Added new incomplete AudioOutputHost Host LowLevel demo.

Demos/Host/Incomplete/AudioInputHost/AudioInputHost.c

@@ -43,7 +43,7 @@ int main(void)
 {
 	SetupHardware();
 
-	puts_P(PSTR(ESC_FG_CYAN "Audio Host Demo running.\r\n" ESC_FG_WHITE));
+	puts_P(PSTR(ESC_FG_CYAN "Audio Input Host Demo running.\r\n" ESC_FG_WHITE));
 
 	LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 	sei();
@@ -208,7 +208,7 @@ void Audio_Task(void)
 	
 			/* Sample reload timer initialization */
 			TIMSK0  = (1 << OCIE0A);
-			OCR0A   = ((F_CPU / 8 / 8000) - 1);
+			OCR0A   = ((F_CPU / 8 / 48000) - 1);
 			TCCR0A  = (1 << WGM01);  // CTC mode
 			TCCR0B  = (1 << CS01);   // Fcpu/8 speed	
 

Demos/Host/Incomplete/AudioInputHost/AudioInputHost.h

@@ -30,11 +30,11 @@
 
 /** \file
  *
- *  Header file for AudioHost.c.
+ *  Header file for AudioInputHost.c.
  */
 
-#ifndef _AUDIO_HOST_H_
-#define _AUDIO_HOST_H_
+#ifndef _AUDIO_INPUT_HOST_H_
+#define _AUDIO_INPUT_HOST_H_
 
 	/* Includes: */
 		#include <avr/io.h>

Demos/Host/Incomplete/AudioInputHost/ConfigDescriptor.c

@@ -120,7 +120,7 @@ uint8_t ProcessConfigurationDescriptor(void)
 		/* Retrieve the endpoint address from the endpoint descriptor */
 		USB_Descriptor_Endpoint_t* EndpointData = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Endpoint_t);
 
-		/* If the endpoint is a IN type endpoint */
+		/* Save the endpoint if it is an IN type endpoint */
 		if (EndpointData->EndpointAddress & ENDPOINT_DESCRIPTOR_DIR_IN)
 		  DataINEndpoint = EndpointData;
 	}
@@ -129,7 +129,7 @@ uint8_t ProcessConfigurationDescriptor(void)
 	StreamingInterfaceAltSetting = AudioStreamingInterface->AlternateSetting;
 	StreamingEndpointAddress     = DataINEndpoint->EndpointAddress;
 
-	/* Configure the HID data IN pipe */
+	/* Configure the Audio data IN pipe */
 	Pipe_ConfigurePipe(AUDIO_DATA_IN_PIPE, EP_TYPE_ISOCHRONOUS, PIPE_TOKEN_IN,
 	                   DataINEndpoint->EndpointAddress, DataINEndpoint->EndpointSize, PIPE_BANK_DOUBLE);
 

