17.6.3.1 Enumeration Process

The USB protocol is a Host/Client protocol. This is the host that starts the enumeration sending requests to the device through the control endpoint. The device handles standard requests as defined in the USB Specification.

Table 17-3. Handled Standard Requests
Request Definition
GET_DESCRIPTOR Returns the current device configuration value.
SET_ADDRESS Sets the device address for all future device access.
SET_CONFIGURATION Sets the device configuration.
GET_CONFIGURATION Returns the current device configuration value.
GET_STATUS Returns status for the specified recipient.
SET_FEATURE Set or Enable a specific feature.
CLEAR_FEATURE Clear or Disable a specific feature.

The device also handles some class requests defined in the CDC class.

Table 17-4. Handled Class Requests
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 tell the DCE device the DTE device is now present.

Unhandled requests are STALLed.