Added default test tone generation mode to the Device mode AudioInput demos.

Demos/Device/ClassDriver/AudioInput/AudioInput.c

@@ -82,9 +82,10 @@ void SetupHardware(void)
 
 	/* Hardware Initialization */
 	LEDs_Init();
-	USB_Init();
+	Buttons_Init();
 	ADC_Init(ADC_FREE_RUNNING | ADC_PRESCALE_32);
 	ADC_SetupChannel(MIC_IN_ADC_CHANNEL);
+	USB_Init();
 
 	/* Start the ADC conversion in free running mode */
 	ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | MIC_IN_ADC_MUX_MASK);
@@ -100,15 +101,29 @@ void ProcessNextSample(void)
 	{
 		/* Clear the sample reload timer compare flag, ready for the next interval */
 		TIFR0 |= (1 << OCF0A);
+		
+		int16_t AudioSample;
 
-		/* Audio sample is ADC value scaled to fit the entire range */
-		int16_t AudioSample = ((SAMPLE_MAX_RANGE / ADC_MAX_RANGE) * ADC_GetResult());
+		#if defined(USE_TEST_TONE)
+			static uint8_t SquareWaveSampleCount;
+			static int16_t CurrentWaveValue;
+			
+			/* In test tone mode, generate a square wave at 1/256 of the sample rate */
+			if (SquareWaveSampleCount++ == 0xFF)
+			  CurrentWaveValue ^= 0x8000;
+			
+			/* Only generate audio if the board button is being pressed */
+			AudioSample = (Buttons_GetStatus() & BUTTONS_BUTTON1) ? CurrentWaveValue : 0;
+		#else
+			/* Audio sample is ADC value scaled to fit the entire range */
+			AudioSample = ((SAMPLE_MAX_RANGE / ADC_MAX_RANGE) * ADC_GetResult());
 
-		#if defined(MICROPHONE_BIASED_TO_HALF_RAIL)
-		/* Microphone is biased to half rail voltage, subtract the bias from the sample value */
-		AudioSample -= (SAMPLE_MAX_RANGE / 2);
+			#if defined(MICROPHONE_BIASED_TO_HALF_RAIL)
+			/* Microphone is biased to half rail voltage, subtract the bias from the sample value */
+			AudioSample -= (SAMPLE_MAX_RANGE / 2);
+			#endif
 		#endif
-
+		
 		Audio_Device_WriteSample16(&Microphone_Audio_Interface, AudioSample);
 	}
 }

Demos/Device/ClassDriver/AudioInput/AudioInput.h

@@ -44,6 +44,7 @@
 
 		#include <LUFA/Version.h>
 		#include <LUFA/Drivers/Board/LEDs.h>
+		#include <LUFA/Drivers/Board/Buttons.h>
 		#include <LUFA/Drivers/Peripheral/ADC.h>
 		#include <LUFA/Drivers/USB/USB.h>
 		#include <LUFA/Drivers/USB/Class/Audio.h>

Demos/Device/ClassDriver/AudioInput/AudioInput.txt

@@ -50,11 +50,13 @@
  *  basic USB Audio 1.0 drivers in all modern OSes (i.e. no special drivers
  *  required).
  *
- *  On start-up the system will automatically enumerate and function
- *  as a USB microphone. Incoming audio from the ADC channel 1 will
- *  be sampled and sent to the host computer.
+ *  On start-up the system will automatically enumerate and function as a 
+ *  USB microphone. By default, the demo will produce a square wave test tone
+ *  when the board button is pressed. If USE_TEST_TONE is not defined in the
+ *  project makefile, incoming audio from the ADC channel 1 will be sampled
+ *  and sent to the host computer instead.
  *
- *  To use, connect a microphone to the ADC channel 1.
+ *  When in microphone mode, connect a microphone to the ADC channel 2.
  *
  *  Under Windows, if a driver request dialogue pops up, select the option
  *  to automatically install the appropriate drivers.
@@ -70,6 +72,12 @@
  *    <td><b>Description:</b></td>
  *   </tr>
  *   <tr>
+ *    <td>USE_TEST_TONE</td>
+ *    <td>Makefile LUFA_OPTS</td>
+ *    <td>When defined, this alters the demo to produce a square wave test tone when the first board button is pressed
+ *        instead of sampling the board microphone.</td>
+ *   </tr>
+ *   <tr>
  *    <td>MICROPHONE_BIASED_TO_HALF_RAIL</td>
  *    <td>Makefile LUFA_OPTS</td>
  *    <td>When defined, this alters the demo so that the half VCC bias of the microphone input is subtracted.</td>

Demos/Device/ClassDriver/AudioInput/makefile

@@ -123,6 +123,7 @@ LUFA_OPTS += -D USE_FLASH_DESCRIPTORS
 LUFA_OPTS += -D USE_STATIC_OPTIONS="(USB_DEVICE_OPT_FULLSPEED | USB_OPT_REG_ENABLED | USB_OPT_AUTO_PLL)"
 
 LUFA_OPTS += -D MICROPHONE_BIASED_TO_HALF_RAIL
+LUFA_OPTS += -D USE_TEST_TONE
 
 
 # Create the LUFA source path variables by including the LUFA root makefile