Changed AudioInput and AudioOutput demos to reload the next sample via an interrupt rather than polling the sample timer.

Demos/Device/ClassDriver/AudioInput/AudioInput.c

@@ -63,8 +63,6 @@ int main(void)
 
 	for (;;)
 	{
-		ProcessNextSample();
-
 		Audio_Device_USBTask(&Microphone_Audio_Interface);
 		USB_USBTask();
 	}
@@ -91,17 +89,14 @@ void SetupHardware(void)
 	ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | MIC_IN_ADC_MUX_MASK);
 }
 
-/** Processes the next audio sample by reading the last ADC conversion and writing it to the audio
+/** ISR to handle the reloading of the data endpoint with the next sample. */
- *  interface, each time the sample reload timer period elapses to give a constant sample rate.
+ISR(TIMER0_COMPA_vect, ISR_BLOCK)
- */
-void ProcessNextSample(void)
 {
+	uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
+
 	/* Check if the sample reload timer period has elapsed, and that the USB bus is ready for a new sample */
-	if ((TIFR0 & (1 << OCF0A)) && Audio_Device_IsReadyForNextSample(&Microphone_Audio_Interface))
+	if (Audio_Device_IsReadyForNextSample(&Microphone_Audio_Interface))
 	{
-		/* Clear the sample reload timer compare flag, ready for the next interval */
-		TIFR0 |= (1 << OCF0A);
-		
 		int16_t AudioSample;
 
 		#if defined(USE_TEST_TONE)
@@ -126,6 +121,8 @@ void ProcessNextSample(void)
 		
 		Audio_Device_WriteSample16(&Microphone_Audio_Interface, AudioSample);
 	}
+
+	Endpoint_SelectEndpoint(PrevEndpoint);
 }
 
 /** Event handler for the library USB Connection event. */
@@ -134,6 +131,7 @@ void EVENT_USB_Device_Connect(void)
 	LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
 
 	/* Sample reload timer initialization */
+	TIMSK0  = (1 << OCIE0A);
 	OCR0A   = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1;
 	TCCR0A  = (1 << WGM01);  // CTC mode
 	TCCR0B  = (1 << CS01);   // Fcpu/8 speed

Demos/Device/ClassDriver/AudioInput/AudioInput.h

@@ -77,7 +77,6 @@
 
 	/* Function Prototypes: */
 		void SetupHardware(void);
-		void ProcessNextSample(void);
 
 		void EVENT_USB_Device_Connect(void);
 		void EVENT_USB_Device_Disconnect(void);

Demos/Device/ClassDriver/AudioOutput/AudioOutput.c

@@ -63,8 +63,6 @@ int main(void)
 
 	for (;;)
 	{
-		ProcessNextSample();
-
 		Audio_Device_USBTask(&Speaker_Audio_Interface);
 		USB_USBTask();
 	}
@@ -85,17 +83,13 @@ void SetupHardware(void)
 	USB_Init();
 }
 
-/** Processes the next audio sample by reading the last ADC conversion and writing it to the audio
+/** ISR to handle the reloading of the PWM timer with the next sample. */
- *  interface, each time the sample reload timer period elapses to give a constant sample rate.
+ISR(TIMER0_COMPA_vect, ISR_BLOCK)
- */
-void ProcessNextSample(void)
-{
-	/* Check if the sample reload timer period has elapsed, and that the USB bus is ready for a new sample */
-	if ((TIFR0 & (1 << OCF0A)) && Audio_Device_IsSampleReceived(&Speaker_Audio_Interface))
 {
-		/* Clear the sample reload timer compare flag, ready for the next interval */
+	uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
-		TIFR0 |= (1 << OCF0A);
 
+	if (Audio_Device_IsSampleReceived(&Speaker_Audio_Interface))
+	{
 		/* Retrieve the signed 16-bit left and right audio samples, convert to 8-bit */
 		int8_t LeftSample_8Bit  = (Audio_Device_ReadSample16(&Speaker_Audio_Interface) >> 8);
 		int8_t RightSample_8Bit = (Audio_Device_ReadSample16(&Speaker_Audio_Interface) >> 8);
@@ -129,6 +123,8 @@ void ProcessNextSample(void)
 
