我目前正在使用stm32微控制器开发USB耳机。我使用X-CUBE-USB-AUDIO包中的示例代码将音频流式传输到PC。一切似乎都很好。现在我想修改代码，允许USB设备通知主机音量/静音的变化。根据USB音频规范1.0 p.30，可选的状态中断端点可用于此目的。所以我修改了设备描述符，以包含那个可选的端点。这是原始描述符：
Information for device STM32 AUDIO Streaming in FS Mode (VID=0x0483 PID=0x5730):
Connection Information:
------------------------------
Device current bus speed: FullSpeed
Device supports USB 1.1 specification
Device supports USB 2.0 specification
Device address: 0x004B
Current configuration value: 0x01
Number of open pipes: 0
Device Descriptor:
------------------------------
0x12 bLength
0x01 bDescriptorType
0x0200 bcdUSB
0x00 bDeviceClass
0x00 bDeviceSubClass
0x00 bDeviceProtocol
0x40 bMaxPacketSize0 (64 bytes)
0x0483 idVendor
0x5730 idProduct
0x0200 bcdDevice
0x01 iManufacturer "STMicroelectronics"
0x02 iProduct "STM32 AUDIO Streaming in FS Mode"
0x03 iSerialNumber "368932633438"
0x01 bNumConfigurations
Configuration Descriptor:
------------------------------
0x09 bLength
0x02 bDescriptorType
0x00CB wTotalLength (203 bytes)
0x03 bNumInterfaces
0x01 bConfigurationValue
0x00 iConfiguration
0xC0 bmAttributes (Self-powered Device)
0x32 bMaxPower (100 mA)
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x00 bInterfaceNumber
0x00 bAlternateSetting
0x00 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x01 bInterfaceSubClass (Audio Control Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
AC Interface Header Descriptor:
------------------------------
0x0A bLength
0x24 bDescriptorType
0x01 bDescriptorSubtype
0x0100 bcdADC
0x0048 wTotalLength (72 bytes)
0x02 bInCollection
0x01 baInterfaceNr(1)
0x02 baInterfaceNr(2)
AC Input Terminal Descriptor:
------------------------------
0x0C bLength
0x24 bDescriptorType
0x02 bDescriptorSubtype
0x12 bTerminalID
0x0101 wTerminalType (USB Streaming)
0x00 bAssocTerminal
0x02 bNrChannels (2 channels)
0x0003 wChannelConfig
0x00 iChannelNames
0x00 iTerminal
AC Feature Unit Descriptor:
------------------------------
0x0A bLength
0x24 bDescriptorType
0x06 bDescriptorSubtype
0x16 bUnitID
0x12 bSourceID
0x01 bControlSize
bmaControls:
0x03 Channel(0) - Mute / Volume
0x00 Channel(1)
0x00 Channel(2)
0x00 iFeature
AC Output Terminal Descriptor:
------------------------------
0x09 bLength
0x24 bDescriptorType
0x03 bDescriptorSubtype
0x14 bTerminalID
0x0301 wTerminalType (Speaker)
0x00 bAssocTerminal
0x16 bSourceID
0x00 iTerminal
AC Input Terminal Descriptor:
------------------------------
0x0C bLength
0x24 bDescriptorType
0x02 bDescriptorSubtype
0x11 bTerminalID
0x0201 wTerminalType (Microphone)
0x00 bAssocTerminal
0x02 bNrChannels (2 channels)
0x0003 wChannelConfig
0x00 iChannelNames
0x00 iTerminal
AC Feature Unit Descriptor:
------------------------------
0x0A bLength
0x24 bDescriptorType
0x06 bDescriptorSubtype
0x15 bUnitID
0x11 bSourceID
0x01 bControlSize
bmaControls:
0x03 Channel(0) - Mute / Volume
0x00 Channel(1)
0x00 Channel(2)
0x00 iFeature
AC Output Terminal Descriptor:
------------------------------
0x09 bLength
0x24 bDescriptorType
0x03 bDescriptorSubtype
0x13 bTerminalID
0x0101 wTerminalType (USB Streaming)
0x00 bAssocTerminal
0x15 bSourceID
0x00 iTerminal
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x01 bInterfaceNumber
0x00 bAlternateSetting
0x00 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x02 bInterfaceSubClass (Audio Streaming Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x01 bInterfaceNumber
0x01 bAlternateSetting
0x02 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x02 bInterfaceSubClass (Audio Streaming Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
