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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>
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<a href="#overview">Overview</a>.<br>
What is NuttX?
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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>
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<a href="#platforms">Supported Platforms</a>.<br>
What target platforms has NuttX been ported to?
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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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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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<td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
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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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<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>
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<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 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.
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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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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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<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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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>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>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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<p>
<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 cards.</li>
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<li>ROMFS filesystem support.</li>
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<b>C Library</b>
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<b>Networking</b>
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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>
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<li>USB device controller drivers available for the NXP LPC214x and TI DM320.</li>
</p>
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<li>Device-dependent USB class drivers available for USB serial and for USB mass storage.</li>
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<li>Bult-in USB trace functionality for USB debug.</li>
</p>
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<b>Graphics Support</b>
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<li>Framebuffer drivers.</li>
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<li>Graphics library and tiny windowing system under developement.</li>
</p>
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<p>
<b>NuttX Add-Ons</b>.
The following packages are available to extend the basic NuttX feature set:
<p>
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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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<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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<p><b>nuttx-0.3.19</b>.
The 31<sup>st</sup> release of NuttX (nuttx-0.3.19) 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>.
<ul>
<li>Add <code>poll()</code> and <code>select()</code> APIs that may be used to monitor for data
availability on character devices or TCP/IP sockets.
</li>
<li>Implemented support TCP/IP connection backlog.
This allows <code>poll()</code>/<code>select()</code> to wake-up on new connections to a listener socket.
</li>
<li>Added definition of a framebuffer driver and implement framebuffer drivers for the
simulated platform and the TI DM320 (untested as of the inital check-in).
</li>
<li>Partially developed a graphics framework based on the framebuffer drivers, however,
this will not be ready for use for a few more release.
Currently this includes only a few color conversion routines and some rasteizing functions.
A tiny windowing system is under development but not ready for check-in yet.
<li>Added support for fixed precision math.
</li>
<li>Added support for outgoing multicast packets.
</li>
</ul>
Several bugs were fixed, the most important of which are:
<li>Fixed an important bug in the TCP/IP buffering logic.
When TCP/IP read-ahead is enabled and not recv() is in-place when a TCP/IP packet is received,
the packet is placed into a read-ahead buffer.
However, the old contents of the read-ahead buffer were not being cleared and old data would
contaminate the newly received buffer.
</li>
<li>Changed the behavior of the serial driver read.
It now returns data as it is available rather than waiting for the full requested read size.
This makes functions like <code>fgetc()</code> work much more smoothly.
</li>
These changes were verified only on the Neuros OSD (ARM) and the Linux simulator using a
Linux development environment.
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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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<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.
<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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<td><hr></td>
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patacongo
committed
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<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>
<p>
<b>STATUS:</b>
This port boots and passes the OS test (examples/ostest).
The port is complete and verifed. As of NuttX 0.3.17, the port includes:
timer interrupts, serial console, USB driver, and SPI-based MMC/SD card
support. A verifed NuttShell (NSH) configuration is also available.
patacongo
committed
</p>
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<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>
<p>
<b>STATUS:</b>
Coding is complete on the basic port (boot logic, system time, serial console),
but no testing has been performed due to some problems I am having with my
JTAG wiggler and OpenOCD on Linux.
</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>
The basic port (timer interrupts, serial ports, network, framebuffe, etc.) is complete.
All implemented features have been verified with the exception of the USB device-side
driver; that implementation is complete but completely untested.
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<b>8052 Microcontroller</b>
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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>Renesas/Hitachi SuperH</b>
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<p>
<b>SH-1 SH7032</b>.
This port uses the Hitachi SH-1 Low-Cost Evaluation Board (SH1_LCEVB1), US7032EVB,
with a GNU arm-elf toolchain* under Linux or Cygwin.
</p>
<p>
<b>STATUS:</b>
This port is availble as of release 0.3.18 of NuttX. The port is basically complete
and many examples run correctly. However, there are remaining instabilities that
make the port un-usable. The nature of these is not understood; the behavior is
that certain SH-1 instructions stop working as advertised. This could be a silicon
problem, some pipeline issue that is not handled properly by the gcc 3.4.5 toolchain
(which has very limit SH-1 support to begin with), or perhaps with the CMON debugger.
At any rate, I have exhausted all of the energy that I am willing to put into this cool
old processor for the time being.
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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 initial release of support for the z16f was made available in NuttX version 0.3.7.
</p>
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<p>
<b>Zilog eZ80Acclaim! Microncontroller</b>.
This port uses the ZiLOG ez80f0910200kitg development kit, eZ80F091 part
and the Zilog ZDS-II Windows command line tools.
The development environment is Cygwin under WinXP.
</p>
<p>
<b>STATUS:</b>
This is a work in progress. Verified ez80 support will be announced in a future NuttX release.
</p>
</td>
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<td valign="top"><img height="20" width="20" src="favicon.ico"></td>
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<b>Zilog Z8Encore!</b>
</td>
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<td><br></td>
<td>
<p>
<b>Zilog Z8Encore! Microncontroller</b>.
This port uses the either:
</p>
<ul>
<li>Zilog z8encore000zco development kit, Z8F6403 part, or</li>
<li>Zilog z8f64200100kit development kit, Z8F6423 part</li>
</ul>
<p>
and the Zilog ZDS-II Windows command line tools.
The development environment is Cygwin under WinXP.
</p>
<p>
<b>STATUS:</b>
This release has been verified only on the ZiLOG ZDS-II Z8Encore! chip simulation
as of nuttx-0.3.9.
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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 ELF toolchain under
Linux or Cygwin. Configurations are available in that buildroot to support ARM,
m68k, m68hc11, m68hc12, and SuperH ports.</blockquote>
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<td>
<a name="environments"><h1>Development Environments</h1></a>
</td>
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</table>
<center><table width="90%">
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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 ELF toolchain under Linux or Cygwin.
That toolchain will support ARM, m68k, m68hc11, m68hc12, and SuperH ports.
The buildroot CVS may be accessed 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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<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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<td>
<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>
</td>
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<b>Cygwin + GNU make + SDCC</b>
</td>
</tr>
<tr>
<td><br></td>
<td>
<p>
I have never tried this combination, but it would probably work just fine.
</p>
</td>
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<b>Cygwin + GNU make + Windows Native Toolchain</b>
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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.
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.