/*
LUFA Library
- Copyright (C) Dean Camera, 2010.
-
+ Copyright (C) Dean Camera, 2012.
+
dean [at] fourwalledcubicle [dot] com
- www.fourwalledcubicle.com
+ www.lufa-lib.org
*/
/*
- Copyright 2010 Dean Camera (dean [at] fourwalledcubicle [dot] com)
+ Copyright 2012 Dean Camera (dean [at] fourwalledcubicle [dot] com)
- Permission to use, copy, modify, distribute, and sell this
+ Permission to use, copy, modify, distribute, and sell this
software and its documentation for any purpose is hereby granted
- without fee, provided that the above copyright notice appear in
+ without fee, provided that the above copyright notice appear in
all copies and that both that the copyright notice and this
- permission notice and warranty disclaimer appear in supporting
- documentation, and that the name of the author not be used in
- advertising or publicity pertaining to distribution of the
+ permission notice and warranty disclaimer appear in supporting
+ documentation, and that the name of the author not be used in
+ advertising or publicity pertaining to distribution of the
software without specific, written prior permission.
The author disclaim all warranties with regard to this
* Main source file for the AudioOutput demo. This file contains the main tasks of the demo and
* is responsible for the initial application hardware configuration.
*/
-
+
#include "AudioOutput.h"
/** Flag to indicate if the streaming audio alternative interface has been selected by the host. */
-bool StreamingAudioInterfaceSelected = false;
+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.
LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
sei();
-
+
for (;;)
{
- USB_Audio_Task();
USB_USBTask();
}
}
/* Disable clock division */
clock_prescale_set(clock_div_1);
-
+
/* Hardware Initialization */
LEDs_Init();
USB_Init();
{
/* Indicate USB enumerating */
LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
-
+
/* Sample reload timer initialization */
- OCR0A = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1;
- TCCR0A = (1 << WGM01); // CTC mode
- TCCR0B = (1 << CS01); // Fcpu/8 speed
-
-#if defined(AUDIO_OUT_MONO)
+ TIMSK0 = (1 << OCIE0A);
+ OCR0A = ((F_CPU / 8 / CurrentAudioSampleFrequency) - 1);
+ TCCR0A = (1 << WGM01); // CTC mode
+ TCCR0B = (1 << CS01); // Fcpu/8 speed
+
+ #if defined(AUDIO_OUT_MONO)
/* Set speaker as output */
- DDRC |= (1 << 6);
-#elif defined(AUDIO_OUT_STEREO)
+ DDRC |= (1 << 6);
+ #elif defined(AUDIO_OUT_STEREO)
/* Set speakers as outputs */
- DDRC |= ((1 << 6) | (1 << 5));
-#elif defined(AUDIO_OUT_PORTC)
+ DDRC |= ((1 << 6) | (1 << 5));
+ #elif defined(AUDIO_OUT_PORTC)
/* Set PORTC as outputs */
- DDRC |= 0xFF;
-#endif
+ DDRC |= 0xFF;
+ #endif
-#if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
+ #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
/* PWM speaker timer initialization */
- TCCR3A = ((1 << WGM30) | (1 << COM3A1) | (1 << COM3A0)
- | (1 << COM3B1) | (1 << COM3B0)); // Set on match, clear on TOP
- TCCR3B = ((1 << WGM32) | (1 << CS30)); // Fast 8-Bit PWM, Fcpu speed
-#endif
+ TCCR3A = ((1 << WGM30) | (1 << COM3A1) | (1 << COM3A0)
+ | (1 << COM3B1) | (1 << COM3B0)); // Set on match, clear on TOP
+ TCCR3B = ((1 << WGM32) | (1 << CS30)); // Fast 8-Bit PWM, F_CPU speed
+ #endif
}
/** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
{
/* Stop the timers */
TCCR0B = 0;
-#if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
+ #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
TCCR3B = 0;
-#endif
+ #endif
-#if defined(AUDIO_OUT_MONO)
+ #if defined(AUDIO_OUT_MONO)
/* Set speaker as input to reduce current draw */
- DDRC &= ~(1 << 6);
-#elif defined(AUDIO_OUT_STEREO)
+ DDRC &= ~(1 << 6);
+ #elif defined(AUDIO_OUT_STEREO)
/* Set speakers as inputs to reduce current draw */
- DDRC &= ~((1 << 6) | (1 << 5));
-#elif defined(AUDIO_OUT_PORTC)
+ DDRC &= ~((1 << 6) | (1 << 5));
+ #elif defined(AUDIO_OUT_PORTC)
/* Set PORTC low */
- PORTC = 0x00;
-#endif
+ PORTC = 0x00;
+ #endif
/* Indicate streaming audio interface not selected */
StreamingAudioInterfaceSelected = false;
*/
void EVENT_USB_Device_ConfigurationChanged(void)
{
- /* Indicate USB connected and ready */
- LEDs_SetAllLEDs(LEDMASK_USB_READY);
+ bool ConfigSuccess = true;
- /* Setup audio stream endpoint */
- if (!(Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPNUM, EP_TYPE_ISOCHRONOUS,
- ENDPOINT_DIR_OUT, AUDIO_STREAM_EPSIZE,
- ENDPOINT_BANK_DOUBLE)))
- {
- LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
- }
+ /* Setup Audio Stream Endpoint */
+ ConfigSuccess &= Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPNUM, EP_TYPE_ISOCHRONOUS, ENDPOINT_DIR_OUT,
+ AUDIO_STREAM_EPSIZE, ENDPOINT_BANK_DOUBLE);
+
+ /* Indicate endpoint configuration success or failure */
+ LEDs_SetAllLEDs(ConfigSuccess ? LEDMASK_USB_READY : LEDMASK_USB_ERROR);
}
-/** Event handler for the USB_UnhandledControlRequest event. This is used to catch standard and class specific
- * control requests that are not handled internally by the USB library (including the Audio class-specific
- * requests) so that they can be handled appropriately for the application.
