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-====== First steps with Lego Mindstorms ======
-===== Intro =====
-My brother has lent me a Lego Mindstorms version 1.5. It is quite old, by the specifications I think that the product may be dated of 1998. **My objective is to make it work under linux** in a modern computer without a serial cable, to let my son work with it.
-{{ :linux:20131230_113225.jpg?direct&400 |}}
-I suppose that if you come to this page you are somewhat familiar with Lego Mindstorms, however, I will describe some of the main elements of the kit:
-    * The RCX is the "brain" of the robot. Is a yellow box that can be programmed. The good part is that you can replace the firmware easily, in fact [[http://tldp.org/HOWTO/Lego/|there are several solutions out there that replace the firmware]].
-    * A device that you can connect to the computer via an RS232. I call in this document "the black box" because of this color.
-    * Motors, sensors, etc. The usual robot stuff.
-===== Options to have it work under Linux =====
-I will try the following options in the same order depicted here:
-  - Use of [[http://bricxcc.sourceforge.net/nqc/|Not Quite C (nqc)]]: it's a programming language similar to C, that can be used to generate code compatible with the RCX (the brain that goes into the robot)
-  - Use of [[http://www.lejos.org/|Lejos]]: it's a Java Virtual Machine for the RCX. This replaces completely the firmware in the RCX as long as the batteries are connected to the unit (RCX). For me it's a good solution because I am quite familiar with Java, so it's a natural way to go. Unfortunately, this is a major obstacle for my son and presumably I will have to do all the programming stuff...
-Of course, there are other options, but I won't discuss here.
-===== RS232 Communication in the XXI Century =====
-Modern computers doesn't have an RS232 interface anymore. The replacement for this are the USB ports, that any computer have lots of them. You can simulate an RS232 with an adapter. For my purposes I've bought an adapter from Star Tech called ICUSB232. Check it out:
-[[http://www.amazon.com/StarTech-RS232-Serial-Adapter-Cable/dp/B000067SNB/ref=sr_1_1?ie=UTF8&qid=1388418081&sr=8-1&keywords=StarTech+USB+to+RS232|{{ :linux:img-20131230-wa0000.jpg?direct&300 |}}]]
-==== Checking that it works under Linux ====
-One step is to check that it works properly under linux. Here are the basic steps:
-Don't plug the USB-RS232 adapter yet!!! Before this, run a ''tail -f /var/log/messages'' or ''tail -f /var/log/syslog'' (depending of your version of Linux). To be sure, just run both at a time:
-<code shell>
-$ sudo tail -f /var/log/messages /var/log/syslog
-</code>
-Now, **plug your cable**. You should view something like this:
-<code>
-Dec 30 12:29:18 petrus kernel: [17198.868053] usb 4-1: new full speed USB device number 3 using uhci_hcd
-Dec 30 12:29:18 petrus mtp-probe: checking bus 4, device 3: "/sys/devices/pci0000:00/0000:00:1a.1/usb4/4-1"
-Dec 30 12:29:18 petrus kernel: [17199.032177] pl2303 4-1:1.0: pl2303 converter detected
-Dec 30 12:29:18 petrus kernel: [17199.044237] usb 4-1: pl2303 converter now attached to ttyUSB0
-Dec 30 12:29:19 petrus mtp-probe: bus: 4, device: 3 was not an MTP device
-</code>
-This **''pl2303 converter now attached to ttyUSB0''** means that your USB device is **''/dev/ttyUSB0''**. This is very important in the further steps.
-===== Not Quite C =====
-This is my first attempt and my first try to make the USB-RS232 adaptor to work. I know that Java doesn't have a good USB or serial support, so the second try will be a major problem. My hopes are that NQC, as probably is made natively in C or similar, will have a native support for USB/RS-232 more robust.
-==== Documentation ====
-NQC is a programming language by itself, don't take it slightly. __You can find documentation about NQC here: [[http://bricxcc.sourceforge.net/nqc/]]__.
-==== Hands on ====
-You can install NQC in Ubuntu by typing:
-<code shell>
-$ sudo apt-get install nqc
-</code>
-My first step will be to reach the RS232 adapter correctly and reach the black box. So, connect your RS232 adapter to the black box and make sure this is on, and with the batteries connected. The "on" in this unit means to move the switch to the biggest triangle:
-{{ :linux:20131230_124252.jpg?direct&300 |}}
-**Optionally**, you can turn on the RCX and point it to the black unit, so both can see each other. Remember that the connection is via infrared.
-Now run the following code:
-<code shell>
-nqc -S/dev/ttyUSB0 -msg 123456
-</code>
-When running it, I've observed no error messages and no ''Could not open serial port or USB device'' message. This is important. When running this command, you should see a green light in the black box during a moment:
-{{ :linux:20131230_135707.jpg?direct&300 |}}
-**Other commands to test proper running**
-You can try other commands that doesn't require to have a program like this:
-<code shell>
-$ nqc -S/dev/ttyUSB0 -pgm 1
-No firmware installed on RCX
-</code>
-==== Install the firmware in the RCX (the yellow box) ====
-The next step is installing the firmware in the RCX. There are various firmwares out there, but for NQC we need the official firmware from LEGO.
