Update the Low Level Audio Input and Audio Output demos to support multiple sample rates.

Remove custom PIDs on the Class Driver Audio device demos and revert back to the original Audio PIDs, as the low level and class driver demo versions are now descriptor compatible once again.

1 files changed, 55 insertions, 1 deletions

diff --git a/Demos/Device/LowLevel/AudioInput/AudioInput.c b/Demos/Device/LowLevel/AudioInput/AudioInput.c
index f62fcbec5..d79167660 100644
--- a/Demos/Device/LowLevel/AudioInput/AudioInput.c
+++ b/Demos/Device/LowLevel/AudioInput/AudioInput.c
@@ -39,6 +39,9 @@
 /** Flag to indicate if the streaming audio alternative interface has been selected by the host. */
 static bool StreamingAudioInterfaceSelected = false;
 
+/** Current audio sampling frequency of the streaming audio endpoint. */
+static 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.
@@ -87,7 +90,7 @@ 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
 }
@@ -152,6 +155,57 @@ void EVENT_USB_Device_ControlRequest(void)
 				Endpoint_ClearSETUP();
 				Endpoint_ClearStatusStage();
 			}
+
+			break;
+		case AUDIO_REQ_SetCurrent:
+			if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT))
+			{
+				/* Extract out the relevant request information to get the target Endpoint index and control being set */
+				uint8_t EndpointIndex   = (uint8_t)USB_ControlRequest.wIndex;
+				uint8_t EndpointControl = (USB_ControlRequest.wValue >> 8);
+				
+				/* Only handle SET CURRENT requests to the audio endpoint's sample frequency property */
+				if ((EndpointIndex == AUDIO_STREAM_EPNUM) && (EndpointControl == AUDIO_EPCONTROL_SamplingFreq))
+				{
+					uint8_t SampleRate[3];
+				
+					Endpoint_ClearSETUP();
+					Endpoint_Read_Control_Stream_LE(SampleRate, sizeof(SampleRate));
+					Endpoint_ClearOUT();
+					
+					/* Set the new sampling frequency to the value given by the host */
+					CurrentAudioSampleFrequency = (((uint32_t)SampleRate[2] << 16) | ((uint32_t)SampleRate[1] << 8) | (uint32_t)SampleRate[0]);
+
+					/* Adjust sample reload timer to the new frequency */
+					OCR0A = ((F_CPU / 8 / CurrentAudioSampleFrequency) - 1);
+				}
+			}
+			
+			break;
+		case AUDIO_REQ_GetCurrent:
+			if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT))
+			{
+				/* Extract out the relevant request information to get the target Endpoint index and control being retrieved */
+				uint8_t EndpointIndex   = (uint8_t)USB_ControlRequest.wIndex;
+				uint8_t EndpointControl = (USB_ControlRequest.wValue >> 8);
+				
+				/* Only handle GET CURRENT requests to the audio endpoint's sample frequency property */
+				if ((EndpointIndex == AUDIO_STREAM_EPNUM) && (EndpointControl == AUDIO_EPCONTROL_SamplingFreq))
+				{
+					uint8_t SampleRate[3];
+					
+					/* Convert the sampling rate value into the 24-bit format the host expects for the property */
+					SampleRate[2] = (CurrentAudioSampleFrequency >> 16);
+					SampleRate[1] = (CurrentAudioSampleFrequency >> 8);
+					SampleRate[0] = (CurrentAudioSampleFrequency &  0xFF);
+				
+					Endpoint_ClearSETUP();
+					Endpoint_Write_Control_Stream_LE(SampleRate, sizeof(SampleRate));
+					Endpoint_ClearOUT();					
+				}
+			}
+
+			break;
 	}
 }