added example which combines USB CDC and MIDI

2 files changed, 570 insertions, 0 deletions

diff --git a/lib/lufa-descriptor-usbserialmidi.c b/lib/lufa-descriptor-usbserialmidi.c
new file mode 100644
index 0000000..21b7f12
--- /dev/null
+++ b/lib/lufa-descriptor-usbserialmidi.c
@@ -0,0 +1,424 @@
+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2014.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2014  Dean Camera (dean [at] fourwalledcubicle [dot] com)
+
+  Permission to use, copy, modify, distribute, and sell this
+  software and its documentation for any purpose is hereby granted
+  without fee, provided that the above copyright notice appear in
+  all copies and that both that the copyright notice and this
+  permission notice and warranty disclaimer appear in supporting
+  documentation, and that the name of the author not be used in
+  advertising or publicity pertaining to distribution of the
+  software without specific, written prior permission.
+
+  The author disclaims all warranties with regard to this
+  software, including all implied warranties of merchantability
+  and fitness.  In no event shall the author be liable for any
+  special, indirect or consequential damages or any damages
+  whatsoever resulting from loss of use, data or profits, whether
+  in an action of contract, negligence or other tortious action,
+  arising out of or in connection with the use or performance of
+  this software.
+*/
+
+/** \file
+ *
+ *  USB Device Descriptors, for library use when in USB device mode. Descriptors are special
+ *  computer-readable structures which the host requests upon device enumeration, to determine
+ *  the device's capabilities and functions.
+ */
+
+#include "lufa-descriptor-usbserialmidi.h"
+
+
+/** Device descriptor structure. This descriptor, located in FLASH memory, describes the overall
+ *  device characteristics, including the supported USB version, control endpoint size and the
+ *  number of device configurations. The descriptor is read out by the USB host when the enumeration
+ *  process begins.
+ */
+const USB_Descriptor_Device_t PROGMEM DeviceDescriptor =
+{
+  .Header                 = {.Size = sizeof(USB_Descriptor_Device_t), .Type = DTYPE_Device},
+
+  .USBSpecification       = VERSION_BCD(1,1,0),
+  .Class                  = USB_CSCP_IADDeviceClass,
+  .SubClass               = USB_CSCP_IADDeviceSubclass,
+  .Protocol               = USB_CSCP_IADDeviceProtocol,
+
+  .Endpoint0Size          = FIXED_CONTROL_ENDPOINT_SIZE,
+
+  .VendorID               = 0x03EB,
+  .ProductID              = 0x204E,
+  .ReleaseNumber          = VERSION_BCD(0,0,1),
+
+  .ManufacturerStrIndex   = STRING_ID_Manufacturer,
+  .ProductStrIndex        = STRING_ID_Product,
+  .SerialNumStrIndex      = USE_INTERNAL_SERIAL,
+
+  .NumberOfConfigurations = FIXED_NUM_CONFIGURATIONS
+};
+
+/** Configuration descriptor structure. This descriptor, located in FLASH memory, describes the usage
+ *  of the device in one of its supported configurations, including information about any device interfaces
+ *  and endpoints. The descriptor is read out by the USB host during the enumeration process when selecting
+ *  a configuration so that the host may correctly communicate with the USB device.
