The Texas Instrument USB Library is a set of data types and functions for creating USB device, host or On-The-Go (OTG) applications. The contents of the USB library and its associated header files fall into four main groups: general purpose functions, device mode specific functions, host mode specific functions, and mode detection and control functions.

The set of general purpose functions are those that are to be used in device, host, and dual mode applications. These include functions to parse USB descriptors and configure features of the USB library. The device specific functions provide the class-independent features required by all USB device applications such as host connection signaling and responding to standard descriptor requests. The USB library also contains a set of modules that handle the class specific requests from the USB host as well as a layer to interact with an application. The USB library provides a set of lower level class-independent host functions required by all USB host applications such as device detection and enumeration, and endpoint management. This lower layer remains mostly invisible to the application, but can be exposed to the application via class specific USB host modules. Like the device mode layer, the host mode class specific modules provide an interface to allow the lower level USB library code to communicate directly over the USB bus and also has a higher level interface that interacts with the application. The USB library also provides functions to configure how the USB controller handles switching between host and device mode operation.