if( ulReceivedAddress != ( unsigned portLONG ) 0 )
			{			
				AT91C_BASE_UDP->UDP_GLBSTATE = AT91C_UDP_FADDEN;
			}
			else
			{
				AT91C_BASE_UDP->UDP_GLBSTATE = 0;
			}			

			AT91C_BASE_UDP->UDP_FADDR = ( AT91C_UDP_FEN | ulReceivedAddress );		
			eDriverState = eNOTHING;
		}
		else
		{		
			/* The TXCOMP was not for any special type of transmission.  See
			if there is any more data to send. */
			prvSendNextSegment();
		}
	}

	if( pxMessage->ulCSR0 & AT91C_UDP_RXSETUP )
	{
		xUSB_REQUEST xRequest;
		unsigned portCHAR ucRequest;
		unsigned portLONG ulRxBytes;

		/* A data packet is available. */	
		ulRxBytes = pxMessage->ulCSR0 >> 16;
		ulRxBytes &= usbRX_COUNT_MASK;

		if( ulRxBytes >= usbEXPECTED_NUMBER_OF_BYTES )
		{
			/* Create an xUSB_REQUEST variable from the raw bytes array. */

			xRequest.ucReqType = pxMessage->ucFifoData[ usbREQUEST_TYPE_INDEX ];
			xRequest.ucRequest = pxMessage->ucFifoData[ usbREQUEST_INDEX ];

			/* NOT PORTABLE CODE! */
			xRequest.usValue = pxMessage->ucFifoData[ usbVALUE_HIGH_BYTE ];
			xRequest.usValue <<= 8;
			xRequest.usValue |= pxMessage->ucFifoData[ usbVALUE_LOW_BYTE ];
						
			xRequest.usIndex = pxMessage->ucFifoData[ usbINDEX_HIGH_BYTE ];
			xRequest.usIndex <<= 8;
			xRequest.usIndex |= pxMessage->ucFifoData[ usbINDEX_LOW_BYTE ];
			
			xRequest.usLength = pxMessage->ucFifoData[ usbLENGTH_HIGH_BYTE ];
			xRequest.usLength <<= 8;
			xRequest.usLength |= pxMessage->ucFifoData[ usbLENGTH_LOW_BYTE ];
	
			/* Manipulate the ucRequestType and the ucRequest parameters to
			generate a zero based request selection.  This is just done to
			break up the requests into subsections for clarity.  The
			alternative would be to have more huge switch statement that would
			be difficult to optimise. */
			ucRequest = ( ( xRequest.ucReqType & 0x60 ) >> 3 );
			ucRequest |= ( xRequest.ucReqType & 0x03 );

			switch( ucRequest )
			{
				case usbSTANDARD_DEVICE_REQUEST:	
							/* Standard Device request */
							prvHandleStandardDeviceRequest( &xRequest );
							break;
	
				case usbSTANDARD_INTERFACE_REQUEST:	
							/* Standard Interface request */
							prvHandleStandardInterfaceRequest( &xRequest );
							break;
	
				case usbSTANDARD_END_POINT_REQUEST:	
							/* Standard Endpoint request */
							prvHandleStandardEndPointRequest( &xRequest );
							break;
	
				case usbCLASS_INTERFACE_REQUEST:	
							/* Class Interface request */
							prvHandleClassInterfaceRequest( &xRequest );
							break;
	
				default:	/* This is not something we want to respond to. */
							prvSendStall();	
			}
		}
	}
}
/*-----------------------------------------------------------*/

static void prvGetStandardDeviceDescriptor( xUSB_REQUEST *pxRequest )
{
	/* The type is in the high byte.  Return whatever has been requested. */
	switch( ( pxRequest->usValue & 0xff00 ) >> 8 )
	{
	    case usbDESCRIPTOR_TYPE_DEVICE:
			prvSendControlData( ( unsigned portCHAR * ) &pxDeviceDescriptor, pxRequest->usLength, sizeof( pxDeviceDescriptor ), pdTRUE );
		    break;
	
	    case usbDESCRIPTOR_TYPE_CONFIGURATION:
			prvSendControlData( ( unsigned portCHAR * ) &( pxConfigDescriptor ), pxRequest->usLength, sizeof( pxConfigDescriptor ), pdTRUE );
		    break;

	    case usbDESCRIPTOR_TYPE_STRING:

