The General USB Process
How Does the Host Know a Device’s Requirements?
Configuration
Descriptor
Device Descriptor
Configuration
Descriptor
Software – General Concepts
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| TM |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
| Interface |
|
|
|
| Interface |
|
|
|
| Interface |
|
| Interface |
| |||||||||||||||
| Descriptor |
|
|
|
| Descriptor |
|
|
|
| Descriptor |
|
|
| Descriptor |
| ||||||||||||||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Endpoint | Endpoint | Endpoint | Endpoint | Endpoint | Endpoint | Endpoint | Endpoint |
Descriptor | Descriptor | Descriptor | Descriptor | Descriptor | Descriptor | Descriptor | Descriptor |
Upon detecting a USB device connection the host, using these descriptors, configures the device and loads the proper driver program. This configuration process is called “enumeration.”