Demos/Host/Incomplete/AudioOutputHost/AudioOutputHost.c

+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2011.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2011  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 disclaim 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
+ *
+ *  Main source file for the AudioOutputHost demo. This file contains the main tasks of
+ *  the demo and is responsible for the initial application hardware configuration.
+ */
+
+#include "AudioOutputHost.h"
+
+/** Main program entry point. This routine configures the hardware required by the application, then
+ *  enters a loop to run the application tasks in sequence.
+ */
+int main(void)
+{
+	SetupHardware();
+
+	puts_P(PSTR(ESC_FG_CYAN "Audio Output Host Demo running.\r\n" ESC_FG_WHITE));
+
+	LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
+	sei();
+
+	for (;;)
+	{
+		Audio_Task();
+		USB_USBTask();
+	}
+}
+
+/** Configures the board hardware and chip peripherals for the demo's functionality. */
+void SetupHardware(void)
+{
+	/* Disable watchdog if enabled by bootloader/fuses */
+	MCUSR &= ~(1 << WDRF);
+	wdt_disable();
+
+	/* Disable clock division */
+	clock_prescale_set(clock_div_1);
+
+	/* Hardware Initialization */
+	Serial_Init(9600, false);
+	Buttons_Init();
+	LEDs_Init();
+	USB_Init();
+
+	/* Create a stdio stream for the serial port for stdin and stdout */
+	Serial_CreateStream(NULL);
+}
+
+/** Event handler for the USB_DeviceAttached event. This indicates that a device has been attached to the host, and
+ *  starts the library USB task to begin the enumeration and USB management process.
+ */
+void EVENT_USB_Host_DeviceAttached(void)
+{
+	puts_P(PSTR(ESC_FG_GREEN "Device Attached.\r\n" ESC_FG_WHITE));
+	LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
+}
+
+/** Event handler for the USB_DeviceUnattached event. This indicates that a device has been removed from the host, and
+ *  stops the library USB task management process.
+ */
+void EVENT_USB_Host_DeviceUnattached(void)
+{
+	puts_P(PSTR(ESC_FG_GREEN "Device Unattached.\r\n" ESC_FG_WHITE));
+	LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
+}
+
+/** Event handler for the USB_DeviceEnumerationComplete event. This indicates that a device has been successfully
+ *  enumerated by the host and is now ready to be used by the application.
+ */
+void EVENT_USB_Host_DeviceEnumerationComplete(void)
+{
+	LEDs_SetAllLEDs(LEDMASK_USB_READY);
+}
+
+/** Event handler for the USB_HostError event. This indicates that a hardware error occurred while in host mode. */
+void EVENT_USB_Host_HostError(const uint8_t ErrorCode)
+{
+	USB_Disable();
+
+	printf_P(PSTR(ESC_FG_RED "Host Mode Error\r\n"
+	                         " -- Error Code %d\r\n" ESC_FG_WHITE), ErrorCode);
+
+	LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
+	for(;;);
+}
+
+/** Event handler for the USB_DeviceEnumerationFailed event. This indicates that a problem occurred while
+ *  enumerating an attached USB device.
+ */
+void EVENT_USB_Host_DeviceEnumerationFailed(const uint8_t ErrorCode,
+                                            const uint8_t SubErrorCode)
+{
+	printf_P(PSTR(ESC_FG_RED "Dev Enum Error\r\n"
+	                         " -- Error Code %d\r\n"
+	                         " -- Sub Error Code %d\r\n"
+	                         " -- In State %d\r\n" ESC_FG_WHITE), ErrorCode, SubErrorCode, USB_HostState);
+
+	LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
+}
+
+void Audio_Task(void)
+{
+	uint8_t ErrorCode;
+
+	switch (USB_HostState)
+	{
+		case HOST_STATE_Addressed:
+			puts_P(PSTR("Getting Config Data.\r\n"));
+
+			/* Get and process the configuration descriptor data */
+			if ((ErrorCode = ProcessConfigurationDescriptor()) != SuccessfulConfigRead)
