Version 32.1 by aas2 on 2016/01/19 15:23
Show last authors
1 = Program LEGO Mindstorms with leJOS and SCCharts =
2
3
4
5 {{toc minLevel="2"/}}
6
7 ----
8
9 == Overview ==
10
11 Mindstorms is a product family from Lego, with sensors, motors and a programmable brick. The newest iteration of the product family is the EV3 programmable brick. Its predecessors are NXT and RCX. In the following we will see how to develop applications for the NXT brick.
12
13 Several open-source, third-party replacements for the offical Lego firmware have been developed. These support many well known programming languages, such as Java, C/C++, Python, Lua, etc. In the following we will use KIELER SCCharts to program Mindstorms running the Lego Java Operating System ([[leJOS>>url:http://www.lejos.org/||shape="rect"]]). Therefore we will first install leJOS NXJ and flash its firmware. Afterwards we will create a simple SCCharts project in KIELER that we will compile and deploy to the NXT brick.
14
15 ----
16
17 == Download and install leJOS ==
18
19 Download and extract the newest archives for your Operating System from [[Sourceforce>>url:http://sourceforge.net/projects/nxt.lejos.p/files/||shape="rect"]] (Linux/Mac) or use the Setup.exe (Windows).
20
21 The further installation is explained in detail at [[http:~~/~~/www.lejos.org/nxt/nxj/tutorial/Preliminaries/GettingStarted.htm>>url:http://www.lejos.org/nxt/nxj/tutorial/Preliminaries/GettingStarted.htm||shape="rect"]].
22
23 Do not forget to flash the download leJOS firmware to the Mindstorms brick as explained in the tutorial!
24
25 === Known issues ===
26
27 ==== Linux ====
28
29 On Linux there is an issue when uploading the firmware because of a kernel module ([[http:~~/~~/ubuntuforums.org/showthread.php?t=1123633>>url:http://ubuntuforums.org/showthread.php?t=1123633||shape="rect"]]). If you can't upload the firmware with your Linux OS, add **blacklist cdc_acm**{{code language="none"}}{{/code}} at the very end of the file **{{code language="none"}}/etc/modprobe.d/blacklist.conf{{/code}}**. Afterwards execute **{{code language="none"}}sudo rmmod cdc_acm{{/code}}**. This will remove the cdc_acm module from the kernel and prevent its restart. Now try to flash the firmware again.
30
31 Another issue is that the development package of **libusb** has to be installed. On Ubuntu you can do this by using **{{code language="none"}}sudo apt-get install libusb-dev{{/code}}**.
32
33 Furthermore, to use USB connection, a java library has to be compiled via **ant**. To do this perform **cd /path/to/leJOS/build** and start **ant**. If the ant build tool is not installed on your system, you can do so via **sudo apt-get install ant**.
34
35 ==== Windows ====
36
37 The setup.exe of the current LEGO Fantom driver for Windows (1.2.0) has an awkward issue. If you get an error message (Developer Error) because an .msi file could not be found, don't panic. The file is part of the downladed archive (in the Products folder) but you have to start it manually.
38
39 ==== Mac OS X ====
40
41 The **leJOS NXJ** tools require a **32 Bit** version of Java. However, newer 32 Bit versions of Java are not longer available for Mac. Thus to use leJOS the installation of **Java 1.6 is required**, which is the last one that supports a 32 Bit mode. You can download the installer for Java 1.6 from [[https:~~/~~/support.apple.com/kb/dl1572?locale=en_US>>url:https://support.apple.com/kb/dl1572?locale=en_US||shape="rect"]]. It will install Java 1.6 to ///System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home// so that the environment variable //LEJOS_NXT_JAVA_HOME//, which is set in the installation instructions, points to the correct path.
42
43 The environment variable LEJOS_NXT_JAVA_HOME is set in the installation tutorial by editing ~~/.profile. However, on a Mac the environment variables defined in this file are not visible for GUI Applications, only for apps started from terminal. Thus to use leJOS together with KIELER one either has to start KIELER from terminal or set the environment variable so that all GUI applications can access it, which seems to be not trivial on Mac (see also [[http:~~/~~/stackoverflow.com/questions/135688/setting-environment-variables-in-os-x>>url:http://stackoverflow.com/questions/135688/setting-environment-variables-in-os-x||shape="rect"]]).
