Learning Linux bus drivers with cainiao first knowledge of USB device descriptors

My ears are still a single loop. I don't know when the music will start to touch me. For a long time, listening to songs only enjoys the melody. Slowly, many things make me feel a little trembling. Keep repeating and continue with this subtle feeling.

After dinner, continue with the USB, and then the USB device descriptor.

Each USB device has some internal data. With this data, the USB host can obtain information about the type and manufacturer of the USB device. This set of Fixed-format data is the USB descriptor. The standard USB device has five USB descriptors: device descriptor, configuration descriptor, interface descriptor, endpoint descriptor, and string descriptor.

A device has only one device descriptor, while a device descriptor can contain multiple configuration descriptors. A Configuration descriptor can contain multiple interface descriptors, and an interface uses several endpoints, there are several endpoint descriptors.

1. For the 18-byte device descriptor of USB, see the following USB protocol.

2. the USB 8-byte configuration descriptor is as follows:

 

3. the USB 8-byte interface descriptor is as follows:

 

4. the USB 7-byte endpoint descriptor is as follows: