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<h1><big><font color="#3c34ec"><i>NuttX RTOS</i></font></big></h1>
<p>Last Updated: February 1, 2008</p>
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<h1>Table of Contents</h1>
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<a href="#overview">Overview</a>.<br>
What is NuttX?
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<a href="#downloads">Downloads</a>.<br>
Where can I get NuttX? What is the current development status?
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<a href="#platforms">Supported Platforms</a>.<br>
What target platforms has NuttX been ported to?
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<a href="#environments">Development Environments</a>.<br>
What kinds of host cross-development platforms can be used with NuttX?
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<a href="#footprint">Memory Footprint</a>.<br>
Just how big is it? Do I have enough memory to use NuttX?
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<a href="#licensing">Licensing</a>.<br>
Are there any licensing restrictions for the use of NuttX? (Almost none)
Will there be problems if I link my proprietary code with NuttX? (No)
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<td>
<a href="#history">Release History</a><br>
What has changed in the last release of NuttX?
What unreleased changes are pending in CVS?
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<td>
<a href="#TODO">Bugs, Issues, <i>Things-To-Do</i></a>.<br>
Software is never finished nor ever tested well enough.
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<a href="#documentation">Other Documentation</a>.<br>
What other NuttX documentation is available?
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<td>
<a href="#trademarks">Trademarks</a>.<br>
Some of the words used in this document belong to other people.
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<a name="overview"><h1>Overview</h1></a>
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Nuttx is a real timed embedded operating system (RTOS).
Its goals are:
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<b>Small Footprint</b>
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Usable in all but the tightest micro-controller environments,
The focus is on the tiny-to-small, deeply embedded environment.
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<b>Rich Feature OS Set</b>
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The goal is to provide implementations of most standard POSIX OS interfaces
to support a rich, multi-threaded development environment for deeply embedded
NON-GOALS: (1) It is not a goal to provide the rich level of OS
features like those provided with Linux.
Small footprint is more important than features.
Standard compliance is more important than small footprint.
(2) There is no MMU-based support for processes.
At present, NuttX assumes a flat address space.
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<b>Highly Scalable</b>
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Fully scalable from tiny (8-bit) to moderate embedded (32-bit).
Scalability with rich feature set is accomplished with:
Many tiny source files, link from static libraries, highly configurable, use of
weak symbols when available.
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<b>Standards Compliance</b>
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<p>
NuttX strives to achieve a high degree of standards compliance.
The primary governing standards are POSIX and ANSI standards.
Additional standard APIs from Unix and other common RTOS's are
adopted for functionality not available under these standards
or for functionality that is not appropriate for the deeply-embedded
RTOS (such as <code>fork()</code>).
</p>
<p>
Because of this standards conformance, software developed under other
standard OSs (such as Linux) should port easily to NuttX.
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<b>Real-Time</b>
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Fully pre-emptible, fixed priority and round-robin scheduling.
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<b>Totally Open</b>
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<b>Feature Set</b>.
Key features of NuttX include:
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<b>Standards Compliant Core Task Management</b>
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<li>Easily extensible to new processor architectures, SoC architecture, or board architectures.
A <a href="NuttxPortingGuide.html">Porting Guide</a> is in development.</li>
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<li>POSIX/ANSI-like task controls, named message queues, counting semaphores, clocks/timers, signals, pthreads, environment variables, filesystem.</li>
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<li>Well documented in the NuttX <a href="NuttxUserGuide.html">User Guide</a>.</li>
</p>
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<b>File system</b>
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<li>Mount-able volumes. Bind mountpoint, filesystem, and block device driver.</li>
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<b>C Library</b>
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<b>Networking</b>
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<p>
<b>NuttX Add-Ons</b>.
The following packages are available to extend the basic NuttX feature set:
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<b>Pascal Compiler with NuttX runtime P-Code interpreter add-on</b>
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<p>
<li>The Pascal add-on is available for download from the
<a href="http://sourceforge.net/project/showfiles.php?group_id=189573">SourceForge</a>
website.</li>
</p>
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<a name="downloads"><h1>Downloads</h1></a>
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The 19th release of NuttX (nuttx-0.3.7) is available for download
from the <a href="http://sourceforge.net/project/showfiles.php?group_id=189573">SourceForge</a>
website.
