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, distribute, and sell this
  13   software and its documentation for any purpose is hereby granted
  14   without fee, provided that the above copyright notice appear in
  15   all 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
  54 /** Main program entry point. This routine contains the overall program flow, including initial
  55  *  setup of all components and the main program loop.
  56  */
  57 int main(void)
  58 {
  59         SetupHardware();
  60
  61         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
  62
  63         for (;;)
  64         {
  65                 ProcessNextSample();
  66
  67                 Audio_Device_USBTask(&Microphone_Audio_Interface);
  68                 USB_USBTask();
  69         }
  70 }
  71
  72 /** Configures the board hardware and chip peripherals for the demo's functionality. */
  73 void SetupHardware(void)
  74 {
  75         /* Disable watchdog if enabled by bootloader/fuses */
  76         MCUSR &= ~(1 << WDRF);
  77         wdt_disable();
  78
  79         /* Disable clock division */
  80         clock_prescale_set(clock_div_1);
  81
  82         /* Hardware Initialization */
  83         LEDs_Init();
  84         USB_Init();
  85         ADC_Init(ADC_FREE_RUNNING | ADC_PRESCALE_32);
  86         ADC_SetupChannel(MIC_IN_ADC_CHANNEL);
  87
  88         /* Start the ADC conversion in free running mode */
  89         ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | MIC_IN_ADC_CHANNEL);
  90 }
  91
  92 /** Processes the next audio sample by reading the last ADC conversion and writing it to the audio
  93  *  interface, each time the sample reload timer period elapses to give a constant sample rate.
  94  */
  95 void ProcessNextSample(void)
  96 {
  97         /* Check if the sample reload timer period has elapsed, and that the USB bus is ready for a new sample */
  98         if ((TIFR0 & (1 << OCF0A)) && Audio_Device_IsReadyForNextSample(&Microphone_Audio_Interface))
  99         {
 100                 TIFR0 |= (1 << OCF0A);
 101
 102                 /* Audio sample is ADC value scaled to fit the entire range */
 103                 int16_t AudioSample = ((SAMPLE_MAX_RANGE / ADC_MAX_RANGE) * ADC_GetResult());
 104
 105                 #if defined(MICROPHONE_BIASED_TO_HALF_RAIL)
 106                 /* Microphone is biased to half rail voltage, subtract the bias from the sample value */
 107                 AudioSample -= (SAMPLE_MAX_RANGE / 2));
 108                 #endif
 109
 110                 Audio_Device_WriteSample16(&Microphone_Audio_Interface, AudioSample);
 111         }
 112 }
 113
 114 /** Event handler for the library USB Connection event. */
 115 void EVENT_USB_Device_Connect(void)
 116 {
 117         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
 118
 119         /* Sample reload timer initialization */
 120         OCR0A   = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1;
 121         TCCR0A  = (1 << WGM01);  // CTC mode
 122         TCCR0B  = (1 << CS01);   // Fcpu/8 speed
 123 }
 124
 125 /** Event handler for the library USB Disconnection event. */
 126 void EVENT_USB_Device_Disconnect(void)
 127 {
 128         /* Stop the sample reload timer */
 129         TCCR0B = 0;
 130
 131         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 132 }
 133
 134 /** Event handler for the library USB Configuration Changed event. */
 135 void EVENT_USB_Device_ConfigurationChanged(void)
 136 {
 137         LEDs_SetAllLEDs(LEDMASK_USB_READY);
 138
 139         if (!(Audio_Device_ConfigureEndpoints(&Microphone_Audio_Interface)))
 140           LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
 141 }
 142
 143 /** Event handler for the library USB Unhandled Control Request event. */
 144 void EVENT_USB_Device_UnhandledControlRequest(void)
 145 {
 146         Audio_Device_ProcessControlRequest(&Microphone_Audio_Interface);
 147 }