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.fourwalledcubicle.com
   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_Audio_Task();
  55                 USB_USBTask();
  56         }
  57 }
  58
  59 /** Configures the board hardware and chip peripherals for the demo's functionality. */
  60 void SetupHardware(void)
  61 {
  62         /* Disable watchdog if enabled by bootloader/fuses */
  63         MCUSR &= ~(1 << WDRF);
  64         wdt_disable();
  65
  66         /* Disable clock division */
  67         clock_prescale_set(clock_div_1);
  68
  69         /* Hardware Initialization */
  70         LEDs_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         OCR0A   = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1;
  89         TCCR0A  = (1 << WGM01);  // CTC mode
  90         TCCR0B  = (1 << CS01);   // Fcpu/8 speed
  91 }
  92
  93 /** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
  94  *  the status LEDs, disables the sample update and PWM output timers and stops the USB and Audio management tasks.
  95  */
  96 void EVENT_USB_Device_Disconnect(void)
  97 {
  98         /* Stop the sample reload timer */
  99         TCCR0B = 0;
 100
 101         /* Indicate streaming audio interface not selected */
 102         StreamingAudioInterfaceSelected = false;
 103
 104         /* Indicate USB not ready */
 105         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 106 }
 107
 108 /** Event handler for the USB_ConfigurationChanged event. This is fired when the host set the current configuration
 109  *  of the USB device after enumeration - the device endpoints are configured.
 110  */
 111 void EVENT_USB_Device_ConfigurationChanged(void)
 112 {
 113         bool ConfigSuccess = true;
 114
 115         /* Setup Audio Stream Endpoint */
 116         ConfigSuccess &= Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPNUM, EP_TYPE_ISOCHRONOUS, ENDPOINT_DIR_IN,
 117                                                     AUDIO_STREAM_EPSIZE, ENDPOINT_BANK_DOUBLE);
 118
 119         /* Indicate endpoint configuration success or failure */
 120         LEDs_SetAllLEDs(ConfigSuccess ? LEDMASK_USB_READY : LEDMASK_USB_ERROR);
 121 }
 122
 123 /** Event handler for the USB_UnhandledControlRequest event. This is used to catch standard and class specific
 124  *  control requests that are not handled internally by the USB library (including the Audio class-specific
 125  *  requests) so that they can be handled appropriately for the application.
 126  */
 127 void EVENT_USB_Device_UnhandledControlRequest(void)
 128 {
 129         /* Process General and Audio specific control requests */
 130         switch (USB_ControlRequest.bRequest)
 131         {
 132                 case REQ_SetInterface:
 133                         /* Set Interface is not handled by the library, as its function is application-specific */
 134                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE))
 135                         {
 136                                 Endpoint_ClearSETUP();
 137
 138                                 /* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */
 139                                 StreamingAudioInterfaceSelected = ((USB_ControlRequest.wValue) != 0);
 140
 141                                 Endpoint_ClearStatusStage();
 142                         }
 143
 144                         break;
 145         }
 146 }
 147
 148 /** Task to manage the Audio interface, reading in ADC samples from the microphone, and them to the host. */
 149 void USB_Audio_Task(void)
 150 {
 151         /* Device must be connected and configured for the task to run */
 152         if (USB_DeviceState != DEVICE_STATE_Configured)
 153           return;
 154
 155         /* Check to see if the streaming interface is selected, if not the host is not receiving audio */
 156         if (!(StreamingAudioInterfaceSelected))
 157           return;
 158
 159         /* Select the audio stream endpoint */
 160         Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 161
 162         /* Check if the current endpoint can be written to and that the next sample should be stored */
 163         if (Endpoint_IsINReady() && (TIFR0 & (1 << OCF0A)))
 164         {
 165                 /* Clear the sample reload timer */
 166                 TIFR0 |= (1 << OCF0A);
 167
 168                 /* Audio sample is ADC value scaled to fit the entire range */
 169                 int16_t AudioSample = ((SAMPLE_MAX_RANGE / ADC_MAX_RANGE) * ADC_GetResult());
 170
 171                 #if defined(MICROPHONE_BIASED_TO_HALF_RAIL)
 172                 /* Microphone is biased to half rail voltage, subtract the bias from the sample value */
 173                 AudioSample -= (SAMPLE_MAX_RANGE / 2);
 174                 #endif
 175
 176                 /* Write the sample to the buffer */
 177                 Endpoint_Write_Word_LE(AudioSample);
 178
 179                 /* Check to see if the bank is now full */
 180                 if (!(Endpoint_IsReadWriteAllowed()))
 181                 {
 182                         /* Send the full packet to the host */
 183                         Endpoint_ClearIN();
 184                 }
 185         }
 186 }