The change log associated with the release is available <a href="#currentrelease">here</a>.
These unreleased changes are listed <a href="#pendingchanges">here</a>.
This release includes the preliminary port of NuttX to the ZiLOG z16f 16-bit microcontroller.
This port was verified using the ZiLOG z16f2800100zcog Development and the ZiLOG ZDS-II toolchain.
See http://www.zilog.com for further information.
I emphasize that this is a preliminary release of the z16f port and is only alpha or, perhaps,
pre-alpha quality as of this writing.
There are a list of known issues in the TODO file in the <a href="TODO.txt">here</a>
The overall quality of NuttX (excluding the z16f port) continues to improve beyond the late beta level.
The z16f port required numerous changes to NuttX to handle:
<ul>
<li>NEAR and FAR addressing, and</li>
<li>Use of a Windows native toolchain in a Cygwin build environment.</li>
</ul>
In addition to the z16f port, at least one very critical bug was found and corrected in NuttX:
The thread-specific errno value of one task was being randomly trashed when a different thread exitted.
This release were verified on the ZiLOG z16f2800100zcog, Neuros OSD (ARM9), and the simulation platforms.
As usual, any feedback about bugs or suggestions for improvement would be greatly appreciated.
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<a name="platforms"><h1>Supported Platforms</h1></a>
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<b>Linux User Mode</b>
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<p>
A user-mode port of NuttX to the x86 Linux platform is available.
The purpose of this port is primarily to support OS feature development.
<b>STATUS:</b>
Does not support interrupts but is otherwise fully functional.
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<b>TI TMS320C5471</b> (also called <b>C5471</b> or <b>TMS320DA180</b> or <b>DA180</b>).
NuttX operates on the ARM7 of this dual core processor.
This port uses the <a href="http://www.spectrumdigital.com/">Spectrum Digital</a>
evaluation board with a GNU arm-elf toolchain* under Linux or Cygwin.
<b>STATUS:</b>
This port is complete, verified, and included in the initial NuttX release.
</p>
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patacongo
committed
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<p>
<b>NXP LPC214x</b>.
Support is provided for the NXP LPC214x family of processors. In particular,
support is provided for the mcu123.com lpc214x evaluation board (LPC2148).
This port also used the GNU arm-eld toolchain* under Linux or Cygwin.
patacongo
committed
</p>
<p>
<b>STATUS:</b>
Initial coding of this port code complete but has not yet been verified.
patacongo
committed
</p>
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<p>
<b>TI TMS320DM320</b> (also called <b>DM320</b>).
NuttX operates on the ARM9 of this dual core processor.
This port uses the
<a href="http://wiki.neurostechnology.com/index.php/Developer_Welcome">Neuros OSD</a>
This port is complete and verified.
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<b>8052 Microcontroller</b>
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<td>
This port uses the <a href="http://www.pjrc.com/">PJRC</a> 87C52 development system
and the <a href="http://sdcc.sourceforge.net/">SDCC</a> toolchain under Linux or Cygwin.
<b>STATUS:</b>
This port is complete but not stable with timer interrupts enabled.
There seems to be some issue when the stack pointer enters into the indirect IRAM
address space during interrupt handling.
This architecture has not been built in some time will likely have some compilation
problems because of SDCC compiler differences.
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<b>Zilog Z16F</b>
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<p>
<b>Zilog z16f Microncontroller</b>.
This port use the Zilog z16f2800100zcog development kit and the Zilog
ZDS-II Windows command line tools.
The preliminary release of support for the z16f was made available in NuttX version 0.3.7.
</p>
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<b>Zilog Z80</b>
</td>
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<p>
<b>Z80 Instruction Set Simulator</b>.
This port uses the <a href="http://sdcc.sourceforge.net/">SDCC</a> toolchain
under Linux or Cygwin (verified using version 2.6.0).
This port has been verified using only a Z80 instruction simulator.
