Intel IXP42X 用户手册

Intel

®

 IXP42X Product Line of Network Processors and IXC1100 Control Plane Processor

DM

September 2006

478

Order Number: 252480-006US

• Number of bytes to transfer
• Index or offset
• Value: used to pass a variable-sized data parameter
• Device request

 shows a summary of all device requests. For a full description of host device 

requests, see the Universal Serial Bus Specification Revision 1.1.

The UDC decodes most standard device commands with no intervention required by the 

user. The following commands are not passed to the user are:

The Set Configuration and Set Interface commands are passed to the user to indicate 

that the host set the specified configuration or interface and the software must take 

any necessary actions. The Get Descriptor and Set Descriptor commands are passed to 

the user to be decoded.

Because the Set Feature and Clear Feature commands are not passed on, the user is 

not able decode the device remote wake-up feature commands. To solve this problem, 

the status bit UDCCS0:DRWF indicates whether or not the device remote wake-up 

feature is enabled. UDCCS0: DRWF is a read-only bit. When the bit is set to 1, the 

device remote wake-up feature is enabled. When the bit is set to 0, the feature is not 

enabled.

In response to the GET_DESCRIPTOR command, the user device sends back a 

description of the UDC configuration. The UDC can physically support more data 

channel bandwidth than the USB specification allows. 

SET_FEATURE

Enables a specific feature such as device remote wake-up or endpoint stalls.

CLEAR_FEATURE

Clears or disables a specific feature.

SET_CONFIGURATION

Configures the UDC for operation. Used after a reset of the Intel XScale

®

 

processor or after a reset has been signalled via the USB.

GET_CONFIGURATION

Returns the current UDC configuration to the host.

SET_DESCRIPTOR

Sets existing descriptors or add new descriptors. Existing descriptors include:

• Device•Configuration
• String•Interface
• Endpoint

GET_DESCRIPTOR

Returns the specified descriptor, if it exists.

SET_INTERFACE

Selects an alternate setting for the UDC’s interface.

GET_INTERFACE

Returns the selected alternate setting for the specified interface.

GET_STATUS

Returns the UDC’s status including: remote wake-up, self-powered, data 

direction, endpoint number, and stall status.

SET_ADDRESS

Sets the UDC’s 7-bit address value for all future device accesses.

SYNCH_FRAME

Sets then reports an endpoint’s synchronization frame.

• Set Address

• Set Feature

• Clear Feature

• Get Configuration

• Get Status

• Get Interface

• Sync  Frame