Zephyr RTOS has an implementation of USB device support pretty much from the beginning. Apart from direct use in the user application, various subsystems in the Zephyr RTOS also make use of device support. Since version v.3.3.0 there is also a new device stack as part of the experimental USB support. Johann will give an overview of USB device support in the Zephyr RTOS from an application perspective. The author will also cover the differences and features in the new experimental support. The presentation will start with configuring USB device support, how to select the desired features (classes) and how to enable USB device support. Johann will give a step-by-step insight into the different USB class implementations and go into their peculiarities and how they work in or with other subsystems. Author will explain how and why some functions are described and configured via the device tree and others are not. Special attention will be given to the configuration and use of the CDC ACM class.