1 files changed, 73 insertions, 1 deletions

diff --git a/Demos/Device/ClassDriver/AudioOutput/AudioOutput.c b/Demos/Device/ClassDriver/AudioOutput/AudioOutput.c
index dbfd10b8b..43267b2a7 100644
--- a/Demos/Device/ClassDriver/AudioOutput/AudioOutput.c
+++ b/Demos/Device/ClassDriver/AudioOutput/AudioOutput.c
@@ -51,6 +51,9 @@ USB_ClassInfo_Audio_Device_t Speaker_Audio_Interface =
 			},
 	};
 
+/** Current audio sampling frequency of the streaming audio endpoint. */
+uint32_t CurrentAudioSampleFrequency = 48000;
+
 
 /** Main program entry point. This routine contains the overall program flow, including initial
  *  setup of all components and the main program loop.
@@ -135,7 +138,7 @@ void EVENT_USB_Device_Connect(void)
 
 	/* Sample reload timer initialization */
 	TIMSK0  = (1 << OCIE0A);
-	OCR0A   = ((F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1);
+	OCR0A   = ((F_CPU / 8 / CurrentAudioSampleFrequency) - 1);
 	TCCR0A  = (1 << WGM01);  // CTC mode
 	TCCR0B  = (1 << CS01);   // Fcpu/8 speed
 
@@ -199,3 +202,72 @@ void EVENT_USB_Device_ControlRequest(void)
 	Audio_Device_ProcessControlRequest(&Speaker_Audio_Interface);
 }
 
+/** Audio class driver callback for the setting and retrieval of streaming endpoint properties. This callback must be implemented
+ *  in the user application to handle property manipulations on streaming audio endpoints.
+ *
+ *  When the DataLength parameter is NULL, this callback should only indicate whether the specified operation is valid for
+ *  the given endpoint index, and should return as fast as possible. When non-NULL, this value may be altered for GET operations
+ *  to indicate the size of the retreived data.
+ *
+ *  \note The length of the retrieved data stored into the Data buffer on GET operations should not exceed the initial value
+ *        of the \c DataLength parameter.
+ *
+ *  \param[in,out] AudioInterfaceInfo  Pointer to a structure containing an Audio Class configuration and state.
+ *  \param[in]     EndpointProperty    Property of the endpoint to get or set, a value from Audio_ClassRequests_t.
+ *  \param[in]     EndpointIndex       Index of the streaming endpoint whose property is being referenced.
+ *  \param[in]     EndpointControl     Parameter of the endpoint to get or set, a value from Audio_EndpointControls_t.
+ *  \param[in,out] DataLength          For SET operations, the length of the parameter data to set. For GET operations, the maximum
+ *                                     length of the retrieved data. When NULL, the function should return whether the given property
+ *                                     and parameter is valid for the requested endpoint without reading or modifying the Data buffer.
+ *  \param[in,out] Data                Pointer to a location where the parameter data is stored for SET operations, or where
+ *                                     the retrieved data is to be stored for GET operations.
+ *
+ *  \return Boolean true if the property get/set was successful, false otherwise
+ */
+bool CALLBACK_Audio_GetSetEndpointProperty(USB_ClassInfo_Audio_Device_t* const AudioInterfaceInfo,
+                                           const uint8_t EndpointProperty,
+                                           const uint8_t EndpointIndex,
+                                           const uint8_t EndpointControl,
+                                           uint16_t* const DataLength,
+                                           uint8_t* Data)
+{
+	/* Check the requested endpoint to see if a supported endpoint is being manipulated */
+	if (EndpointIndex == Speaker_Audio_Interface.Config.DataOUTEndpointNumber)
+	{
+		/* Check the requested control to see if a supported control is being manipulated */
+		if (EndpointControl == AUDIO_EPCONTROL_SamplingFreq)
+		{
+			/* Check the requested property to see if a supported property is being manipulated */
+			if (EndpointProperty == AUDIO_REQ_SetCurrent)
+			{
+				/* Check if we are just testing for a valid property, or actually adjusting it */
+				if (DataLength != NULL)
+				{
+					/* Set the new sampling frequency to the value given by the host */
+					CurrentAudioSampleFrequency = (((uint32_t)Data[2] << 16) | ((uint32_t)Data[1] << 8) | (uint32_t)Data[0]);
+
+					/* Adjust sample reload timer to the new frequency */
+					OCR0A = ((F_CPU / 8 / CurrentAudioSampleFrequency) - 1);				
+				}
+				
+				return true;
+			}
+			else if (EndpointProperty == AUDIO_REQ_GetCurrent)
+			{
+				/* Check if we are just testing for a valid property, or actually reading it */
+				if (DataLength != NULL)
+				{
+					*DataLength = 3;
+
+					Data[2] = (CurrentAudioSampleFrequency >> 16);
+					Data[1] = (CurrentAudioSampleFrequency >> 8);
+					Data[0] = (CurrentAudioSampleFrequency &  0xFF);					
+				}
+				
+				return true;
+			}
+		}
+	}
+	
+	return false;
+}