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<h1><big><font color="#3c34ec"><i>NuttX RTOS</i></font></big></h1>
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<h1>Table of Contents</h1>
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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<td>
<a href="#overview">Overview</a>.<br>
What is NuttX? Look at all those files and features... How can it be a tiny OS?
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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<td>
<a href="#group">NuttX Discussion Group</a>.<br>
Do you want to talk about NuttX features? Do you need some help? Problems? Bugs?
</td>
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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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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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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<td>
<a href="#platforms">Supported Platforms</a>.<br>
What target platforms has NuttX been ported to?
</td>
<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<td>
<a href="#environments">Development Environments</a>.<br>
What kinds of host cross-development platforms can be used with NuttX?
</td>
<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<td>
<a href="#footprint">Memory Footprint</a>.<br>
Just how big is it? Do I have enough memory to use NuttX?
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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<td>
<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 valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<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 valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<td>
<a href="#TODO">Bugs, Issues, <i>Things-To-Do</i></a>.<br>
Software is never finished nor ever tested well enough.
<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<td>
<a href="#documentation">Other Documentation</a>.<br>
What other NuttX documentation is available?
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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<td>
<a href="#trademarks">Trademarks</a>.<br>
Some of the words used in this document belong to other people.
</td>
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<a name="overview"><h1>Overview</h1></a>
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</table>
Nuttx is a real timed embedded operating system (RTOS).
Its goals are:
<p>
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<b>Small Footprint</b>
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<p>
Usable in all but the tightest micro-controller environments,
The focus is on the tiny-to-small, deeply embedded environment.
</p>
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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.
</p>
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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.
</p>
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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.
</p>
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<b>Real-Time</b>
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Fully pre-emptible, fixed priority and round-robin scheduling.
</p>
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<b>Totally Open</b>
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<b>GNU Toolchains</b>
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<p>
Compatible GNU toolchains based on <a href="http://buildroot.uclibc.org/">buildroot</a>
available for
<a href="https://sourceforge.net/project/showfiles.php?group_id=189573&package_id=224585">download</a>
to provide a complete development environment for many architectures.
</p>
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<p>
<b>Feature Set</b>.
Key features of NuttX include:
<p>
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<b>Standards Compliant Core Task Management</b>
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<li>Highly configurable.</li>
</p>
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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>Realtime, deterministic, with support for priority inheritance</li>
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<p>
<li>POSIX/ANSI-like task controls, named message queues, counting semaphores, clocks/timers, signals, pthreads, environment variables, filesystem.</li>
</p>
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<li>Well documented in the NuttX <a href="NuttxUserGuide.html">User Guide</a>.</li>
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<b>File system</b>
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<li>Network, USB (device), serial, CAN, driver architecture.</li>
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<li>RAMDISK, pipes, FIFO, <code>/dev/null</code>, <code>/dev/zero</code> drivers.</li>
</p>
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<li>Mount-able volumes. Bind mountpoint, filesystem, and block device driver.</li>
</p>
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<li>Generic driver for SPI-based MMC/SD/SDH cards.</li>
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<li>ROMFS filesystem support.</li>
</p>
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<p>
<li><a href="NuttXNxFlat.html">NXFLAT</a>.
A new binary format call NXFLAT that can be used to
execute separately linked programs in place in a file system.
</p>
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<b>C Library</b>
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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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<b>Networking</b>
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<li>
A NuttX port of Jeff Poskanzer's <a href="http://acme.com/software/thttpd">THTTPD</a> HTTP server
integrated with <a href="NuttXNxFlat.html">NXFLAT</a> to provide true, embedded CGI.
</li>
</p>
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<b>USB Device Support</b>
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<li><i>Gadget</i>-like architecture for USB device controller drivers and device-dependent USB class drivers.</li>
</p>
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<td><br></td>
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<p>
<li>USB device controller drivers available for the NXP LPC214x and TI DM320.</li>
</p>
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<td><br></td>
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<p>
<li>Device-dependent USB class drivers available for USB serial and for USB mass storage.</li>
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<b>Graphics Support</b>
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<p>
<li>Framebuffer drivers.</li>
</p>
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<td>
<p>
<li>
NX: A graphics library, tiny windowing system and tiny font support.
