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原文转自：https://blog.csdn.net/u012028275/article/details/109955356
设备功能描述符(Device Capability Descriptor)是用于存储特定某项技术或设备功能信息的描述符，和BOS描述符 (BOS Descriptor)一起由Wireless Universal Serial Bus Specification Revision 1.0规范引入，之后在USB 2.0 ECN: Link Power Management (LPM) 、USB3.x Specification、Microsoft OS 2.0 Descriptors Specification 等协议规范都加入了定义。
单个的特定技术或者通用的设备层级的功能通过设备功能描述符(Device Capability Descriptor)来上报。设备功能描述符(Device Capability Descriptor)总是作为GetDescriptor（BOS）请求返回的BOS信息的一部分返回。主机端不能单独读取单个的设备功能描述符(Device Capability Descriptor)，无法使用GetDescriptor()或SetDescriptor()请求直接读取或设置单独的设备功能，只能通过GetDescriptor()请求获取BOS描述符 (BOS Descriptor)并通过wTotalLength字段得到长度来读取整个描述符集。
设备功能描述符(Device Capability Descriptor)具有通用头(generic header)，带有子类型字段(bDevCapabilityType)，这个字段定义了描述符其余部分的布局(layout)。
Offset
Field
Size
Value
Description
0
bLength
1
Number
以字节为单位的描述符大小
1
bDescriptorType
1
Constant
设备功能描述符类型
2
bDevCapabilityType
1
Number
设备功能类型
3
Capability-Dependent
Var
Variable
特定功能的格式
bLength以字节为单位的描述符大小。 bDescriptorType设备功能描述符类型，为DEVICE CAPABILITY(0x10)。 bDevCapabilityType 设备功能类型。
Capability Code
Value
Description
Specification
Wireless_USB
01H
定义一组特定于无线USB的设备级功能
Wireless Universal Serial Bus Specification
USB 2.0 EXTENSION
02H
USB2.0拓展描述符
Universal Serial Bus 3.x Specification
SUPERSPEED_USB
03H
定义一组特定于超高速 USB的设备级功能
Universal Serial Bus 3.x Specification
CONTAIN ER_ID
04H
定义用于在所有操作模式下标识实例的实例唯一ID
Universal Serial Bus 3.x Specification
PLATFORM
05H
定义特定于特定平台/操作系统的设备功能
Microsoft OS 2.0 Descriptors SpecificationUniversal Serial Bus 3.x Specification
POWER_DELIVERY_CAPABILITY
06H
定义此设备的各种PD功能
Universal Serial Bus Power Delivery Specification
BATTERY_IN FO_CAPABILITY
07H
提供设备支持的每个电池的信息
Universal Serial Bus Power Delivery Specification
PD_CONSUMER_PORT_CAPABILITY
08H
描述功耗特性和功能
Universal Serial Bus Power Delivery Specification
PD_PROVIDER_PORT_CAPABILITY
09H
描述电源提供特性和功能
Universal Serial Bus Power Delivery Specification
SUPERSPEED_PLUS
0AH
定义一组特定于SuperSpeed Plus USB设备级的功能
Universal Serial Bus 3.x Specification
PRECISION_TIME_MEASUREMENT
0BH
精密时间测量（PTM）功能描述符
Universal Serial Bus 3.x Specification
Wireless_USB_Ext
0CH
定义一组特定于无线USB 1.1的设备级功能
BILLBOARD
0DH
Billboard capability
AUTHENTICATION
0EH
Authentication Capability Descriptor
BILLBOARD_EX
0FH
Billboard Ex capability
CONFIGURATION SUMMARY
10H
汇总设备实现的功能的配置信息
Universal Serial Bus 3.x Specification
Reserved
00H, 11-FFH
保留供将来使用注意：最新的设备功能类型代码(Device Capability Type Codes)将在usb.org上列出。
Offset
Field
Size
Value
Description
0
bLength
1
Number
Size of this descriptor.
1
bDescriptorType
1
Constant
Descriptor type: DEVICE CAPABILITY Type.
2
bDevCapabilityType
1
Number
Valid values are listed in Table 7-24.
