Demos/Device/ClassDriver/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
  34  *  the demo and is responsible for the initial application hardware configuration.
  35  */
  36
  37 #include "AudioOutput.h"
  38
  39 /** LUFA Audio Class driver interface configuration and state information. This structure is
  40  *  passed to all Audio Class driver functions, so that multiple instances of the same class
  41  *  within a device can be differentiated from one another.
  42  */
  43 USB_ClassInfo_Audio_Device_t Speaker_Audio_Interface =
  44         {
  45                 .Config =
  46                         {
  47                                 .StreamingInterfaceNumber = 1,
  48
  49                                 .DataOUTEndpointNumber    = AUDIO_STREAM_EPNUM,
  50                                 .DataOUTEndpointSize      = AUDIO_STREAM_EPSIZE,
  51                         },
  52         };
  53
  54 /** Main program entry point. This routine contains the overall program flow, including initial
  55  *  setup of all components and the main program loop.
  56  */
  57 int main(void)
  58 {
  59         SetupHardware();
  60
  61         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
  62
  63         for (;;)
  64         {
  65                 ProcessNextSample();
  66
  67                 Audio_Device_USBTask(&Speaker_Audio_Interface);
  68                 USB_USBTask();
  69         }
  70 }
  71
  72 /** Configures the board hardware and chip peripherals for the demo's functionality. */
  73 void SetupHardware(void)
  74 {
  75         /* Disable watchdog if enabled by bootloader/fuses */
  76         MCUSR &= ~(1 << WDRF);
  77         wdt_disable();
  78
  79         /* Disable clock division */
  80         clock_prescale_set(clock_div_1);
  81
  82         /* Hardware Initialization */
  83         LEDs_Init();
  84         USB_Init();
  85 }
  86
  87 /** Processes the next audio sample by reading the last ADC conversion and writing it to the audio
  88  *  interface, each time the sample reload timer period elapses to give a constant sample rate.
  89  */
  90 void ProcessNextSample(void)
  91 {
  92         /* Check if the sample reload timer period has elapsed, and that the USB bus is ready for a new sample */
  93         if ((TIFR0 & (1 << OCF0A)) && Audio_Device_IsSampleReceived(&Speaker_Audio_Interface))
  94         {
  95                 /* Clear the sample reload timer */
  96                 TIFR0 |= (1 << OCF0A);
  97
  98                 /* Retrieve the signed 16-bit left and right audio samples */
  99                 int16_t LeftSample_16Bit  = Audio_Device_ReadSample16(&Speaker_Audio_Interface);
 100                 int16_t RightSample_16Bit = Audio_Device_ReadSample16(&Speaker_Audio_Interface);
 101
 102                 /* Massage signed 16-bit left and right audio samples into signed 8-bit */
 103                 int8_t  LeftSample_8Bit   = (LeftSample_16Bit  >> 8);
 104                 int8_t  RightSample_8Bit  = (RightSample_16Bit >> 8);
 105
 106                 /* Mix the two channels together to produce a mono, 8-bit sample */
 107                 int8_t  MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 108
 109                 /* Get absolute value of mixed sample value */
 110                 uint8_t MixedSample_8Bit_Abs = abs(MixedSample_8Bit);
 111
 112 #if defined(AUDIO_OUT_MONO)
 113                 /* Load the sample into the PWM timer channel */
 114                 OCR3A = ((uint8_t)MixedSample_8Bit ^ (1 << 7));
 115 #elif defined(AUDIO_OUT_STEREO)
 116                 /* Load the dual 8-bit samples into the PWM timer channels */
 117                 OCR3A = ((uint8_t)LeftSample_8Bit  ^ (1 << 7));
 118                 OCR3B = ((uint8_t)RightSample_8Bit ^ (1 << 7));
 119 #elif defined(AUDIO_OUT_PORTC)
 120                 /* Load the 8-bit mixed sample into PORTC */
 121                 PORTC = MixedSample_8Bit;
 122 #endif
 123
 124                 uint8_t LEDMask = LEDS_NO_LEDS;
 125
 126                 if (MixedSample_8Bit_Abs > 2)
 127                   LEDMask |= LEDS_LED1;
 128
 129                 if (MixedSample_8Bit_Abs > 4)
 130                   LEDMask |= LEDS_LED2;
 131
 132                 if (MixedSample_8Bit_Abs > 8)
 133                   LEDMask |= LEDS_LED3;
 134
 135                 if (MixedSample_8Bit_Abs > 16)
 136                   LEDMask |= LEDS_LED4;
 137
 138                 LEDs_SetAllLEDs(LEDMask);
 139         }
 140 }
 141
 142 /** Event handler for the library USB Connection event. */
 143 void EVENT_USB_Device_Connect(void)
 144 {
 145         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
 146
 147         /* Sample reload timer initialization */
 148         OCR0A   = (F_CPU / AUDIO_SAMPLE_FREQUENCY) - 1;
 149         TCCR0A  = (1 << WGM01);  // CTC mode
 150         TCCR0B  = (1 << CS00);   // Fcpu speed
 151
 152 #if defined(AUDIO_OUT_MONO)
 153         /* Set speaker as output */
 154         DDRC   |= (1 << 6);
 155 #elif defined(AUDIO_OUT_STEREO)
 156         /* Set speakers as outputs */
 157         DDRC   |= ((1 << 6) | (1 << 5));
 158 #elif defined(AUDIO_OUT_PORTC)
 159         /* Set PORTC as outputs */
 160         DDRC   |= 0xFF;
 161 #endif
 162
 163 #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 164         /* PWM speaker timer initialization */
 165         TCCR3A  = ((1 << WGM30) | (1 << COM3A1) | (1 << COM3A0)
 166                 | (1 << COM3B1) | (1 << COM3B0)); // Set on match, clear on TOP
 167         TCCR3B  = ((1 << WGM32) | (1 << CS30));  // Fast 8-Bit PWM, Fcpu speed
 168 #endif
 169 }
 170
 171 /** Event handler for the library USB Disconnection event. */
 172 void EVENT_USB_Device_Disconnect(void)
 173 {
 174         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 175
 176         /* Stop the sample reload timer */
 177         TCCR0B = 0;
 178
 179 #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 180         /* Stop the PWM generation timer */
 181         TCCR3B = 0;
 182 #endif
 183
 184 #if defined(AUDIO_OUT_MONO)
 185         /* Set speaker as input to reduce current draw */
 186         DDRC   &= ~(1 << 6);
 187 #elif defined(AUDIO_OUT_STEREO)
 188         /* Set speakers as inputs to reduce current draw */
 189         DDRC   &= ~((1 << 6) | (1 << 5));
 190 #elif defined(AUDIO_OUT_PORTC)
 191         /* Set PORTC low */
 192         PORTC  = 0x00;
 193 #endif
 194 }
 195
 196 /** Event handler for the library USB Configuration Changed event. */
 197 void EVENT_USB_Device_ConfigurationChanged(void)
 198 {
 199         LEDs_SetAllLEDs(LEDMASK_USB_READY);
 200
 201         if (!(Audio_Device_ConfigureEndpoints(&Speaker_Audio_Interface)))
 202           LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
 203 }
 204
 205 /** Event handler for the library USB Unhandled Control Request event. */
 206 void EVENT_USB_Device_UnhandledControlRequest(void)
 207 {
 208         Audio_Device_ProcessControlRequest(&Speaker_Audio_Interface);
 209 }