1. the HID device has at least one report descriptor.
2, each USB configuration under at least one or more interface descriptor, interface descriptor mainly describes the type of device, the number of endpoints used under this interface (excluding endpoint 0), an interface is to achieve a function, the realization of such a function may require endpoint 0 is enough, you may need other endpoints with.
3, each USB interface under at least 0 or more endpoint descriptors, endpoint descriptors are used to describe the various attributes of the endpoint.
4, string descriptor is a string to describe some of the attributes of a device, the description of the attributes include the device manufacturer's name, product name, product serial number, the name of each configuration, the name of each interface.
5, each USB device has at least one or more configuration descriptors, but the host can only choose a certain configuration at the same time, the standard configuration descriptor mainly to the host to describe the current configuration under the device attributes, the current required, the number of interfaces supported, the length of the set of configuration descriptors and so on.
6. A USB device has one or more configuration descriptors. Each configuration has one or more interfaces, and each interface has zero or more endpoints
7. The main role of the report descriptor is to describe the data that the host and the HID device interact with, and to explain to the host which bits of this data are used for what purpose.
8. When the host acquires the set of configuration descriptors, it will first acquire the standard configuration descriptors once, and then acquire all the descriptor information of the set of configuration descriptors according to the value of the length attribute of the set of configuration descriptors inside it, and the set of configuration descriptors has standard configuration descriptors, interface descriptors, endpoint descriptors, and HID descriptors.
9, the endpoint is the realization of the USB device function of the physical buffer entity, the USB host and the device is through the endpoint for data interaction.
10. HID descriptors exist only for HID devices.
11. Each USB device has only one device descriptor, which mainly describes the device type, endpoint 0 maximum packet length, device version, number of configurations and so on to the host.