AS Interface Descriptor:
------------------------------
0x07 bLength
0x24 bDescriptorType
0x01 bDescriptorSubtype
0x12 bTerminalLink
0x01 bDelay
0x0001 wFormatTag (PCM)
AS Format Type 1 Descriptor:
------------------------------
0x0B bLength
0x24 bDescriptorType
0x02 bDescriptorSubtype
0x01 bFormatType (FORMAT_TYPE_1)
0x02 bNrChannels (2 channels)
0x02 bSubframeSize
0x10 bBitResolution (16 bits per sample)
0x01 bSamFreqType (Discrete sampling frequencies)
0x00BB80 tSamFreq(1) (48000 Hz)
Endpoint Descriptor (Audio/MIDI 1.0):
------------------------------
0x09 bLength
0x05 bDescriptorType
0x01 bEndpointAddress (OUT endpoint 1)
0x05 bmAttributes (Transfer: Isochronous / Synch: Asynchronous / Usage: Data)
0x00C4 wMaxPacketSize (1 x 196 bytes)
0x01 bInterval (1 frames)
0x00 bRefresh
0x81 bSynchAddress
AS Isochronous Data Endpoint Descriptor:
------------------------------
0x07 bLength
0x25 bDescriptorType
0x01 bDescriptorSubtype
0x00 bmAttributes
0x00 bLockDelayUnits (undefined)
0x0000 wLockDelay
Endpoint Descriptor (Audio/MIDI 1.0):
------------------------------
0x09 bLength
0x05 bDescriptorType
0x81 bEndpointAddress (IN endpoint 1)
0x01 bmAttributes (Transfer: Isochronous / Synch: None / Usage: Data)
0x0003 wMaxPacketSize (1 x 3 bytes)
0x01 bInterval (1 frames)
0x07 bRefresh
0x00 bSynchAddress
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x02 bInterfaceNumber
0x00 bAlternateSetting
0x00 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x02 bInterfaceSubClass (Audio Streaming Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x02 bInterfaceNumber
0x01 bAlternateSetting
0x01 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x02 bInterfaceSubClass (Audio Streaming Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
AS Interface Descriptor:
------------------------------
0x07 bLength
0x24 bDescriptorType
0x01 bDescriptorSubtype
0x13 bTerminalLink
0x01 bDelay
0x0001 wFormatTag (PCM)
AS Format Type 1 Descriptor:
------------------------------
0x0B bLength
0x24 bDescriptorType
0x02 bDescriptorSubtype
0x01 bFormatType (FORMAT_TYPE_1)
0x02 bNrChannels (2 channels)
0x02 bSubframeSize
0x10 bBitResolution (16 bits per sample)
0x01 bSamFreqType (Discrete sampling frequencies)
0x00BB80 tSamFreq(1) (48000 Hz)
Endpoint Descriptor (Audio/MIDI 1.0):
------------------------------
0x09 bLength
0x05 bDescriptorType
0x82 bEndpointAddress (IN endpoint 2)
0x01 bmAttributes (Transfer: Isochronous / Synch: None / Usage: Data)
0x00C0 wMaxPacketSize (1 x 192 bytes)
0x01 bInterval (1 frames)
0x00 bRefresh
0x00 bSynchAddress
AS Isochronous Data Endpoint Descriptor:
------------------------------
0x07 bLength
0x25 bDescriptorType
0x01 bDescriptorSubtype
0x00 bmAttributes
0x00 bLockDelayUnits (undefined)
0x0000 wLockDelay
Microsoft OS Descriptor is not available. Error code: 0x0000001F
String Descriptor Table
--------------------------------
Index LANGID String
0x00 0x0000 0x0409
0x01 0x0409 "STMicroelectronics"
0x02 0x0409 "STM32 AUDIO Streaming in FS Mode"
0x03 0x0409 "368932633438"
------------------------------
Connection path for device:
USB xHCI Compliant Host Controller
Root Hub
STM32 AUDIO Streaming in FS Mode (VID=0x0483 PID=0x5730) Port: 5
Running on: Windows 10 or greater (Build Version 19043)
Brought to you by TDD v2.15.0, Jun 8 2020, 17:18:07
这是修改后的描述符：
Information for device STM32 AUDIO Streaming in FS Mode (VID=0x0483 PID=0x5730):
Connection Information:
------------------------------
Device current bus speed: FullSpeed
Device supports USB 1.1 specification
Device supports USB 2.0 specification
