C++ Library

The C++ communication library makes it possible to communicate with the NXT using a Bluetooth or network connection. To be able to communicate with the NXT over Bluetooth a partnership between the PC and the NXT has to be established. Use this guide to help you establish a Bluetooth connection. To communicate with the NXT over a network you need to download and run the MonoBrick Tunnel.

With the library it is possible to:

• Communicates with the NXT using Bluetooth or Ethernet
• Supports more than 20 analog and I2C sensors
• Control all three motors
• Send and receive messages using the mailbox system
• Set Brick name, get battery level, read firmware version etc.
• Play tones and sound files
• Use the NXT’s file system to download and upload files
• Start and stop on-brick programs
• Use exceptions to catch sensor and connection errors
• Open and close connections with multiple NXT units
• and more..

Getting Started

To get started you need a C++ compiler. I would recommend Code Blocks with GCC compiler and GDB debugger from MinGW – this can be downloaded here.  Once code blocks is installed do the following

• Download and unzip the C++ library to a folder of your choice
  
• Create a new console C++ project in the same folder
• Add all the files from the library to your project

If you want to communicate over a network remember to link to libwsock32.a – otherwise delete/remove network.h and network.cpp from your project. In Code blocks this is done using project->build option->linker setting->add. The file libwsock32.a is located in the folder (Code Blocks install directory)/MinGW/lib/

To write your fist Bluetooth program simply copy the code below into your main file – remember to change the comport!!. The program will make motor B turn when the touch sensor on port 1 is pressed.

#include <cstdlib>
#include <iostream>
#include <string>
#include <conio.h>
#include "nxt.h"

using namespace std;

//set up the NXT
Connection *connection = new Bluetooth();
Sensor *sensor1 = new Touch(IN_1, connection);
Motor *motorB = new Motor(OUT_B, connection);
int main()
{
  try{
    cout << "Try to connect to the NXT" << endl;
    connection->connect(40);
    cout << "Connected" << endl;
    //connection->connect(1500, "192.168.0.1"); //Network connection
    cout << "Press touch sensor - hit any key to end" << endl;
    while(!_kbhit()){//hit a key to end
      if(sensor1->read()){
        motorB->on(75);
      }
      else{
        motorB->stop();
      }
    }
    connection->disconnect();
  }
  catch (Nxt_exception& e){
    //some error occurred - print it out
    cout << e.what() << endl;
    cout << "error code: " << e.error_code() << endl;
    cout << "error type: " << e.error_type() << endl;
    cout << e.who() << endl;
    connection->disconnect();
  }
  return 0;
}

If you are able to compiled and run the above program you are ready to start using the library and writing your own programs. To view a complete list of available commands and sensor opportunities please consult the library documentation.