Documented in the <a href="NXGraphicsSubsystem.html">NX Graphics Subsystem</a>
manual.
</li>
<p>
<b>NuttX Add-Ons</b>.
The following packages are available to extend the basic NuttX feature set:
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<b>NuttShell (NSH)</b>
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<p>
<li>A small, scalable, bash-like shell for NuttX with rich feature set and small footprint.
See the <a href="NuttShell.html">NuttShell User Guide</a>.</li>
</p>
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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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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>
</td>
</tr>
</table></center>
<p>
<b>Look at all those files and features... How can it be a tiny OS?</b>.
The NuttX feature list (above) is fairly long and if you look at the NuttX
source tree, you will see that there are hundreds of source files comprising
NuttX. How can NuttX be a tiny OS with all of that?
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<b>Lots of Features -- More can be smaller!</b>
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<p>
The philosophy behind that NuttX is that lots of features are great... <i>BUT</i>
also that if you don't use those features, then you should not have to pay a penalty
for the unused features.
And, with NuttX, you don't! If you don't use a feature, it will not
be included in the final executable binary.
You only have to pay the penalty of increased footprint for the features
that you actually use.
</p>
<p>
Using a variety of technologies, NuttX can scale from the very tiny to
the moderate-size system. I have executed NuttX with some simple applications
in as little as 32Kb <i>total</i> memory (code and data).
On the other hand, typical, richly featured NuttX builds require more like 64Kb
(and if all of the features are used, this can push 100Kb).
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<b>Many, many files -- More really is smaller!</b>
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<td><br></td>
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<p>
One may be intimidated by the size NuttX source tree. There are hundreds of source files!
How can that be a tiny OS?
Actually, the large number of files is one of the tricks to keep NuttX small and
as scalable as possible.
Most files contain only a single function.
Sometimes just one tiny function with only a few lines of code.
Why?
</p>
<ul>
<li>
<b>Static Libraries</b>.
Because in the NuttX build processed, objects are compiled and saved into
<i>static libraries</i> (<i>archives</i>).
Then, when the file executable is linked, only the object files that are needed
are extracted from the archive and added to the final executable.
By having many, many tiny source files, you can assure that no code that you do
not execute is ever included in the link.
And by having many, tiny source files you have better granularity --
if you don't use that tiny function of even just a few lines of code, it will
not be included in the binary.
</li>
</ul>
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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<td bgcolor="#5eaee1">
<b>Other Tricks</b>
</td>
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<td><br></td>
<td>
<p>
As mentioned above, the use of many, tiny source files and linking from static
libraries keeps the size of NuttX down.
Other tricks used in NuttX include:
</p>
<ul>
<li>
<b>Configuration Files</b>.
Before you build NuttX, you must provide a configuration file that specifies
what features you plan to use and which features you do not.
This configuration file contains a long list of settings that control
what is built into NuttX and what is not.
There are hundreds of such settings
(see the <a href="NuttxPortingGuide.html#apndxconfigs">NuttX Porting Guide</a>
for a partial list that excludes platform specific settings).
These many, many configuration options allow NuttX to be highly tuned to
meet size requirements.
The downside to all of these configuration options is that it greatly
complicates the maintenance of NuttX -- but that is my problem, not yours.
</li>
<li>
<b>Weak Symbols</b>
The GNU toolchain supports <i>weak</i> symbols and these also help to keep
the size of NuttX down.
Weak symbols prevent object files from being drawn into the link even if they
are accessed from source code.
Careful use of weak symbols is another trick for keep unused code out of the
final binary.
</li>
</ul>
</td>
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<td>
<a name="group"><h1>NuttX Discussion Group</h1></a>
</td>
</tr>
</table>
<p>
Most Nuttx-related discussion occurs on the <a href="http://tech.groups.yahoo.com/group/nuttx/" target="_top"><i>Yahoo!</i> NuttX group</a>.
