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分类: LINUX

2012-04-28 15:18:10

有关usb开发网站:如需了解更的USB知道,请链接到:http://www.usb.org/developers/defined_class

USB Class Codes                     November 17, 2009


USB defines class code information that is used to identify a device’s functionality and to nominally load a device driver based on that functionality. The information is contained in three bytes with the names Base Class, SubClass, and Protocol. (Note that ‘Base Class’ is used in this description to identify the first byte of the Class Code triple. That terminology is not used in the USB Specification). There are two places on a device where class code information can be placed.One place is in the Device Descriptor, and the other is in Interface Descriptors. Some defined class codes are allowed to be used only in a Device Descriptor, others can be used in both Device and Interface Descriptors, and some can only be used in Interface Descriptors. The table below shows the currently defined set of  Base Class values, what the generic usage is, and where that Base Class can be used (either Device or Interface Descriptors or both).

 

Base Class

Descriptor Usage

Description

00h

Device

Use class information in the Interface Descriptors

01h

Interface

Audio  

02h

Both

Communications and CDC Control

03h

Interface

HID (Human Interface Device)

05h

Interface

Physical

06h

Interface

Image

07h

Interface

Printer

08h

Interface

Mass Storage

09h

Device

Hub

0Ah

Interface

CDC-Data

0Bh

Interface

Smart Card

0Dh

Interface

Content Security

0Eh

Interface

Video

0Fh

Interface

Personal Healthcare

DCh

Both

Diagnostic Device

E0h

Interface

Wireless Controller

EFh

Both

Miscellaneous

FEh

Interface

Application Specific

FFh

Both

Vendor Specific


(Device)

This base class is defined to be used in Device Descriptors to indicate that class information should be determined from the Interface Descriptors in the device. There is one class code definition in this base class.  All other values are reserved.

 

This value is also used in Interface Descriptors to indicate a null class code triple.

 

Base Class

SubClass

Protocol

Meaning

00h

00h

00h

Use class code info from Interface Descriptors

 


This base class is defined for Audio capable devices that conform to the Audio Device Class Specification found on the USB-IF website. That specification defines the usable set of SubClass and Protocol values. Values outside of that defined spec are reserved. These class codes may only be used in Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

01h

xxh

xxh

Audio device

 

 

 

This base class is defined for devices that conform to the Communications Device Class Specification found on the USB-IF website. That specification defines the usable set of SubClass and Protocol values. Values outside of that defined spec are reserved.  Note that the Communication Device Class spec requires some class code values (triples) to be used in Device Descriptors and some to be used in Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

02h

xxh

xxh

Communication device class

 

This base class is defined for devices that conform to the HID Device Class Specification found on the USB-IF website. That specification defines the usable set of SubClass and Protocol values.   Values outside of that defined spec are reserved. These class codes can only be used in Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

03h

xxh

xxh

HID device class

 

This base class is defined for devices that conform to the Physical Device Class Specification found on the USB-IF website. That specification defines the usable set of SubClass and Protocol values.  Values outside of that defined spec are reserved. These class codes can only be used in Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

05h

xxh

xxh

Physical device class

 

 

This base class is defined for devices that conform to the Imaging Device Class Specification found on the USB-IF website. That specification defines the usable set of SubClass and Protocol values.   Values outside of that defined spec are reserved.

 

Base Class

SubClass

Protocol

Meaning

06h

01h

01h

Still Imaging device

 

 

This base class is defined for devices that conform to the Printer Device Class Specification found on the USB-IF website.  That specification defines the usable set of SubClass and Protocol values.  Values outside of that defined spec are reserved.  These class codes can only be used in Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

07h

xxh

xxh

Printer device

 

 

This base class is defined for devices that conform to the Mass Storage Device Class Specification found on the USB-IF website. That specification defines the usable set of SubClass and Protocol values. Values outside of that defined spec are reserved. These class codes can only be used in Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

08h

xxh

xxh

Mass Storage device

 

 

This base class is defined for devices that are USB hubs and conform to the definition in the USB specification.  That specification defines the complete triples as shown below.  All other values are reserved.  These class codes can only be used in Device Descriptors.

 

Base Class

SubClass

Protocol

Meaning

09h

00h

00h

Full speed Hub

01h

Hi-speed hub with single TT

02h

Hi-speed hub with multiple TTs

 

 

This base class is defined for devices that conform to the Communications Device Class Specification found on the USB-IF website. That specification defines the usable set of SubClass and Protocol values.Values outside of that defined spec are reserved. These class codes can only be used in Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

0Ah

xxh

xxh

CDC data device

 

 

This base class is defined for devices that conform to the Smart Card Device Class Specification found on the USB-IF website. That specification defines the usable set of SubClass and Protocol values.Values outside of that defined spec are reserved. These class codes can only be used in Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

0Bh

xxh

xxh

Smart Card device

 

 

Base Class 0Dh (Content Security)

This base class is defined for devices that conform to the Content Security Device Class Specification found on the USB-IF website. That specification defines the usable set of SubClass and Protocol values. Values outside of that defined spec are reserved. These class codes can only be used in Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

0Dh

00h

00h

Content Security device

 

 

This base class is defined for devices that conform to the Video Device Class Specification found on the USB-IF website. That specification defines the usable set of SubClass and Protocol values. Values outside of that defined spec are reserved. These class codes can only be used in Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

0Eh

xxh

xxh

Video device

 

 

This base class is defined for devices that conform to the Personal Healthcare Device Class Specification found on the USB-IF website. That specification defines the usable set of SubClass and Protocol values. Values outside of that defined spec are reserved. These class codes should only be used in Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

0Fh

xxh

xxh

Personal Healthcare device

 

This base class is defined for devices that diagnostic devices. There is currently only one value defined. All other values are reserved. This class code can be used in Device or Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

DCh

01h

01h

USB2 Compliance Device.  Definition for this device can be found at

 

USB Class Codes                    

November 17, 2009

USB defines class code information that is used to identify a device’s functionality and to nominally load a device driver based on that functionality. The information is contained in three bytes with the names Base Class, SubClass, and Protocol. (Note that ‘Base Class’ is used in this description to identify the first byte of the Class Code triple. That terminology is not used in the USB Specification). There are two places on a device where class code information can be placed.One place is in the Device Descriptor, and the other is in Interface Descriptors. Some defined class codes are allowed to be used only in a Device Descriptor, others can be used in both Device and Interface Descriptors, and some can only be used in Interface Descriptors. The table below shows the currently defined set of  Base Class values, what the generic usage is, and where that Base Class can be used (either Device or Interface Descriptors or both).

 

Base Class

Descriptor Usage

Description

00h

Device

Use class information in the Interface Descriptors

01h

Interface

Audio  

02h

Both

Communications and CDC Control

03h

Interface

HID (Human Interface Device)

05h

Interface

Physical

06h

Interface

Image

07h

Interface

Printer

08h

Interface

Mass Storage

09h

Device

Hub

0Ah

Interface

CDC-Data

0Bh

Interface

Smart Card

0Dh

Interface

Content Security

0Eh

Interface

Video

0Fh

Interface

Personal Healthcare

DCh

Both

Diagnostic Device

E0h

Interface

Wireless Controller

EFh

Both

Miscellaneous

FEh

Interface

Application Specific

FFh

Both

Vendor Specific

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