+ */
+const USB_Descriptor_Configuration_t PROGMEM ConfigurationDescriptor =
+{
+  .Config =
+    {
+      .Header                 = {.Size = sizeof(USB_Descriptor_Configuration_Header_t), .Type = DTYPE_Configuration},
+
+      .TotalConfigurationSize = sizeof(USB_Descriptor_Configuration_t),
+      .TotalInterfaces        = 4,
+
+      .ConfigurationNumber    = 1,
+      .ConfigurationStrIndex  = NO_DESCRIPTOR,
+
+      .ConfigAttributes       = (USB_CONFIG_ATTR_RESERVED | USB_CONFIG_ATTR_SELFPOWERED),
+
+      .MaxPowerConsumption    = USB_CONFIG_POWER_MA(100)
+    },
+
+  .CDC_IAD =
+    {
+      .Header                 = {.Size = sizeof(USB_Descriptor_Interface_Association_t), .Type = DTYPE_InterfaceAssociation},
+
+      .FirstInterfaceIndex    = INTERFACE_ID_CDC_CCI,
+      .TotalInterfaces        = 2,
+
+      .Class                  = CDC_CSCP_CDCClass,
+      .SubClass               = CDC_CSCP_ACMSubclass,
+      .Protocol               = CDC_CSCP_ATCommandProtocol,
+
+      .IADStrIndex            = NO_DESCRIPTOR
+    },
+
+  .CDC_CCI_Interface =
+    {
+      .Header                 = {.Size = sizeof(USB_Descriptor_Interface_t), .Type = DTYPE_Interface},
+
+      .InterfaceNumber        = INTERFACE_ID_CDC_CCI,
+      .AlternateSetting       = 0,
+
+      .TotalEndpoints         = 1,
+
+      .Class                  = CDC_CSCP_CDCClass,
+      .SubClass               = CDC_CSCP_ACMSubclass,
+      .Protocol               = CDC_CSCP_ATCommandProtocol,
+
+      .InterfaceStrIndex      = NO_DESCRIPTOR
+    },
+
+  .CDC_Functional_Header =
+    {
+      .Header                 = {.Size = sizeof(USB_CDC_Descriptor_FunctionalHeader_t), .Type = DTYPE_CSInterface},
+      .Subtype                = CDC_DSUBTYPE_CSInterface_Header,
+
+      .CDCSpecification       = VERSION_BCD(1,1,0),
+    },
+
+  .CDC_Functional_ACM =
+    {
+      .Header                 = {.Size = sizeof(USB_CDC_Descriptor_FunctionalACM_t), .Type = DTYPE_CSInterface},
+      .Subtype                = CDC_DSUBTYPE_CSInterface_ACM,
+
+      .Capabilities           = 0x06,
+    },
+
+  .CDC_Functional_Union =
+    {
+      .Header                 = {.Size = sizeof(USB_CDC_Descriptor_FunctionalUnion_t), .Type = DTYPE_CSInterface},
+      .Subtype                = CDC_DSUBTYPE_CSInterface_Union,
+
+      .MasterInterfaceNumber  = INTERFACE_ID_CDC_CCI,
+      .SlaveInterfaceNumber   = INTERFACE_ID_CDC_DCI,
+    },
+
+  .CDC_ManagementEndpoint =
+    {
+      .Header                 = {.Size = sizeof(USB_Descriptor_Endpoint_t), .Type = DTYPE_Endpoint},
+
+      .EndpointAddress        = CDC_NOTIFICATION_EPADDR,
+      .Attributes             = (EP_TYPE_INTERRUPT | ENDPOINT_ATTR_NO_SYNC | ENDPOINT_USAGE_DATA),
+      .EndpointSize           = CDC_NOTIFICATION_EPSIZE,
+      .PollingIntervalMS      = 0xFF
+    },
+
+  .CDC_DCI_Interface =
+    {
+      .Header                 = {.Size = sizeof(USB_Descriptor_Interface_t), .Type = DTYPE_Interface},
+
+      .InterfaceNumber        = INTERFACE_ID_CDC_DCI,
+      .AlternateSetting       = 0,
+
+      .TotalEndpoints         = 2,
+
+      .Class                  = CDC_CSCP_CDCDataClass,
+      .SubClass               = CDC_CSCP_NoDataSubclass,
+      .Protocol               = CDC_CSCP_NoDataProtocol,
+
+      .InterfaceStrIndex      = NO_DESCRIPTOR
+    },
+
+  .CDC_DataOutEndpoint =
+    {
+      .Header                 = {.Size = sizeof(USB_Descriptor_Endpoint_t), .Type = DTYPE_Endpoint},
+
+      .EndpointAddress        = CDC_RX_EPADDR,
+      .Attributes             = (EP_TYPE_BULK | ENDPOINT_ATTR_NO_SYNC | ENDPOINT_USAGE_DATA),
+      .EndpointSize           = CDC_TXRX_EPSIZE,
+      .PollingIntervalMS      = 0x05
+    },
+
+  .CDC_DataInEndpoint =
+    {
+      .Header                 = {.Size = sizeof(USB_Descriptor_Endpoint_t), .Type = DTYPE_Endpoint},
