Defined Class Codes

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).

Last Update: Septmeber 22, 2023

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

10h

Interface

Audio/Video Devices

11h

Device

Billboard Device Class

12h

Interface

USB Type-C Bridge Class

13h Interface

USB Bulk Display Protocol Device Class

14h Interface MCTP over USB Protocol Endpoint Device Class
3Ch Interface I3C Device Class

DCh

Both

Diagnostic Device

E0h

Interface

Wireless Controller

EFh

Both

Miscellaneous

FEh

Interface

Application Specific

FFh

Both

Vendor Specific

Base Class 00h (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

 
Base Class 01h (Audio)

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

Base Class 02h (Communications and CDC Control)

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

Base Class 03h (HID – Human Interface Device)

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

Base Class 05h (Physical)

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

Base Class 06h (Still Imaging)

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

Base Class 07h (Printer)

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

Base Class 08h (Mass Storage)

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

Base Class 09h (Hub)

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

Base Class 0Ah (CDC-Data)

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

Base Class 0Bh (Smart Card)

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

Base Class 0Eh (Video)

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

Base Class 0Fh (Personal Healthcare)

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

Base Class 10h (Audio/Video Devices)

The USB Audio/Video (AV) Device Class Definition describes the methods used to communicate with devices or functions embedded in composite devices that are used to manipulate audio, video, voice, and all image- and sound-related functionality. 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

10h

01h

02h

03h 

00h

Audio/Video Device – AVControl Interface

00h

Audio/Video Device – AVData Video Streaming Interface

00h

Audio/Video Device – AVData Audio Streaming Interface

Base Class 11h (Billboard Device)

This base class is defined for devices that conform to the Billboard 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 Device Descriptors.

Base Class

SubClass

Protocol

Meaning

11h

00h

00h

Billboard Device

Base Class 12h (USB Type-C Bridge Device)

This base class is defined for devices that conform to the USB Type-C Bridge 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

12h

00h

00h

USB Type-C Bridge Device

Base Class 13h (USB Bulk Display Protocol Device Class)

This base class is defined for devices that conform to the “VESA USB BDP Device Specification” found at the VESA website. This specification defines the usable set of SubClass and Protocol values. Values outside of this defined spec are reserved. These class codes can only be used in Interface Descriptors.

Base Class

SubClass

Protocol

Meaning

13h

00h

00h

USB BDP Device

Base Class 14h (MCTP over USB Protocol Endpoint Device Class)

This base class is defined for devices that conform to the “MCTP over USB” found at the DMTF website as DSP0283. This specification defines the usable set of SubClass and Protocol values. Values outside of this defined spec are reserved. These class codes can only be used in Interface Descriptors.

 

Base Class

SubClass

Protocol

Meaning

14h

00h

01h:  MCTP 1.x
02h:  MCTP 2.x

MCTP Management-controller and Managed-Device endpoints

01h 01h: MCTP 1.x
02h: MCTP 2.x
MCTP Host Interface endpoint

Base Class 3Ch (I3C Device Class)

This base class is defined for devices that conform to the USB I3C Device Class Specification found on this 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 Descriptions.

Base Class

SubClass

Protocol

Meaning

3Ch

00h

00h

I3C Device

 

Base Class DCh (Diagnostic Device)

This base class is defined for devices that diagnostic devices. This class code can be used in Device or Interface Descriptors. 
Trace is a form of debugging where processor or system activity is made externally visible in real-time or stored and later retrieved for viewing by an applications developer, applications program, or, external equipment specializing observing system activity. 
Design for Debug or Test (Dfx). This refers to a logic block that provides debug or test support (E.g. via Test Access Port (TAP)). 
DvC: Debug Capability on the USB device (Device Capability) 

Base Class

SubClass

Protocol

Meaning

DCh

01h

01h

USB2 Compliance Device. Definition for this device can be found at http://www.intel.com/technology/usb/spec.htm

02h

00h

Debug Target vendor defined. Please see http://www.intel.com/content/www/us/en/io/universal-serial-bus/extensible-host-controler-interface-usb-xhci.html for more info.

01h

GNU Remote Debug Command Set. Please see http://www.intel.com/content/www/us/en/io/universal-serial-bus/extensible-host-controler-interface-usb-xhci.html for more info.

03h

00h

Undefined

01h

Vendor defined Trace protocol on DbC.

04h

00h

Undefined

01h

Vendor defined Dfx protocol on DbC.

05h

00h

Vendor defined Trace protocol over General Purpose (GP) endpoint on DvC.

01h

GNU Protocol protocol over General Purpose (GP) endpoint on DvC.

http://www.gnu.org/software/gdb/

06h

00h

Undefined

01h

Vendor defined Dfx protocol on DvC.

07h

00h

Undefined

01h

Vendor defined Trace protocol on DvC.

08h

00h

Undefined

Base Class E0h (Wireless Controller)

This base class is defined for devices that are Wireless controllers. Values not shown in the table below are reserved. These class codes are to be used in Interface Descriptors, with the exception of the Bluetooth class code which can also be used in a Device Descriptor. 

