diff options
Diffstat (limited to 'Demos/Device/LowLevel/AudioOutput/AudioOutput.c')
| -rw-r--r-- | Demos/Device/LowLevel/AudioOutput/AudioOutput.c | 293 | 
1 files changed, 293 insertions, 0 deletions
| diff --git a/Demos/Device/LowLevel/AudioOutput/AudioOutput.c b/Demos/Device/LowLevel/AudioOutput/AudioOutput.c new file mode 100644 index 0000000000..7966ba6ea2 --- /dev/null +++ b/Demos/Device/LowLevel/AudioOutput/AudioOutput.c @@ -0,0 +1,293 @@ +/* +             LUFA Library +     Copyright (C) Dean Camera, 2017. + +  dean [at] fourwalledcubicle [dot] com +           www.lufa-lib.org +*/ + +/* +  Copyright 2017  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 disclaims 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 AudioOutput demo. This file contains the main tasks of the demo and + *  is responsible for the initial application hardware configuration. + */ + +#include "AudioOutput.h" + +/** Flag to indicate if the streaming audio alternative interface has been selected by the host. */ +static bool StreamingAudioInterfaceSelected = false; + +/** Current audio sampling frequency of the streaming audio endpoint. */ +static uint32_t CurrentAudioSampleFrequency = 48000; + + +/** 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); +	GlobalInterruptEnable(); + +	for (;;) +	{ +		USB_USBTask(); +	} +} + +/** Configures the board hardware and chip peripherals for the demo's functionality. */ +void SetupHardware(void) +{ +#if (ARCH == ARCH_AVR8) +	/* Disable watchdog if enabled by bootloader/fuses */ +	MCUSR &= ~(1 << WDRF); +	wdt_disable(); + +	/* Disable clock division */ +	clock_prescale_set(clock_div_1); +#endif + +	/* Hardware Initialization */ +	LEDs_Init(); +	USB_Init(); +} + +/** Event handler for the USB_Connect event. This indicates that the device is enumerating via the status LEDs, and + *  configures the sample update and PWM timers. + */ +void EVENT_USB_Device_Connect(void) +{ +	/* Indicate USB enumerating */ +	LEDs_SetAllLEDs(LEDMASK_USB_ENUMERATING); + +	/* Sample reload timer initialization */ +	TIMSK0 = (1 << OCIE0A); +	OCR0A  = ((F_CPU / 8 / CurrentAudioSampleFrequency) - 1); +	TCCR0A = (1 << WGM01);  // CTC mode +	TCCR0B = (1 << CS01);   // Fcpu/8 speed + +	#if defined(AUDIO_OUT_MONO) +	/* Set speaker as output */ +	DDRC  |= (1 << 6); +	#elif defined(AUDIO_OUT_STEREO) +	/* Set speakers as outputs */ +	DDRC  |= ((1 << 6) | (1 << 5)); +	#elif defined(AUDIO_OUT_PORTC) +	/* Set PORTC as outputs */ +	DDRC  |= 0xFF; +	#endif + +	#if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO)) +	/* PWM speaker timer initialization */ +	TCCR3A = ((1 << WGM30) | (1 << COM3A1) | (1 << COM3A0) +	                       | (1 << COM3B1) | (1 << COM3B0)); // Set on match, clear on TOP +	TCCR3B = ((1 << WGM32) | (1 << CS30));  // Fast 8-Bit PWM, F_CPU speed +	#endif +} + +/** Event handler for the USB_Disconnect event. This indicates that the device is no longer connected to a host via + *  the status LEDs, disables the sample update and PWM output timers and stops the USB and Audio management tasks. + */ +void EVENT_USB_Device_Disconnect(void) +{ +	/* Stop the timers */ +	TCCR0B = 0; +	#if (defined(AUDIO_OUT_MONO) || defined(AUDIO_OUT_STEREO)) +	TCCR3B = 0; +	#endif + +	#if defined(AUDIO_OUT_MONO) +	