In addition to audio and USB data, the µUSB port supports accessories such as chargers and debug and test cables. The µUSB switch is a special kind of USB switch that allows portable electronic devices to use a single USB port to connect to a number of different devices. The switch detects the type of accessory plugged in by performing impedance detection. As shown on this slide, it can connect the accessory to a charging circuit that will charge the battery, a USB circuit that will pass USB data, and an audio circuit which will play music to external headphones or speakers.