That simulator can be found in the NuttX CVS
<a href="http://nuttx.cvs.sourceforge.net/nuttx/misc/sims/z80sim/">here</a>.
</p>
<p>
<b>STATUS:</b>
This port is complete and stable to the extent that it can be tested
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<b>Other ports</b>
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<p>
There are partial ports for the TI TMS320DM270 and for MIPS.
</p>
<blockquote>* A highly modified <a href="http://buildroot.uclibc.org/">buildroot</a>
is available that may be used to build a NuttX-compatible arm-elf toolchain under
Linux or Cygwin.</blockquote>
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<a name="environments"><h1>Development Environments</h1></a>
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<b>Linux + GNU make + GCC/binutils</b>
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<p>
The is the most natural development environment for NuttX.
Any version of the GCC/binutils toolchain may be used.
There is a highly modified <a href="http://buildroot.uclibc.org/">buildroot</a>
available for download from the
<a href="http://sourceforge.net/project/showfiles.php?group_id=189573">NuttX SourceForge</a>
page.
This download may be used to build a NuttX-compatible arm-elf toolchain under Linux or Cygwin.
Additional support for m68k, m68hc11, and m68hc12 is available in the
<a href="http://nuttx.cvs.sourceforge.net/nuttx/misc/buildroot/">NuttX CVS</a>.
</p>
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<b>Linux + GNU make + SDCC</b>
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<td>
<p>
Also very usable is the Linux environment using the
<a href="http://sdcc.sourceforge.net/">SDCC</a> compiler.
The SDCC compiler provides support for the 8051/2, z80, hc08, and other microcontrollers.
The SDCC-based logic is less well exercised and you will likely find some compilation
issues if you use parts of NuttX with SDCC that have not been well-tested.
</p>
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<b>Cygwin + GNU make + GCC/binutils</b>
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<p>
This combination works well too.
It works just as well as the native Linux environment except
that compilation and build times are a little longer.
The custom NuttX buildroot referenced above may be build in
the Cygwin environment as well.
</p>
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<b>Cygwin + GNU make + SDCC</b>
</td>
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<td><br></td>
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<p>
I have never tried this combination, but it would probably work just fine.
</p>
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<b>Cygwin + GNU make + Windows Native Toolchain</b>
</td>
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<td><br></td>
<td>
<p>
This is a tougher environment.
In this case, the Windows native toolchain is unaware of the the
Cygwin <i>sandbox</i> and, instead, operates in the native Windows environment.
The primary difficulties with this are:
</p>
<ul>
<li>
<b>Paths</b>.
Full paths for the native toolchain must follow Windows standards.
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For example, the path <code>/home/my\ name/nuttx/include</code> my have to be
converted to something like <code>'C:\cygwin\home\my name\nuttx\include'</code>
to be usable by the toolchain.
</li>
<p>
Fortunately, this conversion is done simply using the <code>cygpath</code> utility.
</p>
<li>
<b>Symbolic Links</b>
NuttX depends on symbolic links to install platform-specific directories in the build system.
On Linux, true symbolic links are used.
On Cygwin, emulated symbolic links are used.
Unfortunately, for native Windows applications that operate outside of the
Cygwin <i>sandbox</i>, these symbolic links cannot be used.
</li>
<p>
The NuttX make system works around this limitation by copying the platform
specific directories in place.
These copied directories make work a little more complex, but otherwise work well.
</p>
</ul>
<p>
At present, on the Zilog Z16F port uses a native Windows toolchain
(the Zilog ZDS-II toolchain).
</p.
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<td>
<p>
The primary environmental dependency of NuttX are (1) GNU make,
(2) bash scripting, and (3) Linux utilities (such as sed).
If you have other platforms that support GNU make or make
utilities that are compatible with GNU make, then it is very
likely that NuttX would work in that environment as well (with some
porting effort). If GNU make is not supported, then some significant
modification of the Make system would be required.