			/* The index to the string descriptor is the lower byte. */
		    switch( pxRequest->usValue & 0xff )
			{			
		        case usbLANGUAGE_STRING:
					prvSendControlData( ( unsigned portCHAR * ) &pxLanguageStringDescriptor, pxRequest->usLength, sizeof(pxLanguageStringDescriptor), pdTRUE );
			        break;

		        case usbMANUFACTURER_STRING:
					prvSendControlData( ( unsigned portCHAR * ) &pxManufacturerStringDescriptor, pxRequest->usLength, sizeof( pxManufacturerStringDescriptor ), pdTRUE );
			        break;

		        case usbPRODUCT_STRING:
					prvSendControlData( ( unsigned portCHAR * ) &pxProductStringDescriptor, pxRequest->usLength, sizeof( pxProductStringDescriptor ), pdTRUE );
			        break;

		        case usbCONFIGURATION_STRING:
					prvSendControlData( ( unsigned portCHAR * ) &pxConfigurationStringDescriptor, pxRequest->usLength, sizeof( pxConfigurationStringDescriptor ), pdTRUE );
			        break;

		        case usbINTERFACE_STRING:
					prvSendControlData( ( unsigned portCHAR * ) &pxInterfaceStringDescriptor, pxRequest->usLength, sizeof( pxInterfaceStringDescriptor ), pdTRUE );
			        break;

		        default:
			        /* Don't know what this string is. */
					prvSendStall();
					break;
			}

			break;

	    default:
			/* We are not responding to anything else. */
			prvSendStall();
		    break;
	}
}
/*-----------------------------------------------------------*/

static void prvHandleStandardDeviceRequest( xUSB_REQUEST *pxRequest )
{
unsigned portSHORT usStatus = 0;

	switch( pxRequest->ucRequest )
	{
	    case usbGET_STATUS_REQUEST:
			/* Just send two byte dummy status. */
			prvSendControlData( ( unsigned portCHAR * ) &usStatus, sizeof( usStatus ), sizeof( usStatus ), pdFALSE );
		    break;

	    case usbGET_DESCRIPTOR_REQUEST:
			/* Send device descriptor */
		    prvGetStandardDeviceDescriptor( pxRequest );
		    break;

	    case usbGET_CONFIGURATION_REQUEST:
			/* Send selected device configuration */
			prvSendControlData( ( unsigned portCHAR * ) &ucUSBConfig, sizeof( ucUSBConfig ), sizeof( ucUSBConfig ), pdFALSE );
		    break;

		case usbSET_FEATURE_REQUEST:
		    prvUSBTransmitNull();
		    break;

	    case usbSET_ADDRESS_REQUEST:
	    	
			/* Acknowledge the SET_ADDRESS, but (according to the manual) we
			cannot actually move to the addressed state until we get a TXCOMP
			interrupt from this NULL packet.  Therefore we just remember the
			address and set our state so we know we have received the address. */
	    	prvUSBTransmitNull();			
			eDriverState = eJUST_GOT_ADDRESS;	    	
			ulReceivedAddress = ( unsigned portLONG ) pxRequest->usValue;
		    break;

	    case usbSET_CONFIGURATION_REQUEST:

			/* Acknowledge the SET_CONFIGURATION, but (according to the manual)
			we cannot actually move to the configured state until we get a
			TXCOMP interrupt from this NULL packet.  Therefore we just remember the
			config and set our state so we know we have received the go ahead. */			
			ucUSBConfig = ( unsigned portCHAR ) ( pxRequest->usValue & 0xff );
			eDriverState = eJUST_GOT_CONFIG;
			prvUSBTransmitNull();
		    break;

	    default:

		    /* We don't answer to anything else. */
			prvSendStall();
		    break;
	}
}
/*-----------------------------------------------------------*/

static void prvHandleClassInterfaceRequest( xUSB_REQUEST *pxRequest )
{
	switch( pxRequest->ucRequest )
	{
	    case usbSET_IDLE_REQUEST:
	    	prvUSBTransmitNull();
			break;

