comparison examples/03-Analog/analog-output/render.cpp @ 464:8fcfbfb32aa0 prerelease

Examples reorder with subdirectories. Added header to each project. Moved Doxygen to bottom of render.cpp.

+/*
+ ____  _____ _        _    
+| __ )| ____| |      / \   
+|  _ \|  _| | |     / _ \  
+| |_) | |___| |___ / ___ \ 
+|____/|_____|_____/_/   \_\
+
+The platform for ultra-low latency audio and sensor processing
+
+http://bela.io
+
+A project of the Augmented Instruments Laboratory within the
+Centre for Digital Music at Queen Mary University of London.
+http://www.eecs.qmul.ac.uk/~andrewm
+
+(c) 2016 Augmented Instruments Laboratory: Andrew McPherson,
+  Astrid Bin, Liam Donovan, Christian Heinrichs, Robert Jack,
+  Giulio Moro, Laurel Pardue, Victor Zappi. All rights reserved.
+
+The Bela software is distributed under the GNU Lesser General Public License
+(LGPL 3.0), available here: https://www.gnu.org/licenses/lgpl-3.0.txt
+*/
+
+
+#include <Bela.h>
+#include <rtdk.h>
+#include <cmath>
+
+// Set range for analog outputs designed for driving LEDs
+const float kMinimumAmplitude = (1.5 / 5.0);
+const float kAmplitudeRange = 1.0 - kMinimumAmplitude;
+
+float gFrequency;
+float gPhase;
+float gInverseSampleRate;
+
+bool setup(BelaContext *context, void *userData)
+{
+	// Retrieve a parameter passed in from the initAudio() call
+	gFrequency = *(float *)userData;
+
+	if(context->analogFrames == 0) {
+		rt_printf("Error: this example needs the matrix enabled\n");
+		return false;
+	}
+
+	gInverseSampleRate = 1.0 / context->analogSampleRate;
+	gPhase = 0.0;
+
+	return true;
+}
+
+void render(BelaContext *context, void *userData)
+{
+	for(unsigned int n = 0; n < context->analogFrames; n++) {
+		// Set LED to different phase for each matrix channel
+		float relativePhase = 0.0;
+		for(unsigned int channel = 0; channel < context->analogChannels; channel++) {
+			float out = kMinimumAmplitude + kAmplitudeRange * 0.5f * (1.0f + sinf(gPhase + relativePhase));
+
+			analogWrite(context, n, channel, out);
+
+			// Advance by pi/4 (1/8 of a full rotation) for each channel
+			relativePhase += M_PI * 0.25;
+		}
+
+		gPhase += 2.0 * M_PI * gFrequency * gInverseSampleRate;
+		if(gPhase > 2.0 * M_PI)
+			gPhase -= 2.0 * M_PI;
+	}
+}
+
+void cleanup(BelaContext *context, void *userData)
+{
+
+}
+
+/* ------------ Project Explantation ------------ */
+
+/**
+\example 03-analog-output
+
+Fading LEDs
+-----------
+
+This sketch uses a sine wave to drive the brightness of a series of LEDs 
+connected to the eight analog out pins. Again you can see the nested `for` loop 
+structure but this time for the analog output channels rather than the audio.
+
+- connect an LED in series with a 470ohm resistor between each of the analogOut pins and ground.
+
+Within the first for loop in render we cycle through each frame in the analog 
+output matrix. At each frame we then cycle through the analog output channels 
+with another for loop and set the output voltage according to the phase of a 
+sine tone that acts as an LFO. The analog output pins can provide a voltage of 
+~4.092V.
+
+The output on each pin is set with `analogWrite()` within the for loop that 
+cycles through the analog output channels. This needs to be provided with 
+arguments as follows `analogWrite(context, n, channel, out)`. Channel is 
+where the you give the address of the analog output pin (in this case we cycle 
+through each pin address in the for loop), out is the variable that holds the 
+desired output (in this case set by the sine wave).
+
+Notice that the phase of the brightness cycle for each led is different. This 
+is achieved by updating a variable that stores a relative phase value. This 
+variable is advanced by pi/4 (1/8 of a full rotation) for each channel giving 
+each of the eight LEDs a different phase.
+*/