Ethernut Home Hardware Firmware Tools Download Community
Search | Legals | Deutsch

Creating the Nut/OS Configurator

This article describes the early design of the Nut/OS Configurator. It is largely outdated and kept for historic reasons.

Nut/OS offers three configuration utilities.

The last two are mainly used to create a file named and create a copy of compiler specific Makerules and Makedefs files. The user may modify the include files in include/cfg and then call 'make clean' and 'make install' to rebuild the system.

The file contains a few entries, which are used by the make utility during the rebuild process. It's a plain text file and may be edited manually.

This simple procedure was quite satisfying for Nut/OS 3.4, supporting two similar target CPUs, two host operating systems and two compilers only. However, with the new version 3.5 and upcoming 4.0 of Nut/OS, which is currently under development, many things will completely change. It will be much more configurable, support several target platforms including 32-bit microcontrollers and should not require manual source code modifications when ported to different hardware designs. Obviously the existing configuration tools (or their users) will reach the limits.

WxWidgets Logo Some time had been spent to search the web for similar but more advanced tools and such a tool had been found, the eCos Configuration Tool Version 2. It provides a very versatile GUI based on the highly portable wxWidgets class library. In addition, the configuration rules are based on the Tcl (Tool Command Language, pronounced tickle), which offers capabilities far beyond those simple name=value configurations.

Lua Logo However, the brighter the light, the darker the shadows. The eCos tool makes heavy use of C++ templates, which are difficult to understand and are sometimes difficult to port. Similar, Tcl is heavy stuff too. The author of this preview (quoting Joan Armatrading: Me, myself and I) spent days to make it work on W2K. One really weird part was, that you need to run VC++ in the cygwin environment. Still there had been tons of warnings from the compiler. (Everybody who knows me, is aware, that I hate compiler warnings more than stepping into dog shit.) Beside that, I do not know much about Tcl, but several weeks before starting this project, I stumbled over Lua, a simple and well documented script language designed and implemented by a team at Tecgraf, PUC-Rio, Brazil. The initial intention was, to use Lua as a script language for programming Ethernut applications. I still have no idea, if this is possible, but Lua would also make a good replacement for Tcl as a configuration language.

Nevertheless, the eCos configuration tool is great and exactly what I had been looking for. Within a few days, all the Tcl stuff had been removed. Some days later, the Lua interpreter had been included. Several weeks later the code started working somehow. Bugs had been fixed mainly by throwing things out. As a result, we have code, which is working in most parts, but lost many of its original features. Some are not useful for Nut/OS, others may be re-implemented again later. After having prepared the skeleton, we now hope that more developers will jump in. Of course, I'm aware, that most embedded system developers are not interested in GUI programming. Anyway, if you think this is something for you, please subscribe to the En-Nut-Discussion mailing list to contact us.


The configuration tool is included in the Nut/OS 3.9.9, which is available in the download section.

For insiders: Get the latest development version from CVS HEAD.

Nut/OS Configuration

When creating a Win32 shortcut, make sure to set the working directory to the parent directory of your Nut/OS installation. If you installed Nut/OS in c:\ethernut\nut, then c:\ethernut is the perfect working directory. Or open a DOS window, change to the parent directory and enter nutconf.

When started, a file selection dialog is presented. Navigate to the nut/conf directory, where you should have copied the script files, select the configuration file for your board and press Open. On my German W2K installation, it looks like this.


Here's the same dialog running on Linux:


If you are using an original Ethernut board, then select

For the experimental Nut/OS implementation on the AT91EB40A with ARM7TDMI select

Next the main configuration window will receive the focus.



Sometimes the main window fails to display properly. Drag the window borders, so that the whole view looks similar to the one presented here. The tree on the left side will not be visible, that's still OK. Make sure, that the window part for the tree is large enough. Then terminate the configuration window and open it again. After opening the sample configuration, the tree should be visible. If not or if you completely messed things up, open your Win32 registry editor and remove the complete key at \HKEY_CURRENT_USER\Software\egnite\NutConf. Linux users may remove the hidden file .NutConf in the home directory. This will reset anything to its default.