/* Set speaker as input to reduce current draw */ +	DDRC  &= ~(1 << 6); +	#elif defined(AUDIO_OUT_STEREO) +	/* Set speakers as inputs to reduce current draw */ +	DDRC  &= ~((1 << 6) | (1 << 5)); +	#elif defined(AUDIO_OUT_PORTC) +	/* Set PORTC low */ +	PORTC = 0x00; +	#endif + +	/* Indicate streaming audio interface not selected */ +	StreamingAudioInterfaceSelected = false; + +	/* Indicate USB not ready */ +	LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY); +} + +/** Event handler for the USB_ConfigurationChanged event. This is fired when the host set the current configuration + *  of the USB device after enumeration - the device endpoints are configured. + */ +void EVENT_USB_Device_ConfigurationChanged(void) +{ +	bool ConfigSuccess = true; + +	/* Setup Audio Stream Endpoint */ +	ConfigSuccess &= Endpoint_ConfigureEndpoint(AUDIO_STREAM_EPADDR, EP_TYPE_ISOCHRONOUS, AUDIO_STREAM_EPSIZE, 2); + +	/* Indicate endpoint configuration success or failure */ +	LEDs_SetAllLEDs(ConfigSuccess ? LEDMASK_USB_READY : LEDMASK_USB_ERROR); +} + +/** Event handler for the USB_ControlRequest event. This is used to catch and process control requests sent to + *  the device from the USB host before passing along unhandled control requests to the library for processing + *  internally. + */ +void EVENT_USB_Device_ControlRequest(void) +{ +	/* Process General and Audio specific control requests */ +	switch (USB_ControlRequest.bRequest) +	{ +		case REQ_SetInterface: +			/* Set Interface is not handled by the library, as its function is application-specific */ +			if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_STANDARD | REQREC_INTERFACE)) +			{ +				Endpoint_ClearSETUP(); +				Endpoint_ClearStatusStage(); + +				/* Check if the host is enabling the audio interface (setting AlternateSetting to 1) */ +				StreamingAudioInterfaceSelected = ((USB_ControlRequest.wValue) != 0); +			} + +			break; +		case AUDIO_REQ_GetStatus: +			/* Get Status request can be directed at either the interface or endpoint, neither is currently used +			 * according to the latest USB Audio 1.0 standard, but must be ACKed with no data when requested */ +			if ((USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_INTERFACE)) || +			    (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT))) +			{ +				Endpoint_ClearSETUP(); +				Endpoint_ClearStatusStage(); +			} + +			break; +		case AUDIO_REQ_SetCurrent: +			if (USB_ControlRequest.bmRequestType == (REQDIR_HOSTTODEVICE | REQTYPE_CLASS | REQREC_ENDPOINT)) +			{ +				/* Extract out the relevant request information to get the target Endpoint address and control being set */ +				uint8_t EndpointAddress = (uint8_t)USB_ControlRequest.wIndex; +				uint8_t EndpointControl = (USB_ControlRequest.wValue >> 8); + +				/* Only handle SET CURRENT requests to the audio endpoint's sample frequency property */ +				if ((EndpointAddress == AUDIO_STREAM_EPADDR) && (EndpointControl == AUDIO_EPCONTROL_SamplingFreq)) +				{ +					uint8_t SampleRate[3]; + +					Endpoint_ClearSETUP(); +					Endpoint_Read_Control_Stream_LE(SampleRate, sizeof(SampleRate)); +					Endpoint_ClearIN(); + +					/* Set the new sampling frequency to the value given by the host */ +					CurrentAudioSampleFrequency = (((uint32_t)SampleRate[2] << 