Demos/Device/LowLevel/AudioOutput/AudioOutput.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 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 static bool StreamingAudioInterfaceSelected = false;
  41
  42 /** Current audio sampling frequency of the streaming audio endpoint. */
  43 static uint32_t CurrentAudioSampleFrequency = 48000;
  44
  45
  46 /** Main program entry point. This routine contains the overall program flow, including initial
  47  *  setup of all components and the main program loop.
  48  */
  49 int main(void)
  50 {
  51         SetupHardware();
  52
  53         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
  54         sei();
  55
  56         for (;;)
  57         {
  58                 USB_USBTask();
  59         }
  60 }
  61
  62 /** Configures the board hardware and chip peripherals for the demo's functionality. */
  63 void SetupHardware(void)
  64 {
  65         /* Disable watchdog if enabled by bootloader/fuses */
  66         MCUSR &= ~(1 << WDRF);
  67         wdt_disable();
  68
  69         /* Disable clock division */
  70         clock_prescale_set(clock_div_1);
  71
  72         /* Hardware Initialization */
  73         LEDs_Init();
  74         USB_Init();
  75 }
  76
  77 /** Event handler for the USB_Connect event. This indicates that the device is enumerating via the status LEDs, and
  78  *  configures the sample update and PWM timers.
  79  */
  80 void EVENT_USB_Device_Connect(void)
  81 {
  82         /* Indicate USB enumerating */
  83         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
  84
  85         /* Sample reload timer initialization */
  86         TIMSK0 = (1 << OCIE0A);
  87         OCR0A  = ((F_CPU / 8 / CurrentAudioSampleFrequency) - 1);
  88         TCCR0A = (1 << WGM01);  // CTC mode
  89         TCCR0B = (1 << CS01);   // Fcpu/8 speed
  90
  91         #if defined(AUDIO_OUT_MONO)
  92         /* Set speaker as output */
  93         DDRC  |= (1 << 6);
  94         #elif defined(AUDIO_OUT_STEREO)
  95         /* Set speakers as outputs */
  96         DDRC  |= ((1 << 6) | (1 << 5));
  97         #elif defined(AUDIO_OUT_PORTC)
  98         /* Set PORTC as outputs */
  99         DDRC  |= 0xFF;
 100         #endif
 101
 102         #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 103         /* PWM speaker timer initialization */
 104         TCCR3A = ((1 << WGM30) | (1 << COM3A1) | (1 << COM3A0)
 105                                | (1 << COM3B1) | (1 << COM3B0)); // Set on match, clear on TOP
 106         TCCR3B = ((1 << WGM32) | (1 << CS30));  // Fast 8-Bit PWM, F_CPU speed
 107         #endif
 108 }
 109
 110 /** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
 111  *  the status LEDs, disables the sample update and PWM output timers and stops the USB and Audio management tasks.
 112  */
 113 void EVENT_USB_Device_Disconnect(void)
 114 {
 115         /* Stop the timers */
 116         TCCR0B = 0;
 117         #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 118         TCCR3B = 0;
 119         #endif
 120
 121         #if defined(AUDIO_OUT_MONO)
 122         /* Set speaker as input to reduce current draw */
 123         DDRC  &= ~(1 << 6);
 124         #elif defined(AUDIO_OUT_STEREO)
 125         /* Set speakers as inputs to reduce current draw */
 126         DDRC  &= ~((1 << 6) | (1 << 5));
 127         #elif defined(AUDIO_OUT_PORTC)
 128         /* Set PORTC low */
 129         PORTC = 0x00;
 130         #endif
 131
 132         /* Indicate streaming audio interface not selected */
 133         StreamingAudioInterfaceSelected = false;
 134
 135         /* Indicate USB not ready */
 136         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 137 }
 138
 139 /** Event handler for the USB_ConfigurationChanged event. This is fired when the host set the current configuration
 140  *  of the USB device after enumeration - the device endpoints are configured.
 141  */
 142 void EVENT_USB_Device_ConfigurationChanged(void)
 143 {
 144         bool ConfigSuccess = true;
 145
 146         /* Setup Audio Stream Endpoint */
 147         ConfigSuccess &= Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPNUM, EP_TYPE_ISOCHRONOUS, ENDPOINT_DIR_OUT,
 148                                                     AUDIO_STREAM_EPSIZE, ENDPOINT_BANK_DOUBLE);
 149
 150         /* Indicate endpoint configuration success or failure */
 151         LEDs_SetAllLEDs(ConfigSuccess ? LEDMASK_USB_READY : LEDMASK_USB_ERROR);
 152 }
 153
 154 /** Event handler for the USB_ControlRequest event. This is used to catch and process control requests sent to
 155  *  the device from the USB host before passing along unhandled control requests to the library for processing
 156  *  internally.