+			{
+				if (ErrorCode == ControlError)
+				  puts_P(PSTR(ESC_FG_RED "Control Error (Get Configuration).\r\n"));
+				else
+				  puts_P(PSTR(ESC_FG_RED "Invalid Device.\r\n"));
+
+				printf_P(PSTR(" -- Error Code: %d\r\n" ESC_FG_WHITE), ErrorCode);
+
+				/* Indicate error status */
+				LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
+
+				/* Wait until USB device disconnected */
+				USB_HostState = HOST_STATE_WaitForDeviceRemoval;
+				break;
+			}
+
+			/* Set the device configuration to the first configuration (rarely do devices use multiple configurations) */
+			if ((ErrorCode = USB_Host_SetDeviceConfiguration(1)) != HOST_SENDCONTROL_Successful)
+			{
+				printf_P(PSTR(ESC_FG_RED "Control Error (Set Configuration).\r\n"
+				                         " -- Error Code: %d\r\n" ESC_FG_WHITE), ErrorCode);
+
+				/* Indicate error status */
+				LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
+
+				/* Wait until USB device disconnected */
+				USB_HostState = HOST_STATE_WaitForDeviceRemoval;
+				break;
+			}
+			
+			if ((ErrorCode = USB_Host_SetInterfaceAltSetting(StreamingInterfaceIndex,
+			                                                 StreamingInterfaceAltSetting)) != HOST_SENDCONTROL_Successful)
+			{
+				printf_P(PSTR(ESC_FG_RED "Could not set alternative streaming interface setting.\r\n"
+				                         " -- Error Code: %d\r\n" ESC_FG_WHITE), ErrorCode);
+
+				/* Indicate error status */
+				LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
+
+				/* Wait until USB device disconnected */
+				USB_HostState = HOST_STATE_WaitForDeviceRemoval;
+				break;
+			}
+
+			USB_ControlRequest = (USB_Request_Header_t)
+				{
+					.bmRequestType = (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT),
+					.bRequest      = AUDIO_REQ_SetCurrent,
+					.wValue        = 0x0100,
+					.wIndex        = StreamingEndpointAddress,
+					.wLength       = sizeof(USB_Audio_SampleFreq_t),
+				};
+				
+			USB_Audio_SampleFreq_t SampleRate = AUDIO_SAMPLE_FREQ(48000);
+
+			/* Select the control pipe for the request transfer */
+			Pipe_SelectPipe(PIPE_CONTROLPIPE);
+
+			/* Set the sample rate on the streaming interface endpoint */
+			if ((ErrorCode = USB_Host_SendControlRequest(&SampleRate)) != HOST_SENDCONTROL_Successful)
+			{
+				/* Indicate error status */
+				LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
+
+				/* Wait until USB device disconnected */
+				USB_HostState = HOST_STATE_WaitForDeviceRemoval;
+				break;
+			}
+	
+			/* Sample reload timer initialization */
+			TIMSK0  = (1 << OCIE0A);
+			OCR0A   = ((F_CPU / 8 / 48000) - 1);
+			TCCR0A  = (1 << WGM01);  // CTC mode
+			TCCR0B  = (1 << CS01);   // Fcpu/8 speed	
+			
+			puts_P(PSTR("Speaker Enumerated.\r\n"));
+
+			USB_HostState = HOST_STATE_Configured;
+			break;
+		case HOST_STATE_Configured:
+			break;
+	}
+}
+
+/** ISR to handle the reloading of the endpoint with the next sample. */
+ISR(TIMER0_COMPA_vect, ISR_BLOCK)
+{
+	uint8_t PrevPipe = Pipe_GetCurrentPipe();
+
+	Pipe_SelectPipe(AUDIO_DATA_OUT_PIPE);
+	Pipe_Unfreeze();
+
+	/* Check if the current pipe can be written to (device ready for more data) */
+	if (Pipe_IsOUTReady())
+	{
+		static uint8_t SquareWaveSampleCount;
+		static int16_t CurrentWaveValue;
+			
+		if (SquareWaveSampleCount++ == 0xFF)
+		  CurrentWaveValue ^= 0x8000;
+			
+		/* Only generate audio if the board button is being pressed */
+		int16_t Sample_16Bit = (Buttons_GetStatus() & BUTTONS_BUTTON1) ? CurrentWaveValue : 0;
+		
+		Pipe_Write_16_LE(Sample_16Bit);
+		Pipe_Write_16_LE(Sample_16Bit);
+		
+		if (!(Pipe_IsReadWriteAllowed()))
+		  Pipe_ClearOUT();
+	}
+
+	Pipe_Freeze();
+	Pipe_SelectPipe(PrevPipe);
+}

