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 /* Scheduler Task List */
  40 TASK_LIST
  41 {
  42         { .Task = USB_USBTask          , .TaskStatus = TASK_STOP },
  43         { .Task = USB_Audio_Task       , .TaskStatus = TASK_STOP },
  44 };
  45
  46
  47 /** Main program entry point. This routine configures the hardware required by the application, then
  48  *  starts the scheduler to run the application tasks.
  49  */
  50 int main(void)
  51 {
  52         /* Disable watchdog if enabled by bootloader/fuses */
  53         MCUSR &= ~(1 << WDRF);
  54         wdt_disable();
  55
  56         /* Disable clock division */
  57         clock_prescale_set(clock_div_1);
  58
  59         /* Hardware Initialization */
  60         LEDs_Init();
  61         ADC_Init(ADC_FREE_RUNNING | ADC_PRESCALE_32);
  62         ADC_SetupChannel(MIC_IN_ADC_CHANNEL);
  63
  64         /* Start the ADC conversion in free running mode */
  65         ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | MIC_IN_ADC_CHANNEL);
  66
  67         /* Indicate USB not ready */
  68         UpdateStatus(Status_USBNotReady);
  69
  70         /* Initialize Scheduler so that it can be used */
  71         Scheduler_Init();
  72
  73         /* Initialize USB Subsystem */
  74         USB_Init();
  75
  76         /* Scheduling - routine never returns, so put this last in the main function */
  77         Scheduler_Start();
  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_Connect(void)
  84 {
  85         /* Start USB management task */
  86         Scheduler_SetTaskMode(USB_USBTask, TASK_RUN);
  87
  88         /* Indicate USB enumerating */
  89         UpdateStatus(Status_USBEnumerating);
  90
  91         /* Sample reload timer initialization */
  92         OCR0A   = (F_CPU / AUDIO_SAMPLE_FREQUENCY) - 1;
  93         TCCR0A  = (1 << WGM01);  // CTC mode
  94         TCCR0B  = (1 << CS00);   // Fcpu speed
  95 }
  96
  97 /** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
  98  *  the status LEDs, disables the sample update and PWM output timers and stops the USB and Audio management tasks.
  99  */
 100 void EVENT_USB_Disconnect(void)
 101 {
 102         /* Stop the sample reload timer */
 103         TCCR0B = 0;
 104
 105         /* Stop running audio and USB management tasks */
 106         Scheduler_SetTaskMode(USB_Audio_Task, TASK_STOP);
 107         Scheduler_SetTaskMode(USB_USBTask, TASK_STOP);
 108
 109         /* Indicate USB not ready */
 110         UpdateStatus(Status_USBNotReady);
 111 }
 112
 113 /** Event handler for the USB_ConfigurationChanged event. This is fired when the host set the current configuration
 114  *  of the USB device after enumeration - the device endpoints are configured.
 115  */
 116 void EVENT_USB_ConfigurationChanged(void)
 117 {
 118         /* Setup audio stream endpoint */
 119         Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPNUM, EP_TYPE_ISOCHRONOUS,
 120                                        ENDPOINT_DIR_IN, AUDIO_STREAM_EPSIZE,
 121                                    ENDPOINT_BANK_DOUBLE);
 122
 123         /* Indicate USB connected and ready */
 124         UpdateStatus(Status_USBReady);
 125 }
 126
 127 /** Event handler for the USB_UnhandledControlPacket event. This is used to catch standard and class specific
 128  *  control requests that are not handled internally by the USB library (including the Audio class-specific
 129  *  requests) so that they can be handled appropriately for the application.
 130  */
 131 void EVENT_USB_UnhandledControlPacket(void)
 132 {
 133         /* Process General and Audio specific control requests */
 134         switch (USB_ControlRequest.bRequest)
 135         {
 136                 case REQ_SetInterface:
 137                         /* Set Interface is not handled by the library, as its function is application-specific */
 138                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE))
 139                         {
 140                                 Endpoint_ClearSETUP();
 141
 142                                 /* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */
 143                                 if (USB_ControlRequest.wValue)
 144                                 {
 145                                         /* Start audio task */
 146                                         Scheduler_SetTaskMode(USB_Audio_Task, TASK_RUN);
 147                                 }
 148                                 else
 149                                 {
 150                                         /* Stop audio task */
 151                                         Scheduler_SetTaskMode(USB_Audio_Task, TASK_STOP);
 152                                 }
 153
 154                                 /* Acknowledge status stage */
 155                                 while (!(Endpoint_IsINReady()));
 156                                 Endpoint_ClearIN();
 157                         }
 158
 159                         break;
 160         }
 161 }
 162
 163 /** Function to manage status updates to the user. This is done via LEDs on the given board, if available, but may be changed to
 164  *  log to a serial port, or anything else that is suitable for status updates.
 165  *
 166  *  \param CurrentStatus  Current status of the system, from the AudioInput_StatusCodes_t enum
 167  */
 168 void UpdateStatus(uint8_t CurrentStatus)
 169 {
 170         uint8_t LEDMask = LEDS_NO_LEDS;
 171
 172         /* Set the LED mask to the appropriate LED mask based on the given status code */
 173         switch (CurrentStatus)
 174         {
 175                 case Status_USBNotReady:
 176                         LEDMask = (LEDS_LED1);
 177                         break;
 178                 case Status_USBEnumerating:
 179                         LEDMask = (LEDS_LED1 | LEDS_LED2);
 180                         break;
 181                 case Status_USBReady:
 182                         LEDMask = (LEDS_LED2 | LEDS_LED4);
 183                         break;
 184         }
 185
 186         /* Set the board LEDs to the new LED mask */
 187         LEDs_SetAllLEDs(LEDMask);
 188 }
 189
 190 /** Task to manage the Audio interface, reading in ADC samples from the microphone, and them to the host. */
 191 TASK(USB_Audio_Task)
 192 {
 193         /* Select the audio stream endpoint */
 194         Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 195
 196         /* Check if the current endpoint can be written to and that the next sample should be stored */
 197         if (Endpoint_IsINReady() && (TIFR0 & (1 << OCF0A)))
 198         {
 199                 /* Clear the sample reload timer */
 200                 TIFR0 |= (1 << OCF0A);
 201
 202                 /* Audio sample is ADC value scaled to fit the entire range */
 203                 int16_t AudioSample = ((SAMPLE_MAX_RANGE / ADC_MAX_RANGE) * ADC_GetResult());
 204
 205 #if defined(MICROPHONE_BIASED_TO_HALF_RAIL)
 206                 /* Microphone is biased to half rail voltage, subtract the bias from the sample value */
 207                 AudioSample -= (SAMPLE_MAX_RANGE / 2));
 208 #endif
 209
 210                 /* Write the sample to the buffer */
 211                 Endpoint_Write_Word_LE(AudioSample);
 212
 213                 /* Check to see if the bank is now full */
 214                 if (!(Endpoint_IsReadWriteAllowed()))
 215                 {
 216                         /* Send the full packet to the host */
 217                         Endpoint_ClearIN();
 218                 }
 219         }
 220 }