qmk_firmware/Demos/Device/ClassDriver/AudioInput/AudioInput.c

/*
             LUFA Library
     Copyright (C) Dean Camera, 2010.

  dean [at] fourwalledcubicle [dot] com
           www.lufa-lib.org
*/

/*
  Copyright 2010  Dean Camera (dean [at] fourwalledcubicle [dot] com)

  Permission to use, copy, modify, distribute, and sell this
  software and its documentation for any purpose is hereby granted
  without fee, provided that the above copyright notice appear in
  all copies and that both that the copyright notice and this
  permission notice and warranty disclaimer appear in supporting
  documentation, and that the name of the author not be used in
  advertising or publicity pertaining to distribution of the
  software without specific, written prior permission.

  The author disclaim all warranties with regard to this
  software, including all implied warranties of merchantability
  and fitness.  In no event shall the author be liable for any
  special, indirect or consequential damages or any damages
  whatsoever resulting from loss of use, data or profits, whether
  in an action of contract, negligence or other tortious action,
  arising out of or in connection with the use or performance of
  this software.
*/

/** \file
 *
 *  Main source file for the AudioInput demo. This file contains the main tasks of
 *  the demo and is responsible for the initial application hardware configuration.
 */

#include "AudioInput.h"

/** LUFA Audio Class driver interface configuration and state information. This structure is
 *  passed to all Audio Class driver functions, so that multiple instances of the same class
 *  within a device can be differentiated from one another.
 */
USB_ClassInfo_Audio_Device_t Microphone_Audio_Interface =
	{
		.Config =
			{
				.StreamingInterfaceNumber = 1,

				.DataINEndpointNumber     = AUDIO_STREAM_EPNUM,
				.DataINEndpointSize       = AUDIO_STREAM_EPSIZE,
			},
	};

/** Main program entry point. This routine contains the overall program flow, including initial
 *  setup of all components and the main program loop.
 */
int main(void)
{
	SetupHardware();

	LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
	sei();

	for (;;)
	{
		Audio_Device_USBTask(&Microphone_Audio_Interface);
		USB_USBTask();
	}
}

/** Configures the board hardware and chip peripherals for the demo's functionality. */
void SetupHardware(void)
{
	/* Disable watchdog if enabled by bootloader/fuses */
	MCUSR &= ~(1 << WDRF);
	wdt_disable();

	/* Disable clock division */
	clock_prescale_set(clock_div_1);

	/* Hardware Initialization */
	LEDs_Init();
	Buttons_Init();
	ADC_Init(ADC_FREE_RUNNING | ADC_PRESCALE_32);
	ADC_SetupChannel(MIC_IN_ADC_CHANNEL);
	USB_Init();

	/* Start the ADC conversion in free running mode */
	ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | MIC_IN_ADC_MUX_MASK);
}

/** ISR to handle the reloading of the data endpoint with the next sample. */
ISR(TIMER0_COMPA_vect, ISR_BLOCK)
{
	uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint();

	/* Check if the sample reload timer period has elapsed, and that the USB bus is ready for a new sample */
	if (Audio_Device_IsReadyForNextSample(&Microphone_Audio_Interface))
	{
		int16_t AudioSample;

		#if defined(USE_TEST_TONE)
			static uint8_t SquareWaveSampleCount;
			static int16_t CurrentWaveValue;
			
			/* In test tone mode, generate a square wave at 1/256 of the sample rate */
			if (SquareWaveSampleCount++ == 0xFF)
			  CurrentWaveValue ^= 0x8000;
			
			/* Only generate audio if the board button is being pressed */
			AudioSample = (Buttons_GetStatus() & BUTTONS_BUTTON1) ? CurrentWaveValue : 0;
		#else
			/* Audio sample is ADC value scaled to fit the entire range */
			AudioSample = ((SAMPLE_MAX_RANGE / ADC_MAX_RANGE) * ADC_GetResult());

			#if defined(MICROPHONE_BIASED_TO_HALF_RAIL)
			/* Microphone is biased to half rail voltage, subtract the bias from the sample value */
			AudioSample -= (SAMPLE_MAX_RANGE / 2);
			#endif
		#endif
		
		Audio_Device_WriteSample16(&Microphone_Audio_Interface, AudioSample);
	}

	Endpoint_SelectEndpoint(PrevEndpoint);
}

/** Event handler for the library USB Connection event. */
void EVENT_USB_Device_Connect(void)
{
	LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING);

	/* Sample reload timer initialization */
	TIMSK0  = (1 << OCIE0A);
	OCR0A   = ((F_CPU / 8 / AUDIO_SAMPLE_FREQUENCY) - 1);
	TCCR0A  = (1 << WGM01);  // CTC mode
	TCCR0B  = (1 << CS01);   // Fcpu/8 speed
}

/** Event handler for the library USB Disconnection event. */
void EVENT_USB_Device_Disconnect(void)
{
	/* Stop the sample reload timer */
	TCCR0B = 0;

	LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);
}

/** Event handler for the library USB Configuration Changed event. */
void EVENT_USB_Device_ConfigurationChanged(void)
{
	bool ConfigSuccess = true;

	ConfigSuccess &= Audio_Device_ConfigureEndpoints(&Microphone_Audio_Interface);

	LEDs_SetAllLEDs(ConfigSuccess ? LEDMASK_USB_READY : LEDMASK_USB_ERROR);
}

/** Event handler for the library USB Control Request reception event. */
void EVENT_USB_Device_ControlRequest(void)
{
	Audio_Device_ProcessControlRequest(&Microphone_Audio_Interface);
}