+
+      .EndpointAddress        = CDC_TX_EPADDR,
+      .Attributes             = (EP_TYPE_BULK | ENDPOINT_ATTR_NO_SYNC | ENDPOINT_USAGE_DATA),
+      .EndpointSize           = CDC_TXRX_EPSIZE,
+      .PollingIntervalMS      = 0x05
+    },
+
+  .Audio_ControlInterface =
+    {
+      .Header                   = {.Size = sizeof(USB_Descriptor_Interface_t), .Type = DTYPE_Interface},
+
+      .InterfaceNumber          = INTERFACE_ID_AudioControl,
+      .AlternateSetting         = 0,
+
+      .TotalEndpoints           = 0,
+
+      .Class                    = AUDIO_CSCP_AudioClass,
+      .SubClass                 = AUDIO_CSCP_ControlSubclass,
+      .Protocol                 = AUDIO_CSCP_ControlProtocol,
+
+      .InterfaceStrIndex        = NO_DESCRIPTOR
+    },
+
+  .Audio_ControlInterface_SPC =
+    {
+      .Header                   = {.Size = sizeof(USB_Audio_Descriptor_Interface_AC_t), .Type = DTYPE_CSInterface},
+      .Subtype                  = AUDIO_DSUBTYPE_CSInterface_Header,
+
+      .ACSpecification          = VERSION_BCD(1,0,0),
+      .TotalLength              = sizeof(USB_Audio_Descriptor_Interface_AC_t),
+
+      .InCollection             = 1,
+      .InterfaceNumber          = INTERFACE_ID_AudioStream,
+    },
+
+  .Audio_StreamInterface =
+    {
+      .Header                   = {.Size = sizeof(USB_Descriptor_Interface_t), .Type = DTYPE_Interface},
+
+      .InterfaceNumber          = INTERFACE_ID_AudioStream,
+      .AlternateSetting         = 0,
+
+      .TotalEndpoints           = 2,
+
+      .Class                    = AUDIO_CSCP_AudioClass,
+      .SubClass                 = AUDIO_CSCP_MIDIStreamingSubclass,
+      .Protocol                 = AUDIO_CSCP_StreamingProtocol,
+
+      .InterfaceStrIndex        = NO_DESCRIPTOR
+    },
+
+  .Audio_StreamInterface_SPC =
+    {
+      .Header                   = {.Size = sizeof(USB_MIDI_Descriptor_AudioInterface_AS_t), .Type = DTYPE_CSInterface},
+      .Subtype                  = AUDIO_DSUBTYPE_CSInterface_General,
+
+      .AudioSpecification       = VERSION_BCD(1,0,0),
+
+      .TotalLength              = (sizeof(USB_Descriptor_Configuration_t) -
+                                   offsetof(USB_Descriptor_Configuration_t, Audio_StreamInterface_SPC))
+    },
+
+  .MIDI_In_Jack_Emb =
+    {
+      .Header                   = {.Size = sizeof(USB_MIDI_Descriptor_InputJack_t), .Type = DTYPE_CSInterface},
+      .Subtype                  = AUDIO_DSUBTYPE_CSInterface_InputTerminal,
+
+      .JackType                 = MIDI_JACKTYPE_Embedded,
+      .JackID                   = 0x01,
+
+      .JackStrIndex             = NO_DESCRIPTOR
+    },
+
+  .MIDI_In_Jack_Ext =
+    {
+      .Header                   = {.Size = sizeof(USB_MIDI_Descriptor_InputJack_t), .Type = DTYPE_CSInterface},
+      .Subtype                  = AUDIO_DSUBTYPE_CSInterface_InputTerminal,
+
+      .JackType                 = MIDI_JACKTYPE_External,
+      .JackID                   = 0x02,
+
+      .JackStrIndex             = NO_DESCRIPTOR
+    },
+
+  .MIDI_Out_Jack_Emb =
+    {
+      .Header                   = {.Size = sizeof(USB_MIDI_Descriptor_OutputJack_t), .Type = DTYPE_CSInterface},
+      .Subtype                  = AUDIO_DSUBTYPE_CSInterface_OutputTerminal,
+
+      .JackType                 = MIDI_JACKTYPE_Embedded,
+      .JackID                   = 0x03,
+
+      .NumberOfPins             = 1,
+      .SourceJackID             = {0x02},
+      .SourcePinID              = {0x01},
+
+      .JackStrIndex             = NO_DESCRIPTOR
+    },
+
+  .MIDI_Out_Jack_Ext =
+    {
+      .Header                   = {.Size = sizeof(USB_MIDI_Descriptor_OutputJack_t), .Type = DTYPE_CSInterface},
+      .Subtype                  = AUDIO_DSUBTYPE_CSInterface_OutputTerminal,
+
+      .JackType                 = MIDI_JACKTYPE_External,
