robert@464: /*
robert@464:  ____  _____ _        _    
robert@464: | __ )| ____| |      / \   
robert@464: |  _ \|  _| | |     / _ \  
robert@464: | |_) | |___| |___ / ___ \ 
robert@464: |____/|_____|_____/_/   \_\
robert@464: 
robert@464: The platform for ultra-low latency audio and sensor processing
robert@464: 
robert@464: http://bela.io
robert@464: 
robert@464: A project of the Augmented Instruments Laboratory within the
robert@464: Centre for Digital Music at Queen Mary University of London.
robert@464: http://www.eecs.qmul.ac.uk/~andrewm
robert@464: 
robert@464: (c) 2016 Augmented Instruments Laboratory: Andrew McPherson,
robert@464:   Astrid Bin, Liam Donovan, Christian Heinrichs, Robert Jack,
robert@464:   Giulio Moro, Laurel Pardue, Victor Zappi. All rights reserved.
robert@464: 
robert@464: The Bela software is distributed under the GNU Lesser General Public License
robert@464: (LGPL 3.0), available here: https://www.gnu.org/licenses/lgpl-3.0.txt
robert@464: */
robert@464: 
robert@464: 
robert@464: #include <Bela.h>
robert@464: #include <rtdk.h>
robert@464: #include <cmath>
robert@464: 
robert@464: // Set range for analog outputs designed for driving LEDs
robert@464: const float kMinimumAmplitude = (1.5 / 5.0);
robert@464: const float kAmplitudeRange = 1.0 - kMinimumAmplitude;
robert@464: 
robert@464: float gFrequency;
robert@464: float gPhase;
robert@464: float gInverseSampleRate;
robert@464: 
robert@464: bool setup(BelaContext *context, void *userData)
robert@464: {
robert@464: 	// Retrieve a parameter passed in from the initAudio() call
robert@464: 	gFrequency = *(float *)userData;
robert@464: 
robert@464: 	if(context->analogFrames == 0) {
robert@464: 		rt_printf("Error: this example needs the matrix enabled\n");
robert@464: 		return false;
robert@464: 	}
robert@464: 
robert@464: 	gInverseSampleRate = 1.0 / context->analogSampleRate;
robert@464: 	gPhase = 0.0;
robert@464: 
robert@464: 	return true;
robert@464: }
robert@464: 
robert@464: void render(BelaContext *context, void *userData)
robert@464: {
robert@464: 	for(unsigned int n = 0; n < context->analogFrames; n++) {
robert@464: 		// Set LED to different phase for each matrix channel
robert@464: 		float relativePhase = 0.0;
robert@464: 		for(unsigned int channel = 0; channel < context->analogChannels; channel++) {
robert@464: 			float out = kMinimumAmplitude + kAmplitudeRange * 0.5f * (1.0f + sinf(gPhase + relativePhase));
robert@464: 
robert@464: 			analogWrite(context, n, channel, out);
robert@464: 
robert@464: 			// Advance by pi/4 (1/8 of a full rotation) for each channel
robert@464: 			relativePhase += M_PI * 0.25;
robert@464: 		}
robert@464: 
robert@464: 		gPhase += 2.0 * M_PI * gFrequency * gInverseSampleRate;
robert@464: 		if(gPhase > 2.0 * M_PI)
robert@464: 			gPhase -= 2.0 * M_PI;
robert@464: 	}
robert@464: }
robert@464: 
robert@464: void cleanup(BelaContext *context, void *userData)
robert@464: {
robert@464: 
robert@464: }
robert@464: 
robert@464: /* ------------ Project Explantation ------------ */
robert@464: 
robert@464: /**
robert@500: \example analog-output/render.cpp
robert@464: 
robert@464: Fading LEDs
robert@464: -----------
robert@464: 
robert@464: This sketch uses a sine wave to drive the brightness of a series of LEDs 
robert@464: connected to the eight analog out pins. Again you can see the nested `for` loop 
robert@464: structure but this time for the analog output channels rather than the audio.
robert@464: 
robert@464: - connect an LED in series with a 470ohm resistor between each of the analogOut pins and ground.
robert@464: 
robert@464: Within the first for loop in render we cycle through each frame in the analog 
robert@464: output matrix. At each frame we then cycle through the analog output channels 
robert@464: with another for loop and set the output voltage according to the phase of a 
robert@464: sine tone that acts as an LFO. The analog output pins can provide a voltage of 
robert@464: ~4.092V.
robert@464: 
robert@464: The output on each pin is set with `analogWrite()` within the for loop that 
robert@464: cycles through the analog output channels. This needs to be provided with 
robert@464: arguments as follows `analogWrite(context, n, channel, out)`. Channel is 
robert@464: where the you give the address of the analog output pin (in this case we cycle 
robert@464: through each pin address in the for loop), out is the variable that holds the 
robert@464: desired output (in this case set by the sine wave).
robert@464: 
robert@464: Notice that the phase of the brightness cycle for each led is different. This 
robert@464: is achieved by updating a variable that stores a relative phase value. This 
robert@464: variable is advanced by pi/4 (1/8 of a full rotation) for each channel giving 
robert@464: each of the eight LEDs a different phase.
robert@464: */