Device address: 0x001B
Current configuration value: 0x01
Number of open pipes: 1
Device Descriptor:
------------------------------
0x12 bLength
0x01 bDescriptorType
0x0200 bcdUSB
0x00 bDeviceClass
0x00 bDeviceSubClass
0x00 bDeviceProtocol
0x40 bMaxPacketSize0 (64 bytes)
0x0483 idVendor
0x5730 idProduct
0x0200 bcdDevice
0x01 iManufacturer "STMicroelectronics"
0x02 iProduct "STM32 AUDIO Streaming in FS Mode"
0x03 iSerialNumber "368932633438"
0x01 bNumConfigurations
Configuration Descriptor:
------------------------------
0x09 bLength
0x02 bDescriptorType
0x00D4 wTotalLength (212 bytes)
0x03 bNumInterfaces
0x01 bConfigurationValue
0x00 iConfiguration
0xC0 bmAttributes (Self-powered Device)
0x32 bMaxPower (100 mA)
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x00 bInterfaceNumber
0x00 bAlternateSetting
0x01 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x01 bInterfaceSubClass (Audio Control Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
AC Interface Header Descriptor:
------------------------------
0x0A bLength
0x24 bDescriptorType
0x01 bDescriptorSubtype
0x0100 bcdADC
0x0048 wTotalLength (72 bytes)
0x02 bInCollection
0x01 baInterfaceNr(1)
0x02 baInterfaceNr(2)
AC Input Terminal Descriptor:
------------------------------
0x0C bLength
0x24 bDescriptorType
0x02 bDescriptorSubtype
0x12 bTerminalID
0x0101 wTerminalType (USB Streaming)
0x00 bAssocTerminal
0x02 bNrChannels (2 channels)
0x0003 wChannelConfig
0x00 iChannelNames
0x00 iTerminal
AC Feature Unit Descriptor:
------------------------------
0x0A bLength
0x24 bDescriptorType
0x06 bDescriptorSubtype
0x16 bUnitID
0x12 bSourceID
0x01 bControlSize
bmaControls:
0x03 Channel(0) - Mute / Volume
0x00 Channel(1)
0x00 Channel(2)
0x00 iFeature
AC Output Terminal Descriptor:
------------------------------
0x09 bLength
0x24 bDescriptorType
0x03 bDescriptorSubtype
0x14 bTerminalID
0x0301 wTerminalType (Speaker)
0x00 bAssocTerminal
0x16 bSourceID
0x00 iTerminal
AC Input Terminal Descriptor:
------------------------------
0x0C bLength
0x24 bDescriptorType
0x02 bDescriptorSubtype
0x11 bTerminalID
0x0201 wTerminalType (Microphone)
0x00 bAssocTerminal
0x02 bNrChannels (2 channels)
0x0003 wChannelConfig
0x00 iChannelNames
0x00 iTerminal
AC Feature Unit Descriptor:
------------------------------
0x0A bLength
0x24 bDescriptorType
0x06 bDescriptorSubtype
0x15 bUnitID
0x11 bSourceID
0x01 bControlSize
bmaControls:
0x03 Channel(0) - Mute / Volume
0x00 Channel(1)
0x00 Channel(2)
0x00 iFeature
AC Output Terminal Descriptor:
------------------------------
0x09 bLength
0x24 bDescriptorType
0x03 bDescriptorSubtype
0x13 bTerminalID
0x0101 wTerminalType (USB Streaming)
0x00 bAssocTerminal
0x15 bSourceID
0x00 iTerminal
Endpoint Descriptor (Audio/MIDI 1.0):
------------------------------
0x09 bLength
0x05 bDescriptorType
0x83 bEndpointAddress (IN endpoint 3)
0x03 bmAttributes (Transfer: Interrupt / Synch: None / Usage: Data)
0x0002 wMaxPacketSize (1 x 2 bytes)
0x0A bInterval (10 frames)
0x00 bRefresh
0x00 bSynchAddress
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x01 bInterfaceNumber
0x00 bAlternateSetting
0x00 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x02 bInterfaceSubClass (Audio Streaming Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x01 bInterfaceNumber
0x01 bAlternateSetting
0x02 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x02 bInterfaceSubClass (Audio Streaming Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
AS Interface Descriptor:
------------------------------
0x07 bLength
0x24 bDescriptorType
0x01 bDescriptorSubtype