-===Where is the firmware???===
-Check out the box of mindstorm: it should be a CD which contains the firmware. To get the firmware from the CD, you should face the following scenarios:
-  - The firmware file is in the cd and you can extract directly without hassle. It should be a file like ''firm0309.lgo'' or something like this.
-  - The firmware file is in the CD, but apparently when trying to extract using linux, it fails. This is because the file format of the CD is very old. Try to extract the file using a windows machine or a virtual windows machine. If it is your case, I recommend to make a backup copy of the contents of the CD in another Cd. But copy the contents, not make a copy of the whole cd, because the older filesystem will be kept too.
-  - The firmware file is not in the cd, but it is in one of the *cab files. In that case, you can find instruction in this page:[[http://www.17od.com/2013/01/13/using-lego-mindstorms-on-ubuntu/]]. In a nutshell, ''sudo apt-get install unshield'' and then ''unshield x PATH-TO-YOUR-CAB-FILE''.
-=== Downloading the firmware ===
-Placing the firmware file in the yellow box (the RCX) is called "download the firmware". I particularly think that "download" is not the best word for this, but it's the word used everyplace.
-Run the following command:
-<code shell>
-$ nqc -S/dev/ttyUSB0 -firmware firm0309.lgo
-Downloading firmware:.....................
-</code>
-You should see a message in the RCX about the progress of the download:
-{{ :linux:20131230_135659.jpg?direct&300 |}}
-and a green diode lighting in the black box (it's not easy to see it):
-{{ :linux:20131230_135707.jpg?direct&300 |}}
-After the process is finished, the LCD screen of the RCX should show a 0000 message, and a sound is reproduced:
-{{ :linux:20131230_140058.jpg?direct&300 |}}
-The installation of the firmware will be there until the batteries are removed.
-For example, the following command:
-<code>
-nqc -S/dev/ttyUSB0 -pgm 2
-</code>
-Will have the effect that in the RCX the program number 2 is selected:
-{{ :linux:20131230_142258.jpg?direct&300 |}}
-==== My first program ====
-I've attached a motor to the "C" square of the RCX:
-{{ :linux:20131230_120903.jpg?direct&300 |}}
-And this is my first program:
-<code c>
-task main()
-{
-    OnFwd( OUT_C );
-    Wait( 400 );
-    OnRev( OUT_C );
-    Wait( 400 );
-    Off( OUT_C );
-}
-</code>
-To run and download the program into the RCX, you should do the following:
-<code shell>
-$ nqc -S/dev/ttyUSB0 -d -run Hello.nqc
-Downloading Program:..complete
-Battery Level = 8.7 V
-</code>
-Now, click on the "run" button on the RCX: the program will start, moving the motor in one direction and then in the opposite direction.
-===== Second Attempt: LEJOS =====
-==== Install ant ====
-You should have ''ant'' installed. To do so,
-<code shell>
-$ sudo apt-get install ant
-</code>
-And should have ''libusb-dev'' installed also.
-<code shell>
-sudo apt-get install libusb-dev
-</code>
-After doing that, make sure that the usb.h file is available in your destination system.
-==== Hands on ====
-[[http://www.lejos.org/|Lejos]] is a Java Virtual Machine for the RCX (the yellow box). It's a replacement for the Lego firmware, so, if your CD of mindstorms is broken, it's the perfect solution.
-The web page has a [[http://www.lejos.org/rcx/tutorial/index.html|fantastic tutorial]] that shows the steps to be taken to have this stuff running.
-When I've checked out the web page, the download link didn't work. But you can go directly to the [[http://sourceforge.net/projects/lejos|sourceforge webpage]] in order to download the files.
-When you download and uncompress the file ''leJOS_NXJ_0.9.1beta-3.tar.gz'', you should check out the README.html file.
-Then start by setting the environment variable NXJ_HOME:
-<code shell>
-$ cd LEJOS_NXJ_DIRECTORY   # the files ACKNOWLEDGMENTS.txt, LICENSE.txt, RELEASENOTES.txt should be there
-$ NXJ_HOME=$(pwd)
-$ export NXJ_HOME
-</code>
-Then go to the ''build'' directory and run ''ant''. This is for construct the USB support for java.
-In my case, this command failed. The problem was in the ''build.xml'' file located in NXJ_HOME/build/libnxt. I've reconstructed the compiler command:
-<code shell>
-gcc -Wall -std=gnu99 -fPIC main_jlibnxt.c
-</code>
-And it fails with this error:
-<code>
-main_jlibnxt.c:28:17: fatal error: usb.h: No such file or directory
-</code>
-**Solution:**
-    - Locate the usb.h file in your filesystem: ''find / -iname usb.h 2>/dev/null'': in my system this appears in ''/usr/include/usb.h''
-I've fixed the solution executing the ''make'' command and then:
-<code shell>
-$ cd NXJ_HOME/build
-$ ant
-</code>
-===== Useful Links =====
-  * [[http://www.17od.com/2013/01/13/using-lego-mindstorms-on-ubuntu/]]