Demos/Device/LowLevel/AudioOutput/AudioOutput.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 AudioOutput demo. This file contains the main tasks of the demo and
  34  *  is responsible for the initial application hardware configuration.
  35  */
  36
  37 #include "AudioOutput.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         USB_Init();
  72 }
  73
  74 /** Event handler for the USB_Connect event. This indicates that the device is enumerating via the status LEDs, and
  75  *  configures the sample update and PWM timers.
  76  */
  77 void EVENT_USB_Device_Connect(void)
  78 {
  79         /* Indicate USB enumerating */
  80         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
  81
  82         /* Sample reload timer initialization */
  83         OCR0A   = (F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1;
  84         TCCR0A  = (1 << WGM01);  // CTC mode
  85         TCCR0B  = (1 << CS01);   // Fcpu/8 speed
  86
  87 #if defined(AUDIO_OUT_MONO)
  88         /* Set speaker as output */
  89         DDRC   |= (1 << 6);
  90 #elif defined(AUDIO_OUT_STEREO)
  91         /* Set speakers as outputs */
  92         DDRC   |= ((1 << 6) | (1 << 5));
  93 #elif defined(AUDIO_OUT_PORTC)
  94         /* Set PORTC as outputs */
  95         DDRC   |= 0xFF;
  96 #endif
  97
  98 #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
  99         /* PWM speaker timer initialization */
 100         TCCR3A  = ((1 << WGM30) | (1 << COM3A1) | (1 << COM3A0)
 101                                 | (1 << COM3B1) | (1 << COM3B0)); // Set on match, clear on TOP
 102         TCCR3B  = ((1 << WGM32) | (1 << CS30));  // Fast 8-Bit PWM, F_CPU speed
 103 #endif
 104 }
 105
 106 /** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
 107  *  the status LEDs, disables the sample update and PWM output timers and stops the USB and Audio management tasks.
 108  */
 109 void EVENT_USB_Device_Disconnect(void)
 110 {
 111         /* Stop the timers */
 112         TCCR0B = 0;
 113 #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 114         TCCR3B = 0;
 115 #endif
 116
 117 #if defined(AUDIO_OUT_MONO)
 118         /* Set speaker as input to reduce current draw */
 119         DDRC   &= ~(1 << 6);
 120 #elif defined(AUDIO_OUT_STEREO)
 121         /* Set speakers as inputs to reduce current draw */
 122         DDRC   &= ~((1 << 6) | (1 << 5));
 123 #elif defined(AUDIO_OUT_PORTC)
 124         /* Set PORTC low */
 125         PORTC  = 0x00;
 126 #endif
 127
 128         /* Indicate streaming audio interface not selected */
 129         StreamingAudioInterfaceSelected = false;
 130
 131         /* Indicate USB not ready */
 132         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 133 }
 134
 135 /** Event handler for the USB_ConfigurationChanged event. This is fired when the host set the current configuration
 136  *  of the USB device after enumeration - the device endpoints are configured.
 137  */
 138 void EVENT_USB_Device_ConfigurationChanged(void)
 139 {
 140         bool ConfigSuccess = true;
 141
 142         /* Setup Audio Stream Endpoint */
 143         ConfigSuccess &= Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPNUM, EP_TYPE_ISOCHRONOUS, ENDPOINT_DIR_OUT,
 144                                                     AUDIO_STREAM_EPSIZE, ENDPOINT_BANK_DOUBLE);
 145
 146         /* Indicate endpoint configuration success or failure */
 147         LEDs_SetAllLEDs(ConfigSuccess ? LEDMASK_USB_READY : LEDMASK_USB_ERROR);
 148 }
 149
 150 /** Event handler for the USB_UnhandledControlRequest event. This is used to catch standard and class specific
 151  *  control requests that are not handled internally by the USB library (including the Audio class-specific
 152  *  requests) so that they can be handled appropriately for the application.
 153  */
 154 void EVENT_USB_Device_UnhandledControlRequest(void)
 155 {
 156         /* Process General and Audio specific control requests */
 157         switch (USB_ControlRequest.bRequest)
 158         {
 159                 case REQ_SetInterface:
 160                         /* Set Interface is not handled by the library, as its function is application-specific */
 161                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE))
 162                         {
 163                                 Endpoint_ClearSETUP();
 164                                 Endpoint_ClearStatusStage();
 165
 166                                 /* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */
 167                                 StreamingAudioInterfaceSelected = ((USB_ControlRequest.wValue) != 0);
 168                         }
 169
 170                         break;
 171         }
 172 }
 173
 174 /** Task to manage the Audio interface, reading in audio samples from the host, and outputting them to the speakers/LEDs as
 175  *  desired.
 176  */
 177 void USB_Audio_Task(void)
 178 {
 179         /* Device must be connected and configured for the task to run */
 180         if (USB_DeviceState != DEVICE_STATE_Configured)
 181           return;
 182
 183         /* Check to see if the streaming interface is selected, if not the host is not receiving audio */
 184         if (!(StreamingAudioInterfaceSelected))
 185           return;
 186
 187         /* Select the audio stream endpoint */
 188         Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 189
 190         /* Check if the current endpoint can be read from (contains a packet) and that the next sample should be read */
 191         if (Endpoint_IsOUTReceived() && (TIFR0 & (1 << OCF0A)))
 192         {
 193                 /* Clear the sample reload timer */
 194                 TIFR0 |= (1 << OCF0A);
 195
 196                 /* Retrieve the signed 16-bit left and right audio samples, convert to 8-bit */
 197                 int8_t  LeftSample_8Bit   = ((int16_t)Endpoint_Read_Word_LE() >> 8);
 198                 int8_t  RightSample_8Bit  = ((int16_t)Endpoint_Read_Word_LE() >> 8);
 199
 200                 /* Mix the two channels together to produce a mono, 8-bit sample */
 201                 int8_t  MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 202
 203                 /* Check to see if the bank is now empty */
 204                 if (!(Endpoint_IsReadWriteAllowed()))
 205                 {
 206                         /* Acknowledge the packet, clear the bank ready for the next packet */
 207                         Endpoint_ClearOUT();
 208                 }
 209
 210 #if defined(AUDIO_OUT_MONO)
 211                 /* Load the sample into the PWM timer channel */
 212                 OCR3A = (MixedSample_8Bit ^ (1 << 7));
 213 #elif defined(AUDIO_OUT_STEREO)
 214                 /* Load the dual 8-bit samples into the PWM timer channels */
 215                 OCR3A = (LeftSample_8Bit  ^ (1 << 7));
 216                 OCR3B = (RightSample_8Bit ^ (1 << 7));
 217 #elif defined(AUDIO_OUT_PORTC)
 218                 /* Load the 8-bit mixed sample into PORTC */
 219                 PORTC = MixedSample_8Bit;
 220 #endif
 221
 222                 uint8_t LEDMask = LEDS_NO_LEDS;
 223
 224                 /* Turn on LEDs as the sample amplitude increases */
 225                 if (MixedSample_8Bit > 16)
 226                   LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3 | LEDS_LED4);
 227                 else if (MixedSample_8Bit > 8)
 228                   LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3);
 229                 else if (MixedSample_8Bit > 4)
 230                   LEDMask = (LEDS_LED1 | LEDS_LED2);
 231                 else if (MixedSample_8Bit > 2)
 232                   LEDMask = (LEDS_LED1);
 233
 234                 LEDs_SetAllLEDs(LEDMask);
 235         }
 236 }
 237