Copy over schedulerless host demos to ClassDrivers directory, for later...

Copy over schedulerless host demos to ClassDrivers directory, for later modification to new Host mode USB class drivers.

Demos/Host/ClassDriver/CDCHost/CDCHost.c

+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2009.
+              
+  dean [at] fourwalledcubicle [dot] com
+      www.fourwalledcubicle.com
+*/
+
+/*
+  Copyright 2009  Dean Camera (dean [at] fourwalledcubicle [dot] com)
+
+  Permission to use, copy, modify, and distribute this software
+  and its documentation for any purpose and without fee is hereby
+  granted, 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 CDCHost demo. This file contains the main tasks of
+ *  the demo and is responsible for the initial application hardware configuration.
+ */
+ 
+#include "CDCHost.h"
+
+/** Main program entry point. This routine configures the hardware required by the application, then
+ *  starts the scheduler to run the application tasks.
+ */
+int main(void)
+{
+	SetupHardware();
+
+	puts_P(PSTR(ESC_RESET ESC_BG_WHITE ESC_INVERSE_ON ESC_ERASE_DISPLAY
+	       "CDC Host Demo running.\r\n" ESC_INVERSE_OFF));
+
+	LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
+
+	for (;;)
+	{
+		CDC_Host_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 */
+	SerialStream_Init(9600, false);
+	LEDs_Init();
+	USB_Init();
+}
+
+/** 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_DeviceAttached(void)
+{
+	puts_P(PSTR("Device Attached.\r\n"));
+	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_DeviceUnattached(void)
+{
+	puts_P(PSTR("\r\nDevice Unattached.\r\n"));
+	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_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_HostError(const uint8_t ErrorCode)
+{
+	USB_ShutDown();
+
+	puts_P(PSTR(ESC_BG_RED "Host Mode Error\r\n"));
+	printf_P(PSTR(" -- Error Code %d\r\n"), 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_DeviceEnumerationFailed(const uint8_t ErrorCode, const uint8_t SubErrorCode)
+{
+	puts_P(PSTR(ESC_BG_RED "Dev Enum Error\r\n"));
+	printf_P(PSTR(" -- Error Code %d\r\n"), ErrorCode);
+	printf_P(PSTR(" -- Sub Error Code %d\r\n"), SubErrorCode);
+	printf_P(PSTR(" -- In State %d\r\n"), USB_HostState);
+	
+	LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
+}
+
+/** Task to set the configuration of the attached device after it has been enumerated, and to read in
+ *  data received from the attached CDC device and print it to the serial port.
+ */
+void CDC_Host_Task(void)
+{
+	uint8_t ErrorCode;
+
+	switch (USB_HostState)
+	{
+		case HOST_STATE_Addressed:
+			/* Standard request to set the device configuration to configuration 1 */
+			USB_ControlRequest = (USB_Request_Header_t)
+				{
+					.bmRequestType = (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_DEVICE),
+					.bRequest      = REQ_SetConfiguration,
+					.wValue        = 1,
+					.wIndex        = 0,
+					.wLength       = 0,
+				};
+
+			/* Select the control pipe for the request transfer */
+			Pipe_SelectPipe(PIPE_CONTROLPIPE);
+
+			/* Send the request, display error and wait for device detach if request fails */
+			if ((ErrorCode = USB_Host_SendControlRequest(NULL)) != HOST_SENDCONTROL_Successful)
+			{
+				puts_P(PSTR("Control Error (Set Configuration).\r\n"));
+				printf_P(PSTR(" -- Error Code: %d\r\n"), ErrorCode);
+
+				/* Indicate error via status LEDs */
+				LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
+
+				/* Wait until USB device disconnected */
+				while (USB_IsConnected);
+				break;
+			}
+				
+			USB_HostState = HOST_STATE_Configured;
+			break;
+		case HOST_STATE_Configured:
+			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("Control Error (Get Configuration).\r\n"));
+				else
+				  puts_P(PSTR("Invalid Device.\r\n"));
+
+				printf_P(PSTR(" -- Error Code: %d\r\n"), ErrorCode);
+				
+				/* Indicate error via status LEDs */
+				LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
+
+				/* Wait until USB device disconnected */
+				while (USB_IsConnected);
+				break;
+			}
+
+			puts_P(PSTR("CDC Device Enumerated.\r\n"));
+				
+			USB_HostState = HOST_STATE_Ready;
+			break;
+		case HOST_STATE_Ready:
+			/* Select and the data IN pipe */
+			Pipe_SelectPipe(CDC_DATAPIPE_IN);
+
+			/* Check to see if a packet has been received */
+			if (Pipe_IsINReceived())
+			{
+				/* Check if data is in the pipe */
+				if (Pipe_IsReadWriteAllowed())
+				{
+					/* Get the length of the pipe data, and create a new buffer to hold it */
+					uint16_t BufferLength = Pipe_BytesInPipe();
+					uint8_t  Buffer[BufferLength];
+					
+					/* Read in the pipe data to the temporary buffer */
+					Pipe_Read_Stream_LE(Buffer, BufferLength);
+									
+					/* Print out the buffer contents to the USART */
+					for (uint16_t BufferByte = 0; BufferByte < BufferLength; BufferByte++)
+					  putchar(Buffer[BufferByte]);
+				}
+
+				/* Clear the pipe after it is read, ready for the next packet */
+				Pipe_ClearIN();
+			}
+
+			/* Select and unfreeze the notification pipe */
+			Pipe_SelectPipe(CDC_NOTIFICATIONPIPE);
+			Pipe_Unfreeze();
+			
+			/* Check if a packet has been received */
+			if (Pipe_IsINReceived())
+			{
+				/* Discard the unused event notification */
+				Pipe_ClearIN();
+			}
+			
+			/* Freeze notification IN pipe after use */
+			Pipe_Freeze();
+						
+			break;
+	}
+}