16) | ((uint32_t)SampleRate[1] << 8) | (uint32_t)SampleRate[0]); + +					/* Adjust sample reload timer to the new frequency */ +					OCR0A = ((F_CPU / 8 / CurrentAudioSampleFrequency) - 1); +				} +			} + +			break; +		case AUDIO_REQ_GetCurrent: +			if (USB_ControlRequest.bmRequestType == (REQDIR_DEVICETOHOST | REQTYPE_CLASS | REQREC_ENDPOINT)) +			{ +				/* Extract out the relevant request information to get the target Endpoint address and control being retrieved */ +				uint8_t EndpointAddress = (uint8_t)USB_ControlRequest.wIndex; +				uint8_t EndpointControl = (USB_ControlRequest.wValue >> 8); + +				/* Only handle GET CURRENT requests to the audio endpoint's sample frequency property */ +				if ((EndpointAddress == AUDIO_STREAM_EPADDR) && (EndpointControl == AUDIO_EPCONTROL_SamplingFreq)) +				{ +					uint8_t SampleRate[3]; + +					/* Convert the sampling rate value into the 24-bit format the host expects for the property */ +					SampleRate[2] = (CurrentAudioSampleFrequency >> 16); +					SampleRate[1] = (CurrentAudioSampleFrequency >> 8); +					SampleRate[0] = (CurrentAudioSampleFrequency &  0xFF); + +					Endpoint_ClearSETUP(); +					Endpoint_Write_Control_Stream_LE(SampleRate, sizeof(SampleRate)); +					Endpoint_ClearOUT(); +				} +			} + +			break; +	} +} + +/** ISR to handle the reloading of the PWM timer with the next sample. */ +ISR(TIMER0_COMPA_vect, ISR_BLOCK) +{ +	uint8_t PrevEndpoint = Endpoint_GetCurrentEndpoint(); + +	/* Select the audio stream endpoint */ +	Endpoint_SelectEndpoint(AUDIO_STREAM_EPADDR); + +	/* Check if the current endpoint can be read from (contains a packet) and the host is sending data */ +	if (Endpoint_IsOUTReceived() && StreamingAudioInterfaceSelected) +	{ +		/* Retrieve the signed 16-bit left and right audio samples, convert to 8-bit */ +		int8_t LeftSample_8Bit   = ((int16_t)Endpoint_Read_16_LE() >> 8); +		int8_t RightSample_8Bit  = ((int16_t)Endpoint_Read_16_LE() >> 8); + +		/* Mix the two channels together to produce a mono, 8-bit sample */ +		int8_t MixedSample_8Bit  = (((int16_t)LeftSample_8Bit + (int16_t)RightSample_8Bit) >> 1); + +		/* Check to see if the bank is now empty */ +		if (!(Endpoint_IsReadWriteAllowed())) +		{ +			/* Acknowledge the packet, clear the bank ready for the next packet */ +			Endpoint_ClearOUT(); +		} + +		#if defined(AUDIO_OUT_MONO) +		/* Load the sample into the PWM timer channel */ +		OCR3A = (MixedSample_8Bit ^ (1 << 7)); +		#elif defined(AUDIO_OUT_STEREO) +		/* Load the dual 8-bit samples into the PWM timer channels */ +		OCR3A = (LeftSample_8Bit  ^ (1 << 7)); +		OCR3B = (RightSample_8Bit ^ (1 << 7)); +		#elif defined(AUDIO_OUT_PORTC) +		/* Load the 8-bit mixed sample into PORTC */ +		PORTC = MixedSample_8Bit; +		#endif + +		uint8_t LEDMask = LEDS_NO_LEDS; + +		/* Turn on LEDs as the sample amplitude increases */ +		if (MixedSample_8Bit > 16) +		  LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3 | LEDS_LED4); +		else if (MixedSample_8Bit > 8) +		  LEDMask = (LEDS_LED1 | LEDS_LED2 | LEDS_LED3); +		else if (MixedSample_8Bit > 4) +		  LEDMask = (LEDS_LED1 | LEDS_LED2); +		else if (MixedSample_8Bit > 2) +		  LEDMask = (LEDS_LED1); + +		LEDs_SetAllLEDs(LEDMask); +	} + +	Endpoint_SelectEndpoint(PrevEndpoint); +} + | 
