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 <cmath>
robert@464: 
robert@464: float gPhase;
robert@464: float gInverseSampleRate;
robert@464: int gAudioFramesPerAnalogFrame;
robert@464: 
robert@542: // Set the analog channels to read from
robert@542: int gSensorInputFrequency = 0;
robert@542: int gSensorInputAmplitude = 1;
robert@464: 
robert@464: bool setup(BelaContext *context, void *userData)
robert@464: {
robert@542: 	
robert@542: 	// Check if analog channels are enabled
robert@464: 	if(context->analogFrames == 0 || context->analogFrames > context->audioFrames) {
robert@464: 		rt_printf("Error: this example needs analog enabled, with 4 or 8 channels\n");
robert@464: 		return false;
robert@464: 	}
robert@464: 
robert@542: 	// Check that we have the same number of inputs and outputs.
robert@542: 	if(context->audioInChannels != context->audioOutChannels ||
robert@542: 			context->analogInChannels != context-> analogOutChannels){
robert@542: 		printf("Error: for this project, you need the same number of input and output channels.\n");
robert@542: 		return false;
robert@542: 	}
robert@542: 
robert@542: 	// Useful calculations
robert@464: 	gAudioFramesPerAnalogFrame = context->audioFrames / context->analogFrames;
robert@464: 	gInverseSampleRate = 1.0 / context->audioSampleRate;
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: 	float frequency = 440.0;
robert@464: 	float amplitude = 0.8;
robert@464: 
robert@464: 	// There are twice as many audio frames as matrix frames since audio sample rate
robert@464: 	// is twice as high
robert@464: 
robert@464: 	for(unsigned int n = 0; n < context->audioFrames; n++) {
robert@464: 		if(!(n % gAudioFramesPerAnalogFrame)) {
robert@542: 			// On even audio samples: read analog inputs and update frequency and amplitude
robert@464: 			frequency = map(analogRead(context, n/gAudioFramesPerAnalogFrame, gSensorInputFrequency), 0, 1, 100, 1000);
robert@464: 			amplitude = analogRead(context, n/gAudioFramesPerAnalogFrame, gSensorInputAmplitude);
robert@464: 		}
robert@464: 
robert@464: 		float out = amplitude * sinf(gPhase);
robert@464: 
robert@542: 		for(unsigned int channel = 0; channel < context->audioOutChannels; channel++) {
robert@542: 			audioWrite(context, n, channel, out);
robert@542: 		}
robert@464: 
robert@542: 		// Update and wrap phase of sine tone
robert@464: 		gPhase += 2.0 * M_PI * frequency * 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: 
robert@464: /**
robert@500: \example analog-input/render.cpp
robert@464: 
robert@464: Connecting potentiometers
robert@464: -------------------------
robert@464: 
robert@464: This sketch produces a sine tone, the frequency and amplitude of which are 
robert@542: modulated by data received on the analog input pins. Before looping through each audio 
robert@542: frame, we declare a value for the `frequency` and `amplitude` of our sine tone; 
robert@542: we adjust these values by taking in data from analog sensors (for example potentiometers)
robert@542: with `analogRead()`.
robert@464: 
robert@464: - connect a 10K pot to 3.3V and GND on its 1st and 3rd pins.
robert@464: - connect the 2nd middle pin of the pot to analogIn 0.
robert@464: - connect another 10K pot in the same way but with the middle pin connected to analogIn 1.
robert@464: 
robert@464: The important thing to notice is that audio is sampled twice as often as analog 
robert@464: data. The audio sampling rate is 44.1kHz (44100 frames per second) and the 
robert@524: analog sampling rate is 22.05kHz (22050 frames per second). Notice that we are 
robert@524: processing the analog data and updating frequency and amplitude only on every 
robert@524: second audio sample, since the analog sampling rate is half that of the audio.
robert@524: 
robert@524: ````
robert@524: if(!(n % gAudioFramesPerAnalogFrame)) {
robert@524:     // Even audio samples: update frequency and amplitude from the matrix
robert@524:     frequency = map(analogRead(context, n/gAudioFramesPerAnalogFrame, gSensorInputFrequency), 0, 1, 100, 1000);
robert@524:     amplitude = analogRead(context, n/gAudioFramesPerAnalogFrame, gSensorInputAmplitude);
robert@524: }
robert@524: ````
robert@464: 
robert@464: */