+      .JackID                   = 0x04,
+
+      .NumberOfPins             = 1,
+      .SourceJackID             = {0x01},
+      .SourcePinID              = {0x01},
+
+      .JackStrIndex             = NO_DESCRIPTOR
+    },
+
+  .MIDI_In_Jack_Endpoint =
+    {
+      .Endpoint =
+        {
+          .Header              = {.Size = sizeof(USB_Audio_Descriptor_StreamEndpoint_Std_t), .Type = DTYPE_Endpoint},
+
+          .EndpointAddress     = MIDI_STREAM_OUT_EPADDR,
+          .Attributes          = (EP_TYPE_BULK | ENDPOINT_ATTR_NO_SYNC | ENDPOINT_USAGE_DATA),
+          .EndpointSize        = MIDI_STREAM_EPSIZE,
+          .PollingIntervalMS   = 0x05
+        },
+
+      .Refresh                  = 0,
+      .SyncEndpointNumber       = 0
+    },
+
+  .MIDI_In_Jack_Endpoint_SPC =
+    {
+      .Header                   = {.Size = sizeof(USB_MIDI_Descriptor_Jack_Endpoint_t), .Type = DTYPE_CSEndpoint},
+      .Subtype                  = AUDIO_DSUBTYPE_CSEndpoint_General,
+
+      .TotalEmbeddedJacks       = 0x01,
+      .AssociatedJackID         = {0x01}
+    },
+
+  .MIDI_Out_Jack_Endpoint =
+    {
+      .Endpoint =
+        {
+          .Header              = {.Size = sizeof(USB_Audio_Descriptor_StreamEndpoint_Std_t), .Type = DTYPE_Endpoint},
+
+          .EndpointAddress     = MIDI_STREAM_IN_EPADDR,
+          .Attributes          = (EP_TYPE_BULK | ENDPOINT_ATTR_NO_SYNC | ENDPOINT_USAGE_DATA),
+          .EndpointSize        = MIDI_STREAM_EPSIZE,
+          .PollingIntervalMS   = 0x05
+        },
+
+      .Refresh                  = 0,
+      .SyncEndpointNumber       = 0
+    },
+
+  .MIDI_Out_Jack_Endpoint_SPC =
+    {
+      .Header                   = {.Size = sizeof(USB_MIDI_Descriptor_Jack_Endpoint_t), .Type = DTYPE_CSEndpoint},
+      .Subtype                  = AUDIO_DSUBTYPE_CSEndpoint_General,
+
+      .TotalEmbeddedJacks       = 0x01,
+      .AssociatedJackID         = {0x03}
+    }
+};
+
+/** Language descriptor structure. This descriptor, located in FLASH memory, is returned when the host requests
+ *  the string descriptor with index 0 (the first index). It is actually an array of 16-bit integers, which indicate
+ *  via the language ID table available at USB.org what languages the device supports for its string descriptors.
+ */
+const USB_Descriptor_String_t PROGMEM LanguageString = USB_STRING_DESCRIPTOR_ARRAY(LANGUAGE_ID_ENG);
+
+/** Manufacturer descriptor string. This is a Unicode string containing the manufacturer's details in human readable
+ *  form, and is read out upon request by the host when the appropriate string ID is requested, listed in the Device
+ *  Descriptor.
+ */
+#ifndef USB_MANUFACTURER
+const USB_Descriptor_String_t PROGMEM ManufacturerString = USB_STRING_DESCRIPTOR(L"Dean Camera");
+#else
+const USB_Descriptor_String_t PROGMEM ManufacturerString = USB_STRING_DESCRIPTOR(USB_MANUFACTURER);
+#endif
+
+/** Product descriptor string. This is a Unicode string containing the product's details in human readable form,
+ *  and is read out upon request by the host when the appropriate string ID is requested, listed in the Device
+ *  Descriptor.
+ */
+#ifndef USB_PRODUCT
+const USB_Descriptor_String_t PROGMEM ProductString = USB_STRING_DESCRIPTOR(L"LUFA CDC MIDI Demo");
+#else
+const USB_Descriptor_String_t PROGMEM ProductString = USB_STRING_DESCRIPTOR(USB_PRODUCT);
+#endif
+
+/** This function is called by the library when in device mode, and must be overridden (see library "USB Descriptors"
+ *  documentation) by the application code so that the address and size of a requested descriptor can be given
+ *  to the USB library. When the device receives a Get Descriptor request on the control endpoint, this function
+ *  is called so that the descriptor details can be passed back and the appropriate descriptor sent back to the
+ *  USB host.
