Step 3: Prepare Your USB Socket
You will have to prewire your USB socket. This is how I decided to wire it. Black and yellow are optional if you don't want to use this on Apple products. They require you to wire these so that your USB emulates a typical Apple charger.
Red (1): +5VDC
Black (2): Data (~2.4VDC)
Yellow (3): Data (~1.8VDC)
White (4): Ground