 		LEDs_SetAllLEDs(LEDMask);
 	}
+	
+	Endpoint_SelectEndpoint(PrevEndpoint);	
 }
 
 /** Event handler for the library USB Connection event. */
@@ -137,6 +133,7 @@ void EVENT_USB_Device_Connect(void)
 	LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
 
 	/* Sample reload timer initialization */
+	TIMSK0  = (1 << OCIE0A);
 	OCR0A   = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1;
 	TCCR0A  = (1 << WGM01);  // CTC mode
 	TCCR0B  = (1 << CS01);   // Fcpu/8 speed

Demos/Device/ClassDriver/AudioOutput/AudioOutput.h

@@ -64,7 +64,6 @@
 
 	/* Function Prototypes: */
 		void SetupHardware(void);
-		void ProcessNextSample(void);
 
 		void EVENT_USB_Device_Connect(void);
 		void EVENT_USB_Device_Disconnect(void);

Demos/Device/LowLevel/AudioInput/AudioInput.c

@@ -51,7 +51,6 @@ int main(void)
 
 	for (;;)
 	{
-		USB_Audio_Task();
 		USB_USBTask();
 	}
 }
@@ -86,6 +85,7 @@ void EVENT_USB_Device_Connect(void)
 	LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
 
 	/* Sample reload timer initialization */
+	TIMSK0  = (1 << OCIE0A);
 	OCR0A   = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1;
 	TCCR0A  = (1 << WGM01);  // CTC mode
 	TCCR0B  = (1 << CS01);   // Fcpu/8 speed
@@ -145,26 +145,17 @@ void EVENT_USB_Device_UnhandledControlRequest(void)
 	}
 }
 
-/** Task to manage the Audio interface, reading in ADC samples from the microphone, and them to the host. */
+/** ISR to handle the reloading of the data endpoint with the next sample. */
-void USB_Audio_Task(void)
+ISR(TIMER0_COMPA_vect, ISR_BLOCK)
 {
-	/* Device must be connected and configured for the task to run */
+	uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
-	if (USB_DeviceState != DEVICE_STATE_Configured)
-	  return;
-
-	/* Check to see if the streaming interface is selected, if not the host is not receiving audio */
-	if (!(StreamingAudioInterfaceSelected))
-	  return;
 
 	/* Select the audio stream endpoint */
 	Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 
-	/* Check if the current endpoint can be written to and that the next sample should be stored */
+	/* Check if the current endpoint can be written to and that the audio interface is enabled */
-	if (Endpoint_IsINReady() && (TIFR0 & (1 << OCF0A)))
+	if (Endpoint_IsINReady() && StreamingAudioInterfaceSelected)
 	{
-		/* Clear the sample reload timer */
-		TIFR0 |= (1 << OCF0A);
-
 		int16_t AudioSample;
 
 		#if defined(USE_TEST_TONE)
@@ -197,5 +188,7 @@ void USB_Audio_Task(void)
 			Endpoint_ClearIN();
 		}
 	}
+
+	Endpoint_SelectEndpoint(PrevEndpoint);
 }
 

Demos/Device/LowLevel/AudioInput/AudioInput.h

@@ -77,7 +77,6 @@
 
 	/* Function Prototypes: */
 		void SetupHardware(void);
-		void USB_Audio_Task(void);
 
 		void EVENT_USB_Device_Connect(void);
 		void EVENT_USB_Device_Disconnect(void);

Demos/Device/LowLevel/AudioOutput/AudioOutput.c

@@ -51,7 +51,6 @@ int main(void)
 
 	for (;;)
 	{
-		USB_Audio_Task();
 		USB_USBTask();
 	}
 }
@@ -80,6 +79,7 @@ void EVENT_USB_Device_Connect(void)
 	LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
 