0x12 bTerminalLink
0x01 bDelay
0x0001 wFormatTag (PCM)
AS Format Type 1 Descriptor:
------------------------------
0x0B bLength
0x24 bDescriptorType
0x02 bDescriptorSubtype
0x01 bFormatType (FORMAT_TYPE_1)
0x02 bNrChannels (2 channels)
0x02 bSubframeSize
0x10 bBitResolution (16 bits per sample)
0x01 bSamFreqType (Discrete sampling frequencies)
0x00BB80 tSamFreq(1) (48000 Hz)
Endpoint Descriptor (Audio/MIDI 1.0):
------------------------------
0x09 bLength
0x05 bDescriptorType
0x01 bEndpointAddress (OUT endpoint 1)
0x05 bmAttributes (Transfer: Isochronous / Synch: Asynchronous / Usage: Data)
0x00C4 wMaxPacketSize (1 x 196 bytes)
0x01 bInterval (1 frames)
0x00 bRefresh
0x81 bSynchAddress
AS Isochronous Data Endpoint Descriptor:
------------------------------
0x07 bLength
0x25 bDescriptorType
0x01 bDescriptorSubtype
0x00 bmAttributes
0x00 bLockDelayUnits (undefined)
0x0000 wLockDelay
Endpoint Descriptor (Audio/MIDI 1.0):
------------------------------
0x09 bLength
0x05 bDescriptorType
0x81 bEndpointAddress (IN endpoint 1)
0x01 bmAttributes (Transfer: Isochronous / Synch: None / Usage: Data)
0x0003 wMaxPacketSize (1 x 3 bytes)
0x01 bInterval (1 frames)
0x07 bRefresh
0x00 bSynchAddress
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x02 bInterfaceNumber
0x00 bAlternateSetting
0x00 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x02 bInterfaceSubClass (Audio Streaming Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
Interface Descriptor:
------------------------------
0x09 bLength
0x04 bDescriptorType
0x02 bInterfaceNumber
0x01 bAlternateSetting
0x01 bNumEndPoints
0x01 bInterfaceClass (Audio Device Class)
0x02 bInterfaceSubClass (Audio Streaming Interface)
0x00 bInterfaceProtocol (Audio Protocol undefined)
0x00 iInterface
AS Interface Descriptor:
------------------------------
0x07 bLength
0x24 bDescriptorType
0x01 bDescriptorSubtype
0x13 bTerminalLink
0x01 bDelay
0x0001 wFormatTag (PCM)
AS Format Type 1 Descriptor:
------------------------------
0x0B bLength
0x24 bDescriptorType
0x02 bDescriptorSubtype
0x01 bFormatType (FORMAT_TYPE_1)
0x02 bNrChannels (2 channels)
0x02 bSubframeSize
0x10 bBitResolution (16 bits per sample)
0x01 bSamFreqType (Discrete sampling frequencies)
0x00BB80 tSamFreq(1) (48000 Hz)
Endpoint Descriptor (Audio/MIDI 1.0):
------------------------------
0x09 bLength
0x05 bDescriptorType
0x82 bEndpointAddress (IN endpoint 2)
0x01 bmAttributes (Transfer: Isochronous / Synch: None / Usage: Data)
0x00C0 wMaxPacketSize (1 x 192 bytes)
0x01 bInterval (1 frames)
0x00 bRefresh
0x00 bSynchAddress
AS Isochronous Data Endpoint Descriptor:
------------------------------
0x07 bLength
0x25 bDescriptorType
0x01 bDescriptorSubtype
0x00 bmAttributes
0x00 bLockDelayUnits (undefined)
0x0000 wLockDelay
Microsoft OS Descriptor is not available. Error code: 0x0000001F
String Descriptor Table
--------------------------------
Index LANGID String
0x00 0x0000 0x0409
0x01 0x0409 "STMicroelectronics"
0x02 0x0409 "STM32 AUDIO Streaming in FS Mode"
0x03 0x0409 "368932633438"
------------------------------
Connection path for device:
USB xHCI Compliant Host Controller
Root Hub
STM32 AUDIO Streaming in FS Mode (VID=0x0483 PID=0x5730) Port: 5
Running on: Windows 10 or greater (Build Version 19043)
Brought to you by TDD v2.15.0, Jun 8 2020, 17:18:07
我所做的改变是：
- 添加AC中断端点描述符
- 更改配置描述符中的wTotalLength
- 将AC接口描述符中的bNumEndPoints从0更改为1
USB设备似乎枚举良好，并且有音频，但当查看Beagle USB逻辑分析器的输出时，我没有看到主机从中断端点请求任何数据。所以我的问题是，我修改描述符的方式有问题吗？还是其他原因？是否有人设法使USB音频设备的状态中断端点正常工作？
运行于：Windows 10或更高版本(内部版本19043(
根据我的经验，Windows无法处理此中断。在Linux或MacOS上尝试一下。