You are cordially invited to <a href="http://groups.yahoo.com/group/nuttx/join" target="_top">join</a>.
I make a special effort to answer any questions and provide any help that I can.
</p>
<table width ="100%">
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<td>
<a name="downloads"><h1>Downloads</h1></a>
</td>
</tr>
</table>
This 47<sup>th</sup> release of NuttX was made on December 21, 2009 and 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>.
The previous NuttX release was 4.14.
The major revision number has been incremented to indicate that an
incompatibility with previous nuttx releases has been introduced.
This version adopts standard fixed width integer names as specified by the
ANSII C99 standard.
The core logic of NuttX is older than that standard and did not conform to it.
If you have applications running on nuttx-4.14, those applications should continue
to build and execute without problem on nuttx-5.0.
However, if you have device drivers or other OS-internal logic, you will probably
have to make some minor changes to your code to use this version.
Below is a summary of those changes:
<li>If you include <code>sys/types.h</code> to get the non-standard, fixed width
integer types (<code>uint32</code>, <code>uint16</code>, <code>ubyte</code>, etc.),
that is no longer necessary.
<li>Instead, you will need to include <code>stdint.h</code> where the new fixed width
integer types are defined (<code>uint32_t</code>, <code>uint16_t</code>, <code>uint8_t</code>, etc.).
<li>You will have to change all occurrences of the following types:
<ul><pre>
uint32 -> uint32_t
uint16 -> uint16_t
ubyte -> uint8_t
uint8 -> uint8_t
sint32 -> int32_t
sint16 -> int16_t
sint8 -> int8_t
</pre></ul>
<li>In addition, the non-standard type <code>boolean</code> must replaced with the
standard type <code>bool</code>.
The type definition for <code>bool</code> is in <code>stdbool.h</code>.
This change in typing caused small changes to many, many files.
The changes was verified that all configurations in the release still build correctly
(other than the SDCC-based configurations).
Regression testing was performed on a few configurations, but it is possible that minor build
issues still exist (if you encounter any, please let me know and I will
help you to fix them).
In the course of the regression testing, several important bugs unrelated
to the type changes were found and corrected.
Two of these are critical bugs:
<li>Fixed an important error in the RX FIFO handling logic of the LM3S6918
Ethernet driver.
<li>Corrected the handling of TCP sequence numbers in the TCP stack.
And other less important bug fixes as detailed in the <a href="#currentrelease">ChangeLog</a>.
</p>
<p>
The primary focus of this release was standards compatibility, but a few new
features were added including a (1) Flash Translation Layer (FTL) that will
support filesystems on a FLASH device and (2) partial ports for the STM32F107VC
and HCS12 M9S12NE64 MCUs. Those ports are very incomplete as of this writing.
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<a name="platforms"><h1>Supported Platforms</h1></a>
</td>
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</table>
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<td bgcolor="#5eaee1">
<b>Linux User Mode</b>
</td>
</tr>
<tr>
<td><br></td>
<td>
A user-mode port of NuttX to the x86 Linux/Cygwin platform is available.
The purpose of this port is primarily to support OS feature development.
<ul>
<p>
<b>STATUS:</b>
Does not support interrupts but is otherwise fully functional.
</p>
</ul>
<td valign="top"><img height="20" width="20" src="favicon.ico"></td>
<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.
<ul>
<p>
<b>STATUS:</b>
This port is complete, verified, and included in the initial NuttX release.
</p>
</ul>
<tr>
<td><br></td>
<td><hr></td>
</tr>
patacongo
committed
<tr>
<td><br></td>
<td>
<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-elf toolchain* under Linux or Cygwin.
patacongo
committed
</p>
<ul>
<p>
<b>STATUS:</b>
This port boots and passes the OS test (examples/ostest).
The port is complete and verified. As of NuttX 0.3.17, the port includes:
timer interrupts, serial console, USB driver, and SPI-based MMC/SD card
support. A verified NuttShell <a href="NuttShell.html">(NSH)</a>
configuration is also available.
