scoppy/docs/wiki/Signal-Generator.md

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Signal Generator

Square Wave

Generates a square wave on GPIO 22. The frequency defaults to 1kHz.

Sine Wave (PWM)

Generates a square wave on GPIO 22 where the duty cycle changes according to the sine function. The frequency of the sine wave is 1kHz.

This PWM signal can be converted to a sine wave by the addition of a low pass filter. A filter using a 1k resistor and 0.1uF capacitor should work.

See this All About Circuits article for more information.