		/* This minimal implementation ignores these. */
	    case usbGET_REPORT_REQUEST:
	    case usbGET_IDLE_REQUEST:
	    case usbGET_PROTOCOL_REQUEST:
	    case usbSET_REPORT_REQUEST:
	    case usbSET_PROTOCOL_REQUEST:	
	    default:

			prvSendStall();
			break;
	}
}
/*-----------------------------------------------------------*/

static void prvGetStandardInterfaceDescriptor( xUSB_REQUEST *pxRequest )
{
	switch( ( pxRequest->usValue & ( unsigned portSHORT ) 0xff00 ) >> 8 )
	{
	    case usbHID_REPORT_DESCRIPTOR:
			prvSendControlData( ( unsigned portCHAR * ) pxReportDescriptor, pxRequest->usLength, sizeof( pxReportDescriptor ), pdTRUE );
		    break;

	    default:

			/* Don't expect to send any others. */
			prvSendStall();
		    break;
	}
}
/*-----------------------------------------------------------*/

static void prvHandleStandardInterfaceRequest( xUSB_REQUEST *pxRequest )
{
unsigned portSHORT usStatus = 0;

	switch( pxRequest->ucRequest )
	{
	    case usbGET_STATUS_REQUEST:
			/* Send dummy 2 bytes. */
			prvSendControlData( ( unsigned portCHAR * ) &usStatus, sizeof( usStatus ), sizeof( usStatus ), pdFALSE );
			break;

	    case usbGET_DESCRIPTOR_REQUEST:
			prvGetStandardInterfaceDescriptor( pxRequest );
			break;

		/* This minimal implementation does not respond to these. */
	    case usbGET_INTERFACE_REQUEST:
	    case usbSET_FEATURE_REQUEST:
	    case usbSET_INTERFACE_REQUEST:	

	    default:
			prvSendStall();
			break;
	}
}
/*-----------------------------------------------------------*/

static void prvHandleStandardEndPointRequest( xUSB_REQUEST *pxRequest )
{
	switch( pxRequest->ucRequest )
	{
		/* This minimal implementation does not expect to respond to these. */
	    case usbGET_STATUS_REQUEST:
	    case usbCLEAR_FEATURE_REQUEST:
	    case usbSET_FEATURE_REQUEST:

	    default:			
			prvSendStall();
			break;
	}
}
/*-----------------------------------------------------------*/

static void vInitUSBInterface( void )
{
volatile unsigned portLONG ulTemp;

	/* Create the queue used to communicate between the USB ISR and task. */
	xUSBInterruptQueue = xQueueCreate( usbQUEUE_LENGTH + 1, sizeof( xISRStatus * ) );

	/* Initialise a few state variables. */
	pxCharsForTx.ulNextCharIndex = ( unsigned portLONG ) 0;
	ucUSBConfig = ( unsigned portCHAR ) 0;
	eDriverState = eNOTHING;

	/* HARDWARE SETUP */

    /* Set the PLL USB Divider */
    AT91C_BASE_CKGR->CKGR_PLLR |= AT91C_CKGR_USBDIV_1;

    /* Enables the 48MHz USB clock UDPCK and System Peripheral USB Clock. */
    AT91C_BASE_PMC->PMC_SCER = AT91C_PMC_UDP;
    AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_UDP);

    /* Setup the PIO for the USB pull up resistor. */
    AT91F_PIO_CfgOutput(AT91C_BASE_PIOA,AT91C_PIO_PA16);

    /* Start without the pullup - this will get set at the end of this
	function. */
    AT91F_PIO_SetOutput( AT91C_BASE_PIOA, AT91C_PIO_PA16 );

	/* When using the USB debugger the peripheral registers do not always get
	set to the correct default values.  To make sure set the relevant registers
	manually here. */
	AT91C_BASE_UDP->UDP_IDR = ( unsigned portLONG ) 0xffffffff;
	AT91C_BASE_UDP->UDP_ICR = ( unsigned portLONG ) 0xffffffff;
	AT91C_BASE_UDP->UDP_CSR[ 0 ] = ( unsigned portLONG ) 0x00;
	AT91C_BASE_UDP->UDP_CSR[ 1 ] = ( unsigned portLONG ) 0x00;
	AT91C_BASE_UDP->UDP_GLBSTATE = 0;
	AT91C_BASE_UDP->UDP_FADDR = 0;

	/* Enable the transceiver. */
	AT91C_UDP_TRANSCEIVER_ENABLE = 0;

