Updating Device State

At some point during the initialization you'll receive a SET_ADDRESS request that will move the device from the Default state to the Address state. If you are working on Linux, you'll also receive a SET_CONFIGURATION request that will move the device from the Address state to the Configured state. Additionally, some requests are only valid in certain states– for example SET_CONFIGURATION is only valid if the device is in the Address state. For this reason usb-4.rs will need to keep track of the device's current state.

The device state should be tracked using a resource so that it's preserved across multiple executions of the USBD event handler. The usb2 crate has a State enum with the 3 possible USB states: Default, Address and Configured. You can use that enum or roll your own.

✅ Start tracking and updating the device state to move your request handling forward:

1. Update the handling of the USBRESET event: Instead of ignoring it, we now want it to change the state of the USB device. See section 9.1 USB Device States of the USB specification for details on what to do.

2. Update the handling of SET_ADDRESS requests: See the section on Handling SET_ADDRESS Requests of this tutorial for details.

3. Implement the handling of GET_DESCRIPTOR Configuration requests: See the section on Handling GET_DESCRIPTOR Configuration Requests of this tutorial for details.