Trill/square-visual/render.cpp

Trill Square GUI

This example shows how to communicate with the Trill Square sensor using the Trill library. It visualises the X-Y position of the touch in real time on the GUI.

In this file Trill sensor is scanned in an AuxiliaryTask running in parallel with the audio thread and the horizontal and vertical position and size are stored in global variables.

Click the GUI button to see the visualisation. Touch position and size are displayed in the sketch.

/*
 ____  _____ _        _
| __ )| ____| |      / \
|  _ \|  _| | |     / _ \
| |_) | |___| |___ / ___ \
|____/|_____|_____/_/   \_\
http://bela.io
*/
#include <Bela.h>
#include <cmath>
#include <libraries/Trill/Trill.h>
#include <libraries/Gui/Gui.h>

// Gui object declaration
Gui gui;

// Trill object declaration
Trill touchSensor;

// Horizontal and vertical position for Trill sensor
float gTouchPosition[2] = { 0.0 , 0.0 };
// Touch size
float gTouchSize = 0.0;

// Sleep time for auxiliary task
unsigned int gTaskSleepTime = 12000; // microseconds

// Time period (in seconds) after which data will be sent to the GUI
float gTimePeriod = 0.015;

/*
* Function to be run on an auxiliary task that reads data from the Trill sensor.
* Here, a loop is defined so that the task runs recurrently for as long as the
* audio thread is running.
*/
void loop(void*)
{
        while(!Bela_stopRequested())
        {
                // Read locations from Trill sensor
                touchSensor.readI2C();
                /*
                * The Trill Square sensor can detect multiple touches but will
                * not be able to clearly differentiate their locations, so we
                * normally use the compoundTouch... methods to retrieve the
                * average of the location and size of the detected touches
                */
                gTouchSize = touchSensor.compoundTouchSize();
                gTouchPosition[0] = touchSensor.compoundTouchHorizontalLocation();
                gTouchPosition[1] = touchSensor.compoundTouchLocation();
                usleep(gTaskSleepTime);
        }
}

bool setup(BelaContext *context, void *userData)
{
        // Setup a Trill Square on i2c bus 1, using the default mode and address
        if(touchSensor.setup(1, Trill::SQUARE) != 0) {
                fprintf(stderr, "Unable to initialise Trill Square\n");
                return false;
        }

        touchSensor.printDetails();

        // Set and schedule auxiliary task for reading sensor data from the I2C bus
        Bela_runAuxiliaryTask(loop);

        // Setup GUI
        gui.setup(context->projectName);
        return true;
}

void render(BelaContext *context, void *userData)
{
        static unsigned int count = 0;
        for(unsigned int n = 0; n < context->audioFrames; n++) {
                // Send X-Y position of the touch and size to the GUI
                // after some time has elapsed.
                if(count >= gTimePeriod*context->audioSampleRate)
                {
                        gui.sendBuffer(0, gTouchPosition);
                        gui.sendBuffer(1, gTouchSize);

                        count = 0;
                }
                count ++;
        }
}

void cleanup(BelaContext *context, void *userData)
{}