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