Compiling Programs

Introduction

Programs created with MATRIX HAL allow you to directly access sensors and components on the MATRIX device through C++. This guide will show you how to create and run an LED demo in MATRIX HAL. The final result being a rainbow LED sequence.

Creating A Program

Making Your Project Directory

Use the following commands to create a folder to hold your MATRIX HAL projects, in the home directory ~/ of your MATRIX device. 

cd ~/
mkdir matrix-hal-project
cd matrix-hal-project

Create a file called app.cpp in your project folder, and paste the code below.

The following code turns the Everloop rainbow for 10 seconds.

/*
 * Everloop rainbow example
 */

/////////////////////////
// INCLUDE STATEMENTS //
///////////////////////

// System calls
#include <unistd.h>
// Input/output streams and functions
#include <iostream>
// Included for sin() function.
#include <cmath>

// Interfaces with Everloop
#include "matrix_hal/everloop.h"
// Holds data for Everloop
#include "matrix_hal/everloop_image.h"
// Communicates with MATRIX device
#include "matrix_hal/matrixio_bus.h"

int main() {
  ////////////////////
  // INITIAL SETUP //
  //////////////////

  // Create MatrixIOBus object for hardware communication
  matrix_hal::MatrixIOBus bus;
  // Initialize bus and exit program if error occurs
  if (!bus.Init()) return false;

  /////////////////
  // MAIN SETUP //
  ///////////////

  // Holds the number of LEDs on MATRIX device
  int ledCount = bus.MatrixLeds();
  // Create EverloopImage object, with size of ledCount
  matrix_hal::EverloopImage everloop_image(ledCount);
  // Create Everloop object
  matrix_hal::Everloop everloop;
  // Set everloop to use MatrixIOBus bus
  everloop.Setup(&bus);

  // Variables used for sine wave rainbow logic
  float counter = 0;
  const float freq = 0.375;

  // 10 sec loop for rainbow effect 250*40000 microsec = 10 sec
  for (int i = 0; i <= 250; i++) {
    // For each led in everloop_image.leds, set led value
    for (matrix_hal::LedValue &led : everloop_image.leds) {
      // Sine waves 120 degrees out of phase for rainbow
      led.red =
          (std::sin(freq * counter + (M_PI / 180 * 240)) * 155 + 100) / 10;
      led.green =
          (std::sin(freq * counter + (M_PI / 180 * 120)) * 155 + 100) / 10;
      led.blue = (std::sin(freq * counter + 0) * 155 + 100) / 10;
      // If MATRIX Creator, increment by 0.51
      if (ledCount == 35) {
        counter = counter + 0.51;
      }
      // If MATRIX Voice, increment by 1.01
      if (ledCount == 18) {
        counter = counter + 1.01;
      }
    }

    // Updates the LEDs
    everloop.Write(&everloop_image);

    // If i is 0 (first run)
    if (i == 0) {
      // Output everloop status to console
      std::cout << "Everloop set to rainbow for 10 seconds." << std::endl;
    }
    // If i is cleanly divisible by 25
    if ((i % 25) == 0) {
      std::cout << "Time remaining (s) : " << 10 - (i / 25) << std::endl;
    }

    // Sleep for 40000 microseconds
    usleep(40000);
  }

  // Updates the Everloop on the MATRIX device
  everloop.Write(&everloop_image);

  // For each led in everloop_image.leds, set led value to 0
  for (matrix_hal::LedValue &led : everloop_image.leds) {
    // Turn off Everloop
    led.red = 0;
    led.green = 0;
    led.blue = 0;
    led.white = 0;
  }

  // Updates the Everloop on the MATRIX device
  everloop.Write(&everloop_image);

  return 0;
}

Compiling your Program

The command below will use g++ to link the libmatrix_creator_hal.so library file when compiling your program.

g++ -o app app.cpp -std=c++11 -lmatrix_creator_hal

Running your Program

Run the following command to start the demo program.

cd ~/matrix-hal-project
./app

Result

Next Steps

Now that everything is properly installed, view our function references to see what you can do with MATRIX HAL, or view the code examples.

Contents