Demos/Device/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_t Microphone_Audio_Interface =
  44         {
  45                 .StreamingInterfaceNumber = 1,
  46
  47                 .DataINEndpointNumber     = AUDIO_STREAM_EPNUM,
  48                 .DataINEndpointSize       = 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 (Microphone_Audio_Interface.InterfaceEnabled)
  63                   ProcessNextSample();
  64
  65                 USB_Audio_USBTask(&Microphone_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         ADC_Init(ADC_FREE_RUNNING | ADC_PRESCALE_32);
  84         ADC_SetupChannel(MIC_IN_ADC_CHANNEL);
  85
  86         /* Start the ADC conversion in free running mode */
  87         ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | MIC_IN_ADC_CHANNEL);
  88 }
  89
  90 /** Processes the next audio sample by reading the last ADC conversion and writing it to the audio
  91  *  interface, each time the sample reload timer period elapses to give a constant sample rate.
  92  */
  93 void ProcessNextSample(void)
  94 {
  95         if ((TIFR0 & (1 << OCF0A)) && USB_Audio_IsReadyForNextSample(&Microphone_Audio_Interface))
  96         {
  97                 TIFR0 |= (1 << OCF0A);
  98
  99                 /* Audio sample is ADC value scaled to fit the entire range */
 100                 int16_t AudioSample = ((SAMPLE_MAX_RANGE / ADC_MAX_RANGE) * ADC_GetResult());
 101
 102 #if defined(MICROPHONE_BIASED_TO_HALF_RAIL)
 103                 /* Microphone is biased to half rail voltage, subtract the bias from the sample value */
 104                 AudioSample -= (SAMPLE_MAX_RANGE / 2));
 105 #endif
 106
 107                 USB_Audio_WriteSample16(AudioSample);
 108         }
 109 }
 110
 111 /** Event handler for the library USB Connection event. */
 112 void EVENT_USB_Connect(void)
 113 {
 114         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
 115
 116         /* Sample reload timer initialization */
 117         OCR0A   = (F_CPU / AUDIO_SAMPLE_FREQUENCY) - 1;
 118         TCCR0A  = (1 << WGM01);  // CTC mode
 119         TCCR0B  = (1 << CS00);   // Fcpu speed
 120 }
 121
 122 /** Event handler for the library USB Disconnection event. */
 123 void EVENT_USB_Disconnect(void)
 124 {
 125         /* Stop the sample reload timer */
 126         TCCR0B = 0;
 127
 128         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 129 }
 130
 131 /** Event handler for the library USB Configuration Changed event. */
 132 void EVENT_USB_ConfigurationChanged(void)
 133 {
 134         LEDs_SetAllLEDs(LEDMASK_USB_READY);
 135
 136         if (!(USB_Audio_ConfigureEndpoints(&Microphone_Audio_Interface)))
 137           LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
 138 }
 139
 140 /** Event handler for the library USB Unhandled Control Packet event. */
 141 void EVENT_USB_UnhandledControlPacket(void)
 142 {
 143         USB_Audio_ProcessControlPacket(&Microphone_Audio_Interface);
 144 }