Demos/Device/LowLevel/AudioOutput/AudioOutput.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2009.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6       www.fourwalledcubicle.com
   7 */
   8
   9 /*
  10   Copyright 2009  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, and distribute this software
  13   and its documentation for any purpose and without fee is hereby
  14   granted, provided that the above copyright notice appear in all
  15   copies and that both that the copyright notice and this
  16   permission notice and warranty disclaimer appear in supporting
  17   documentation, and that the name of the author not be used in
  18   advertising or publicity pertaining to distribution of the
  19   software without specific, written prior permission.
  20
  21   The author disclaim all warranties with regard to this
  22   software, including all implied warranties of merchantability
  23   and fitness.  In no event shall the author be liable for any
  24   special, indirect or consequential damages or any damages
  25   whatsoever resulting from loss of use, data or profits, whether
  26   in an action of contract, negligence or other tortious action,
  27   arising out of or in connection with the use or performance of
  28   this software.
  29 */
  30
  31 /** \file
  32  *
  33  *  Main source file for the AudioOutput demo. This file contains the main tasks of the demo and
  34  *  is responsible for the initial application hardware configuration.
  35  */
  36
  37 #include "AudioOutput.h"
  38
  39 /** Flag to indicate if the streaming audio alternative interface has been selected by the host. */
  40 bool StreamingAudioInterfaceSelected = false;
  41
  42 /** Main program entry point. This routine contains the overall program flow, including initial
  43  *  setup of all components and the main program loop.
  44  */
  45 int main(void)
  46 {
  47         SetupHardware();
  48
  49         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
  50
  51         for (;;)
  52         {
  53                 USB_Audio_Task();
  54                 USB_USBTask();
  55         }
  56 }
  57
  58 /** Configures the board hardware and chip peripherals for the demo's functionality. */
  59 void SetupHardware(void)
  60 {
  61         /* Disable watchdog if enabled by bootloader/fuses */
  62         MCUSR &= ~(1 << WDRF);
  63         wdt_disable();
  64
  65         /* Disable clock division */
  66         clock_prescale_set(clock_div_1);
  67
  68         /* Hardware Initialization */
  69         LEDs_Init();
  70         USB_Init();
  71 }
  72
  73 /** Event handler for the USB_Connect event. This indicates that the device is enumerating via the status LEDs, and
  74  *  configures the sample update and PWM timers.
  75  */
  76 void EVENT_USB_Device_Connect(void)
  77 {
  78         /* Indicate USB enumerating */
  79         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
  80
  81         /* Sample reload timer initialization */
  82         OCR0A   = (F_CPU / AUDIO_SAMPLE_FREQUENCY) - 1;
  83         TCCR0A  = (1 << WGM01);  // CTC mode
  84         TCCR0B  = (1 << CS00);   // Fcpu speed
  85
  86 #if defined(AUDIO_OUT_MONO)
  87         /* Set speaker as output */
  88         DDRC   |= (1 << 6);
  89 #elif defined(AUDIO_OUT_STEREO)
  90         /* Set speakers as outputs */
  91         DDRC   |= ((1 << 6) | (1 << 5));
  92 #elif defined(AUDIO_OUT_PORTC)
  93         /* Set PORTC as outputs */
  94         DDRC   |= 0xFF;
  95 #endif
  96
  97 #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
  98         /* PWM speaker timer initialization */
  99         TCCR3A  = ((1 << WGM30) | (1 << COM3A1) | (1 << COM3A0)
 100                                 | (1 << COM3B1) | (1 << COM3B0)); // Set on match, clear on TOP
 101         TCCR3B  = ((1 << WGM32) | (1 << CS30));  // Fast 8-Bit PWM, Fcpu speed
 102 #endif
 103 }
 104
 105 /** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
 106  *  the status LEDs, disables the sample update and PWM output timers and stops the USB and Audio management tasks.
 107  */
 108 void EVENT_USB_Device_Disconnect(void)
 109 {
 110         /* Stop the timers */
 111         TCCR0B = 0;
 112 #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 113         TCCR3B = 0;
 114 #endif
 115
 116 #if defined(AUDIO_OUT_MONO)
 117         /* Set speaker as input to reduce current draw */
 118         DDRC   &= ~(1 << 6);
 119 #elif defined(AUDIO_OUT_STEREO)
 120         /* Set speakers as inputs to reduce current draw */
 121         DDRC   &= ~((1 << 6) | (1 << 5));
 122 #elif defined(AUDIO_OUT_PORTC)
 123         /* Set PORTC low */
 124         PORTC  = 0x00;
 125 #endif
 126
 127         /* Indicate streaming audio interface not selected */
 128         StreamingAudioInterfaceSelected = false;
 129
 130         /* Indicate USB not ready */
 131         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 132 }
 133
 134 /** Event handler for the USB_ConfigurationChanged event. This is fired when the host set the current configuration
 135  *  of the USB device after enumeration - the device endpoints are configured.
