Conclusion
The original Otamatone, a purely analog japanese musical synthesizer, was extremely difficult to play. There are larger distances between the higher notes than the lower notes on the ribbon controller so that an inexperienced player could hardly tell what exact note he or she will be playing when pressing on a certain part of the ribbon. However, with our Embedded control of digital otamatone, everyone can play an otamatone easily with an external keyboard and enjoy its beautiful (or note) melody.
Future Works
To be honest, we don't picture ourselves working on this project again in the future, but who knows! Here is the future works section!
Custom PCB and Otamatone Fleet
The circuit is not that complicated, but it's complicated enough that we believe the project will benefit from custom PCBs. Currently, we are soldering AA batteries to supply the 4.5V power needed by the Otamatone PCB, and also the 3V power needed by the relays. With a custom PCB, we may be able to get away with a single power supply for both sources, and possible a compact form factor that fits into the original Otamatone enclosure. We can also replace the four digital potentiometers with one 100 kOhm digit pot chip to reduce the size.
We can also add another relay into the circuit to widen the covered music notes of one Digital Otamatone. We can then add more Otamatones and have them cover different octaves by a central controller.
Melody Extraction and Replay
Our original plan was to add a melody extraction feature such that a user can sing a song, and the RPi can extract the melody and play it through the Otamatone. The RPi can also record some melodies for the user to replay. This can also be made a web service: people can upload wav files to the RPi can there can be a live stream that sends back the sound played by the Otamatone.
But anyway, we may (probably won't) get back to this project and add some features to it in the future. Meanwhile, if anyone is interested in building off of this project, please feel free to do so :)