 157  */
 158 void EVENT_USB_Device_ControlRequest(void)
 159 {
 160         /* Process General and Audio specific control requests */
 161         switch (USB_ControlRequest.bRequest)
 162         {
 163                 case REQ_SetInterface:
 164                         /* Set Interface is not handled by the library, as its function is application-specific */
 165                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE))
 166                         {
 167                                 Endpoint_ClearSETUP();
 168                                 Endpoint_ClearStatusStage();
 169
 170                                 /* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */
 171                                 StreamingAudioInterfaceSelected = ((USB_ControlRequest.wValue) != 0);
 172                         }
 173
 174                         break;
 175                 case AUDIO_REQ_GetStatus:
 176                         /* Get Status request can be directed at either the interface or endpoint, neither is currently used
 177                          * according to the latest USB Audio 1.0 standard, but must be ACKed with no data when requested */
 178                         if ((USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_INTERFACE)) ||
 179                             (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT)))
 180                         {
 181                                 Endpoint_ClearSETUP();
 182                                 Endpoint_ClearStatusStage();
 183                         }
 184
 185                         break;
 186                 case AUDIO_REQ_SetCurrent:
 187                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT))
 188                         {
 189                                 /* Extract out the relevant request information to get the target Endpoint address and control being set */
 190                                 uint8_t EndpointAddress = (uint8_t)USB_ControlRequest.wIndex;
 191                                 uint8_t EndpointControl = (USB_ControlRequest.wValue >> 8);
 192
 193                                 /* Only handle SET CURRENT requests to the audio endpoint's sample frequency property */
 194                                 if ((EndpointAddress == (ENDPOINT_DIR_OUT | AUDIO_STREAM_EPNUM)) && (EndpointControl == AUDIO_EPCONTROL_SamplingFreq))
 195                                 {
 196                                         uint8_t SampleRate[3];
 197
 198                                         Endpoint_ClearSETUP();
 199                                         Endpoint_Read_Control_Stream_LE(SampleRate, sizeof(SampleRate));
 200                                         Endpoint_ClearOUT();
 201
 202                                         /* Set the new sampling frequency to the value given by the host */
 203                                         CurrentAudioSampleFrequency = (((uint32_t)SampleRate[2] << 16) | ((uint32_t)SampleRate[1] << 8) | (uint32_t)SampleRate[0]);
 204
 205                                         /* Adjust sample reload timer to the new frequency */
 206                                         OCR0A = ((F_CPU / 8 / CurrentAudioSampleFrequency) - 1);
 207                                 }
 208                         }
 209
 210                         break;
 211                 case AUDIO_REQ_GetCurrent:
 212                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT))
 213                         {
 214                                 /* Extract out the relevant request information to get the target Endpoint address and control being retrieved */
 215                                 uint8_t EndpointAddress = (uint8_t)USB_ControlRequest.wIndex;
 216                                 uint8_t EndpointControl = (USB_ControlRequest.wValue >> 8);
 217
 218                                 /* Only handle GET CURRENT requests to the audio endpoint's sample frequency property */
 219                                 if ((EndpointAddress == (ENDPOINT_DIR_OUT | AUDIO_STREAM_EPNUM)) && (EndpointControl == AUDIO_EPCONTROL_SamplingFreq))
 220                                 {
 221                                         uint8_t SampleRate[3];
 222
 223                                         /* Convert the sampling rate value into the 24-bit format the host expects for the property */
 224                                         SampleRate[2] = (CurrentAudioSampleFrequency >> 16);
 225                                         SampleRate[1] = (CurrentAudioSampleFrequency >> 8);
 226                                         SampleRate[0] = (CurrentAudioSampleFrequency &  0xFF);
 227
 228                                         Endpoint_ClearSETUP();
 229                                         Endpoint_Write_Control_Stream_LE(SampleRate, sizeof(SampleRate));
 230                                         Endpoint_ClearOUT();
 231                                 }
 232                         }
 233
 234                         break;
 235         }
 236 }
 237
 238 /** ISR to handle the reloading of the PWM timer with the next sample. */
 239 ISR(TIMER0_COMPA_vect, ISR_BLOCK)
 240 {
 241         uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
 242
 243         /* Select the audio stream endpoint */
 244         Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 245
 246         /* Check if the current endpoint can be read from (contains a packet) and the host is sending data */
 247         if (Endpoint_IsOUTReceived() && StreamingAudioInterfaceSelected)
 248         {
 249                 /* Retrieve the signed 16-bit left and right audio samples, convert to 8-bit */
 250                 int8_t LeftSample_8Bit   = ((int16_t)Endpoint_Read_16_LE() >> 8);
 251                 int8_t RightSample_8Bit  = ((int16_t)Endpoint_Read_16_LE() >> 8);
 252
 253                 /* Mix the two channels together to produce a mono, 8-bit sample */
 254                 int8_t MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 255
 256                 /* Check to see if the bank is now empty */
 257                 if (!(Endpoint_IsReadWriteAllowed()))
 258                 {
 259                         /* Acknowledge the packet, clear the bank ready for the next packet */
 260                         Endpoint_ClearOUT();
 261                 }
 262
 263                 #if defined(AUDIO_OUT_MONO)
 264                 /* Load the sample into the PWM timer channel */
 265                 OCR3A = (MixedSample_8Bit ^ (1 << 7));
 266                 #elif defined(AUDIO_OUT_STEREO)
 267                 /* Load the dual 8-bit samples into the PWM timer channels */
 268                 OCR3A = (LeftSample_8Bit  ^ (1 << 7));
 269                 OCR3B = (RightSample_8Bit ^ (1 << 7));
 270                 #elif defined(AUDIO_OUT_PORTC)
 271                 /* Load the 8-bit mixed sample into PORTC */
 272                 PORTC = MixedSample_8Bit;
 273                 #endif
 274
 275                 uint8_t LEDMask = LEDS_NO_LEDS;
 276
 277                 /* Turn on LEDs as the sample amplitude increases */
 278                 if (MixedSample_8Bit > 16)
 279                   LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3 | LEDS_LED4);
 280                 else if (MixedSample_8Bit > 8)
 281                   LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3);
 282                 else if (MixedSample_8Bit > 4)
 283                   LEDMask = (LEDS_LED1 | LEDS_LED2);
 284                 else if (MixedSample_8Bit > 2)
 285                   LEDMask = (LEDS_LED1);
 286
 287                 LEDs_SetAllLEDs(LEDMask);
 288         }
 289
 290         Endpoint_SelectEndpoint(PrevEndpoint);
 291 }
 292