Demos/Host/ClassDriver/CDCHost/CDCHost.h

+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2009.
+              
+  dean [at] fourwalledcubicle [dot] com
+      www.fourwalledcubicle.com
+*/
+
+/*
+  Copyright 2009  Dean Camera (dean [at] fourwalledcubicle [dot] com)
+
+  Permission to use, copy, modify, and distribute this software
+  and its documentation for any purpose and without fee is hereby
+  granted, 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 CDCHost.c.
+ */
+
+#ifndef _CDC_HOST_H_
+#define _CDC_HOST_H_
+
+	/* Includes: */
+		#include <avr/io.h>
+		#include <avr/wdt.h>
+		#include <avr/pgmspace.h>
+		#include <avr/power.h>
+		#include <stdio.h>
+
+		#include <LUFA/Version.h>
+		#include <LUFA/Drivers/Misc/TerminalCodes.h>
+		#include <LUFA/Drivers/USB/USB.h>
+		#include <LUFA/Drivers/Peripheral/SerialStream.h>
+		#include <LUFA/Drivers/Board/LEDs.h>
+		
+		#include "ConfigDescriptor.h"
+		
+	/* Macros: */
+		/** Pipe number for the CDC data IN pipe */
+		#define CDC_DATAPIPE_IN                1
+
+		/** Pipe number for the CDC data OUT pipe */
+		#define CDC_DATAPIPE_OUT               2
+
+		/** Pipe number for the CDC notification pipe */
+		#define CDC_NOTIFICATIONPIPE           3
+
+		/** 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 SetupHardware(void);
+		void CDC_Host_Task(void);
+	
+		void EVENT_USB_HostError(const uint8_t ErrorCode);
+		void EVENT_USB_DeviceAttached(void);
+		void EVENT_USB_DeviceUnattached(void);
+		void EVENT_USB_DeviceEnumerationFailed(const uint8_t ErrorCode, const uint8_t SubErrorCode);
+		void EVENT_USB_DeviceEnumerationComplete(void);
+		
+#endif

Demos/Host/ClassDriver/CDCHost/CDCHost.txt

+/** \file
+ *
+ *  This file contains special DoxyGen information for the generation of the main page and other special
+ *  documentation pages. It is not a project source file.
+ */
+ 
+/** \mainpage CDC Host Demo
+ *
+ *  \section SSec_Info USB Information:
+ *
+ *  The following table gives a rundown of the USB utilization of this demo.
+ *
+ *  <table>
+ *   <tr>
+ *    <td><b>USB Mode:</b></td>
+ *    <td>Host</td>
+ *   </tr>
+ *   <tr>
+ *    <td><b>USB Class:</b></td>
+ *    <td>Communications Device Class (CDC)</td>
+ *   </tr>
+ *   <tr> 
+ *    <td><b>USB Subclass:</b></td>
+ *    <td>Abstract Control Model (ACM)</td>
+ *   </tr>
+ *   <tr>
+ *    <td><b>Relevant Standards:</b></td>
+ *    <td>USBIF CDC Class Standard</td>
+ *   </tr>
+ *   <tr>
+ *    <td><b>Usable Speeds:</b></td>
+ *    <td>Full Speed Mode</td>
+ *   </tr>
+ *  </table>
+ *
+ *  \section SSec_Description Project Description: 
+ *
+ *  CDC host demonstration application. This gives a simple reference application
+ *  for implementing a USB CDC host, for CDC devices using the standard ACM profile.
+ *  
+ *  This demo prints out received CDC data through the serial port.
+ *  
+ *  Not that this demo is only compatible with devices which report the correct CDC
+ *  and ACM class, subclass and protocol values. Most USB-Serial cables have vendor
+ *  specific features, thus use vendor-specific class/subclass/protocol codes to force
+ *  the user to use specialized drivers. This demo is not compatible with such devices.
+ *
+ *  \section SSec_Options Project Options
+ *
+ *  The following defines can be found in this demo, which can control the demo behaviour when defined, or changed in value.
+ *
+ *  <table>
+ *   <tr>
+ *    <td>
+ *     None
+ *    </td>
+ *   </tr>
+ *  </table>
+ */

