Microsoft Windows CE 3.0  

USB_CONFIGURATION

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This structure describes information about a specific USB device configuration. USB devices may support several different configutations, in which different interfaces on the device may behave in different ways.

typedef struct { UCHAR
bLength, 
UCHAR
bDescriptorType, 
USHORT
wTotalLength, 
UCHAR
bNumInterfaces, 
UCHAR
bConfigurationValue, 
UCHAR
iConfiguration, 
UCHAR
bmAttributes, 
UCHAR
MaxPower
} USB_CONFIGURATION;
bLength
Size of this structure in bytes.
bDescriptorType
The constant value CONFIGURATION.
wTotalLength
The total length of data returned for this configuration. This includes the combined length of all stuctures — USB_CONFIGURATION, USB_INTERFACE, USB_ENDPOINT and any class- or vendor-specific structures — returned as part of the configuration information.
bNumInterfaces
The number of interfaces supported as part of this configuration.
bConfigurationValue
This configuration's value, used when the USB system software of a USB device driver requests this configuration.
iConfiguration
Index of a string descriptor describing this configuration.
bmAttributes
Eight bits of configuration characteristics. Bits 0..4 are reserved and should be 0. If bit 5 is set to 1, this configuration supports remote wakeup. If bit 6 is set to 1, then in this configuration the USB device uses power both from the bus and from an external source (e.g. battery or wall socket). The MaxPowermember gives the amount of bus power required during normal operation.
MaxPower
The amount of power required in this configuration when the USB device is fully operational, expressed in units of 2 milliamps (that is, a value of 50 represent power consumption of 100mA). This member is used if the bmAttributesmember indicates that the device requires bus power.

Remarks

In Windows CE 3.0, the UHCI driver software always chooses the first available configuration for a USB device, regardless of whether that configuration is suitable for use on the bus due to power limitations, bandwidth availability, etc.



 Last updated on Tuesday, July 13, 2004

© 2004 Microsoft Corporation. All rights reserved.