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I'm trying to emulate via Arduino the volume down button of the remote mounted on iphone earbuds, and I can't find anywhere how that function is achieved; I imagine that certain passive components housed in the earbuds are shorted to the mic-gnd TRRS pins (upper ring and sleeve), but I can't really figure which ones.

Thanks.

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I found this form to have some answers. It looks like pressing different buttons shorts the signal pin and ground with different resistor values. In this diagram, that would be pin 3 for GND and pin 4 for signal.

Colin G
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See here the volume buttons are connected to a little IC inside the remote. It's a little more complicated than you'd expect, using little chirps instead of just passives.

Some Hardware Guy
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