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_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_Audio_USBTask(&Speaker_Audio_Interface);
  66                 USB_USBTask();
  67         }
  68 }
  69
  70 /** Configures the board hardware and chip peripherals for the demo's functionality. */
  71 void SetupHardware(void)
  72 {
  73         /* Disable watchdog if enabled by bootloader/fuses */
  74         MCUSR &= ~(1 << WDRF);
  75         wdt_disable();
  76
  77         /* Disable clock division */
  78         clock_prescale_set(clock_div_1);
  79
  80         /* Hardware Initialization */
  81         LEDs_Init();
  82         USB_Init();
  83 }
  84
  85 /** Processes the next audio sample by reading the last ADC conversion and writing it to the audio
  86  *  interface, each time the sample reload timer period elapses to give a constant sample rate.
  87  */
  88 void ProcessNextSample(void)
  89 {
  90         if ((TIFR0 & (1 << OCF0A)) && USB_Audio_IsSampleReceived(&Speaker_Audio_Interface))
  91         {
  92                 /* Clear the sample reload timer */
  93                 TIFR0 |= (1 << OCF0A);
  94
  95                 /* Retrieve the signed 16-bit left and right audio samples */
  96                 int16_t LeftSample_16Bit  = (int16_t)USB_Audio_ReadSample16();
  97                 int16_t RightSample_16Bit = (int16_t)USB_Audio_ReadSample16();
  98
  99                 /* Massage signed 16-bit left and right audio samples into signed 8-bit */
 100                 int8_t  LeftSample_8Bit   = (LeftSample_16Bit  >> 8);
 101                 int8_t  RightSample_8Bit  = (RightSample_16Bit >> 8);
 102
 103                 /* Mix the two channels together to produce a mono, 8-bit sample */
 104                 int8_t  MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 105
 106 #if defined(AUDIO_OUT_MONO)
 107                 /* Load the sample into the PWM timer channel */
 108                 OCRxA = ((uint8_t)MixedSample_8Bit ^ (1 << 7));
 109 #elif defined(AUDIO_OUT_STEREO)
 110                 /* Load the dual 8-bit samples into the PWM timer channels */
 111                 OCRxA = ((uint8_t)LeftSample_8Bit  ^ (1 << 7));
 112                 OCRxB = ((uint8_t)RightSample_8Bit ^ (1 << 7));
 113 #elif defined(AUDIO_OUT_PORTC)
 114                 PORTC = MixedSample_8Bit;
 115 #else
 116                 uint8_t LEDMask = LEDS_NO_LEDS;
 117
 118                 /* Make mixed sample value positive (absolute) */
 119                 if (MixedSample_8Bit < 0)
 120                   MixedSample_8Bit = -MixedSample_8Bit;
 121
 122                 if (MixedSample_8Bit > ((128 / 8) * 1))
 123                   LEDMask |= LEDS_LED1;
 124
 125                 if (MixedSample_8Bit > ((128 / 8) * 2))
 126                   LEDMask |= LEDS_LED2;
 127
 128                 if (MixedSample_8Bit > ((128 / 8) * 3))
 129                   LEDMask |= LEDS_LED3;
 130
 131                 if (MixedSample_8Bit > ((128 / 8) * 4))
 132                   LEDMask |= LEDS_LED4;
 133
 134                 LEDs_SetAllLEDs(LEDMask);
 135 #endif
 136         }
 137 }
 138
 139 /** Event handler for the library USB Connection event. */
 140 void EVENT_USB_Connect(void)
 141 {
 142         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
 143
 144         /* Sample reload timer initialization */
 145         OCR0A   = (F_CPU / AUDIO_SAMPLE_FREQUENCY) - 1;
 146         TCCR0A  = (1 << WGM01);  // CTC mode
 147         TCCR0B  = (1 << CS00);   // Fcpu speed
 148
 149 #if defined(AUDIO_OUT_MONO)
 150         /* Set speaker as output */
 151         DDRC   |= (1 << 6);
 152 #elif defined(AUDIO_OUT_STEREO)
 153         /* Set speakers as outputs */
 154         DDRC   |= ((1 << 6) | (1 << 5));
 155 #elif defined(AUDIO_OUT_PORTC)
 156         /* Set PORTC as outputs */
 157         DDRC   |= 0xFF;
 158 #endif
 159
 160 #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 161         /* PWM speaker timer initialization */
 162         TCCRxA  = ((1 << WGMx0) | (1 << COMxA1) | (1 << COMxA0)
 163                                                         | (1 << COMxB1) | (1 << COMxB0)); // Set on match, clear on TOP
 164         TCCRxB  = ((1 << WGMx2) | (1 << CSx0));  // Fast 8-Bit PWM, Fcpu speed
 165 #endif
 166 }
 167
 168 /** Event handler for the library USB Disconnection event. */
 169 void EVENT_USB_Disconnect(void)
 170 {
 171         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 172
 173         /* Stop the sample reload timer */
 174         TCCR0B = 0;
 175
 176 #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 177         /* Stop the PWM generation timer */
 178         TCCRxB = 0;
 179 #endif
 180
 181 #if defined(AUDIO_OUT_MONO)
 182         /* Set speaker as input to reduce current draw */
 183         DDRC   &= ~(1 << 6);
 184 #elif defined(AUDIO_OUT_STEREO)
 185         /* Set speakers as inputs to reduce current draw */
 186         DDRC   &= ~((1 << 6) | (1 << 5));
 187 #elif defined(AUDIO_OUT_PORTC)
 188         /* Set PORTC low */
 189         PORTC  = 0x00;
 190 #endif
 191 }
 192
 193 /** Event handler for the library USB Configuration Changed event. */
 194 void EVENT_USB_ConfigurationChanged(void)
 195 {
 196         LEDs_SetAllLEDs(LEDMASK_USB_READY);
 197
 198         if (!(USB_Audio_ConfigureEndpoints(&Speaker_Audio_Interface)))
 199           LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
 200 }
 201
 202 /** Event handler for the library USB Unhandled Control Packet event. */
 203 void EVENT_USB_UnhandledControlPacket(void)
 204 {
 205         USB_Audio_ProcessControlPacket(&Speaker_Audio_Interface);
 206 }