+ */
+uint16_t CALLBACK_USB_GetDescriptor(const uint16_t wValue,
+                                    const uint8_t wIndex,
+                                    const void** const DescriptorAddress)
+{
+  const uint8_t  DescriptorType   = (wValue >> 8);
+  const uint8_t  DescriptorNumber = (wValue & 0xFF);
+
+  const void* Address = NULL;
+  uint16_t    Size    = NO_DESCRIPTOR;
+
+  switch (DescriptorType)
+  {
+    case DTYPE_Device:
+      Address = &DeviceDescriptor;
+      Size    = sizeof(USB_Descriptor_Device_t);
+      break;
+    case DTYPE_Configuration:
+      Address = &ConfigurationDescriptor;
+      Size    = sizeof(USB_Descriptor_Configuration_t);
+      break;
+    case DTYPE_String:
+      switch (DescriptorNumber)
+      {
+        case STRING_ID_Language:
+          Address = &LanguageString;
+          Size    = pgm_read_byte(&LanguageString.Header.Size);
+          break;
+        case STRING_ID_Manufacturer:
+          Address = &ManufacturerString;
+          Size    = pgm_read_byte(&ManufacturerString.Header.Size);
+          break;
+        case STRING_ID_Product:
+          Address = &ProductString;
+          Size    = pgm_read_byte(&ProductString.Header.Size);
+          break;
+      }
+
+      break;
+  }
+
+  *DescriptorAddress = Address;
+  return Size;
+}
+
diff --git a/lib/lufa-descriptor-usbserialmidi.h b/lib/lufa-descriptor-usbserialmidi.h
new file mode 100644
index 0000000..2a07acf
--- /dev/null
+++ b/lib/lufa-descriptor-usbserialmidi.h
@@ -0,0 +1,146 @@
+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2014.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2014  Dean Camera (dean [at] fourwalledcubicle [dot] com)
+
+  Permission to use, copy, modify, distribute, and sell this
+  software and its documentation for any purpose is hereby granted
+  without fee, provided that the above copyright notice appear in
+  all copies and that both that the copyright notice and this
+  permission notice and warranty disclaimer appear in supporting
+  documentation, and that the name of the author not be used in
+  advertising or publicity pertaining to distribution of the
+  software without specific, written prior permission.
+
+  The author disclaims all warranties with regard to this
+  software, including all implied warranties of merchantability
+  and fitness.  In no event shall the author be liable for any
+  special, indirect or consequential damages or any damages
+  whatsoever resulting from loss of use, data or profits, whether
+  in an action of contract, negligence or other tortious action,
+  arising out of or in connection with the use or performance of
+  this software.
+*/
+
+/** \file
+ *
+ *  Header file for Descriptors.c.
+ */
+
+#ifndef _DESCRIPTORS_H_
+#define _DESCRIPTORS_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+  /* Includes: */
+    #include <avr/pgmspace.h>
+
+    #include <LUFA/Drivers/USB/USB.h>
+
+  /* Macros: */
+    /** Endpoint address of the CDC interface's device-to-host data IN endpoint. */
+    #define CDC_TX_EPADDR                 (ENDPOINT_DIR_IN  | 1)
+
+    /** Endpoint address of the CDC interface's host-to-device data OUT endpoint. */
+    #define CDC_RX_EPADDR                 (ENDPOINT_DIR_OUT | 2)
+
+    /** Endpoint address of the CDC interface's device-to-host notification IN endpoint. */
+    #define CDC_NOTIFICATION_EPADDR       (ENDPOINT_DIR_IN  | 3)
+
+    /** Size in bytes of the CDC device-to-host notification IN endpoints. */
+    #define CDC_NOTIFICATION_EPSIZE        8
+
+    /** Size in bytes of the CDC data IN and OUT endpoints. */
+    #define CDC_TXRX_EPSIZE                16
+
+    /** Endpoint address of the MIDI streaming data IN endpoint, for device-to-host data transfers. */
+    #define MIDI_STREAM_IN_EPADDR         (ENDPOINT_DIR_IN  | 4)
+
+    /** Endpoint address of the MIDI streaming data OUT endpoint, for host-to-device data transfers. */
+    #define MIDI_STREAM_OUT_EPADDR        (ENDPOINT_DIR_OUT | 5)
+
+    /** Endpoint size in bytes of the Audio isochronous streaming data IN and OUT endpoints. */
+    #define MIDI_STREAM_EPSIZE             64
+
+  /* Type Defines: */
+    /** Type define for the device configuration descriptor structure. This must be defined in the
+     *  application code, as the configuration descriptor contains several sub-descriptors which
+     *  vary between devices, and which describe the device's usage to the host.