 136  */
 137 void EVENT_USB_Device_ConfigurationChanged(void)
 138 {
 139         /* Indicate USB connected and ready */
 140         LEDs_SetAllLEDs(LEDMASK_USB_READY);
 141
 142         /* Setup audio stream endpoint */
 143         if (!(Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPNUM, EP_TYPE_ISOCHRONOUS,
 144                                              ENDPOINT_DIR_OUT, AUDIO_STREAM_EPSIZE,
 145                                          ENDPOINT_BANK_DOUBLE)))
 146         {
 147                 LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
 148         }
 149 }
 150
 151 /** Event handler for the USB_UnhandledControlRequest event. This is used to catch standard and class specific
 152  *  control requests that are not handled internally by the USB library (including the Audio class-specific
 153  *  requests) so that they can be handled appropriately for the application.
 154  */
 155 void EVENT_USB_Device_UnhandledControlRequest(void)
 156 {
 157         /* Process General and Audio specific control requests */
 158         switch (USB_ControlRequest.bRequest)
 159         {
 160                 case REQ_SetInterface:
 161                         /* Set Interface is not handled by the library, as its function is application-specific */
 162                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE))
 163                         {
 164                                 Endpoint_ClearSETUP();
 165
 166                                 /* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */
 167                                 StreamingAudioInterfaceSelected = ((USB_ControlRequest.wValue) != 0);
 168
 169                                 Endpoint_ClearStatusStage();
 170                         }
 171
 172                         break;
 173         }
 174 }
 175
 176 /** Task to manage the Audio interface, reading in audio samples from the host, and outputting them to the speakers/LEDs as
 177  *  desired.
 178  */
 179 void USB_Audio_Task(void)
 180 {
 181         /* Device must be connected and configured for the task to run */
 182         if (USB_DeviceState != DEVICE_STATE_Configured)
 183           return;
 184
 185         /* Check to see if the streaming interface is selected, if not the host is not receiving audio */
 186         if (!(StreamingAudioInterfaceSelected))
 187           return;
 188
 189         /* Select the audio stream endpoint */
 190         Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 191
 192         /* Check if the current endpoint can be read from (contains a packet) and that the next sample should be read */
 193         if (Endpoint_IsOUTReceived() && (TIFR0 & (1 << OCF0A)))
 194         {
 195                 /* Clear the sample reload timer */
 196                 TIFR0 |= (1 << OCF0A);
 197
 198                 /* Retrieve the signed 16-bit left and right audio samples */
 199                 int16_t LeftSample_16Bit  = (int16_t)Endpoint_Read_Word_LE();
 200                 int16_t RightSample_16Bit = (int16_t)Endpoint_Read_Word_LE();
 201
 202                 /* Check to see if the bank is now empty */
 203                 if (!(Endpoint_IsReadWriteAllowed()))
 204                 {
 205                         /* Acknowledge the packet, clear the bank ready for the next packet */
 206                         Endpoint_ClearOUT();
 207                 }
 208
 209                 /* Massage signed 16-bit left and right audio samples into signed 8-bit */
 210                 int8_t  LeftSample_8Bit   = (LeftSample_16Bit  >> 8);
 211                 int8_t  RightSample_8Bit  = (RightSample_16Bit >> 8);
 212
 213                 /* Mix the two channels together to produce a mono, 8-bit sample */
 214                 int8_t  MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 215
 216                 /* Get absolute value of mixed sample value */
 217                 uint8_t MixedSample_8Bit_Abs = abs(MixedSample_8Bit);
 218
 219 #if defined(AUDIO_OUT_MONO)
 220                 /* Load the sample into the PWM timer channel */
 221                 OCR3A = ((uint8_t)MixedSample_8Bit ^ (1 << 7));
 222 #elif defined(AUDIO_OUT_STEREO)
 223                 /* Load the dual 8-bit samples into the PWM timer channels */
 224                 OCR3A = ((uint8_t)LeftSample_8Bit  ^ (1 << 7));
 225                 OCR3B = ((uint8_t)RightSample_8Bit ^ (1 << 7));
 226 #elif defined(AUDIO_OUT_PORTC)
 227                 /* Load the 8-bit mixed sample into PORTC */
 228                 PORTC = MixedSample_8Bit;
 229 #endif
 230
 231                 uint8_t LEDMask = LEDS_NO_LEDS;
 232
 233                 if (MixedSample_8Bit_Abs > 2)
 234                   LEDMask |= LEDS_LED1;
 235
 236                 if (MixedSample_8Bit_Abs > 4)
 237                   LEDMask |= LEDS_LED2;
 238
 239                 if (MixedSample_8Bit_Abs > 8)
 240                   LEDMask |= LEDS_LED3;
 241
 242                 if (MixedSample_8Bit_Abs > 16)
 243                   LEDMask |= LEDS_LED4;
 244
 245                 LEDs_SetAllLEDs(LEDMask);
 246         }
 247 }