44
45 ----
46
47 == Test the Mindstorm ==
48
49 A simple Hello World application for the Mindstorms is developed as part of the leJOS tutorial [[http:~~/~~/www.lejos.org/nxt/nxj/tutorial/Preliminaries/FirstProgram.htm>>url:http://www.lejos.org/nxt/nxj/tutorial/Preliminaries/FirstProgram.htm||shape="rect"]]
50
51 If this works with your device, you are able to start using KIELER to develop applications for the NXT brick.
52
53 ----
54
55 == Download and Configure KIELER
56 ==
57
58 Download and unpack the nightly build of KIELER for your OS. It is available at the [[doc:Downloads]] page.\\
59
60 **Note:** Java 1.8 is needed on all operating systems, with Java 1.7 not all plugins of KIELER will be loaded. **On Windows**, you will need to download the **32 Bit version of KIELER** – even if you have a 64 bit operating system! Otherwise flashing the brick and uploading to the brick will fail.
61
62 === The Eclipse plugin for leJOS ===
63
64 There is an Eclipse plugin for leJOS which adds a project creation wizard and launch configuration to the platform.
65
66 1. You have to install it via the Eclipse Marketplace (//Help > Eclipse Marketplace...//).
67 OR
68 1. Install the plugin manually (Help > Install new Software...). Use the following update site\\
69 11. for NXT: [[http:~~/~~/www.lejos.org/tools/eclipse/plugin/nxj/>>url:http://www.lejos.org/tools/eclipse/plugin/nxj/||shape="rect"]]
70 11. for EV3: [[http:~~/~~/www.lejos.org/tools/eclipse/plugin/ev3/>>url:http://www.lejos.org/tools/eclipse/plugin/ev3/||shape="rect"]]
71
72 If you have an **NXT** **brick**, install the **leJOS NXJ** Plug-in. If you have an **EV3 brick**, install the **leJOS EV3** plugin.
73
74 [[image:attach:lejos_eclipse_plugin.png]]
75
76 After the installation, the plugin requires a **little configuration**. Go to //Window > Preferences > leJOS NXJ// (//Window > Preferences > leJOS EV3 //respectively) and enter the base directory of your **leJOS** **installation** in the **NXJ_HOME field**.
77
78 For EV3 the plugin requires the IP address to connect to the brick (it may work without, but its safer to directly set the name. Reduces headache ). Check **Connect to named brick** and enter the **IP adress** of the brick (displayed on the brick at startup).
79
80 ----
81
82 == Creating an Example Project ==
83
84 The following shows how to create a project, that will turn on a light if a button is pressed.
85
86 === Create a new project: ===
87
88 1. Choose //File > New > Project > KIELER SCCharts > SCCharts Project//
89 1. In the project creation wizard that opens, select //Mindstorms NXJ// or// Mindstorms EV3// (depending on your brick) as environment and hit //finish//
90 1. The project wizard from the leJOS plugin opens. Set the project name to //Flashlight// and click //finish//.
91 1. The project is created and the model file is opened in an editor (This might take a few seconds).
92
93 === Edit the model: ===
94
95 Change the contents of the model file to the following code and save it.
96
97 {{code language="sct" theme="Eclipse" title="Floodlight.sct"}}
98 scchart Flashlight {
99
100 @Wrapper TouchSensor, S4
101 input bool button;
102
103 @Wrapper Floodlight, S1
104 output bool light;
105
106 initial state lightOff
107 --> lightOn with button / light = true;
108
109 state lightOn
110 --> lightOff with !button / light = false;
111 }
112 {{/code}}
113
114 This model will start in the state lightOff. If the button is pressed, it will turn on the light and change to the corresponding state, where the light is turned off, as soon as the button is not pressed anymore.
115
116 The annotations on the input and output variable are used to define which wrapper code is used to set / read them. **@Wrapper TouchSensor, S4** will set the input variable to true iff the touch sensor on the port S4 is pressed. **@Wrapper Floodlight, S1** on the output variable will turn on the red led of the light sensor that is attatched to port S1 iff the variable is true.
117
118 The available wrapper code snippets are defined in the //snippets// directory of the project in ftl files (FreeMarker template files).
119
120 **Note:** The Floodlight of the EV3 has a pretty high latency when switching between on and off.
