Demos/Device/ClassDriver/AudioInput/AudioInput.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 AudioInput demo. This file contains the main tasks of
  34  *  the demo and is responsible for the initial application hardware configuration.
  35  */
  36
  37 #include "AudioInput.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 Microphone_Audio_Interface =
  44         {
  45                 .Config =
  46                         {
  47                                 .StreamingInterfaceNumber = 1,
  48
  49                                 .DataINEndpointNumber     = AUDIO_STREAM_EPNUM,
  50                                 .DataINEndpointSize       = AUDIO_STREAM_EPSIZE,
  51                         },
  52
  53                 .State =
  54                         {
  55                                 // Leave all state values to their defaults
  56                         }
  57         };
  58
  59 /** Main program entry point. This routine contains the overall program flow, including initial
  60  *  setup of all components and the main program loop.
  61  */
  62 int main(void)
  63 {
  64         SetupHardware();
  65
  66         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
  67
  68         for (;;)
  69         {
  70                 if (Microphone_Audio_Interface.State.InterfaceEnabled)
  71                   ProcessNextSample();
  72
  73                 Audio_Device_USBTask(&Microphone_Audio_Interface);
  74                 USB_USBTask();
  75         }
  76 }
  77
  78 /** Configures the board hardware and chip peripherals for the demo's functionality. */
  79 void SetupHardware(void)
  80 {
  81         /* Disable watchdog if enabled by bootloader/fuses */
  82         MCUSR &= ~(1 << WDRF);
  83         wdt_disable();
  84
  85         /* Disable clock division */
  86         clock_prescale_set(clock_div_1);
  87
  88         /* Hardware Initialization */
  89         LEDs_Init();
  90         USB_Init();
  91         ADC_Init(ADC_FREE_RUNNING | ADC_PRESCALE_32);
  92         ADC_SetupChannel(MIC_IN_ADC_CHANNEL);
  93
  94         /* Start the ADC conversion in free running mode */
  95         ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | MIC_IN_ADC_CHANNEL);
  96 }
  97
  98 /** Processes the next audio sample by reading the last ADC conversion and writing it to the audio
  99  *  interface, each time the sample reload timer period elapses to give a constant sample rate.
 100  */
 101 void ProcessNextSample(void)
 102 {
 103         if ((TIFR0 & (1 << OCF0A)) && Audio_Device_IsReadyForNextSample(&Microphone_Audio_Interface))
 104         {
 105                 TIFR0 |= (1 << OCF0A);
 106
 107                 /* Audio sample is ADC value scaled to fit the entire range */
 108                 int16_t AudioSample = ((SAMPLE_MAX_RANGE / ADC_MAX_RANGE) * ADC_GetResult());
 109
 110 #if defined(MICROPHONE_BIASED_TO_HALF_RAIL)
 111                 /* Microphone is biased to half rail voltage, subtract the bias from the sample value */
 112                 AudioSample -= (SAMPLE_MAX_RANGE / 2));
 113 #endif
 114
 115                 Audio_Device_WriteSample16(AudioSample);
 116         }
 117 }
 118
 119 /** Event handler for the library USB Connection event. */
 120 void EVENT_USB_Connect(void)
 121 {
 122         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
 123
 124         /* Sample reload timer initialization */
 125         OCR0A   = (F_CPU / AUDIO_SAMPLE_FREQUENCY) - 1;
 126         TCCR0A  = (1 << WGM01);  // CTC mode
 127         TCCR0B  = (1 << CS00);   // Fcpu speed
 128 }
 129
 130 /** Event handler for the library USB Disconnection event. */
 131 void EVENT_USB_Disconnect(void)
 132 {
 133         /* Stop the sample reload timer */
 134         TCCR0B = 0;
 135
 136         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 137 }
 138
 139 /** Event handler for the library USB Configuration Changed event. */
 140 void EVENT_USB_ConfigurationChanged(void)
 141 {
 142         LEDs_SetAllLEDs(LEDMASK_USB_READY);
 143
 144         if (!(Audio_Device_ConfigureEndpoints(&Microphone_Audio_Interface)))
 145           LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
 146 }
 147
 148 /** Event handler for the library USB Unhandled Control Packet event. */
 149 void EVENT_USB_UnhandledControlPacket(void)
 150 {
 151         Audio_Device_ProcessControlPacket(&Microphone_Audio_Interface);
 152 }