How earphone remotes (with play/skip buttons) work on a single wire

The linked answer is close, but not entirely correct. There isn't a specialized wire for buttons; it uses the microphone line.<p>Play/pause will usually be connected directly to ground. The other functions connect to ground through different impedances. While each impedance level is roughly twice the last one (which makes the detection circuit simpler) having one level at 1 ohm and the next at 2 ohms is not practical due to noise. Also, due to the way that parallel impedances work, you do not get a binary encoding of the buttons pressed. (Do you ever really want to skip the track and increase the volume at the same time anyway?)

But what I want to know is then how the microphone signal is implemented with the 4-wire system, in addition to playback controls.

Why does the title include "on a single wire"?<p>The current stackexchange question does not use the phrase "single wire" and more importantly nothing about your headphones will work with a single wire.

A little off topic, but this not standard additional features reminds me about fictitious features of the <i>Martian Headsets</i> models in <a href="http://www.joelonsoftware.com/items/2008/03/17.html" rel="nofollow">http://www.joelonsoftware.com/items/2008/03/17.html</a>

It's cool to know how this works, I've been trying to repair a couple of senhaisher plug headPhones+mic for the Iphone (they broke at the jack) and I couldn't make them work. I am courrently able to use them to listenimg only. The mic and the controls are not working. And I tried all the combinations at the jack...(well maybe not all or it would be working perfectly).<p>I tried to find some diagrams but was unable. Maybe this will help me.

"modern" headset remotes that work with devices from a major vendor have long since abandoned the analog resistor approach in favor of a digital system.<p>The details of the implementation aren't disclosed, but people have seen a whiff of it, e.g. here:<p><a href="http://superuser.com/questions/107378/what-is-the-apple-mikey-hid-driver-for" rel="nofollow">http://superuser.com/questions/107378/what-is-the-apple-mike...</a>

<a href="http://en.wikipedia.org/wiki/1-Wire" rel="nofollow">http://en.wikipedia.org/wiki/1-Wire</a><p>Probably not used in headphones, but it could be.

This is kind of lacking.