DUE FFT

https://votecharlie.com/blog/2016/03/fft-examples.html

https://www.arduinolibraries.info/libraries/arduino-fft

Прочитать!

https://www.waitingforfriday.com/?p=53

http://wiki.openmusiclabs.com/wiki/ArduinoFHT

FFT для меги

http://arduino.ru/projects/analizator-spektra-zvuka-na-arduino

https://www.arduinolibraries.info/libraries/arduino-fft

http://wiki.openmusiclabs.com/wiki/ArduinoFFT