comparison examples/06-Sensors/capacitive-touch/render.cpp @ 501:6962184f8567 prerelease

Additional name changes to doxygen example title.

+/*
+ ____  _____ _        _    
+| __ )| ____| |      / \   
+|  _ \|  _| | |     / _ \  
+| |_) | |___| |___ / ___ \ 
+|____/|_____|_____/_/   \_\
+
+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 <cmath>
+#include <rtdk.h>
+#include "I2C_MPR121.h"
+
+// How many pins there are
+#define NUM_TOUCH_PINS 12
+
+// Define this to print data to terminal
+#undef DEBUG_MPR121
+
+// Change this to change how often the MPR121 is read (in Hz)
+int readInterval = 50;
+
+// Change this threshold to set the minimum amount of touch
+int threshold = 40;
+
+// This array holds the continuous sensor values
+int sensorValue[NUM_TOUCH_PINS];
+
+// ---- test code stuff -- can be deleted for your example ----
+
+// 12 notes of a C major scale...
+float gFrequencies[NUM_TOUCH_PINS] = {261.63, 293.66, 329.63, 349.23, 392.00, 440.00, 493.88, 523.25, 587.33, 659.25, 698.25, 783.99};
+
+// This is internal stuff for the demo
+float gNormFrequencies[NUM_TOUCH_PINS];
+float gPhases[NUM_TOUCH_PINS] = {0};
+
+// ---- internal stuff -- do not change -----
+
+I2C_MPR121 mpr121;			// Object to handle MPR121 sensing
+AuxiliaryTask i2cTask;		// Auxiliary task to read I2C
+
+int readCount = 0;			// How long until we read again...
+int readIntervalSamples = 0; // How many samples between reads
+
+void readMPR121();
+
+// setup() is called once before the audio rendering starts.
+// Use it to perform any initialisation and allocation which is dependent
+// on the period size or sample rate.
+//
+// userData holds an opaque pointer to a data structure that was passed
+// in from the call to initAudio().
+//
+// Return true on success; returning false halts the program.
+
+bool setup(BelaContext *context, void *userData)
+{
+	if(!mpr121.begin(1, 0x5A)) {
+		rt_printf("Error initialising MPR121\n");
+		return false;
+	}
+	
+	i2cTask = Bela_createAuxiliaryTask(readMPR121, 50, "bela-mpr121");
+	readIntervalSamples = context->audioSampleRate / readInterval;
+	
+	for(int i = 0; i < NUM_TOUCH_PINS; i++) {
+		gNormFrequencies[i] = 2.0 * M_PI * gFrequencies[i] / context->audioSampleRate;
+	}
+	
+	return true;
+}
+
+// render() is called regularly at the highest priority by the audio engine.
+// Input and output are given from the audio hardware and the other
+// ADCs and DACs (if available). If only audio is available, numAnalogFrames
+// will be 0.
+
+void render(BelaContext *context, void *userData)
+{
+	for(int n = 0; n < context->audioFrames; n++) {
+		// Keep this code: it schedules the touch sensor readings
+		if(++readCount >= readIntervalSamples) {
+			readCount = 0;
+			Bela_scheduleAuxiliaryTask(i2cTask);
+		}
+		
+		float sample = 0.0;
+		
+		// This code can be replaced with your favourite audio code
+		for(int i = 0; i < NUM_TOUCH_PINS; i++) {
+			float amplitude = sensorValue[i] / 400.0;
+			
+			// Prevent clipping
+			if(amplitude > 0.5)
+				amplitude = 0.5;
+			
+			sample += amplitude * sinf(gPhases[i]);
+			gPhases[i] += gNormFrequencies[i];
+			if(gPhases[i] > 2.0 * M_PI)
+				gPhases[i] -= 2.0 * M_PI;
+		}
+		
+		for(int ch = 0; ch < context->audioChannels; ch++)
+			context->audioOut[context->audioChannels * n + ch] = sample;
+	}
+}
+
+// cleanup() is called once at the end, after the audio has stopped.
+// Release any resources that were allocated in setup().
+
+void cleanup(BelaContext *context, void *userData)
+{
+	// Nothing to do here
+}
+
+
+// Auxiliary task to read the I2C board
+void readMPR121()
+{
+	for(int i = 0; i < NUM_TOUCH_PINS; i++) {
+		sensorValue[i] = -(mpr121.filteredData(i) - mpr121.baselineData(i));
+		sensorValue[i] -= threshold;
+		if(sensorValue[i] < 0)
+			sensorValue[i] = 0;
+#ifdef DEBUG_MPR121
+		rt_printf("%d ", sensorValue[i]);
+#endif
+	}
+#ifdef DEBUG_MPR121
+	rt_printf("\n");
+#endif
+	
+	// You can use this to read binary on/off touch state more easily
+	//rt_printf("Touched: %x\n", mpr121.touched());
+}
+
+/* ------------ Project Explantation ------------ */
+
+/**
+\example 06-capacitive-touch
+
+Capacitive touch sensing with MPR121
+---------------------------
+
+This sketch allows you to hook up an MPR121 capactive touch sensing device
+to Bela, for example the SparkFun Capacitive Touch Sensor Breakout - MPR121.
+The breakout board gives you 12 electrode connections.
+
+To get this working with Bela you need to connect the breakout board to the I2C
+terminal on the Bela board. See the Pin guide for details of which pin is which.
+
+The sensor data will then be available for you to use in the array 
+`sensorValue[NUM_TOUCH_PINS]`.
+*/