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
  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         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         TIMSK0 = (1 << OCIE0A);
  84         OCR0A  = ((F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1);
  85         TCCR0A = (1 << WGM01);  // CTC mode
  86         TCCR0B = (1 << CS01);   // Fcpu/8 speed
  87
  88         #if defined(AUDIO_OUT_MONO)
  89         /* Set speaker as output */
  90         DDRC  |= (1 << 6);
  91         #elif defined(AUDIO_OUT_STEREO)
  92         /* Set speakers as outputs */
  93         DDRC  |= ((1 << 6) | (1 << 5));
  94         #elif defined(AUDIO_OUT_PORTC)
  95         /* Set PORTC as outputs */
  96         DDRC  |= 0xFF;
  97         #endif
  98
  99         #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 100         /* PWM speaker timer initialization */
 101         TCCR3A = ((1 << WGM30) | (1 << COM3A1) | (1 << COM3A0)
 102                                | (1 << COM3B1) | (1 << COM3B0)); // Set on match, clear on TOP
 103         TCCR3B = ((1 << WGM32) | (1 << CS30));  // Fast 8-Bit PWM, F_CPU speed
 104         #endif
 105 }
 106
 107 /** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via
 108  *  the status LEDs, disables the sample update and PWM output timers and stops the USB and Audio management tasks.
 109  */
 110 void EVENT_USB_Device_Disconnect(void)
 111 {
 112         /* Stop the timers */
 113         TCCR0B = 0;
 114         #if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO))
 115         TCCR3B = 0;
 116         #endif
 117
 118         #if defined(AUDIO_OUT_MONO)
 119         /* Set speaker as input to reduce current draw */
 120         DDRC  &= ~(1 << 6);
 121         #elif defined(AUDIO_OUT_STEREO)
 122         /* Set speakers as inputs to reduce current draw */
 123         DDRC  &= ~((1 << 6) | (1 << 5));
 124         #elif defined(AUDIO_OUT_PORTC)
 125         /* Set PORTC low */
 126         PORTC = 0x00;
 127         #endif
 128
 129         /* Indicate streaming audio interface not selected */
 130         StreamingAudioInterfaceSelected = false;
 131
 132         /* Indicate USB not ready */
 133         LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
 134 }
 135
 136 /** Event handler for the USB_ConfigurationChanged event. This is fired when the host set the current configuration
 137  *  of the USB device after enumeration - the device endpoints are configured.
 138  */
 139 void EVENT_USB_Device_ConfigurationChanged(void)
 140 {
 141         bool ConfigSuccess = true;
 142
 143         /* Setup Audio Stream Endpoint */
 144         ConfigSuccess &= Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPNUM, EP_TYPE_ISOCHRONOUS, ENDPOINT_DIR_OUT,
 145                                                     AUDIO_STREAM_EPSIZE, ENDPOINT_BANK_DOUBLE);
 146
 147         /* Indicate endpoint configuration success or failure */
 148         LEDs_SetAllLEDs(ConfigSuccess ? LEDMASK_USB_READY : LEDMASK_USB_ERROR);
 149 }
 150
 151 /** Event handler for the USB_ControlRequest event. This is used to catch and process control requests sent to
 152  *  the device from the USB host before passing along unhandled control requests to the library for processing
 153  *  internally.
 154  */
 155 void EVENT_USB_Device_ControlRequest(void)
 156 {
 157         /* Process General and Audio specific control requests */
 158         switch (USB_ControlRequest.bRequest)
 159         {
 160                 case REQ_SetInterface:
 161                         /* Set Interface is not handled by the library, as its function is application-specific */
 162                         if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE))
 163                         {
 164                                 Endpoint_ClearSETUP();
 165                                 Endpoint_ClearStatusStage();
 166
 167                                 /* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */
 168                                 StreamingAudioInterfaceSelected = ((USB_ControlRequest.wValue) != 0);
 169                         }
 170
 171                         break;
 172         }
 173 }
 174
 175 /** ISR to handle the reloading of the PWM timer with the next sample. */
 176 ISR(TIMER0_COMPA_vect, ISR_BLOCK)
 177 {
 178         uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
 179
 180         /* Select the audio stream endpoint */
 181         Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 182
 183         /* Check if the current endpoint can be read from (contains a packet) and the host is sending data */
 184         if (Endpoint_IsOUTReceived() && StreamingAudioInterfaceSelected)
 185         {
 186                 /* Retrieve the signed 16-bit left and right audio samples, convert to 8-bit */
 187                 int8_t LeftSample_8Bit   = ((int16_t)Endpoint_Read_Word_LE() >> 8);
 188                 int8_t RightSample_8Bit  = ((int16_t)Endpoint_Read_Word_LE() >> 8);
 189
 190                 /* Mix the two channels together to produce a mono, 8-bit sample */
 191                 int8_t MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 192
 193                 /* Check to see if the bank is now empty */
 194                 if (!(Endpoint_IsReadWriteAllowed()))
 195                 {
 196                         /* Acknowledge the packet, clear the bank ready for the next packet */
 197                         Endpoint_ClearOUT();
 198                 }
 199
 200                 #if defined(AUDIO_OUT_MONO)
 201                 /* Load the sample into the PWM timer channel */
 202                 OCR3A = (MixedSample_8Bit ^ (1 << 7));
 203                 #elif defined(AUDIO_OUT_STEREO)
 204                 /* Load the dual 8-bit samples into the PWM timer channels */
 205                 OCR3A = (LeftSample_8Bit  ^ (1 << 7));
 206                 OCR3B = (RightSample_8Bit ^ (1 << 7));
 207                 #elif defined(AUDIO_OUT_PORTC)
 208                 /* Load the 8-bit mixed sample into PORTC */
 209                 PORTC = MixedSample_8Bit;
 210                 #endif
 211
 212                 uint8_t LEDMask = LEDS_NO_LEDS;
 213
 214                 /* Turn on LEDs as the sample amplitude increases */
 215                 if (MixedSample_8Bit > 16)
 216                   LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3 | LEDS_LED4);
 217                 else if (MixedSample_8Bit > 8)
 218                   LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3);
 219                 else if (MixedSample_8Bit > 4)
 220                   LEDMask = (LEDS_LED1 | LEDS_LED2);
 221                 else if (MixedSample_8Bit > 2)
 222                   LEDMask = (LEDS_LED1);
 223
 224                 LEDs_SetAllLEDs(LEDMask);
 225         }
 226
 227         Endpoint_SelectEndpoint(PrevEndpoint);
 228 }
 229