What is the ipod shuffle USB wiring in the TRS connector?

Question

The ipod shuffle uses a TRS connector which looks like a standard 3.5 mm audio plug. somehow they are using this for USB also. ie to sync music from the PC. How is this done? normally it takes 5 wires for USB. the TRS connector has 3!

Answer 1

Each end has 4 wires, 2 data, +5V & Common

iPod Shuffle  End

http://pinouts.ru/PortableDevices/ipod_s...

USB End

http://pinouts.ru/Slots/USB_pinout.shtml