Next we need to configure the local host environment. If you didn't follow the recommendations for subdirectories above, then the configuration utility may have failed to load the component repository. No big deal, we will configure everything right now. Select Edit/Settings from the main menu. The settings notebook will appear.

nutconf06-linux nutconf03a The first page contains one item only, the path to the so called repository file, name repository.nut. This file contains the main Lua Script and defines the configuration capabilities of the system. You may use the browse button to locate this file.

nutconf03c Let's have a look to the second settings page by clicking on the Build tab.

The source directory should be the one where you installed the Nut/OS source code. The configuration utility will scan this directory for files with basename Makedefs and use the file extension as a platform identifier and add them to the Platform drop down list. Select

nutconf03b The entries for first and last include directories can be ignored for GCC. They may used to set specific include directories, which will be searched before (First) or after (Last) the standard directories in the source tree. When compiling with ImageCraft, then set Last to the ImageCraft include directory (e.g. c:/icc/include).

Usually the configurator will set the first directory to the include subdirectory in the build tree, if this entry had been left empty. Thus, if you add any special path, you may have to add the include dir of the build tree too.

If you are familiar with rebuilding previous Nut/OS releases, you will notice a significant change in this new release. Now we distinguish between the source directory and the build directory.

The big advantage is, that in most cases the source directory will not require any changes. The configuration tool will create all configuration dependant files in the build directory. And this is also the directory, where the Makefiles are placed and executed and the final binaries are created. By changing the build directory, you are able to create different build environments from the same source tree. Or you may select different source trees as well.

Note, that pressing the browse button allows you to create new directories.

The last item on this page specifies the directory, where the resulting Nut/OS libraries will be installed. ImageCraft users should set this to the ImageCraft library path (e.g. c:/icc/lib). For GCC it is a good idea to keep the libraries within the build tree.

nutconf03d On the third page of the settings notebook we specify the paths of the tools to use. Nut/OS comes with its own set of tools located in tools/win32 and tools/linux. This path should be first, followed by one or more paths required by the compiler. Add

Use the full, absolute pathnames and add a semicolon at the end. These entries are not required, if you included them already in your system PATH environment, which is usually the case on Linux. The configurator will add these entries to the system PATH setting when running the compiler. If you are going to rebuild Nut/OS on the command line, no entry is required here.

nutconf03e Entries on the last page of the settings notebook are used to create a sample application directory. Nut/OS comes with a few samples, which demonstrate its capabilities. The configurator can create a new directory for you, copying the sources from the source tree and creating templates for the Makefiles. Such a directory is also quite usefull when writing your own Nut/OS applications.

ImageCraft users do not need to specify and create an application directory. Instead they can directly load prepared ICCAVR projects in the appicc directory into the IDE and use the build-in programmer.

When using GCC, you may select programmer too. This is quite useful, because applications may be build and uploaded to the target board in one go with make burn.

When done with the settings dialog, press OK. The settings will be stored in the Windows registry or a configuration file in the Linux home directory. In case you changed the repository file, you need to stop and restart the configurator now.

Hopefully you can finally see the full component tree in the main window. When using standard Ethernut boards and loading the related configuration, you won't need to change any settings in the component tree except selecting the correct compiler under Tools. You may then skip the rest of this chapter and move forward to build the Nut/OS libraries.


Currently there are four different types of components.

The first library module is named nutarch and is something special. Right now, it doesn't represent a real library. Thus, the underlying modules don't represent source code modules neither. The purpose of this tree branch is to offer some general options, which influence all other components. If you look to the previous screenshot, you will notice, that the microcontroller, which is typically selected after loading a configuration file, had been deselected. As a result, all other libraries are greyed out, because they are disabled. If you select any CPU, they will be at least partly re-enabled.