3
Capability-Dependent
Var
Variable
Capability-specific format.
Capability Code
Value
Description
Wireless_USB
01H
Defines the set of Wireless USB-specific device level capabilities.
Reserved
00H, 02-FFH
Reserved for future use.
Capability Code
Value
Description
Wireless_USB
01H
Defines the set of Wireless USB-specific device level capabilities.
Wireless_USB_Ext
02H
Defines the set of Wireless USB 1.1-specific device levelcapabilities.
Reserved
00H, 03-FFH
Reserved for future use.
Offset
Field
Size
Value
Description
0
bLength
1
Number
Size of this descriptor.
1
bDescriptorType
1
Constant
Descriptor type: DEVICE CAPABILITY Type.
2
bDevCapabilityType
1
Number
Valid values are listed in Table 9-14.
3
Capability-Dependent
Var
Variable
Capability-specific format.
Capability Code
Value
Description
Wireless_USB
01H
Defines the set of Wireless USB-specific device level capabilities
USB 2.0 EXTENSION
02H
USB 2.0 Extension Descriptor
SUPERSPEED_USB
03H
Defines the set of SuperSpeed USB specific device level capabilities
CONTAIN ER_ID
04H
Defines the instance unique ID used to identify the instance across all operating modes
Reserved
00H, 05-FFH
Reserved for future use
Capability Code
Value
Description
Wireless_USB
01H
Defines the set of Wireless USB-specific device level capabilities
USB 2.0 EXTENSION
02H
USB 2.0 Extension Descriptor
SUPERSPEED_USB
03H
Defines the set of SuperSpeed USB specific device level capabilities
CONTAINER_ID
04H
Defines the instance unique ID used to identify the instance across all operating modes
PLATFORM
05H
Defines a device capability specific to a particular platform/operating system
POWER_DELIVERY_CAPABILITY
06H
Defines the various PD Capabilities of this device
BATTERY_INFO_CAPABILITY
07H
Provides information on each battery supported by the device
PD_CONSUMER_PORT_CAPABILITY
08H
The consumer characteristics of a port on the device
PD_PROVIDER_PORT_CAPABILITY
09H
The provider characteristics of a port on the device
SUPERSPEED_PLUS
0AH
Defines the set of SuperSpeed Plus USB specific device level capabilities
PRECISION_TIME_MEASUREMENT
0BH
Precision Time Measurement (PTM) Capability Descriptor
Wireless_USB_Ext
0CH
Defines the set of Wireless USB 1.1-specific device level capabilities
Reserved
00H, 0D-FFH
Reserved for future use
Capability Code
Value
Description
Wireless_USB
01H
Defines the set of Wireless USB-specific device level capabilities
USB 2.0 EXTENSION
02H
USB 2.0 Extension Descriptor
SUPERSPEED_USB
03H
Defines the set of SuperSpeed USB specific device level capabilities
CONTAINER_ID
04H
Defines the instance unique ID used to identify the instance across all operating modes
PLATFORM
05H
Defines a device capability specific to a particular platform/operating system
POWER_DELIVERY_CAPABILITY
06H
Defines the various PD Capabilities of this device
BATTERY_INFO_CAPABILITY
07H
Provides information on each battery supported by the device
PD_CONSUMER_PORT_CAPABILITY
08H
The consumer characteristics of a port on the device
PD_PROVIDER_PORT_CAPABILITY
09H
The provider characteristics of a port on the device
SUPERSPEED_PLUS
0AH
Defines the set of SuperSpeed Plus USB specific device level capabilities
PRECISION_TIME_MEASUREMENT
0BH
Precision Time Measurement (PTM) Capability Descriptor
Wireless_USB_Ext
0CH
Defines the set of Wireless USB 1.1-specific device level capabilities
BILLBOARD
0DH
Billboard capability
AUTHENTICATION
0EH
Authentication Capability Descriptor
BILLBOARD_EX
0FH
Billboard Ex capability
CONFIGURATION SUMMARY
10H
Summarizes configuration information for a function implemented by the device
Reserved
00H, 11-FFH
Reserved for future useNote: The most up-to-date Device Capability Type Codes will be listed on usb.org.
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