This project won the Pi Zero contest! I still don't have a Pi Zero, but the reward from the contest is going straight back into this project. I used some of the gift card money to buy a teensy3.2 with the audio+SD adapter board.

I've been really conflicted about using the Teensy+audio board because it feels like cheating. I actually breadboarded the audio circuitry and was in the process of debugging the audio input and frequency detection code for Arduino. Then I won the contest, discovered the audio board for the teensy and decided to change everything. Even though the arduino solution is vastly more complex, requires a lot more work, and gives much worse results, there is something more satisfying about designing and making it myself.

But anyway, this gives me a big step forward and I eagerly await the package. In the meantime, here is a list of the changes. They will be reflected in the description and parts list as well.

• A Teensy3.2 with audio adapter board will be in control rather than a Pi Zero or Arduino.
• The audio board will handle microphone input, output, and SD card connection.
• Frequency detection will be done using the Teensy's FFT capabilities.
• The notes will be painted blue or red and a simpler illumination method will be used, such as lighting up the note name or just some simple LEDs mounted on the notes. I need to try some things and see what looks best.

Here is a simple diagram of the electronics

Now I'm off to delve into the teensy audio library to learn how to program this thing.