Lego Mindstorms NXT is a programmable robotics kit released by Lego in late July 2006.[1] It replaced the first-generation Lego Mindstorms kit, which was called the Robotics Invention System. The base kit ships in two versions: the Retail Version (set #8527)[2] and the Education Base Set (set #9797).[3] It comes with the NXT-G programming software, or optionally LabVIEW for LEGO MINDSTORMS. [4] A variety of unofficial languages exist, such as NXC, NBC, leJOS NXJ, and RobotC. A new version of the set, the new Lego Mindstorms NXT 2.0, was released on August 1, 2009, featuring a color sensor and other upgraded capabilities.
The main component in the kit is a brick-shaped computer called the NXT Intelligent Brick. It can take input from up to four sensors and control up to three motors, via RJ12 cables, very much similar to but incompatible with RJ11 phone cords. The brick has a 100x64 pixel monochrome LCD display and four buttons that can be used to navigate a user interface using hierarchical menus. It also has a speaker and can play sound files at sampling rates up to 8 kHz. Power is supplied by 6 AA (1.5 V each) batteries in the consumer version of the kit and by a Li-Ion rechargeable battery and charger in the educational version.
The Intelligent Brick remains unchanged with NXT 2.0. A black version of the brick was made to celebrate the 10th anniversary of the Mindstorms System with no change to the internals.
Lego has released the firmware for the NXT Intelligent Brick as Open Source, along with schematics for all hardware components.[5] This makes the LEGO NXT brick an open-source hardware system, though it is not marketed as such.
Several developer kits are available that contain documentation for the NXT:
Very simple programs can be created using the menu on the NXT Intelligent Brick. More complicated programs and sound files can be downloaded using a USB port or wirelessly using Bluetooth. Files can also be copied between two NXT bricks wirelessly, and some mobile phones can be used as a remote control. Up to three NXT bricks can communicate simultaneously via Bluetooth when user created programs are run.
The retail version of the kit includes software for writing programs that run on Microsoft and Macintosh personal computers. The software is based on National Instruments LabVIEW and provides a visual programming language for writing simple programs and downloading them to the NXT Brick. This means that rather than requiring users to write lines of code, they instead can use flowchart like "blocks" to design their program.
Some books about programming are the Lego Mindstorms Nxt-G Programming guide. This book is good for intermediate robot builders.
NXT-G v1.0 is a graphical programming environment that comes bundled with the NXT. With careful construction of MyBlocks to encapsulate complexity, NXT-G can be used for real-world programming. Parallel "sequence beams" are actually parallel threads, so this software is quite good for running a handful of parallel sense/respond loops (example: wait 60 seconds, play a "bonk" sound at low volume if battery is low, loop), or blending autonomous control with bluetooth or other "remote control". The language supports virtual instruments for all LEGO branded and most 3rd party sensors/components. Community support is significant, for example: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=191310
Free tools (Visual Studio Express and the Robotics Developer Studio) allow you to program using the C# language. Sample Project on coding4fun Other languages are supported as well including IronPython and VB.NET
Bricx Command Center (BricxCC) is the integrated development environment (IDE) used to write, compile, and edit NBC and NXC programs for the NXT. Also, as BricxCC was originally made for the RCX, programs for it can be written using NQC via BricxCC. Different firmwares can be flashed to the NXT using BricxCC.
BricxCC has many utilities such as NeXTExplorer (upload/download files, defragment the NXT, use file hex viewer), NeXTScreen (view what's on the NXT's LCD display, and capture images and video).
Next Byte Codes (NBC) is a simple open source language with an assembly language syntax that can be used to program the NXT brick. BricxCC also has the capability to decompile standard .rxe NXT executables to NBC
Not eXactly C (NXC) is a high level open-source language,[6] similar to C, built on the NBC compiler. It can also be used to program the NXT brick. NXC is basically NQC for the NXT.[7] It is one of the most widely used third-party programming languages for the NXT.
