SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
The device USB device first attaches to the host as an FS device. In the reset mechanism, the USB core requests HS operation. If the HS negotiation in the reset phase succeeds, further transactions are at HS; otherwise, they are at FS. After reset, the USB driver checks for the speed of the device, whether it is FS or HS. Depending on the speed configured by the host, the standard USB device requests are answered with the corresponding descriptors.
Some standard device requests are not supported by the driver because the USB driver is dedicated for use by the ROM code for peripheral booting. Table 34-37 lists the standard device requests supported by the driver.
Request | Description | Support |
---|---|---|
CLEAR_FEATURE | Sets or clears a specific feature | Supported only for the ENDPOINT_HALT feature |
GET_CONFIGURATION | Returns the current device configuration value | Yes |
GET_DESCRIPTOR | Returns the specified descriptor | Yes |
GET_INTERFACE | Returns the selected alternate setting for the specified interface | Yes |
GET_STATUS | Returns the status for the specified recipient | Yes |
SET_ADDRESS | Sets the device address | Yes |
SET_CONFIGURATION | Sets the device configuration | Yes |
SET_DESCRIPTOR | Updates existing descriptors or adds new descriptors | Runtime updating of descriptors is not supported. |
SET_FEATURE | Sets or enables a specific feature | Supported only for the ENDPOINT_HALT feature |
SET_INTERFACE | Selects an alternate setting in an interface | Runtime setting of alternate features is not supported. |
SYNCH_FRAME | Sets and reports an endpoint synchronization frame | No, because isochronous transfers are not used |