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 Audio Output 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_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         TCCRxA  = ((1 << WGMx0) | (1 << COMxA1) | (1 << COMxA0)
 100                                 | (1 << COMxB1) | (1 << COMxB0)); // Set on match, clear on TOP
 101         TCCRxB  = ((1 << WGMx2) | (1 << CSx0));  // 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_Disconnect(void)
 109 {
 110         /* Stop the timers */
 111         TCCR0B = 0;
 112 #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 113         TCCRxB = 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_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_UnhandledControlPacket 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_UnhandledControlPacket(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                                 /* Acknowledge status stage */
 170                                 while (!(Endpoint_IsINReady()));
 171                                 Endpoint_ClearIN();
 172                         }
 173
 174                         break;
 175         }
 176 }
 177
 178 /** Task to manage the Audio interface, reading in audio samples from the host, and outputting them to the speakers/LEDs as
 179  *  desired.
 180  */
 181 void USB_Audio_Task(void)
 182 {
 183         /* Check to see if the streaming interface is selected, if not the host is not receiving audio */
 184         if (!(StreamingAudioInterfaceSelected))
 185           return;
 186
 187         /* Select the audio stream endpoint */
 188         Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 189
 190         /* Check if the current endpoint can be read from (contains a packet) and that the next sample should be read */
 191         if (Endpoint_IsOUTReceived() && (TIFR0 & (1 << OCF0A)))
 192         {
 193                 /* Clear the sample reload timer */
 194                 TIFR0 |= (1 << OCF0A);
 195
 196                 /* Retrieve the signed 16-bit left and right audio samples */
 197                 int16_t LeftSample_16Bit  = (int16_t)Endpoint_Read_Word_LE();
 198                 int16_t RightSample_16Bit = (int16_t)Endpoint_Read_Word_LE();
 199
 200                 /* Check to see if the bank is now empty */
 201                 if (!(Endpoint_IsReadWriteAllowed()))
 202                 {
 203                         /* Acknowledge the packet, clear the bank ready for the next packet */
 204                         Endpoint_ClearOUT();
 205                 }
 206
 207                 /* Massage signed 16-bit left and right audio samples into signed 8-bit */
 208                 int8_t  LeftSample_8Bit   = (LeftSample_16Bit  >> 8);
 209                 int8_t  RightSample_8Bit  = (RightSample_16Bit >> 8);
 210
 211 #if defined(AUDIO_OUT_MONO)
 212                 /* Mix the two channels together to produce a mono, 8-bit sample */
 213                 int8_t  MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 214
 215                 /* Load the sample into the PWM timer channel */
 216                 OCRxA = ((uint8_t)MixedSample_8Bit ^ (1 << 7));
 217 #elif defined(AUDIO_OUT_STEREO)
 218                 /* Load the dual 8-bit samples into the PWM timer channels */
 219                 OCRxA = ((uint8_t)LeftSample_8Bit  ^ (1 << 7));
 220                 OCRxB = ((uint8_t)RightSample_8Bit ^ (1 << 7));
 221 #elif defined(AUDIO_OUT_PORTC)
 222                 /* Mix the two channels together to produce a mono, 8-bit sample */
 223                 int8_t  MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 224
 225                 PORTC = MixedSample_8Bit;
 226 #else
 227                 uint8_t LEDMask = LEDS_NO_LEDS;
 228
 229                 /* Make left channel positive (absolute) */
 230                 if (LeftSample_8Bit < 0)
 231                   LeftSample_8Bit = -LeftSample_8Bit;
 232
 233                 /* Make right channel positive (absolute) */
 234                 if (RightSample_8Bit < 0)
 235                   RightSample_8Bit = -RightSample_8Bit;
 236
 237                 /* Set first LED based on sample value */
 238                 if (LeftSample_8Bit < ((128 / 8) * 1))
 239                   LEDMask |= LEDS_LED2;
 240                 else if (LeftSample_8Bit < ((128 / 8) * 3))
 241                   LEDMask |= (LEDS_LED1 | LEDS_LED2);
 242                 else
 243                   LEDMask |= LEDS_LED1;
 244
 245                 /* Set second LED based on sample value */
 246                 if (RightSample_8Bit < ((128 / 8) * 1))
 247                   LEDMask |= LEDS_LED4;
 248                 else if (RightSample_8Bit < ((128 / 8) * 3))
 249                   LEDMask |= (LEDS_LED3 | LEDS_LED4);
 250                 else
 251                   LEDMask |= LEDS_LED3;
 252
 253                 LEDs_SetAllLEDs(LEDMask);
 254 #endif
 255         }
 256 }