Demos/Host/ClassDriver/CDCHost/ConfigDescriptor.c

+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2009.
+              
+  dean [at] fourwalledcubicle [dot] com
+      www.fourwalledcubicle.com
+*/
+
+/*
+  Copyright 2009  Dean Camera (dean [at] fourwalledcubicle [dot] com)
+
+  Permission to use, copy, modify, and distribute this software
+  and its documentation for any purpose and without fee is hereby
+  granted, 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"
+
+/** 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 CDC interface descriptor containing bulk data IN and OUT endpoints, and an interrupt event endpoint.
+ *
+ *  \return An error code from the CDCHost_GetConfigDescriptorDataCodes_t enum.
+ */
+uint8_t ProcessConfigurationDescriptor(void)
+{
+	uint8_t* ConfigDescriptorData;
+	uint16_t ConfigDescriptorSize;
+	uint8_t  FoundEndpoints = 0;
+	
+	/* Get Configuration Descriptor size from the device */
+	if (USB_GetDeviceConfigDescriptor(&ConfigDescriptorSize, NULL) != HOST_SENDCONTROL_Successful)
+	  return ControlError;
+	
+	/* Ensure that the Configuration Descriptor isn't too large */
+	if (ConfigDescriptorSize > MAX_CONFIG_DESCRIPTOR_SIZE)
+	  return DescriptorTooLarge;
+	  
+	/* Allocate enough memory for the entire config descriptor */
+	ConfigDescriptorData = alloca(ConfigDescriptorSize);
+
+	/* Retrieve the entire configuration descriptor into the allocated buffer */
+	USB_GetDeviceConfigDescriptor(&ConfigDescriptorSize, ConfigDescriptorData);
+	
+	/* Validate returned data - ensure first entry is a configuration header descriptor */
+	if (DESCRIPTOR_TYPE(ConfigDescriptorData) != DTYPE_Configuration)
+	  return InvalidConfigDataReturned;
+	
+	/* Get the CDC control interface from the configuration descriptor */
+	if (USB_GetNextDescriptorComp(&ConfigDescriptorSize, &ConfigDescriptorData,
+	                              DComp_NextCDCControlInterface) != DESCRIPTOR_SEARCH_COMP_Found)
+	{
+		/* Descriptor not found, error out */
+		return NoCDCInterfaceFound;
+	}
+
+	/* Get the IN and OUT data endpoints for the CDC interface */
+	while (FoundEndpoints != ((1 << CDC_NOTIFICATIONPIPE) | (1 << CDC_DATAPIPE_IN) | (1 << CDC_DATAPIPE_OUT)))
+	{
+		/* Fetch the next bulk or interrupt endpoint from the current CDC interface */
+		if (USB_GetNextDescriptorComp(&ConfigDescriptorSize, &ConfigDescriptorData,
+		                              DComp_NextInterfaceCDCDataEndpoint) != DESCRIPTOR_SEARCH_COMP_Found)
+		{
+			/* Check to see if the control interface's notification pipe has been found, if so search for the data interface */
+			if (FoundEndpoints & (1 << CDC_NOTIFICATIONPIPE))
+			{
+				/* Get the next CDC data interface from the configuration descriptor (CDC class has two CDC interfaces) */
+				if (USB_GetNextDescriptorComp(&ConfigDescriptorSize, &ConfigDescriptorData, 
+				                              DComp_NextCDCDataInterface) != DESCRIPTOR_SEARCH_COMP_Found)
+				{
+					/* Descriptor not found, error out */
+					return NoCDCInterfaceFound;
+				}
+			}
+			else
+			{
+				/* Clear the found endpoints mask, since any already processed endpoints aren't in the CDC interface we need */
+				FoundEndpoints = 0;
+
+				/* Disable any already configured pipes from the invalid CDC interfaces */
+				Pipe_SelectPipe(CDC_NOTIFICATIONPIPE);
+				Pipe_DisablePipe();
+				Pipe_SelectPipe(CDC_DATAPIPE_IN);
+				Pipe_DisablePipe();
+				Pipe_SelectPipe(CDC_DATAPIPE_OUT);
+				Pipe_DisablePipe();
+			
+				/* Get the next CDC control interface from the configuration descriptor (CDC class has two CDC interfaces) */
+				if (USB_GetNextDescriptorComp(&ConfigDescriptorSize, &ConfigDescriptorData,
+				                              DComp_NextCDCControlInterface) != DESCRIPTOR_SEARCH_COMP_Found)
+				{
+					/* Descriptor not found, error out */
+					return NoCDCInterfaceFound;
+				}
+			}
+
+			/* Fetch the next bulk or interrupt endpoint from the current CDC interface */