</p>
<p>
<b>Development Environments:</b>
1) Linux with native Linux GNU toolchain, 2) Cygwin with Cygwin GNU toolchain, or 3) Cygwin
with Windows native toolchain (CodeSourcery or devkitARM). A DIY toolchain for Linux
or Cygwin is provided by the NuttX
<a href="http://sourceforge.net/project/showfiles.php?group_id=189573&package_id=224585">buildroot</a>
package.
</p>
</ul>
patacongo
committed
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<td><hr></td>
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<td><br></td>
<td>
<p>
<b>STMicro STR71x</b>.
Support is provided for the STMicro STR71x family of processors. In particular,
support is provided for the Olimex STR-P711 evaluation board.
This port also used the GNU arm-elf toolchain* under Linux or Cygwin.
</p>
<ul>
<p>
<b>STATUS:</b>
Integration is complete on the basic port (boot logic, system time, serial console).
Two configurations have been verified: (1) The board boots and passes the OS test
with console output visible on UART0, and the NuttShell <a href="NuttShell.html">(NSH)</a>
is fully functional with interrupt driven serial console. An SPI driver is available
but untested (because the Olimex card slot appears to accept only MMC cards; I have
only SD cards). Additional features are needed: USB driver, MMC integration, to name two.
</p>
<p>
<b>Development Environments:</b>
1) Linux with native Linux GNU toolchain, 2) Cygwin with Cygwin GNU toolchain, or 3) Cygwin
with Windows native toolchain (CodeSourcery or devkitARM). A DIY toolchain for Linux
or Cygwin is provided by the NuttX
<a href="http://sourceforge.net/project/showfiles.php?group_id=189573&package_id=224585">buildroot</a>
package.
</p>
</ul>
<tr>
<td valign="top"><img height="20" width="20" src="favicon.ico"></td>
<td bgcolor="#5eaee1">
<b>ARM920T</b>.
</td>
</tr>
<tr>
<td><br></td>
<td>
<p>
<b>Freescale MC9328MX1</b> or <b>i.MX1</b>.
This port uses the Freescale MX1ADS development board with a GNU arm-elf toolchain*
under either Linux or Cygwin.
</p>
<ul>
<p>
<b>STATUS:</b>
This port is in progress. Coding is complete on the basic port (timer, serial console, SPI).
Verified support for the i.MX1 will be announced in a future release of NuttX (work was
been temporarily stopped to support the Luminary LM3S6918 and I have not yet worked around
some development tool issues.).
</p>
</ul>
<td valign="top"><img height="20" width="20" src="favicon.ico"></td>
</td>
</tr>
<tr>
<td><br></td>
<td>
<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>
<ul>
<p>
<b>STATUS:</b>
The basic port (timer interrupts, serial ports, network, framebuffer, etc.) is complete.
All implemented features have been verified with the exception of the USB device-side
driver; that implementation is complete but untested.
</p>
</ul>
<tr>
<td valign="top"><img height="20" width="20" src="favicon.ico"></td>
<td bgcolor="#5eaee1">
<b>ARM Cortex-M3</b>.
</td>
</tr>
<tr>
<td><br></td>
<td>
<p>
<b>Luminary LM3S6918</b>.
This port uses the <a href=" http://www.micromint.com/">Micromint</a> Eagle-100 development
board with a GNU arm-elf toolchain* under either Linux or Cygwin.
<ul>
<p>
<b>STATUS:</b>
The initial, release of this port was included in NuttX version 0.4.6.
The current port includes timer, serial console, Ethernet, SSI, and microSD support.
There are working configurations the NuttX OS test, to run the <a href="NuttShell.html">NuttShell
(NSH)</a>, the NuttX networking test, and the uIP web server.
</p>
<p>
<b>Development Environments:</b>
1) Linux with native Linux GNU toolchain, 2) Cygwin with Cygwin GNU toolchain, or 3) Cygwin
with Windows native toolchain (CodeSourcery or devkitARM). A DIY toolchain for Linux