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 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_USBTask();
  55         }
  56 }
  57
  58 /** Configures the board hardware and chip peripherals for the demo's functionality. */
  59 void SetupHardware(void)
  60 {
  61         /* Disable watchdog if enabled by bootloader/fuses */
  62         MCUSR &= ~(1 << WDRF);
  63         wdt_disable();
  64
  65         /* Disable clock division */
  66         clock_prescale_set(clock_div_1);
  67
  68         /* Hardware Initialization */
  69         LEDs_Init();
  70         USB_Init();
  71 }
  72
  73 /** Event handler for the USB_Connect event. This indicates that the device is enumerating via the status LEDs, and
  74  *  configures the sample update and PWM timers.
  75  */
  76 void EVENT_USB_Device_Connect(void)
  77 {
  78         /* Indicate USB enumerating */
  79         LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);
  80
  81         /* Sample reload timer initialization */
  82         TIMSK0 = (1 << OCIE0A);
  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_ControlRequest event. This is used to catch and process control requests sent to
 151  *  the device from the USB host before passing along unhandled control requests to the library for processing
 152  *  internally.
 153  */
 154 void EVENT_USB_Device_ControlRequest(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 /** ISR to handle the reloading of the PWM timer with the next sample. */
 175 ISR(TIMER0_COMPA_vect, ISR_BLOCK)
 176 {
 177         uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();
 178
 179         /* Select the audio stream endpoint */
 180         Endpoint_SelectEndpoint(AUDIO_STREAM_EPNUM);
 181
 182         /* Check if the current endpoint can be read from (contains a packet) and the host is sending data */
 183         if (Endpoint_IsOUTReceived() && StreamingAudioInterfaceSelected)
 184         {
 185                 /* Retrieve the signed 16-bit left and right audio samples, convert to 8-bit */
 186                 int8_t LeftSample_8Bit   = ((int16_t)Endpoint_Read_Word_LE() >> 8);
 187                 int8_t RightSample_8Bit  = ((int16_t)Endpoint_Read_Word_LE() >> 8);
 188
 189                 /* Mix the two channels together to produce a mono, 8-bit sample */
 190                 int8_t MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1);
 191
 192                 /* Check to see if the bank is now empty */
 193                 if (!(Endpoint_IsReadWriteAllowed()))
 194                 {
 195                         /* Acknowledge the packet, clear the bank ready for the next packet */
 196                         Endpoint_ClearOUT();
 197                 }
 198
 199                 #if defined(AUDIO_OUT_MONO)
 200                 /* Load the sample into the PWM timer channel */
 201                 OCR3A = (MixedSample_8Bit ^ (1 << 7));
 202                 #elif defined(AUDIO_OUT_STEREO)
 203                 /* Load the dual 8-bit samples into the PWM timer channels */
 204                 OCR3A = (LeftSample_8Bit  ^ (1 << 7));
 205                 OCR3B = (RightSample_8Bit ^ (1 << 7));
 206                 #elif defined(AUDIO_OUT_PORTC)
 207                 /* Load the 8-bit mixed sample into PORTC */
 208                 PORTC = MixedSample_8Bit;
 209                 #endif
 210
 211                 uint8_t LEDMask = LEDS_NO_LEDS;
 212
 213                 /* Turn on LEDs as the sample amplitude increases */
 214                 if (MixedSample_8Bit > 16)
 215                   LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3 | LEDS_LED4);
 216                 else if (MixedSample_8Bit > 8)
 217                   LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3);
 218                 else if (MixedSample_8Bit > 4)
 219                   LEDMask = (LEDS_LED1 | LEDS_LED2);
 220                 else if (MixedSample_8Bit > 2)
 221                   LEDMask = (LEDS_LED1);
 222
 223                 LEDs_SetAllLEDs(LEDMask);
 224         }
 225
 226         Endpoint_SelectEndpoint(PrevEndpoint);
 227 }
 228