Furthermore, modules and options may be disabled or enabled depending on specific options being activated or deactivated. Such dependencies are defined in the Lua configuration scripts.

Options, which the user can activate or deactivate are called boolean options. You can change their state by clicking on the check box. Other options and even some boolean options do have values. You can change the option value by clicking into the second column of the component tree.


The property window on the upper right shows the value and some other interesting information about the currently selected option. These properties are used when finally creating the build directory.

Building Nut/OS Libraries

nutconf08 nutconf04-linux
Select Build/Generate Build Tree on the main menu. After confirming the message box, the configuration tool creates a new directory or modifies an already existing one, using the build path specified in the settings dialog. It creates all required Makefiles and, most important, it also creates some C language header files in the the cfg subdirectory. These files are included into the Nut/OS source code to tailor the system to a specific hardware.

Next select Build/Build Nut/OS on the main menu. The configurator will now call the make utility to clean any previous build in the current build tree and create new Nut/OS libraries in the install directory specified in the settings notebook.


If this step fails, then the best chance for detecting the problem is by doing it manually. Go to a shell prompt or DOS window, change to the build directory and type make clean first and then make install.

Creating a Directory for Nut/OS Applications

This step doesn't make much sense for ImageCraft users, who can simply load prepared projects contained in the appicc directory.

When selecting Build/Create Sample Directory on the main menu and confirming the information popup, the configurator will create a new or update an existing directory for application development and fill in a few ready-to-run samples. It is recommended to use these samples as templates for your own projects.

nutconf10 ETHERNUT 1.x NOTE
When creating a new directory, then the configurator will also create the required file Nut/OS AVR libraries are always build for both Ethernet Controllers, the Realtek 8019AS and the SMSC LAN91C111. However, applications need to register the correct device and typically check, wether ETHERNUT2 is defined or not. Newly created files define this item for Ethernut 2.x applications by default. Use any text editor and delete HWDEF line in that file before building your applications.

Under the Hood

As described above, the Nut/OS configuration is based on two main items, the component repository and configuration. Both are specified by Lua scripts, which are not yet fully using the language and the resulting capabilites. Right now the usage is limited to filling Lua variables, which are then retrieved by the configuration tool.

The repository consists of several files. The main file is named repository.nut by default and specifies additional files to be included. All these files are located in the conf directory.

The second group of files specify option values. Again written in Lua, each file contains option settings for a specific target hardware. The file ethernut2.conf serves as a simple example. Users may load this file as a template, modify certain values and store the new configuration in a new configuration file. It is expected, that hardware vendors will provide ready to use Nut/OS configurations.

As you can see in the .conf files, configurations look quite simple. They can be limited to the old name=value scheme. In fact, the repository scripts are not that difficult either. They just add some kind of structure by using Lua arrays. They may look a bit weird first, because Lua recognizes two types of array indices, enumerated and named. It is always a good idea, to look into the Lua language definition and try a few samples using a ready build Lua interpreter.

The following table lists all named array indices known by the Configurator.

Keyword Description Compo. Option
name Unique internal name of a component. Yes No
macro C macro name. This string is used for the #define statement in the header file. No Yes
script Includes the specified configuration file. Yes No
subdir Source code subdirectory. Yes No
brief Brief description, displayed in the Configurator's component tree. Yes Yes
description More detailed description. Provides additional information to the user. Yes Yes
requires List of features required to enable this item. Yes Yes
provides List of features provided by this item. Yes Yes
options List of component options. Yes No
active_if Not used.
flavor Option flavor. Either boolean, data or booldata. No Yes
type Option type. Either integer, bool or enumerated No Yes
ctype Not used.
file Name of the file to store the option. No Yes
sources List of source file of this component. If the component is enabled, the specified files are added to the Makefile. Yes No
targets Explicite target file. Yes No
choices Available choices if the option type is enumerated No Yes
makedefs Items added to No Yes

The Configurator's Source Code

First of all, care has been taken not to force everyone using a either a GUI or rewriting the whole thing. Actually no C++ code directly calls any Lua code. Instead, a C wrapper (did you know that such things exist?) protects C++ from Lua and vice versa. This way, it should be possible to create a simple command line tool written in C and re-use the interpreter interface as well as the parts which create the final build tree.