121
122 **Note: **To view ftl files with highlighting, you may want to install the //FreeMarker IDE// feature from the JBoss Tools. However, this is not necessary to work with KIELER. JBoss Tools is available in the Eclipse Market Place and via update site. The update site for Eclipse Luna is [[http:~~/~~/download.jboss.org/jbosstools/updates/stable/luna/>>url:http://download.jboss.org/jbosstools/updates/stable/luna/||shape="rect"]] . Note that only the //FreeMarker IDE// feature is required (Abridged JBoss Tools > FreeMarker IDE).**
123 **
124
125 === Launch the project: ===
126
127 With the mouse over the SCT file in the project explorer, perform //Right Click > Run As > KiCo Compilation.//
128
129 A launch config is created, which compiles the model to Java code and creates wrapper code from the annotations in the model file. Afterwards this output is compiled and deployed to the Mindstorms brick, by using the launch shortcut from the leJOS plugin. If any errors occur, you can see them in the Console View.
130
131 For a deeper understanding of the project launch and initialization, take a look at the [[wiki page for Prom>>url:http://rtsys.informatik.uni-kiel.de/confluence/pages/viewpage.action?pageId=13762626||shape="rect"]].
132
133 ----
134
135 == Using the Remote Console (RConsole) ==
136
137 The display of the **NXT brick** is rather small compared to a Monitor. To ease debugging, one can print to a Remote Console (RConsole), if the USB cable is connected. This enables easier collection for example of sensor data.
138
139 To use the RConsole, **uncomment** the **RConsole** lines in the wrapper code template **Main.ftl**. Start the **nxjconsoleviewer** tool in the bin directory of your **leJOS installation**. Now, when **starting the application**, the brick tries to connect with the nxjconsoleviewer. **Press the //Connect//** button. If connected succesfully, RConsole.println(...) commands will be written to this window.
140
141 The **EV3 brick** has a similar feature. However it does not require any code changes. Just run the ev3console program in the bin directory of your leJOS installation from command line. The output of the brick will be printed to this command line.
142
143 ----
144
145 == Problem Solving ==
146
147 The following presents typical issues and how to solve them.
148
149 |=(((
150 Issue
151 )))|=(((
152 Typical Error Messages
153 )))|=(((
154 Description
155 )))|=(((
156 Solution
157 )))
158 |(((
159 leJOS EV3 does not support Java 8
160 )))|(((
161 "java.lang.UnsupportedClassVersionError"
162
163 "unsupported major.minor version"
164 )))|(((
165 You compile the sources in your project with Java 8 and upload them to the brick. However the lejos EV3 does not support Java 8
166 )))|(((
167 Go to the project properties and switch to Java 7 (Right Click on project > Properties > Java Compiler > Compiler compliance level)
168 )))
169 |(% colspan="1" %)(% colspan="1" %)
170 (((
171 Uploading to the brick does not respond
172 )))|(% colspan="1" %)(% colspan="1" %)
173 (((
174
175 )))|(% colspan="1" %)(% colspan="1" %)
176 (((
177 You compile a file successfully and when uploading the result, the connected brick is found. Anyway the upload does not terminate and does not react.
178 )))|(% colspan="1" %)(% colspan="1" %)
179 (((
180 Flash the brick with the current leJOS firmware. If the brick is recognized correctly and the attempt to upload a compiled file fails then the firmware on the brick might be outdated.
181 )))
182 |(% colspan="1" %)(% colspan="1" %)
183 (((
184 Compilation and uploading works from command line but not when using KIELER
185 )))|(% colspan="1" %)(% colspan="1" %)
186 (((
187 This Java instance does not support a 32-bit JVM. Please install the desired version.
188 )))|(% colspan="1" %)(% colspan="1" %)
189 (((
190 You can compile and upload code to the brick using the command line tools but when using KIELER an error message apprears because Java does not support 32-bit JVM.
191 )))|(% colspan="1" %)(% colspan="1" %)
192 (((
193 Set the LEJOS_NXT_JAVA_HOME environment variable, such that it points to an 32-bit JDK and is visible for GUI applications (or at least KIELER). The process to do so differs on every OS. As alternative, execute KIELER from terminal.
194 )))
195 |(% colspan="1" %)(% colspan="1" %)
196 (((
197 Brick does nothing after program finished and prints "Program exit"
198 )))|(% colspan="1" %)(% colspan="1" %)
199 (((
200
201 )))|(% colspan="1" %)(% colspan="1" %)
202 (((
203 A program was uploaded and finished without errors. Afterwards the brick prints "Program exit" but does not open the main menu.
204 )))|(% colspan="1" %)(% colspan="1" %)
205 (((
206 This is normal behaviour if uploading a program in debug mode instead run mode (//Debug As// instead //Run As// in Eclipse). To get back to the main menu, press the ENTER and ESCAPE button of the brick at the same time.
207 )))
208
209
210
211

Navigation

Quick Links

KIELER on GitHub
RTSYS Homepage