bus Recovery

[Adafruit TCA4307 Hot-Swap I2C Buffer with Stuck Bus Recovery](https://www.adafruit.com/product/5159)
As we've been adding  [STEMMA QT connectors](https://learn.adafruit.com/introducing-adafruit-stemma-qt/what-is-stemma-qt) to our breakouts and dev boards, folks have been really enjoying the simplicity and speed of plugging in I2C sensors and devices for quick iteration and...

In Stock
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[Related Guides to the Product](https://learn.adafruit.com/products/5159/guides)

## Related Guides

- [Adafruit TCA4307 Hot-Swap I2C Buffer](https://learn.adafruit.com/adafruit-tca4307.md)
- [MIDI Laser Harp with Time of Flight Distance Sensors](https://learn.adafruit.com/midi-laser-harp-time-of-flight-sensors.md)
- [Working with Multiple Same Address I2C Devices](https://learn.adafruit.com/working-with-multiple-i2c-devices.md)
- [Working with I2C Devices](https://learn.adafruit.com/working-with-i2c-devices.md)
- [I2C Addresses and Troublesome Chips](https://learn.adafruit.com/i2c-addresses.md)
- [Adafruit TCA9548A 1-to-8 I2C Multiplexer Breakout](https://learn.adafruit.com/adafruit-tca9548a-1-to-8-i2c-multiplexer-breakout.md)
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