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<title>NuttX</title>
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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>
</tr>
<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<td>
<a href="#downloads">Downloads</a>.<br>
Where can I get NuttX? What is the current development status?
</td>
<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?
</td>
<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?
</td>
<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?
</td>
<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>
<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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<b>Rich Feature OS Set</b>
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<td><br></td>
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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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<p>
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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<p>
Fully pre-emptible, fixed priority and round-robin scheduling.
</p>
<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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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>
</tr>
<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>
</p>
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<li>Realtime, deterministic, with support for priority inheritance</li>
</p>
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<td><br></td>
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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>On-demand paging.</li>
</p>
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<li>Well documented in the NuttX <a href="NuttxUserGuide.html">User Guide</a>.</li>
<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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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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<td><br></td>
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<p>
<li>RAMDISK, pipes, FIFO, <code>/dev/null</code>, <code>/dev/zero</code> drivers.</li>
</p>
</tr>
<li>Mount-able volumes. Bind mountpoint, filesystem, and block device driver.</li>
</p>
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<td><br></td>
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<p>
<li>Generic driver for SPI-based MMC/SD/SDH cards.</li>
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<p>
<li>ROMFS filesystem support.</li>
</p>
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<td><br></td>
<td>
<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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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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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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</p>
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<p>
<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>
</tr>
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<b>FLASH Support</b>
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<td><br></td>
<td>
<p>
<li><i>MTD</i>-inspired interface for <i>M</i>emory <i>T</i>echnology <i>D</i>evices.</li>
</p>
</tr>
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<td><br></td>
<td>
<p>
<li><i>FTL</i>. Simple <i>F</i>lash <i>T</i>ranslation <i>L</i>ayer support file systems on FLASH.</li>
</p>
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<td><br></td>
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<p>
<li>Support for SPI-based FLASH devices.</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>USB Device Support</b>
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<p>
<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>
<td>
<p>
<li>USB device controller drivers available for the NXP LPC214x, LPC313x, STMicro STM32 and TI DM320.</li>
</p>
</tr>
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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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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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<b>Graphics Support</b>
</td>
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<td><br></td>
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<p>
<li>Framebuffer drivers.</li>
</p>
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<td><br></td>
<td>
<p>
<li>LCD drivers for both parallel and SPI LCDs and OLEDs.</li>
</p>
</tr>
NX: A graphics library, tiny windowing system and tiny font support that works with either framebuffer or LCD drivers.
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>
</td>
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<tr>
<td><br></td>
<td>
<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>
</tr>
<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
<td bgcolor="#5eaee1">
<b>Pascal Compiler with NuttX runtime P-Code interpreter add-on</b>
</td>
</tr>
<tr>
<td><br></td>
<td>
<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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</p>
<center><table width="90%">
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<b>Lots of Features -- More can be smaller!</b>
</td>
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<td><br></td>
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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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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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<b>Many, many files -- More really is smaller!</b>
</td>
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<td><br></td>
<td>
<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>
</td>
</tr>
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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>
</tr>
<tr>
<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>
</tr>
<table width ="100%">
<tr bgcolor="#e4e4e4">
<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%">
<tr bgcolor="#e4e4e4">
<td>
<a name="downloads"><h1>Downloads</h1></a>
</td>
</tr>
</table>
This 60<sup>th</sup> release of NuttX, Version 5.13, was made on November 9, 2010 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>.
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<p>
AVR32, www.mcuzone.com AVR32DEV1
<ul>
<p>
The port for the www.mcuzone.com AVRDEV1 board based on the Atmel
AT32UC3B0256 MCU was (almost) fully integrated. The port now
successfully passes the NuttX OS test (examples/ostest). A
NuttShell (NSH) configuration is in place (see the
<a href="http://www.nuttx.org/NuttShell.html">NSH User Guide</a>).
Testing of that NSH configuration, however, has been postponed
(because it got bumped by the Olimex LPC1766-STK port -- see below)
</p>
<p>
Current Status: I think I have a hardware problem with my serial
port setup. There is a good chance that the NSH port is complete
and functional, but I am not yet able to demonstrate that. At
present, I get nothing coming in the serial RXD line (probably
because the pins are configured wrong or I have the MAX232
connected wrong).
</p>
<p>
A complete port will include drivers for additional AVR32 UC3
devices -- like SPI and USB --- and will be available in a later
release, time permitting.
</p>
</ul>
</p>
<p>
LPC1766, Olimex LPC1766-STK
<ul>
<p>
Support for the Olimex-LPC1766 is newly added to NuttX and is
still undergoing development, test, and integration. Verified
configurations for the NuttX OS test and for the NuttShell (NSH,
see the <a href="ttp://www.nuttx.org/NuttShell.html">NSH User Guide</a>).
Additional USB configurations are in the release as well, but
they have not yet been verified. Goals for NuttX-5.14 include:
(1) An Ethernet driver, (2) Verified USB support, and (3) SD
card support.
</p>
</ul>
</p>
Additional changes and bugfixes as detailed in the ChangeLog.
<table width ="100%">
<tr bgcolor="#e4e4e4">
<td>
<a name="platforms"><h1>Supported Platforms</h1></a>
</td>
</tr>
</table>
<td valign="top"><img height="20" width="20" src="favicon.ico"></td>
<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
</td>
</tr>
<tr>
<td><br></td>
<td><hr></td>
</tr>
<tr>
<td><br></td>
<td>
<p>
<b>NXP LPC2378</b>.
Support is provided for the NXP LPC2378 MCU. In particular,
support is provided for the Olimex-LPC2378 development board.
This port was contributed by Rommel Marcelo is was first released in NuttX-5.3.
This port also used the GNU arm-elf toolchain* under Linux or Cygwin.
</p>
<ul>
<p>
<b>STATUS:</b>
This port boots and passes the OS test (examples/ostest) and includes a
working implementation of the NuttShell (<a href="NuttShell.html">NSH</a>).
The port is complete and verified.
As of NuttX 5.3, the port includes only basic timer interrupts and serial console support.
</p>
<p>
<b>Development Environments:</b> (Same as for the NXP LPC214x).
</p>
</ul>
</td>
</tr>
<tr>
<td><br></td>
<td><hr></td>
</tr>
<tr>
<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 only partially tested. Additional features are needed: USB driver, MMC integration,
to name two (the slot on the board appears to accept on MMC card dimensions; I have only
SD cards).
An SPI-based ENC29J60 Ethernet driver for add-on hardware is under development and
should be available in the NuttX 5.5 release.
</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>