There&#x27;s been info on doing this with Espruino for about a year now: <a href="http:&#x2F;&#x2F;www.espruino.com&#x2F;Headphone" rel="nofollow">http:&#x2F;&#x2F;www.espruino.com&#x2F;Headphone</a>. There&#x27;s even an online-only version of the Web IDE that does two-way communications: <a href="http:&#x2F;&#x2F;espruino.github.io&#x2F;EspruinoWebIDE" rel="nofollow">http:&#x2F;&#x2F;espruino.github.io&#x2F;EspruinoWebIDE</a><p>With 3.3v logic, it turns out you don&#x27;t even need the transistor - just a capacitor and bias resistors.