 	/* Sample reload timer initialization */
+	TIMSK0 = (1 << OCIE0A);
 	OCR0A  = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1;
 	TCCR0A = (1 << WGM01);  // CTC mode
 	TCCR0B = (1 << CS01);   // Fcpu/8 speed
@@ -171,28 +171,17 @@ void EVENT_USB_Device_UnhandledControlRequest(void)
 	}
 }
 
-/** Task to manage the Audio interface, reading in audio samples from the host, and outputting them to the speakers/LEDs as
+/** ISR to handle the reloading of the PWM timer with the next sample. */
- *  desired.
+ISR(TIMER0_COMPA_vect, ISR_BLOCK)
- */
-void USB_Audio_Task(void)
 {
-	/* Device must be connected and configured for the task to run */
+	uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
-	if (USB_DeviceState != DEVICE_STATE_Configured)
-	  return;
-
-	/* Check to see if the streaming interface is selected, if not the host is not receiving audio */
-	if (!(StreamingAudioInterfaceSelected))
-	  return;
 
 	/* Select the audio stream endpoint */
 	Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 
-	/* Check if the current endpoint can be read from (contains a packet) and that the next sample should be read */
+	/* Check if the current endpoint can be read from (contains a packet) and the host is sending data */
-	if (Endpoint_IsOUTReceived() && (TIFR0 & (1 << OCF0A)))
+	if (Endpoint_IsOUTReceived() && StreamingAudioInterfaceSelected)
 	{
-		/* Clear the sample reload timer */
-		TIFR0 |= (1 << OCF0A);
-
 		/* Retrieve the signed 16-bit left and right audio samples, convert to 8-bit */
 		int8_t LeftSample_8Bit   = ((int16_t)Endpoint_Read_Word_LE() >> 8);
 		int8_t RightSample_8Bit  = ((int16_t)Endpoint_Read_Word_LE() >> 8);
@@ -233,5 +222,7 @@ void USB_Audio_Task(void)
 
 		LEDs_SetAllLEDs(LEDMask);
 	}
+	
+	Endpoint_SelectEndpoint(PrevEndpoint);
 }
 

Demos/Device/LowLevel/AudioOutput/AudioOutput.h

@@ -63,7 +63,6 @@
 
 	/* Function Prototypes: */
 		void SetupHardware(void);
-		void USB_Audio_Task(void);
 
 		void EVENT_USB_Device_Connect(void);
 		void EVENT_USB_Device_Disconnect(void);

LUFA/Drivers/USB/Class/Host/HID.h

@@ -97,8 +97,8 @@
 					bool     DataOUTPipeDoubleBank; /**< Indicates if the HID interface's OUT data pipe should use double banking. */
 
 					uint8_t  HIDInterfaceProtocol; /**< HID interface protocol value to match against if a specific
-					                                *   boot subclass protocol is required, a value from the \ref HID_BootProtocols_t
+					                                *   boot subclass protocol is required, a protocol value from the
-					                                *   enum.
+					                                *   \ref HID_Descriptor_ClassSubclassProtocol_t enum.
 					                                */
 					#if !defined(HID_HOST_BOOT_PROTOCOL_ONLY)
 					HID_ReportInfo_t* HIDParserData; /**< HID parser data to store the parsed HID report data, when boot protocol

LUFA/ManPages/ChangeLog.txt

@@ -57,6 +57,7 @@
   *  - Better algorithm to extract and convert the internal device serial number into a string descriptor (if present)
   *  - All USB class drivers are now automatically included when LUFA/Drivers/USB.h is included, and no longer need to be seperately included
   *  - All LowLevel demos changed to use the constants and types defined in the USB class drivers
+  *  - Changed AudioInput and AudioOutput demos to reload the next sample via an interrupt rather than polling the sample timer
   *
   *  <b>Fixed:</b>
   *  - Fixed USB_GetHIDReportItemInfo() function modifying the given report item's data when the report item does not exist