Communications Device Class (CDC) is generally implemented in embedded systems like mobile phones to achieve more than one functionality from the device, so that a phone may be used as a modem, fax, or network port. This class provides simple serial communication functionality. Refer to the USB CDC Serial example in TivaWareTM for C Series as a starting point for more complex serial communications and file transfers. The data interfaces are generally used to perform bulk data transfer using Bulk USB Device. There is an example program in TivaWare that features a simple data-echoing application. This serves as a basis for a more complicated data transferring application.