- from Stephen Crane github
- requires an amplifier on the PWM output pin, e.g., this one
- original implementation by Clive Webster in Webbotlib
- ported to Arduino by Gabriel Petrut
- Stephen Crane modified it to use pins other than pin 10 with the help of this tutorial
- see blog articles
- add support for ARM processors with DAC
- PWM filter not required with DAC, but still need audio amp and speaker. DACs can source only about 1 ma
- tested on Teensy 3.2, 3.5, 3.6, LC, DUE, ZERO/circuitplayground express
- Teensy forum
- separate port/hack for MBED ARM with DAC repository
- also added AVR support for Leonardo pin 5 (timer 3)