Demos/Device/LowLevel/AudioOutput/AudioOutput.c

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2020.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6            www.lufa-lib.org
   7 */
   8
   9 /*
  10   Copyright 2020  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 disclaims 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         GlobalInterruptEnable();
  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 #if (ARCH == ARCH_AVR8)
  66         /* Disable watchdog if enabled by bootloader/fuses */
  67         MCUSR &= ~(1 << WDRF);
  68         wdt_disable();
  69
  70         /* Disable clock division */
  71         clock_prescale_set(clock_div_1);
  72 #endif
  73
  74         /* Hardware Initialization */
  75         LEDs_Init();
  76         USB_Init();
  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         TIMSK0 = (1 << OCIE0A);
  89         OCR0A  = ((F_CPU / 8 / CurrentAudioSampleFrequency) - 1);
  90         TCCR0A = (1 << WGM01);  // CTC mode
  91         TCCR0B = (1 << CS01);   // Fcpu/8 speed
  92
  93         #if defined(AUDIO_OUT_MONO)
  94         /* Set speaker as output */
  95         DDRC  |= (1 << 6);
  96         #elif defined(AUDIO_OUT_STEREO)
  97         /* Set speakers as outputs */
  98         DDRC  |= ((1 << 6) | (1 << 5));
  99         #elif defined(AUDIO_OUT_PORTC)
 100         /* Set PORTC as outputs */
 101         DDRC  |= 0xFF;
 102         #endif
 103
 104         #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 105         /* PWM speaker timer initialization */
 106         TCCR3A = ((1 << WGM30) | (1 << COM3A1) | (1 << COM3A0)
 107                                | (1 << COM3B1) | (1 << COM3B0)); // Set on match, clear on TOP
 108         TCCR3B = ((1 << WGM32) | (1 << CS30));  // Fast 8-Bit PWM, F_CPU speed
 109         #endif
 110 }
 111
 112 /** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
 113  *  the status LEDs, disables the sample update and PWM output timers and stops the USB and Audio management tasks.
 114  */
 115 void EVENT_USB_Device_Disconnect(void)
 116 {
 117         /* Stop the timers */
 118         TCCR0B = 0;
 119         #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 120         TCCR3B = 0;
 121         #endif
 122
 123         #if defined(AUDIO_OUT_MONO)
 124         /* Set speaker as input to reduce current draw */
 125         DDRC  &= ~(1 << 6);
 126         #elif defined(AUDIO_OUT_STEREO)
 127         /* Set speakers as inputs to reduce current draw */
 128         DDRC  &= ~((1 << 6) | (1 << 5));
 129         #elif defined(AUDIO_OUT_PORTC)
 130         /* Set PORTC low */
 131         PORTC = 0x00;
 132         #endif
 133
 134         /* Indicate streaming audio interface not selected */
 135         StreamingAudioInterfaceSelected = false;
 136
 137         /* Indicate USB not ready */
 138         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 139 }
 140
 141 /** Event handler for the USB_ConfigurationChanged event. This is fired when the host set the current configuration
 142  *  of the USB device after enumeration - the device endpoints are configured.
 143  */
 144 void EVENT_USB_Device_ConfigurationChanged(void)
 145 {
 146         bool ConfigSuccess = true;
 147
 148         /* Setup Audio Stream Endpoint */
 149         ConfigSuccess &= Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPADDR, EP_TYPE_ISOCHRONOUS, AUDIO_STREAM_EPSIZE, 2);
 150
 151         /* Indicate endpoint configuration success or failure */
 152         LEDs_SetAllLEDs(ConfigSuccess ? LEDMASK_USB_READY : LEDMASK_USB_ERROR);
 153 }
 154
 155 /** Event handler for the USB_ControlRequest event. This is used to catch and process control requests sent to
 156  *  the device from the USB host before passing along unhandled control requests to the library for processing
 157  *  internally.