+			if (USB_GetNextDescriptorComp(&ConfigDescriptorSize, &ConfigDescriptorData,
+			                              DComp_NextInterfaceCDCDataEndpoint) != DESCRIPTOR_SEARCH_COMP_Found)
+			{
+				/* Descriptor not found, error out */
+				return NoEndpointFound;
+			}
+		}
+		
+		USB_Descriptor_Endpoint_t* EndpointData = DESCRIPTOR_PCAST(ConfigDescriptorData, USB_Descriptor_Endpoint_t);
+
+		/* Check if the found endpoint is a interrupt or bulk type descriptor */
+		if ((EndpointData->Attributes & EP_TYPE_MASK) == EP_TYPE_INTERRUPT)
+		{
+			/* If the endpoint is a IN type interrupt endpoint */
+			if (EndpointData->EndpointAddress & ENDPOINT_DESCRIPTOR_DIR_IN)
+			{							   
+				/* Configure the notification pipe */
+				Pipe_ConfigurePipe(CDC_NOTIFICATIONPIPE, EP_TYPE_INTERRUPT, PIPE_TOKEN_IN,
+								   EndpointData->EndpointAddress, EndpointData->EndpointSize, PIPE_BANK_SINGLE);
+
+				Pipe_SetInfiniteINRequests();
+				Pipe_SetInterruptPeriod(EndpointData->PollingIntervalMS);
+				
+				/* Set the flag indicating that the notification pipe has been found */
+				FoundEndpoints |= (1 << CDC_NOTIFICATIONPIPE);
+			}
+		}
+		else
+		{
+			/* Check if the endpoint is a bulk IN or bulk OUT endpoint */
+			if (EndpointData->EndpointAddress & ENDPOINT_DESCRIPTOR_DIR_IN)
+			{
+				/* Configure the data IN pipe */
+				Pipe_ConfigurePipe(CDC_DATAPIPE_IN, EP_TYPE_BULK, PIPE_TOKEN_IN,
+								   EndpointData->EndpointAddress, EndpointData->EndpointSize, PIPE_BANK_SINGLE);
+
+				Pipe_SetInfiniteINRequests();
+				Pipe_Unfreeze();
+				
+				/* Set the flag indicating that the data IN pipe has been found */
+				FoundEndpoints |= (1 << CDC_DATAPIPE_IN);
+			}
+			else
+			{
+				/* Configure the data OUT pipe */
+				Pipe_ConfigurePipe(CDC_DATAPIPE_OUT, EP_TYPE_BULK, PIPE_TOKEN_OUT,
+								   EndpointData->EndpointAddress, EndpointData->EndpointSize, PIPE_BANK_SINGLE);
+				
+				Pipe_Unfreeze();
+				
+				/* Set the flag indicating that the data OUT pipe has been found */
+				FoundEndpoints |= (1 << CDC_DATAPIPE_OUT);
+			}
+		}
+	}
+
+	/* 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 CDC control Class, Subclass and Protocol values.
+ *
+ *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
+ */
+uint8_t DComp_NextCDCControlInterface(void* CurrentDescriptor)
+{
+	if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
+	{
+		/* Check the CDC descriptor class, subclass and protocol, break out if correct control interface found */
+		if ((DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Class    == CDC_CONTROL_CLASS)    &&
+		    (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).SubClass == CDC_CONTROL_SUBCLASS) &&
+		    (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Protocol == CDC_CONTROL_PROTOCOL))
+		{
+			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 CDC data Class, Subclass and Protocol values.
+ *
+ *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
+ */
+uint8_t DComp_NextCDCDataInterface(void* CurrentDescriptor)
+{
+	if (DESCRIPTOR_TYPE(CurrentDescriptor) == DTYPE_Interface)
+	{
+		/* Check the CDC descriptor class, subclass and protocol, break out if correct data interface found */
+		if ((DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Class    == CDC_DATA_CLASS)    &&
+		    (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).SubClass == CDC_DATA_SUBCLASS) &&
+		    (DESCRIPTOR_CAST(CurrentDescriptor, USB_Descriptor_Interface_t).Protocol == CDC_DATA_PROTOCOL))
+		{
+			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 bulk IN or OUT endpoint, or interrupt IN endpoint within the current interface,
+ *  aborting the search if another interface descriptor is found before the required endpoint (so that it may be compared
+ *  using a different comparator to determine if it is another CDC class interface).
+ *
+ *  \return A value from the DSEARCH_Return_ErrorCodes_t enum
+ */