This is based on the Sine Wave example provided by the official Raspberry Pi Pico Playground: https://github.com/raspberrypi/pico-playground/tree/master/audio/sine_wave.
Requirements:
- Raspberry Pico SDK
- Pico-Extras (https://github.com/raspberrypi/pico-extras)
In this one, the example from the playground source has been simplified by having the SPDIF and the I2S defines and related code removed, leaving only the PWM audio example that can be directly tested, or can be used as a foundation for other Pico Audio PWM projects.