This is an FM synthesizer running on an Analog Devices ADSP-BF706 DSP chip, all packed into a tiny Arduino-compatible feather form factor! Perfect for those 80’s FM keyboard sounds.

To view the code check out the Blackfin+ Arduino core on github: deanm1278/ArduinoCore-blackfin
And the accompanying AudioFX library: deanm1278/audioFX // Read more: original article.