The aim of the project is to create a tuner for musical instruments but with a particular interface: an object turns counterclockwise if the frequency of the played note is too high and clockwise if it is too low.
The non-binding specifications have allowed a lot of freedom in the realization: the rotation is shown using a ring of LEDs, and the audio processing is done on an Arduino. A display is used to show the note you selected and a small speaker allows to listen to it for a rough first tuning. For simplicity, it was restricted to a guitar, but the idea can be expanded or modified to adapt to any instrument!

The main goal was to obtain a compact device, to carry with you along with the guitar, and at a low cost, to stay in line with what the market already offers.
An Arduino Nano was chosen due to its small size and sufficient processing power, accompanied by a crown of 16 LEDs and a display of less than an inch.
On the dedicated page you can find components, schematics and assembly instructions!

To find the right tuning, a series of audio samples are recorded, and then processed via FFT to find the main frequency of the signal. Then this is compared with the correct frequencies and it is decided what to display.
You can find the complete code on GitLab, while in the dedicated section you can find explanations of how it works and the libraries used.