Demos/Device/LowLevel/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 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
  51         for (;;)
  52         {
  53                 USB_Audio_Task();
  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         ADC_Init(ADC_FREE_RUNNING | ADC_PRESCALE_32);
  71         ADC_SetupChannel(MIC_IN_ADC_CHANNEL);
  72         USB_Init();
  73
  74         /* Start the ADC conversion in free running mode */
  75         ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | MIC_IN_ADC_CHANNEL);
  76 }
  77
  78 /** Event handler for the USB_Connect event. This indicates that the device is enumerating via the status LEDs, and
  79  *  configures the sample update and PWM timers.
  80  */
  81 void EVENT_USB_Connect(void)
  82 {
  83         /* Indicate USB enumerating */
  84         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
  85
  86         /* Sample reload timer initialization */
  87         OCR0A   = (F_CPU / AUDIO_SAMPLE_FREQUENCY) - 1;
  88         TCCR0A  = (1 << WGM01);  // CTC mode
  89         TCCR0B  = (1 << CS00);   // Fcpu speed
  90 }
  91
  92 /** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
  93  *  the status LEDs, disables the sample update and PWM output timers and stops the USB and Audio management tasks.
  94  */
  95 void EVENT_USB_Disconnect(void)
  96 {
  97         /* Stop the sample reload timer */
  98         TCCR0B = 0;
  99
 100         /* Indicate streaming audio interface not selected */
 101         StreamingAudioInterfaceSelected = false;
 102
 103         /* Indicate USB not ready */
 104         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 105 }
 106
 107 /** Event handler for the USB_ConfigurationChanged event. This is fired when the host set the current configuration
 108  *  of the USB device after enumeration - the device endpoints are configured.
 109  */
 110 void EVENT_USB_ConfigurationChanged(void)
 111 {
 112         /* Indicate USB connected and ready */
 113         LEDs_SetAllLEDs(LEDMASK_USB_READY);
 114
 115         /* Setup audio stream endpoint */
 116         if (!(Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPNUM, EP_TYPE_ISOCHRONOUS,
 117                                              ENDPOINT_DIR_IN, AUDIO_STREAM_EPSIZE,
 118                                          ENDPOINT_BANK_DOUBLE)))
 119         {
 120                 LEDs_SetAllLEDs(LEDMASK_USB_ERROR);
 121         }
 122 }
 123
 124 /** Event handler for the USB_UnhandledControlPacket 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_UnhandledControlPacket(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
 139                                 /* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */
 140                                 StreamingAudioInterfaceSelected = ((USB_ControlRequest.wValue) != 0);
 141
 142                                 /* Acknowledge status stage */
 143                                 while (!(Endpoint_IsINReady()));
 144                                 Endpoint_ClearIN();
 145                         }
 146
 147                         break;
 148         }
 149 }
 150
 151 /** Task to manage the Audio interface, reading in ADC samples from the microphone, and them to the host. */
 152 void USB_Audio_Task(void)
 153 {
 154         /* Check to see if the streaming interface is selected, if not the host is not receiving audio */
 155         if (!(StreamingAudioInterfaceSelected))
 156           return;
 157
 158         /* Select the audio stream endpoint */
 159         Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 160
 161         /* Check if the current endpoint can be written to and that the next sample should be stored */
 162         if (Endpoint_IsINReady() && (TIFR0 & (1 << OCF0A)))
 163         {
 164                 /* Clear the sample reload timer */
 165                 TIFR0 |= (1 << OCF0A);
 166
 167                 /* Audio sample is ADC value scaled to fit the entire range */
 168                 int16_t AudioSample = ((SAMPLE_MAX_RANGE / ADC_MAX_RANGE) * ADC_GetResult());
 169
 170 #if defined(MICROPHONE_BIASED_TO_HALF_RAIL)
 171                 /* Microphone is biased to half rail voltage, subtract the bias from the sample value */
 172                 AudioSample -= (SAMPLE_MAX_RANGE / 2));
 173 #endif
 174
 175                 /* Write the sample to the buffer */
 176                 Endpoint_Write_Word_LE(AudioSample);
 177
 178                 /* Check to see if the bank is now full */
 179                 if (!(Endpoint_IsReadWriteAllowed()))
 180                 {
 181                         /* Send the full packet to the host */
 182                         Endpoint_ClearIN();
 183                 }
 184         }
 185 }