</p>
</td>
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</table></center>
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<td>
<a name="footprint"><h1>Memory Footprint</h1></a>
</td>
</tr>
</table>
The build for this ARM7 target that includes most of the OS features and
a broad range of OS tests. The size of this executable as given by the
Linux <tt>size</tt> command is (3/9/07):
<pre>
text data bss dec hex filename
53272 428 3568 57268 dfb4 nuttx
</pre>
This build for the ARM9 target includes a significant subset of OS
features, a filesystem, Ethernet driver, full TCP/IP, UDP and (minimal)
ICMP stacks (via uIP) and a small network test application: (11/8/07,
configuration netconfig, examples/nettest)
</p>
<pre>
text data bss dec hex filename
<p>
Another build for the ARM9 target includes a minimal OS feature
set, Ethernet driver, full TCP/IP and (minimal) ICMP stacks, and
a small webserver: (11/20/07, configuration uipconfig, examples/uip)
</p>
<pre>
text data bss dec hex filename
52040 72 4148 56260 dbc4 nuttx
</pre>
A reduced functionality OS test for the 8052 target requires only
about 18-19Kb:
<pre>
Stack starts at: 0x21 (sp set to 0x20) with 223 bytes available.
Other memory:
Name Start End Size Max
---------------- -------- -------- -------- --------
PAGED EXT. RAM 0 256
EXTERNAL RAM 0x0100 0x02fd 510 7936
ROM/EPROM/FLASH 0x2100 0x6e55 19798 24384
</pre>
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<tr bgcolor="#e4e4e4">
<td>
<a name="licensing"><h1>Licensing</h1></a>
</td>
</tr>
</table>
<ul>
<p>
NuttX is available under the highly permissive
<a href="http://en.wikipedia.org/wiki/BSD_license">BSD license</a>.
you should feel absolutely free to use NuttX in any environment and
without any concern for jeopardizing any proprietary software that
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<td>
<a name="history"><h1>Release History</h1></a>
</td>
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</table>
<ul>
<p>
The current NuttX Change Log is available in CVS <a href="http://nuttx.cvs.sourceforge.net/*checkout*/nuttx/nuttx/ChangeLog">here</a>.
ChangeLog snapshots associated with the current release are available below.
</p>
</ul>
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<td><img src="favicon.ico"></td>
<td>
</td>
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<td><img src="favicon.ico"></td>
<td>
<a href="#currentrelease">ChangeLog for Current Release</a><br>
</td>
</tr>
<tr>
<td><img src="favicon.ico"></td>
<td>
<a href="#pendingchanges">Unreleased Changes</a>
</td>
</tr>
</table></center>
<table width ="100%">
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<td>
0.3.7 2008-01-31 Gregory Nutt <spudmonkey@racsa.co.cr>
* Added support for the Zilog Z16F using the Zilog Z16F2800100ZCOG
Development Kit.
* Add support toolchains that do not support making of dependencies
* Fix Cygwin build with spaces in directory names
* Name make system changes to deal with non-GNU toolchains (i.e., Zilog)
* Add support for Windows native toolchains that cannot follow Cygwin soft links
* Modified serial driver interface to handle hardware with non-16550A-like
interrupt architecture (like the Z16F)
* Added a "dumb" serial console driver to simplify OS bringup
* Corrected a bug that caused the errno value of one task to be clobbered
when a different task exits. Effects all architectures.
</pre></ul>
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<a name="pendingchanges">Unreleased Changes</a>
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0.3.8 2008-xx-xx Gregory Nutt <spudmonkey@racsa.co.cr>
* Added a test case to verify the Pascal P-Code interpreter
* 'errno' is now defined to be *get_errno_ptr() with no name conflicts
* Integrated pascal test case on the simulation platform. Needs pascal-0.1.1.
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<a name="TODO"><h1>Bugs, Issues, <i>Things-To-Do</i></h1></a>
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The current list of NuttX <i>Things-To-Do</i> in CVS <a href="http://nuttx.cvs.sourceforge.net/*checkout*/nuttx/nuttx/TODO">here</a>.
A snapshot of the <i>To-Do</i> list associated with the current release are available <a href="TODO.txt">here</a>.
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<a name="documentation"><h1>Other Documentation</h1></a>
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