Demos/Host/Incomplete/AudioOutputHost/AudioOutputHost.h

+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2011.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2011  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 disclaim 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 AudioOutputHost.c.
+ */
+
+#ifndef _AUDIO_OUTPUT_HOST_H_
+#define _AUDIO_OUTPUT_HOST_H_
+
+	/* Includes: */
+		#include <avr/io.h>
+		#include <avr/wdt.h>
+		#include <avr/pgmspace.h>
+		#include <avr/power.h>
+		#include <avr/interrupt.h>
+		#include <stdio.h>
+
+		#include <LUFA/Version.h>
+		#include <LUFA/Drivers/Misc/TerminalCodes.h>
+		#include <LUFA/Drivers/USB/USB.h>
+		#include <LUFA/Drivers/Peripheral/Serial.h>
+		#include <LUFA/Drivers/Board/LEDs.h>
+		#include <LUFA/Drivers/Board/Buttons.h>
+
+		#include "ConfigDescriptor.h"
+
+	/* Macros: */
+		/** LED mask for the library LED driver, to indicate that the USB interface is not ready. */
+		#define LEDMASK_USB_NOTREADY      LEDS_LED1
+
+		/** LED mask for the library LED driver, to indicate that the USB interface is enumerating. */
+		#define LEDMASK_USB_ENUMERATING  (LEDS_LED2 | LEDS_LED3)
+
+		/** LED mask for the library LED driver, to indicate that the USB interface is ready. */
+		#define LEDMASK_USB_READY        (LEDS_LED2 | LEDS_LED4)
+
+		/** LED mask for the library LED driver, to indicate that an error has occurred in the USB interface. */
+		#define LEDMASK_USB_ERROR        (LEDS_LED1 | LEDS_LED3)
+
+	/* Function Prototypes: */
+		void Audio_Task(void);
+		void SetupHardware(void);
+
+		void EVENT_USB_Host_HostError(const uint8_t ErrorCode);
+		void EVENT_USB_Host_DeviceAttached(void);
+		void EVENT_USB_Host_DeviceUnattached(void);
+		void EVENT_USB_Host_DeviceEnumerationFailed(const uint8_t ErrorCode,
+		                                            const uint8_t SubErrorCode);
+		void EVENT_USB_Host_DeviceEnumerationComplete(void);
+
+#endif
+