Base Class

SubClass

Protocol

Meaning

E0h

01h

01h

Bluetooth Programming Interface. Get specific information from www.bluetooth.com.

02h

UWB Radio Control Interface. Definition for this is found in the Wireless USB Specification in Chapter 8.

03h

Remote NDIS. Information can be found at: http://www.microsoft.com/windowsmobile/mobileoperators/default.mspx

04h

Bluetooth AMP Controller. Get specific information from www.bluetooth.com.

2h

01h

Host Wire Adapter Control/Data interface. Definition can be found in the Wireless USB Specification in Chapter 8.

02h

Device Wire Adapter Control/Data interface. Definition can be found in the Wireless USB Specification in Chapter 8.

03h

Device Wire Adapter Isochronous interface. Definition can be found in the Wireless USB Specification in Chapter 8.

Base Class EFh (Miscellaneous)

This base class is defined for miscellaneous device definitions. Values not shown in the table below are reserved. The use of these class codes (Device or Interface descriptor) are specifically annotated in each entry below.

Base Class

SubClass

Protocol

Meaning

EFh

01h

01h

Active Sync device. This class code can be used in either Device or Interface Descriptors. Contact Microsoft for more information on this class.

02h

Palm Sync. This class code can be used in either Device or Interface Descriptors.

02h

01h

Interface Association Descriptor. The usage of this class code triple is defined in the Interface Association Descriptor ECN that is provided on www.usb.org . This class code may only be used in Device Descriptors.

02h

Wire Adapter Multifunction Peripheral programming interface. Definition can be found in the Wireless USB Specification in Chapter 8. This class code may only be used in Device Descriptors

03h

01h

Cable Based Association Framework. This is defined in the Association Model addendum to the Wireless USB specification. This class code may only be used in Interface Descriptors.

04h

01h

RNDIS over Ethernet.

Connecting a host to the Internet via Ethernet mobile device. The device appears to the host as an Ethernet gateway device.

This class code may only be used in Interface Descriptors.

02h

RNDIS over WiFi.

Connecting a host to the Internet via WiFi enabled mobile device. The device represents itself to the host as an 802.11 compliant network device.

This class code may only be used in Interface Descriptors.

03h

RNDIS over WiMAX

Connecting a host to the Internet via WiMAX enabled mobile device. The device is represented to the host as an 802.16 network device.

This class code may only be used in Interface Descriptors.

04h

RNDIS over WWAN

Connecting a host to the Internet via a device using mobile broadband, i.e. WWAN (GSM/CDMA).

This class code may only be used in Interface Descriptors.

05h

RNDIS for Raw IPv4

Connecting a host to the Internet using raw IPv4 via non-Ethernet mobile device. Devices that provide raw IPv4, not in an Ethernet packet, may use this form to in lieu of other stock types.

This class code may only be used in Interface Descriptors.

06h

RNDIS for Raw IPv6

Connecting a host to the Internet using raw IPv6 via non-Ethernet mobile device. Devices that provide raw IPv6, not in an Ethernet packet, may use this form to in lieu of other stock types.

This class code may only be used in Interface Descriptors.

07h

RNDIS for GPRS

Connecting a host to the Internet over GPRS mobile device using the device’s cellular radio

05h

00h

USB3 Vision Control Interface

Machine Vision Device conforming to the USB3 Vision specification. This standard covers cameras and other related devices that are typically used in machine vision, industrial, and embedded applications.

Reference: http://visiononline.org/

This class code may only be used in Interface Descriptors.

01h

USB3 Vision Event Interface

02h

USB3 Vision Streaming Interface

06h

01h

STEP. Stream Transport Efficient Protocol for content protection.

02h

STEP RAW. Stream Transport Efficient Protocol for Raw content protection.

07h

01h

Command Interface in IAD

The DVB Common Interface (DVB-CI) specification describes a system whereby a removable CI Conditional Access Module (CICAM), given the appropriate usage rights, unscrambles protected pay-TV content and routes it over the same interface back to a TV receiver for display. An interface association for a DVB-CI function will contain a DVB-CI Command Interface for command, control, and status information, it may contain a DVB-CI Media Interface for audiovisual data streams, and it may also contain a CDC EEM interface to provide bridged networking to the CICAM.

Reference: https://www.dvb.org/standards/dvb-ci-plus

01h

Command Interface in Interface Descriptor

02h

Media Interface in Interface Descriptor

Base Class FEh (Application Specific)

This base class is defined for devices that conform to several class specifications 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

FEh

01h

01h

Device Firmware Upgrade. Device class definition provided on www.usb.org .

02h

00h

IRDA Bridge device. Device class definition provided on www.usb.org .

03h

00h

USB Test and Measurement Device. Definition provided in the USB Test and Measurement Class spec found on www.usb.org .

01h

USB Test and Measurement Device conforming to the USBTMC USB488 Subclass Specification found on www.usb.org.

Base Class FFh (Vendor Specific)

This base class is defined for vendors to use as they please. These class codes can be used in both Device and Interface Descriptors.

Base Class

SubClass

Protocol

Meaning

FFh

xxh

xxh

Vendor specific