In any case, you need the Lua source code, which can be downloaded from the Lua download page. Version 5.02 was used for the configuration preview.

If you decided to build the GUI version, you need to download the wxWidget source code from here. While the Lua interpreter will compile almost immediately without problems, it may take some time to set all the required compile options for wxWidgets. Best try some samples included in the wxWidgets distribution before taking the big step to the Nut/OS configuration tool. If you fail, try to get help from the wxWidgets' mailing list on wxWidgets related items. Do not post wxWidgets related questions to the Nut/OS mailing list unless they are closely related to the configuration tool. The same applies for Lua related problems.

Building the Configurator on Linux

The following packages had been recently used to build the Configurator on Debian Linux

Name Version Description
ethernut 3.9.9 Nut/OS source code from CVS head
gcc-3.3 3.3.4-13 GNU C compiler
g++-3.3 3.3.4-13 GNU C++ compiler
wxwin2.4-headers wxWindows Cross-platform C++ GUI toolkit (header files)
libwxbase2.4 wxBase library (runtime) - non-GUI support classes
libwxbase2.4-dev wxBase library (development) - non-GUI support classes
libwxgtk2.4 wxWindows Cross-platform C++ GUI toolkit (GTK+ runtime)
libwxgtk2.4-dev wxWindows Cross-platform C++ GUI toolkit (GTK+ development)
lua50 5.0.2-5 Lua 5.0 small embeddable language
liblua50 5.0.2-5 Main interpreter library for the Lua 5.0
liblua50-dev 5.0.2-5 Main interpreter library for Lua 5.0: Static library and headers
liblualib50 5.0.2-5 Extension library for the Lua 5.0 programming language
liblualib50-dev 5.0.2-5 Extension library for Lua 5.0: Static library and headers

Get the latests Nut/OS source code via anonymous CVS from SourceForge.

cvs login
cvs -z3 co nut
Simply press enter on the password prompt. More info is available at the project's CVS page.

The wxWidgets (this is how wxWindows is called today) libraries for GTK+ are available in tar and rpm format at the wxWidgets website.

Lua rpms can be downloaded from Or you can download source in gziped tar archives from the official Lua download page.

On Debian you can use apt-get with the package names given in the table above. They are part of the testing environment. If you are running stable, make sure to include a proper entry in /etc/apt/sources.list and use

apt-get -t testing libwxbase2.4
for example. It is also a good idea to create or modify /etc/apt/preferences to pin the rest of your system to stable. Check this mailing list post for a more detailed explanation.

Debian's stable release is still at GCC version 2.95. So you have to mix with GCC 3.3 from the testing release as well. Neither wxWidgets nor Lua 5.0 will correctly compile with GCC 2.95.

If you need to keep your previous version of GCC beside 3.3, it may be sometimes difficult to force building with GCC 3.3. One way is to

export MAKEFLAGS="CXX=g++-3.3" "CC=gcc-3.3"
before running make. You can run
make versions
to verify, that the correct versions are in place. The resulting output should be similar to
grep VERSION *.h *.c
nutconf.h:#define VERSION "1.1.1"
nutcomponent.c:#define NUT_CONFIGURE_VERSION   "1.1.1"
wx-config --version
gcc-3.3 --version
gcc-3.3 (GCC) 3.3.4 (Debian 1:3.3.4-13)
Copyright (C) 2003 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO

g++-3.3 --version
g++-3.3 (GCC) 3.3.4 (Debian 1:3.3.4-13)
Copyright (C) 2003 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO

lua -v
Lua 5.0.2  Copyright (C) 1994-2004 Tecgraf, PUC-Rio

Good luck!