Demos/Device/LowLevel/AudioInput/AudioInput.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2010.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6            www.lufa-lib.org
   7 */
   8
   9 /*
  10   Copyright 2010  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 Audio Input demo. This file contains the main tasks of the demo and
  34  *  is responsible for the initial application hardware configuration.
  35  */
  36
  37 #include "AudioInput.h"
  38
  39 /** Flag to indicate if the streaming audio alternative interface has been selected by the host. */
  40 bool StreamingAudioInterfaceSelected = false;
  41
  42 /** Main program entry point. This routine contains the overall program flow, including initial
  43  *  setup of all components and the main program loop.
  44  */
  45 int main(void)
  46 {
  47         SetupHardware();
  48
  49         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
  50         sei();
  51
  52         for (;;)
  53         {
  54                 USB_USBTask();
  55         }
  56 }
  57
  58 /** Configures the board hardware and chip peripherals for the demo's functionality. */
  59 void SetupHardware(void)
  60 {
  61         /* Disable watchdog if enabled by bootloader/fuses */
  62         MCUSR &= ~(1 << WDRF);
  63         wdt_disable();
  64
  65         /* Disable clock division */
  66         clock_prescale_set(clock_div_1);
  67
  68         /* Hardware Initialization */
  69         LEDs_Init();
  70         Buttons_Init();
  71         ADC_Init(ADC_FREE_RUNNING | ADC_PRESCALE_32);
  72         ADC_SetupChannel(MIC_IN_ADC_CHANNEL);
  73         USB_Init();
  74
  75         /* Start the ADC conversion in free running mode */
  76         ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | MIC_IN_ADC_MUX_MASK);
  77 }
  78
  79 /** Event handler for the USB_Connect event. This indicates that the device is enumerating via the status LEDs, and
  80  *  configures the sample update and PWM timers.
  81  */
  82 void EVENT_USB_Device_Connect(void)
  83 {
  84         /* Indicate USB enumerating */
  85         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
  86
  87         /* Sample reload timer initialization */
  88         TIMSK0  = (1 << OCIE0A);
  89         OCR0A   = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1;
  90         TCCR0A  = (1 << WGM01);  // CTC mode
  91         TCCR0B  = (1 << CS01);   // Fcpu/8 speed
  92 }
  93
  94 /** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
  95  *  the status LEDs, disables the sample update and PWM output timers and stops the USB and Audio management tasks.
  96  */
  97 void EVENT_USB_Device_Disconnect(void)
  98 {
  99         /* Stop the sample reload timer */
 100         TCCR0B = 0;
 101
 102         /* Indicate streaming audio interface not selected */
 103         StreamingAudioInterfaceSelected = false;
 104
 105         /* Indicate USB not ready */
 106         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 107 }
 108
 109 /** Event handler for the USB_ConfigurationChanged event. This is fired when the host set the current configuration
 110  *  of the USB device after enumeration - the device endpoints are configured.
 111  */
 112 void EVENT_USB_Device_ConfigurationChanged(void)
 113 {
 114         bool ConfigSuccess = true;
 115
 116         /* Setup Audio Stream Endpoint */
 117         ConfigSuccess &= Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPNUM, EP_TYPE_ISOCHRONOUS, ENDPOINT_DIR_IN,
 118                                                     AUDIO_STREAM_EPSIZE, ENDPOINT_BANK_DOUBLE);
 119
 120         /* Indicate endpoint configuration success or failure */
 121         LEDs_SetAllLEDs(ConfigSuccess ? LEDMASK_USB_READY : LEDMASK_USB_ERROR);
 122 }
 123
 124 /** Event handler for the USB_UnhandledControlRequest event. This is used to catch standard and class specific
 125  *  control requests that are not handled internally by the USB library (including the Audio class-specific
 126  *  requests) so that they can be handled appropriately for the application.
 127  */
 128 void EVENT_USB_Device_UnhandledControlRequest(void)
 129 {
 130         /* Process General and Audio specific control requests */
 131         switch (USB_ControlRequest.bRequest)
 132         {
 133                 case REQ_SetInterface:
 134                         /* Set Interface is not handled by the library, as its function is application-specific */
 135                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE))
 136                         {
 137                                 Endpoint_ClearSETUP();
 138                                 Endpoint_ClearStatusStage();
 139
 140                                 /* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */
 141                                 StreamingAudioInterfaceSelected = ((USB_ControlRequest.wValue) != 0);
 142                         }
 143
 144                         break;
 145         }
 146 }
 147
 148 /** ISR to handle the reloading of the data endpoint with the next sample. */
 149 ISR(TIMER0_COMPA_vect, ISR_BLOCK)
 150 {
 151         uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
 152
 153         /* Select the audio stream endpoint */
 154         Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 155
 156         /* Check if the current endpoint can be written to and that the audio interface is enabled */
 157         if (Endpoint_IsINReady() && StreamingAudioInterfaceSelected)
 158         {
 159                 int16_t AudioSample;
 160
 161                 #if defined(USE_TEST_TONE)
 162                         static uint8_t SquareWaveSampleCount;
 163                         static int16_t CurrentWaveValue;
 164
 165                         /* In test tone mode, generate a square wave at 1/256 of the sample rate */
 166                         if (SquareWaveSampleCount++ == 0xFF)
 167                           CurrentWaveValue ^= 0x8000;
 168
 169                         /* Only generate audio if the board button is being pressed */
 170                         AudioSample = (Buttons_GetStatus() & BUTTONS_BUTTON1) ? CurrentWaveValue : 0;
 171                 #else
 172                         /* Audio sample is ADC value scaled to fit the entire range */
 173                         AudioSample = ((SAMPLE_MAX_RANGE / ADC_MAX_RANGE) * ADC_GetResult());
 174
 175                         #if defined(MICROPHONE_BIASED_TO_HALF_RAIL)
 176                         /* Microphone is biased to half rail voltage, subtract the bias from the sample value */
 177                         AudioSample -= (SAMPLE_MAX_RANGE / 2);
 178                         #endif
 179                 #endif
 180
 181                 /* Write the sample to the buffer */
 182                 Endpoint_Write_Word_LE(AudioSample);
 183
 184                 /* Check to see if the bank is now full */
 185                 if (!(Endpoint_IsReadWriteAllowed()))
 186                 {
 187                         /* Send the full packet to the host */
 188                         Endpoint_ClearIN();
 189                 }
 190         }
 191
 192         Endpoint_SelectEndpoint(PrevEndpoint);
 193 }
 194