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 |
| CONTAINER_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_INFO_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。 |
Wireless USB 1.x Device Capability Descriptor
| 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. |
Wireless USB 1.0 Device Capability Type Codes
| 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. |
Wireless USB 1.1 Device Capability Type Codes
| 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. |
USB 3.x Device Capability Descriptor
| 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. |
USB 3.0 Device Capability Type Codes
| 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 |
| Reserved |
00H, 05-FFH |
Reserved for future use |
USB 3.1 Device Capability Type Codes
| 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 |
USB 3.2 Device Capability Type Codes
| 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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