Common guidelines for USB tests and samples

Overview

In general, all USB samples and tests are platform agnostic and should not require a platform-specific overlay. Though there may be exceptions to that already in the tree, the goal is to avoid platform-specific overlays. There is no obligation for a USB sample or USB test to support a specific platform.

Board configuration

Default USB device and host controller

USB support uses the zephyr_udc0 node label to assign the default USB device controller and the zephyr_uhc0 node label to assign the default USB host controller. Depending on what a board supports, it has to assign these node labels to be able to execute samples and tests in the tree.

Supported features for the board metadata

There are only two supported features for the board metadata file that are used by Twister to pick up a sample or a test. For a board with a USB controller supporting device mode, the feature is usbd. For a board with a USB controller supporting host mode, the feature is usbh.

See Board Configuration for more details.

Deprecated features

The feature usb_device should not be used anymore. This feature belongs to the legacy USB device stack, which is deprecated and will be removed.

Tests Twister configuration

USB tests may require additional hardware or software setup. These tests should use fixtures described in the table below.

Fixture	Use case
usb_host_connected	The test implements USB device functionality, and requires a USB host to be connected to the board under test.
usb_device_connected	The test implements USB host functionality, and requires a USB device to be connected to the board under test.