What do you get? A rich ecosystem of fantastic little accessories. Now take a world of hackers, tinkerers and creative technicians and give them a three-channel interface plus low voltage. Not a lot, but the microphone that’s embedded into your innocuous-looking earbuds does need a little bit of power, which can be harvested (pdf) to power, say, a microprocessor in an accessory. What not a lot of people realize is that the headphone socket also supplies a tiny amount of power. It also sports a surprisingly robust three-channel communication interface: One channel in (for the microphone) and two channels out (for the left and right stereo channel). For next to no money, intrepid hackers can buy a development pack to start hacking with the headphone socket.
