Demos/Device/LowLevel/AudioInput/AudioInput.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2011.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6            www.lufa-lib.org
   7 */
   8
   9 /*
  10   Copyright 2011  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 static bool StreamingAudioInterfaceSelected = false;
  41
  42
  43 /** Main program entry point. This routine contains the overall program flow, including initial
  44  *  setup of all components and the main program loop.
  45  */
  46 int main(void)
  47 {
  48         SetupHardware();
  49
  50         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
  51         sei();
  52
  53         for (;;)
  54         {
  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         Buttons_Init();
  72         ADC_Init(ADC_FREE_RUNNING | ADC_PRESCALE_32);
  73         ADC_SetupChannel(MIC_IN_ADC_CHANNEL);
  74         USB_Init();
  75
  76         /* Start the ADC conversion in free running mode */
  77         ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | MIC_IN_ADC_MUX_MASK);
  78 }
  79
  80 /** Event handler for the USB_Connect event. This indicates that the device is enumerating via the status LEDs, and
  81  *  configures the sample update and PWM timers.
  82  */
  83 void EVENT_USB_Device_Connect(void)
  84 {
  85         /* Indicate USB enumerating */
  86         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
  87
  88         /* Sample reload timer initialization */
  89         TIMSK0  = (1 << OCIE0A);
  90         OCR0A   = ((F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1);
  91         TCCR0A  = (1 << WGM01);  // CTC mode
  92         TCCR0B  = (1 << CS01);   // Fcpu/8 speed
  93 }
  94
  95 /** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
  96  *  the status LEDs, disables the sample update and PWM output timers and stops the USB and Audio management tasks.
  97  */
  98 void EVENT_USB_Device_Disconnect(void)
  99 {
 100         /* Stop the sample reload timer */
 101         TCCR0B = 0;
 102
 103         /* Indicate streaming audio interface not selected */
 104         StreamingAudioInterfaceSelected = false;
 105
 106         /* Indicate USB not ready */
 107         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 108 }
 109
 110 /** Event handler for the USB_ConfigurationChanged event. This is fired when the host set the current configuration
 111  *  of the USB device after enumeration - the device endpoints are configured.
 112  */
 113 void EVENT_USB_Device_ConfigurationChanged(void)
 114 {
 115         bool ConfigSuccess = true;
 116
 117         /* Setup Audio Stream Endpoint */
 118         ConfigSuccess &= Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPNUM, EP_TYPE_ISOCHRONOUS, ENDPOINT_DIR_IN,
 119                                                     AUDIO_STREAM_EPSIZE, ENDPOINT_BANK_DOUBLE);
 120
 121         /* Indicate endpoint configuration success or failure */
 122         LEDs_SetAllLEDs(ConfigSuccess ? LEDMASK_USB_READY : LEDMASK_USB_ERROR);
 123 }
 124
 125 /** Event handler for the USB_ControlRequest event. This is used to catch and process control requests sent to
 126  *  the device from the USB host before passing along unhandled control requests to the library for processing
 127  *  internally.
 128  */
 129 void EVENT_USB_Device_ControlRequest(void)
 130 {
 131         /* Process General and Audio specific control requests */
 132         switch (USB_ControlRequest.bRequest)
 133         {
 134                 case REQ_SetInterface:
 135                         /* Set Interface is not handled by the library, as its function is application-specific */
 136                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE))
 137                         {
 138                                 Endpoint_ClearSETUP();
 139                                 Endpoint_ClearStatusStage();
 140
 141                                 /* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */
 142                                 StreamingAudioInterfaceSelected = ((USB_ControlRequest.wValue) != 0);
 143                         }
 144
 145                         break;
 146         }
 147 }
 148
 149 /** ISR to handle the reloading of the data endpoint with the next sample. */
 150 ISR(TIMER0_COMPA_vect, ISR_BLOCK)
 151 {
 152         uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
 153
 154         /* Select the audio stream endpoint */
 155         Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 156
 157         /* Check if the current endpoint can be written to and that the audio interface is enabled */
 158         if (Endpoint_IsINReady() && StreamingAudioInterfaceSelected)
 159         {
 160                 int16_t AudioSample;
 161
 162                 #if defined(USE_TEST_TONE)
 163                         static uint8_t SquareWaveSampleCount;
 164                         static int16_t CurrentWaveValue;
 165
 166                         /* In test tone mode, generate a square wave at 1/256 of the sample rate */
 167                         if (SquareWaveSampleCount++ == 0xFF)
 168                           CurrentWaveValue ^= 0x8000;
 169
 170                         /* Only generate audio if the board button is being pressed */
 171                         AudioSample = (Buttons_GetStatus() & BUTTONS_BUTTON1) ? CurrentWaveValue : 0;
 172                 #else
 173                         /* Audio sample is ADC value scaled to fit the entire range */
 174                         AudioSample = ((SAMPLE_MAX_RANGE / ADC_MAX_RANGE) * ADC_GetResult());
 175
 176                         #if defined(MICROPHONE_BIASED_TO_HALF_RAIL)
 177                         /* Microphone is biased to half rail voltage, subtract the bias from the sample value */
 178                         AudioSample -= (SAMPLE_MAX_RANGE / 2);
 179                         #endif
 180                 #endif
 181
 182                 /* Write the sample to the buffer */
 183                 Endpoint_Write_Word_LE(AudioSample);
 184
 185                 /* Check to see if the bank is now full */
 186                 if (!(Endpoint_IsReadWriteAllowed()))
 187                 {
 188                         /* Send the full packet to the host */
 189                         Endpoint_ClearIN();
 190                 }
 191         }
 192
 193         Endpoint_SelectEndpoint(PrevEndpoint);
 194 }
 195