The Tiny Code Reader from Useful Sensors is a small, low-cost hardware module that reads QR codes. It's designed to be a simple way to provision a system, for example, by providing the Wi-Fi network name and password or providing input when there's no keyboard.

Internally, the Tiny Code Reader bundles an image sensor and a small microcontroller into a single board, but to make it as easy as possible to build into products, the folks at Useful Sensors wanted to hide those implementation details. It returns information about any QR codes it sees over an I2C connection.

The board uses a standard STEMMA QT / Qwiic connector for the I2C interface. If you're using a standard connector, the wire colors are yellow for SCL, blue for SDA, red for 3.3V, and black for GND. The sensor supports I2C bus speeds of up to 400k baud with 3.3V power; other voltage levels (like, 5V) are not supported.

The sensor uses an image sensor internally, so you need to make sure that the lens has a clear field of view. It can be mounted in any orientation, which shouldn't affect the code recognition quality. There's a mounting hole for a screw in the top left, and some alternative pads in case you don't want to use a QT connector but want to wire in directly. The edge with these pads is designed to snap off, in case you need to reduce the size of the board further.

There's even some example code for CircuitPython here!