Demos/Device/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_t Speaker_Audio_Interface =
  44         {
  45                 .StreamingInterfaceNumber = 1,
  46
  47                 .DataOUTEndpointNumber    = AUDIO_STREAM_EPNUM,
  48                 .DataOUTEndpointSize      = AUDIO_STREAM_EPSIZE,
  49         };
  50
  51 /** Main program entry point. This routine contains the overall program flow, including initial
  52  *  setup of all components and the main program loop.
  53  */
  54 int main(void)
  55 {
  56         SetupHardware();
  57
  58         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
  59
  60         for (;;)
  61         {
  62                 if (Speaker_Audio_Interface.InterfaceEnabled)
  63                   ProcessNextSample();
  64
  65                 USB_USBTask();
  66         }
  67 }
  68
  69 /** Configures the board hardware and chip peripherals for the demo's functionality. */
  70 void SetupHardware(void)
  71 {
  72         /* Disable watchdog if enabled by bootloader/fuses */
  73         MCUSR &= ~(1 << WDRF);
  74         wdt_disable();
  75
  76         /* Disable clock division */
  77         clock_prescale_set(clock_div_1);
  78
  79         /* Hardware Initialization */
  80         LEDs_Init();
  81         USB_Init();
  82 }
  83
  84 /** Processes the next audio sample by reading the last ADC conversion and writing it to the audio
  85  *  interface, each time the sample reload timer period elapses to give a constant sample rate.
  86  */
  87 void ProcessNextSample(void)
  88 {
  89         if ((TIFR0 & (1 << OCF0A)) && USB_Audio_IsSampleReceived(&Speaker_Audio_Interface))
  90         {
  91                 /* Clear the sample reload timer */
  92                 TIFR0 |= (1 << OCF0A);
  93
  94                 /* Retrieve the signed 16-bit left and right audio samples */
  95                 int16_t LeftSample_16Bit  = (int16_t)USB_Audio_ReadSample16();
  96                 int16_t RightSample_16Bit = (int16_t)USB_Audio_ReadSample16();
  97
  98                 /* Massage signed 16-bit left and right audio samples into signed 8-bit */
  99                 int8_t  LeftSample_8Bit   = (LeftSample_16Bit  >> 8);
 100                 int8_t  RightSample_8Bit  = (RightSample_16Bit >> 8);
 101
 102                 /* Mix the two channels together to produce a mono, 8-bit sample */
 103                 int8_t  MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 104
 105 #if defined(AUDIO_OUT_MONO)
 106                 /* Load the sample into the PWM timer channel */
 107                 OCRxA = ((uint8_t)MixedSample_8Bit ^ (1 << 7));
 108 #elif defined(AUDIO_OUT_STEREO)
 109                 /* Load the dual 8-bit samples into the PWM timer channels */
 110                 OCRxA = ((uint8_t)LeftSample_8Bit  ^ (1 << 7));
 111                 OCRxB = ((uint8_t)RightSample_8Bit ^ (1 << 7));
 112 #elif defined(AUDIO_OUT_PORTC)
 113                 PORTC = MixedSample_8Bit;
 114 #else
 115                 uint8_t LEDMask = LEDS_NO_LEDS;
 116
 117                 /* Make mixed sample value positive (absolute) */
 118                 if (MixedSample_8Bit < 0)
 119                   MixedSample_8Bit = -MixedSample_8Bit;
 120
 121                 if (MixedSample_8Bit > ((128 / 8) * 1))
 122                   LEDMask |= LEDS_LED1;
 123
 124                 if (MixedSample_8Bit > ((128 / 8) * 2))
 125                   LEDMask |= LEDS_LED2;
 126
 127                 if (MixedSample_8Bit > ((128 / 8) * 3))
 128                   LEDMask |= LEDS_LED3;
 129
 130                 if (MixedSample_8Bit > ((128 / 8) * 4))
 131                   LEDMask |= LEDS_LED4;
 132
 133                 LEDs_SetAllLEDs(LEDMask);
 134 #endif
 135         }
 136 }
 137
 138 /** Event handler for the library USB Connection event. */
 139 void EVENT_USB_Connect(void)
 140 {
 141         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
 142
 143         /* Sample reload timer initialization */
 144         OCR0A   = (F_CPU / AUDIO_SAMPLE_FREQUENCY) - 1;
 145         TCCR0A  = (1 << WGM01);  // CTC mode
 146         TCCR0B  = (1 << CS00);   // Fcpu speed
 147
 148 #if defined(AUDIO_OUT_MONO)
 149         /* Set speaker as output */
 150         DDRC   |= (1 << 6);
 151 #elif defined(AUDIO_OUT_STEREO)
 152         /* Set speakers as outputs */
 153         DDRC   |= ((1 << 6) | (1 << 5));
 154 #elif defined(AUDIO_OUT_PORTC)
 155         /* Set PORTC as outputs */
 156         DDRC   |= 0xFF;
 157 #endif
 158
 159 #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 160         /* PWM speaker timer initialization */
 161         TCCRxA  = ((1 << WGMx0) | (1 << COMxA1) | (1 << COMxA0)
 162                                                         | (1 << COMxB1) | (1 << COMxB0)); // Set on match, clear on TOP
 163         TCCRxB  = ((1 << WGMx2) | (1 << CSx0));  // Fast 8-Bit PWM, Fcpu speed
 164 #endif
 165 }
 166
 167 /** Event handler for the library USB Disconnection event. */
 168 void EVENT_USB_Disconnect(void)
 169 {
 170         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 171
 172         /* Stop the sample reload timer */
 173         TCCR0B = 0;
 174
 175 #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 176         /* Stop the PWM generation timer */
 177         TCCRxB = 0;
 178 #endif
 179
 180 #if defined(AUDIO_OUT_MONO)
 181         /* Set speaker as input to reduce current draw */
 182         DDRC   &= ~(1 << 6);
 183 #elif defined(AUDIO_OUT_STEREO)
 184         /* Set speakers as inputs to reduce current draw */
 185         DDRC   &= ~((1 << 6) | (1 << 5));
 186 #elif defined(AUDIO_OUT_PORTC)
 187         /* Set PORTC low */
 188         PORTC  = 0x00;
 189 #endif
 190 }
 191
 192 /** Event handler for the library USB Configuration Changed event. */
 193 void EVENT_USB_ConfigurationChanged(void)
 194 {
 195         LEDs_SetAllLEDs(LEDMASK_USB_READY);
 196
 197         if (!(USB_Audio_ConfigureEndpoints(&Speaker_Audio_Interface)))
 198           LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
 199 }
 200
 201 /** Event handler for the library USB Unhandled Control Packet event. */
 202 void EVENT_USB_UnhandledControlPacket(void)
 203 {
 204         USB_Audio_ProcessControlPacket(&Speaker_Audio_Interface);
 205 }