+     */
+    typedef struct
+    {
+      USB_Descriptor_Configuration_Header_t     Config;
+
+      // CDC Control Interface
+      USB_Descriptor_Interface_Association_t    CDC_IAD;
+      USB_Descriptor_Interface_t                CDC_CCI_Interface;
+      USB_CDC_Descriptor_FunctionalHeader_t     CDC_Functional_Header;
+      USB_CDC_Descriptor_FunctionalACM_t        CDC_Functional_ACM;
+      USB_CDC_Descriptor_FunctionalUnion_t      CDC_Functional_Union;
+      USB_Descriptor_Endpoint_t                 CDC_ManagementEndpoint;
+
+      // CDC Data Interface
+      USB_Descriptor_Interface_t                CDC_DCI_Interface;
+      USB_Descriptor_Endpoint_t                 CDC_DataOutEndpoint;
+      USB_Descriptor_Endpoint_t                 CDC_DataInEndpoint;
+
+      // MIDI Audio Control Interface
+      USB_Descriptor_Interface_t                Audio_ControlInterface;
+      USB_Audio_Descriptor_Interface_AC_t       Audio_ControlInterface_SPC;
+
+      // MIDI Audio Streaming Interface
+      USB_Descriptor_Interface_t                Audio_StreamInterface;
+      USB_MIDI_Descriptor_AudioInterface_AS_t   Audio_StreamInterface_SPC;
+      USB_MIDI_Descriptor_InputJack_t           MIDI_In_Jack_Emb;
+      USB_MIDI_Descriptor_InputJack_t           MIDI_In_Jack_Ext;
+      USB_MIDI_Descriptor_OutputJack_t          MIDI_Out_Jack_Emb;
+      USB_MIDI_Descriptor_OutputJack_t          MIDI_Out_Jack_Ext;
+      USB_Audio_Descriptor_StreamEndpoint_Std_t MIDI_In_Jack_Endpoint;
+      USB_MIDI_Descriptor_Jack_Endpoint_t       MIDI_In_Jack_Endpoint_SPC;
+      USB_Audio_Descriptor_StreamEndpoint_Std_t MIDI_Out_Jack_Endpoint;
+      USB_MIDI_Descriptor_Jack_Endpoint_t       MIDI_Out_Jack_Endpoint_SPC;
+    } USB_Descriptor_Configuration_t;
+
+    /** Enum for the device interface descriptor IDs within the device. Each interface descriptor
+     *  should have a unique ID index associated with it, which can be used to refer to the
+     *  interface from other descriptors.
+     */
+    enum InterfaceDescriptors_t
+    {
+      INTERFACE_ID_CDC_CCI = 0, /**< CDC CCI interface descriptor ID */
+      INTERFACE_ID_CDC_DCI = 1, /**< CDC DCI interface descriptor ID */
+      INTERFACE_ID_AudioControl = 2, /**< Audio control interface descriptor ID */
+      INTERFACE_ID_AudioStream  = 3, /**< Audio streaming interface descriptor ID */
+    };
+
+    /** Enum for the device string descriptor IDs within the device. Each string descriptor should
+     *  have a unique ID index associated with it, which can be used to refer to the string from
+     *  other descriptors.
+     */
+    enum StringDescriptors_t
+    {
+      STRING_ID_Language     = 0, /**< Supported Languages string descriptor ID (must be zero) */
+      STRING_ID_Manufacturer = 1, /**< Manufacturer string ID */
+      STRING_ID_Product      = 2, /**< Product string ID */
+    };
+
+  /* Function Prototypes: */
+    uint16_t CALLBACK_USB_GetDescriptor(const uint16_t wValue,
+                                        const uint8_t wIndex,
+                                        const void** const DescriptorAddress)
+                                        ATTR_WARN_UNUSED_RESULT ATTR_NON_NULL_PTR_ARG(3);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+