+/** Event handler for the USB_ControlRequest event. This is used to catch and process control requests sent to
+ * the device from the USB host before passing along unhandled control requests to the library for processing
+ * internally.
*/
-void EVENT_USB_Device_UnhandledControlRequest(void)
+void EVENT_USB_Device_ControlRequest(void)
{
/* Process General and Audio specific control requests */
switch (USB_ControlRequest.bRequest)
if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE))
{
Endpoint_ClearSETUP();
-
+ Endpoint_ClearStatusStage();
+
/* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */
StreamingAudioInterfaceSelected = ((USB_ControlRequest.wValue) != 0);
-
+ }
+
+ break;
+ case AUDIO_REQ_GetStatus:
+ /* Get Status request can be directed at either the interface or endpoint, neither is currently used
+ * according to the latest USB Audio 1.0 standard, but must be ACKed with no data when requested */
+ if ((USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_INTERFACE)) ||
+ (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT)))
+ {
+ 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 address and control being set */
+ uint8_t EndpointAddress = (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 ((EndpointAddress == (ENDPOINT_DIR_OUT | 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 address and control being retrieved */
+ uint8_t EndpointAddress = (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 ((EndpointAddress == (ENDPOINT_DIR_OUT | 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;
}
}
-/** Task to manage the Audio interface, reading in audio samples from the host, and outputting them to the speakers/LEDs as
- * desired.
- */
-void USB_Audio_Task(void)
+/** ISR to handle the reloading of the PWM timer with the next sample. */
+ISR(TIMER0_COMPA_vect, ISR_BLOCK)
{
- /* Device must be connected and configured for the task to run */
- 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;
+ uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
/* 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 */
- if (Endpoint_IsOUTReceived() && (TIFR0 & (1 << OCF0A)))
- {
- /* Clear the sample reload timer */
- TIFR0 |= (1 << OCF0A);
+ /* Check if the current endpoint can be read from (contains a packet) and the host is sending data */
+ if (Endpoint_IsOUTReceived() && StreamingAudioInterfaceSelected)
+ {
/* 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);
+ int8_t LeftSample_8Bit = ((int16_t)Endpoint_Read_16_LE() >> 8);
+ int8_t RightSample_8Bit = ((int16_t)Endpoint_Read_16_LE() >> 8);
/* Mix the two channels together to produce a mono, 8-bit sample */
- int8_t MixedSample_8Bit = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
+ int8_t MixedSample_8Bit = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
/* Check to see if the bank is now empty */
if (!(Endpoint_IsReadWriteAllowed()))
Endpoint_ClearOUT();
}
-#if defined(AUDIO_OUT_MONO)
+ #if defined(AUDIO_OUT_MONO)
/* Load the sample into the PWM timer channel */
OCR3A = (MixedSample_8Bit ^ (1 << 7));
-#elif defined(AUDIO_OUT_STEREO)
+ #elif defined(AUDIO_OUT_STEREO)
/* Load the dual 8-bit samples into the PWM timer channels */
OCR3A = (LeftSample_8Bit ^ (1 << 7));
OCR3B = (RightSample_8Bit ^ (1 << 7));
-#elif defined(AUDIO_OUT_PORTC)
+ #elif defined(AUDIO_OUT_PORTC)
/* Load the 8-bit mixed sample into PORTC */
PORTC = MixedSample_8Bit;
-#endif
+ #endif
uint8_t LEDMask = LEDS_NO_LEDS;
LEDs_SetAllLEDs(LEDMask);
}
+
+ Endpoint_SelectEndpoint(PrevEndpoint);
}
+
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