 158  */
 159 void EVENT_USB_Device_ControlRequest(void)
 160 {
 161         /* Process General and Audio specific control requests */
 162         switch (USB_ControlRequest.bRequest)
 163         {
 164                 case REQ_SetInterface:
 165                         /* Set Interface is not handled by the library, as its function is application-specific */
 166                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE))
 167                         {
 168                                 Endpoint_ClearSETUP();
 169                                 Endpoint_ClearStatusStage();
 170
 171                                 /* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */
 172                                 StreamingAudioInterfaceSelected = ((USB_ControlRequest.wValue) != 0);
 173                         }
 174
 175                         break;
 176                 case AUDIO_REQ_GetStatus:
 177                         /* Get Status request can be directed at either the interface or endpoint, neither is currently used
 178                          * according to the latest USB Audio 1.0 standard, but must be ACKed with no data when requested */
 179                         if ((USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_INTERFACE)) ||
 180                             (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT)))
 181                         {
 182                                 Endpoint_ClearSETUP();
 183                                 Endpoint_ClearStatusStage();
 184                         }
 185
 186                         break;
 187                 case AUDIO_REQ_SetCurrent:
 188                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT))
 189                         {
 190                                 /* Extract out the relevant request information to get the target Endpoint address and control being set */
 191                                 uint8_t EndpointAddress = (uint8_t)USB_ControlRequest.wIndex;
 192                                 uint8_t EndpointControl = (USB_ControlRequest.wValue >> 8);
 193
 194                                 /* Only handle SET CURRENT requests to the audio endpoint's sample frequency property */
 195                                 if ((EndpointAddress == AUDIO_STREAM_EPADDR) && (EndpointControl == AUDIO_EPCONTROL_SamplingFreq))
 196                                 {
 197                                         uint8_t SampleRate[3];
 198
 199                                         Endpoint_ClearSETUP();
 200                                         Endpoint_Read_Control_Stream_LE(SampleRate, sizeof(SampleRate));
 201                                         Endpoint_ClearIN();
 202
 203                                         /* Set the new sampling frequency to the value given by the host */
 204                                         CurrentAudioSampleFrequency = (((uint32_t)SampleRate[2] << 16) | ((uint32_t)SampleRate[1] << 8) | (uint32_t)SampleRate[0]);
 205
 206                                         /* Adjust sample reload timer to the new frequency */
 207                                         OCR0A = ((F_CPU / 8 / CurrentAudioSampleFrequency) - 1);
 208                                 }
 209                         }
 210
 211                         break;
 212                 case AUDIO_REQ_GetCurrent:
 213                         if (USB_ControlRequest.bmRequestType == (REQDIR_DEVICETOHOST | REQTYPE_CLASS | REQREC_ENDPOINT))
 214                         {
 215                                 /* Extract out the relevant request information to get the target Endpoint address and control being retrieved */
 216                                 uint8_t EndpointAddress = (uint8_t)USB_ControlRequest.wIndex;
 217                                 uint8_t EndpointControl = (USB_ControlRequest.wValue >> 8);
 218
 219                                 /* Only handle GET CURRENT requests to the audio endpoint's sample frequency property */
 220                                 if ((EndpointAddress == AUDIO_STREAM_EPADDR) && (EndpointControl == AUDIO_EPCONTROL_SamplingFreq))
 221                                 {
 222                                         uint8_t SampleRate[3];
 223
 224                                         /* Convert the sampling rate value into the 24-bit format the host expects for the property */
 225                                         SampleRate[2] = (CurrentAudioSampleFrequency >> 16);
 226                                         SampleRate[1] = (CurrentAudioSampleFrequency >> 8);
 227                                         SampleRate[0] = (CurrentAudioSampleFrequency &  0xFF);
 228
 229                                         Endpoint_ClearSETUP();
 230                                         Endpoint_Write_Control_Stream_LE(SampleRate, sizeof(SampleRate));
 231                                         Endpoint_ClearOUT();
 232                                 }
 233                         }
 234
 235                         break;
 236         }
 237 }
 238
 239 /** ISR to handle the reloading of the PWM timer with the next sample. */
 240 ISR(TIMER0_COMPA_vect, ISR_BLOCK)
 241 {
 242         uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
 243
 244         /* Select the audio stream endpoint */
 245         Endpoint_SelectEndpoint(AUDIO_STREAM_EPADDR);
 246
 247         /* Check if the current endpoint can be read from (contains a packet) and the host is sending data */
 248         if (Endpoint_IsOUTReceived() && StreamingAudioInterfaceSelected)
 249         {
 250                 /* Retrieve the signed 16-bit left and right audio samples, convert to 8-bit */
 251                 int8_t LeftSample_8Bit   = ((int16_t)Endpoint_Read_16_LE() >> 8);
 252                 int8_t RightSample_8Bit  = ((int16_t)Endpoint_Read_16_LE() >> 8);
 253
 254                 /* Mix the two channels together to produce a mono, 8-bit sample */
 255                 int8_t MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 256
 257                 /* Check to see if the bank is now empty */
 258                 if (!(Endpoint_IsReadWriteAllowed()))
 259                 {
 260                         /* Acknowledge the packet, clear the bank ready for the next packet */
 261                         Endpoint_ClearOUT();
 262                 }
 263
 264                 #if defined(AUDIO_OUT_MONO)
 265                 /* Load the sample into the PWM timer channel */
 266                 OCR3A = (MixedSample_8Bit ^ (1 << 7));
 267                 #elif defined(AUDIO_OUT_STEREO)
 268                 /* Load the dual 8-bit samples into the PWM timer channels */
 269                 OCR3A = (LeftSample_8Bit  ^ (1 << 7));
 270                 OCR3B = (RightSample_8Bit ^ (1 << 7));
 271                 #elif defined(AUDIO_OUT_PORTC)
 272                 /* Load the 8-bit mixed sample into PORTC */
 273                 PORTC = MixedSample_8Bit;
 274                 #endif
 275
 276                 uint8_t LEDMask = LEDS_NO_LEDS;
 277
 278                 /* Turn on LEDs as the sample amplitude increases */
 279                 if (MixedSample_8Bit > 16)
 280                   LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3 | LEDS_LED4);
 281                 else if (MixedSample_8Bit > 8)
 282                   LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3);
 283                 else if (MixedSample_8Bit > 4)
 284                   LEDMask = (LEDS_LED1 | LEDS_LED2);
 285                 else if (MixedSample_8Bit > 2)
 286                   LEDMask = (LEDS_LED1);
 287
 288                 LEDs_SetAllLEDs(LEDMask);
 289         }
 290
 291         Endpoint_SelectEndpoint(PrevEndpoint);
 292 }
 293