19.1.5.3.3 Enumeration Process
The USB protocol is a host/client protocol. The host starts the enumeration, sending requests to the device through the control endpoint. The device handles standard requests as defined in the USB specification.
| Request | Definition |
|---|---|
| GET_DESCRIPTOR | Returns the current device configuration value |
| SET_ADDRESS | Sets the device address for all future device accesses |
| SET_CONFIGURATION | Sets the device configuration |
| GET_CONFIGURATION | Returns the current device configuration value |
| GET_STATUS | Returns status for the specified recipient |
| SET_FEATURE | Used to set or enable a specific feature |
| CLEAR_FEATURE | Used to clear or disable a specific feature |
The device also handles some class requests defined in the CDC class.
| Request | Definition |
|---|---|
| SET_LINE_CODING | Configures DTE rate, stop bits, parity and number of character bits |
| GET_LINE_CODING | Requests current DTE rate, stop bits, parity and number of character bits |
| SET_CONTROL_LINE_STATE | RS-232 signal used to indicate to the DCE device that the DTE device is now present |
Unhandled requests are stalled.