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         /* Setup audio stream endpoint */
 140         Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPNUM, EP_TYPE_ISOCHRONOUS,
 141                                        ENDPOINT_DIR_OUT, AUDIO_STREAM_EPSIZE,
 142                                    ENDPOINT_BANK_DOUBLE);
 143
 144         /* Indicate USB connected and ready */
 145         LEDs_SetAllLEDs(LEDMASK_USB_READY);
 146 }
 147
 148 /** Event handler for the USB_UnhandledControlPacket event. This is used to catch standard and class specific
 149  *  control requests that are not handled internally by the USB library (including the Audio class-specific
 150  *  requests) so that they can be handled appropriately for the application.
 151  */
 152 void EVENT_USB_UnhandledControlPacket(void)
 153 {
 154         /* Process General and Audio specific control requests */
 155         switch (USB_ControlRequest.bRequest)
 156         {
 157                 case REQ_SetInterface:
 158                         /* Set Interface is not handled by the library, as its function is application-specific */
 159                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE))
 160                         {
 161                                 Endpoint_ClearSETUP();
 162
 163                                 /* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */
 164                                 StreamingAudioInterfaceSelected = ((USB_ControlRequest.wValue) != 0);
 165
 166                                 /* Acknowledge status stage */
 167                                 while (!(Endpoint_IsINReady()));
 168                                 Endpoint_ClearIN();
 169                         }
 170
 171                         break;
 172         }
 173 }
 174
 175 /** Task to manage the Audio interface, reading in audio samples from the host, and outputting them to the speakers/LEDs as
 176  *  desired.
 177  */
 178 void USB_Audio_Task(void)
 179 {
 180         /* Check to see if the streaming interface is selected, if not the host is not receiving audio */
 181         if (!(StreamingAudioInterfaceSelected))
 182           return;
 183
 184         /* Select the audio stream endpoint */
 185         Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 186
 187         /* Check if the current endpoint can be read from (contains a packet) and that the next sample should be read */
 188         if (Endpoint_IsOUTReceived() && (TIFR0 & (1 << OCF0A)))
 189         {
 190                 /* Clear the sample reload timer */
 191                 TIFR0 |= (1 << OCF0A);
 192
 193                 /* Retrieve the signed 16-bit left and right audio samples */
 194                 int16_t LeftSample_16Bit  = (int16_t)Endpoint_Read_Word_LE();
 195                 int16_t RightSample_16Bit = (int16_t)Endpoint_Read_Word_LE();
 196
 197                 /* Check to see if the bank is now empty */
 198                 if (!(Endpoint_IsReadWriteAllowed()))
 199                 {
 200                         /* Acknowledge the packet, clear the bank ready for the next packet */
 201                         Endpoint_ClearOUT();
 202                 }
 203
 204                 /* Massage signed 16-bit left and right audio samples into signed 8-bit */
 205                 int8_t  LeftSample_8Bit   = (LeftSample_16Bit  >> 8);
 206                 int8_t  RightSample_8Bit  = (RightSample_16Bit >> 8);
 207
 208 #if defined(AUDIO_OUT_MONO)
 209                 /* Mix the two channels together to produce a mono, 8-bit sample */
 210                 int8_t  MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 211
 212                 /* Load the sample into the PWM timer channel */
 213                 OCRxA = ((uint8_t)MixedSample_8Bit ^ (1 << 7));
 214 #elif defined(AUDIO_OUT_STEREO)
 215                 /* Load the dual 8-bit samples into the PWM timer channels */
 216                 OCRxA = ((uint8_t)LeftSample_8Bit  ^ (1 << 7));
 217                 OCRxB = ((uint8_t)RightSample_8Bit ^ (1 << 7));
 218 #elif defined(AUDIO_OUT_PORTC)
 219                 /* Mix the two channels together to produce a mono, 8-bit sample */
 220                 int8_t  MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 221
 222                 PORTC = MixedSample_8Bit;
 223 #else
 224                 uint8_t LEDMask = LEDS_NO_LEDS;
 225
 226                 /* Make left channel positive (absolute) */
 227                 if (LeftSample_8Bit < 0)
 228                   LeftSample_8Bit = -LeftSample_8Bit;
 229
 230                 /* Make right channel positive (absolute) */
 231                 if (RightSample_8Bit < 0)
 232                   RightSample_8Bit = -RightSample_8Bit;
 233
 234                 /* Set first LED based on sample value */
 235                 if (LeftSample_8Bit < ((128 / 8) * 1))
 236                   LEDMask |= LEDS_LED2;
 237                 else if (LeftSample_8Bit < ((128 / 8) * 3))
 238                   LEDMask |= (LEDS_LED1 | LEDS_LED2);
 239                 else
 240                   LEDMask |= LEDS_LED1;
 241
 242                 /* Set second LED based on sample value */
 243                 if (RightSample_8Bit < ((128 / 8) * 1))
 244                   LEDMask |= LEDS_LED4;
 245                 else if (RightSample_8Bit < ((128 / 8) * 3))
 246                   LEDMask |= (LEDS_LED3 | LEDS_LED4);
 247                 else
 248                   LEDMask |= LEDS_LED3;
 249
 250                 LEDs_SetAllLEDs(LEDMask);
 251 #endif
 252         }
 253 }