TivaWare for C Series USB Library is a set of data types and functions for initializing and configuring the USB module in host, device, and OTG modes on TM4C123x MCUs. It consists of license- and royalty-free drivers with example applications to accelerate USB implementation on TM4C123x devices. The capabilities and organization of the USB library functions are governed by the design goals such that it must be written entirely in C. The library functions are easy to understand and are reasonably efficient in terms of memory and processor usage. The USB library can be built with more than one tool chain, it is built over Driver lib APIs to provide a higher level of support for USB. This includes implementations of common USB classes. The layered structure of the USB library means that developers can choose the extent to which they use the library functions. To speed up and ease application development, a number of examples for each of the three modes, namely Host, Device, and OTG are also provided. TI is a member of USB implementers forums which shows a strong commitment towards USB, in not only the current TM4C123x family of devices, but also going forward.