	/* Enable the USB interrupts - other interrupts get enabled as the
	enumeration process progresses. */
	AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_UDP, usbINTERRUPT_PRIORITY, ((unsigned int) 0x0 <<  5) , ( void (*)( void ) ) vUSBISREntry );
	AT91F_AIC_EnableIt( AT91C_BASE_AIC, AT91C_ID_UDP );

	/* Wait a short while before making our presence known. */
	vTaskDelay( usbINIT_DELAY );
    AT91F_PIO_ClearOutput(AT91C_BASE_PIOA, AT91C_PIO_PA16 );
}
/*-----------------------------------------------------------*/

static void prvSendControlData( unsigned portCHAR *pucData, unsigned portSHORT usRequestedLength, unsigned portLONG ulLengthToSend, portLONG lSendingDescriptor )
{
	if( ( ( unsigned portLONG ) usRequestedLength < ulLengthToSend ) )
	{
		/* Cap the data length to that requested. */
		ulLengthToSend = ( unsigned portSHORT ) usRequestedLength;
	}
	else if( ( ulLengthToSend < ( unsigned portLONG ) usRequestedLength ) && lSendingDescriptor )
	{
		/* We are sending a descriptor.  If the descriptor is an exact
		multiple of the FIFO length then it will have to be terminated
		with a NULL packet.  Set the state to indicate this if
		necessary. */
		if( ( ulLengthToSend % usbFIFO_LENGTH ) == 0 )
		{
			eDriverState = eSENDING_EVEN_DESCRIPTOR;
		}
	}

	/* Here we assume that the previous message has been sent.  THERE IS NO
	BUFFER OVERFLOW PROTECTION HERE.

	Copy the data to send into the buffer as we cannot send it all at once
	(if it is greater than 8 bytes in length). */
	memcpy( pxCharsForTx.ucTxBuffer, pucData, ulLengthToSend );

	/* Reinitialise the buffer index so we start sending from the start of
	the data. */
	pxCharsForTx.ulTotalDataLength = ulLengthToSend;
	pxCharsForTx.ulNextCharIndex = ( unsigned portLONG ) 0;

	/* Send the first 8 bytes now.  The rest will get sent in response to
	TXCOMP interrupts. */
	prvSendNextSegment();
}
/*-----------------------------------------------------------*/

static void prvSendNextSegment( void )
{
volatile unsigned portLONG ulNextLength, ulStatus, ulLengthLeftToSend;

	/* Is there any data to send? */
	if( pxCharsForTx.ulTotalDataLength > pxCharsForTx.ulNextCharIndex )
	{
		ulLengthLeftToSend = pxCharsForTx.ulTotalDataLength - pxCharsForTx.ulNextCharIndex;
	
		/* We can only send 8 bytes to the fifo at a time. */
		if( ulLengthLeftToSend > usbFIFO_LENGTH )
		{
			ulNextLength = usbFIFO_LENGTH;
		}
		else
		{
			ulNextLength = ulLengthLeftToSend;
		}

		/* Wait until we can place data in the fifo.  THERE IS NO TIMEOUT
		HERE! */
		while( AT91C_BASE_UDP->UDP_CSR[ usbEND_POINT_0 ] & AT91C_UDP_TXPKTRDY )
		{
			vTaskDelay( usbSHORTEST_DELAY );
		}

		/* Write the data to the FIFO. */
		while( ulNextLength > ( unsigned portLONG ) 0 )
		{
			AT91C_BASE_UDP->UDP_FDR[ usbEND_POINT_0 ] = pxCharsForTx.ucTxBuffer[ pxCharsForTx.ulNextCharIndex ];
	
			ulNextLength--;
			pxCharsForTx.ulNextCharIndex++;
		}
	
		/* Start the transmission. */
		portENTER_CRITICAL();
		{
			ulStatus = AT91C_BASE_UDP->UDP_CSR[ usbEND_POINT_0 ];
			usbCSR_SET_BIT( &ulStatus, ( ( unsigned portLONG ) 0x10 ) );
			AT91C_BASE_UDP->UDP_CSR[ usbEND_POINT_0 ] = ulStatus;
		}
		portEXIT_CRITICAL();
	}
	else
	{
		/* There is no data to send.  If we were sending a descriptor and the
		descriptor was an exact multiple of the max packet size then we need
		to send a null to terminate the transmission. */
		if( eDriverState == eSENDING_EVEN_DESCRIPTOR )
		{
			prvUSBTransmitNull();
			eDriverState = eNOTHING;
		}
	}
}