On the one hand I cringe at using the audio input for effectively a DC signal, but on the other hand it is probably sitting there unused on a lot of machines so it isn&#x27;t like you&#x27;re losing a capability. As with many folks I&#x27;d probably use a small uC and have it emulate a keyboard (maximal re-use of known interfaces) but hats off to the creative use of pulseaudio.