Robolab 2.9 Robolab is the older programming environment originally used on the RCX programmable brick. Version 2.9 has been updated so that it can be used to program the NXT brick. Lego has announced that it will stop officially supporting Robolab but Robolab 2.9 is still available [8] and there are still many user forums and other sources of help available.
Developed by the Carnegie Mellon Robotic's Academy, ROBOTC is a programming-language based on C for VEX, the new VEX Cortex, FIRST Tech Challenge, and Lego Mindstorms. ROBOTC runs a very optimized firmware which allows the NXT to run programs very quickly, and also compresses the files so that you can fit a large amount of programs into your NXT. Like other NXT languages, ROBOTC requires this firmware to be downloaded from the ROBOTC interface in order to run.
NXTGCC is a GCC toolchain for programming the NXT firmware in C.
leJOS NXJ is a high level open source language based on Java that uses custom firmware developed by the leJOS team.[9]
To be able to write in C/C++, nxtOSEK can be used, but that requires custom firmware too.[10]
To write files on the NXT itself, ICON by Steve Hassenplug is an ideal resource.
MATLAB and Simulink code for LEGO MINDSTORMS NXT programming is freely available.
pbLua is a port of the Lua programming language, a general purpose scripting language, for Lego Mindstorms.
A port of GNAT is available for the NXT. It relies on a dedicated run-time kernel based on the Ravenscar profile, the same used on the Goce satellite: this permits to use high-level Ada features to develop concurrent and real-time systems on the MINDSTORMS NXT.
URBI is yet another language and is a parallel and event-driven language, with interfaces to C++/Java and Matlab. It also has a component architecture (UObject) for distribution. Urbi is compatible with many robots, including Nao (cf Robocup), Bioloid or Aibo.[11]
FLL Nxt Navigation An open source program to help navigation on the FLL competition table. It uses NXT-G and .txt files to write programs.
ruby-nxt is a library to program the NXT for the Ruby programming language. Unlike the other languages for the NXT the code is not compiled to a binary file. Instead the code is directly transmitted to the NXT via a bluetooth connection.
Robotics.NXT is a Haskell interface to NXT over Bluetoooth. It supports direct commands, messages and many sensors (also unofficial). It has also support for a simple message-based control of a NXT brick via remotely executed program (basic NXC code included).
LibNXT is a utility library for talking to the LEGO Mindstorms NXT intelligent brick at a relatively low level. LibNXT is targeted mainly at the platforms that the official Lego Minstorms NXT software overlooks, namely Linux and other unices. It will work on any POSIX-compliant operating system where libusb 0.1 <http://libusb.sf.net/> is supported. Windows support is also possible with the win32 port of libusb.
PyNXC is a project which converts Python code to "Not Exactly C" (NXC) code, to download to LEGO MINDSTORMS Robots.
NXT-Python is a python module, which communicates with the NXT via USB or Bloetooth. It supports direct commands and several aftermarket sensors.
The Lego Mindstorms 1.0 base kit incudes:[12]
In the Lego Mindstorms 2.0 base kit, it includes: 2 Touch sensors, one Color sensor (detects different colors), and an Ultrasonic sensor.
These parts are not included in the Lego Mindstorms NXT base kit and may be bought separately:[17]
The sensors come assembled and programmed. In the software (see Programming above), you can decide what to do with the information that comes from the sensors (for example you can program the robot move forward until it touches something).
Lego also sells an adapter to the Vernier sensor product line. Vernier produces data collection devices and related software for use in education.
Sensors are connected to the NXT brick using a 6-position modular connector that features both analog and digital interfaces. The analog interface is backward-compatible (using an adapter) with the older Robotics Invention System. The digital interface is capable of both I2C and RS-485 communication.
| Pin | Name | Function | Color | Pin Numbering |
|---|---|---|---|---|
| 1 | ANALOG | Analog interface, +9V Supply | white |
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| 2 | GND | Ground | black |
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| 3 | GND | Ground | red |
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| 4 | IPOWERA | +4.3V Supply | green |
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| 5 | DIGIAI0 | I2C Clock (SCL), RS-485 B | yellow |
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| 6 | DIGIAI1 | I2C Data (SDA), RS-485 A | blue |
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