Demos/Host/Incomplete/AudioOutputHost/ConfigDescriptor.c

+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2011.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2011  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 disclaim 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 Configuration Descriptor processing routines, to determine the correct pipe configurations
+ *  needed to communication with an attached USB device. Descriptors are special  computer-readable structures
+ *  which the host requests upon device enumeration, to determine the device's capabilities and functions.
+ */
+
+#include "ConfigDescriptor.h"
+
+/** Index of the currently used Audio Streaming Interface within the device. */
+uint8_t StreamingInterfaceIndex      = 0;
+
+/** Alternative Setting of the currently used Audio Streaming Interface within the device. */
+uint8_t StreamingInterfaceAltSetting = 0;
+
+/** Address of the streaming audio endpoint currently in use within the device. */
+uint8_t StreamingEndpointAddress     = 0;
+
+
+/** Reads and processes an attached device's descriptors, to determine compatibility and pipe configurations. This
+ *  routine will read in the entire configuration descriptor, and configure the hosts pipes to correctly communicate
+ *  with compatible devices.
+ *
+ *  This routine searches for a Streaming Audio interface descriptor containing a valid Isochronous audio endpoint.
+ *
+ *  \return An error code from the \ref RNDISHost_GetConfigDescriptorDataCodes_t enum.
+ */
+uint8_t ProcessConfigurationDescriptor(void)
+{
+	uint8_t  ConfigDescriptorData[512];
+	void*    CurrConfigLocation = ConfigDescriptorData;
+	uint16_t CurrConfigBytesRem;
+
+	USB_Descriptor_Interface_t* AudioControlInterface   = NULL;
+	USB_Descriptor_Interface_t* AudioStreamingInterface = NULL;
+	USB_Descriptor_Endpoint_t*  DataOUTEndpoint         = NULL;
+
+	/* Retrieve the entire configuration descriptor into the allocated buffer */
+	switch (USB_Host_GetDeviceConfigDescriptor(1, &CurrConfigBytesRem, ConfigDescriptorData, sizeof(ConfigDescriptorData)))
+	{
+		case HOST_GETCONFIG_Successful:
+			break;
+		case HOST_GETCONFIG_InvalidData:
+			return InvalidConfigDataReturned;
+		case HOST_GETCONFIG_BuffOverflow:
+			return DescriptorTooLarge;
+		default:
+			return ControlError;
+	}
+
+	while (!(DataOUTEndpoint))
+	{
+		/* See if we've found a likely compatible interface, and if there is an endpoint within that interface */
+		if (!(AudioControlInterface) ||
+		    USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
+		                              DComp_NextAudioInterfaceDataEndpoint) != DESCRIPTOR_SEARCH_COMP_Found)
+		{
+			/* Check if we haven't found an Audio Control interface yet, or if we have run out of related Audio Streaming interfaces */
+			if (!(AudioControlInterface) ||
+			    USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
+			                              DComp_NextAudioStreamInterface) != DESCRIPTOR_SEARCH_COMP_Found)
+			{
+				/* Find a new Audio Control interface if the current one doesn't contain a compatible streaming interface */
+				if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
+											  DComp_NextAudioControlInterface) != DESCRIPTOR_SEARCH_COMP_Found)
+				{
+					/* Descriptor not found, error out */
+					return NoCompatibleInterfaceFound;
+				}
+
+				/* Save the interface in case we need to refer back to it later */
+				AudioControlInterface = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Interface_t);			
+
+				/* Find the next Audio Streaming interface within that Audio Control interface */
+				if (USB_GetNextDescriptorComp(&CurrConfigBytesRem, &CurrConfigLocation,
+										  DComp_NextAudioStreamInterface) != DESCRIPTOR_SEARCH_COMP_Found)
+				{
+					/* Descriptor not found, error out */
+					return NoCompatibleInterfaceFound;
+				}
+			}
+
+			/* Save the interface in case we need to refer back to it later */
+			AudioStreamingInterface = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Interface_t);
+
+			/* Skip the remainder of the loop as we have not found an endpoint yet */
+			continue;
+		}
+
+		/* Retrieve the endpoint address from the endpoint descriptor */
+		USB_Descriptor_Endpoint_t* EndpointData = DESCRIPTOR_PCAST(CurrConfigLocation, USB_Descriptor_Endpoint_t);
+
+		/* Save the endpoint if it is an OUT type endpoint */
+		if (!(EndpointData->EndpointAddress & ENDPOINT_DESCRIPTOR_DIR_IN))
+		  DataOUTEndpoint = EndpointData;
+	}
+
+	StreamingInterfaceIndex      = AudioStreamingInterface->InterfaceNumber;
+	StreamingInterfaceAltSetting = AudioStreamingInterface->AlternateSetting;
+	StreamingEndpointAddress     = DataOUTEndpoint->EndpointAddress;
+
+	/* Configure the Audio data OUT pipe */
+	Pipe_ConfigurePipe(AUDIO_DATA_OUT_PIPE, EP_TYPE_ISOCHRONOUS, PIPE_TOKEN_OUT,
+	                   DataOUTEndpoint->EndpointAddress, DataOUTEndpoint->EndpointSize, PIPE_BANK_DOUBLE);
+
+	/* Valid data found, return success */
+	return SuccessfulConfigRead;
+}
+
+/** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
+ *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
+ *  descriptor processing if an incompatible descriptor configuration is found.
+ *
+ *  This comparator searches for the next Interface descriptor of the correct Audio Control Class, Subclass and Protocol values.
+ *
+ *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
+ */
+uint8_t DComp_NextAudioControlInterface(void* CurrentDescriptor)
+{
+	USB_Descriptor_Header_t* Header = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Header_t);
+
+	if (Header->Type == DTYPE_Interface)
+	{
+		USB_Descriptor_Interface_t* Interface = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Interface_t);
+
+		if ((Interface->Class    == AUDIO_CSCP_AudioClass) &&
+		    (Interface->SubClass == AUDIO_CSCP_ControlSubclass) &&
+		    (Interface->Protocol == AUDIO_CSCP_ControlProtocol))
+		{
+			return DESCRIPTOR_SEARCH_Found;
+		}
+	}
+
+	return DESCRIPTOR_SEARCH_NotFound;
+}
+
+/** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
+ *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
+ *  descriptor processing if an incompatible descriptor configuration is found.
+ *
+ *  This comparator searches for the next Interface descriptor of the correct Audio Streaming Class, Subclass and Protocol values.
+ *
+ *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
+ */
+uint8_t DComp_NextAudioStreamInterface(void* CurrentDescriptor)
+{
+	USB_Descriptor_Header_t* Header = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Header_t);
+
+	if (Header->Type == DTYPE_Interface)
+	{
+		USB_Descriptor_Interface_t* Interface = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Interface_t);
+
+		if ((Interface->Class    == AUDIO_CSCP_AudioClass) &&
+		    (Interface->SubClass == AUDIO_CSCP_AudioStreamingSubclass) &&
+		    (Interface->Protocol == AUDIO_CSCP_StreamingProtocol))
+		{
+			return DESCRIPTOR_SEARCH_Found;
+		}
+	}
+
+	return DESCRIPTOR_SEARCH_NotFound;
+}
+
+/** Descriptor comparator function. This comparator function is can be called while processing an attached USB device's
+ *  configuration descriptor, to search for a specific sub descriptor. It can also be used to abort the configuration
+ *  descriptor processing if an incompatible descriptor configuration is found.
+ *
+ *  This comparator searches for the next Isochronous Endpoint descriptor within the current interface, aborting the
+ *  search if another interface descriptor is found before the next endpoint.
+ *
+ *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
+ */
+uint8_t DComp_NextAudioInterfaceDataEndpoint(void* CurrentDescriptor)
+{
+	USB_Descriptor_Header_t* Header = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Header_t);
+
+	if (Header->Type == DTYPE_Endpoint)
+	{
+		USB_Descriptor_Endpoint_t* Endpoint = DESCRIPTOR_PCAST(CurrentDescriptor, USB_Descriptor_Endpoint_t);
+
+		if ((Endpoint->Attributes & EP_TYPE_MASK) == EP_TYPE_ISOCHRONOUS)
+		  return DESCRIPTOR_SEARCH_Found;
+	}
+	else if (Header->Type == DTYPE_Interface)
+	{
+		return DESCRIPTOR_SEARCH_Fail;