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<h1><big><font color="#3c34ec"><i>NuttX RTOS</i></font></big></h1>
<p>Last Updated: March 21, 2007</p>
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<h1>Table of Contents</h1>
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<td><a href="#overview">Overview</a></td>
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<td><a href="#downloads">Downloads</a></td>
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<td><a href="#platforms">Supported Platforms</a></td>
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<td><a href="#footprint">Memory Footprint</a></td>
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<td><a href="#licensing">Licensing</a></td>
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<td><a href="#history">Release History</a></td>
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<td><a href="#documentation">Other Documentation</a></td>
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<a name="overview"><h1>Overview</h1></a>
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<b>Goals</b>.
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 most standard POSIX OS interfaces to support
a rich multi-threaded development environment.
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NON-GOALS: (1) It is not a goal to provide OS subsystems such
as network or USB (but these could obviously be added).
(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 functionaly that is not appropriate for the deeply-embedded
RTOS (such as <code>fork()</code>).
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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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Non-restrictive BSD license.
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<a name="downloads"><h1>Downloads</h1></a>
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<p>
The fourth release of NuttX (nuttx-0.2.1) is avalable for download
from the <a href="http://sourceforge.net/project/showfiles.php?group_id=189573">SourceForge</a>
website.
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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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A user-mode port of NuttX to the x86 Linux platform is available.
The purpose of this port is primarily to support OS feature developement.
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<b>STATUS:</b>
Does not support interrupts but is otherwise fully functional.
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<b>ARM7TDMI</b>.
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<b>TI TMS320C5471</b> (also called a <b>C5471</b> or <b>TMS320DM180</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*.
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<b>STATUS:</b>
This port is complete, verified, and included in the initial NuttX release.
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<b>ARM9EJS</b>.
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<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>
with a GNU arm-elf toolchain*.
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<b>STATUS:</b>
This port is code complete but totally untested due to hardware issues with my OSD.
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<b>8052 Microcontroller</b>
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<b>PJRC 87C52 Development Board</b>.
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.
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<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.
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<b>Other ports</b>
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There are partial ports for the TI TMS320DM270 and for MIPS.
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<blockquote>* A highly modified <a href="http://buildroot.uclibc.org/">buildroot</a>
is available that be used to build a NuttX-compatible arm-elf toolchain.</blockquote>
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<a name="footprint"><h1>Memory Footprint</h1></a>
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<p><b>C5471 (Arm7)</b>
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):
</p>
<pre>
text data bss dec hex filename
53272 428 3568 57268 dfb4 nuttx
</pre>
<p><b>87C52</b>
A reduced functionality OS test for the 8052 target requires only
about 18-19Kb:
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<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
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<p>
NuttX is available under the highly permissive
<a href="http://en.wikipedia.org/wiki/BSD_license">BSD license</a>.
Other than some fine print that you agree to respect the copyright
you should feel absolutely free to use NuttX in any environment and
without any concern for jeopardizing any proprietary software that
you may link with it.
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<a name="history"><h1>Release History</h1></a>
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<ul><pre>
0.1.0 2007-03-09 Gregory Nutt <spudmonkey@racsa.co.cr>
* Initial Release
* Support for Linux user mode simulation and TI
TMS320C5471 (Arm7) provided
0.1.1 2007-03-14 Gregory Nutt <spudmonkey@racsa.co.cr>
* Corrected an error in interrupt level context switching
for C5471
* Added fgets() and gets() logic; verified c5471 console read.
* Corrected error in reading from the C5471 serial port:
Improper use of semaphore can cause deadlock.
* Fixed an error in the memory cleanup: The idle task
cannot take sempahores (because it must always be ready
to run).
* Tasks can now accept a configurable maximum number of
input parameters (argc)
* _task_init() was divided into separate functions that
require fewer parameters. This was necessary to keep
the stack usage down for the 8051/2 (which has only
256 bytes of stack).
* Attempts to use C5471 console from interrupt handlers
can cause errors. Added a special path for this case.
* Refuse calls to sem_wait and sem_trywait from interrupt
handlers. This was happening because interrupt handlers
were calling printf-like functions.
* Added strtok() and strtok_r()
* Added a simple shell called nsh (see examples/nsh).
* Platform support for 8052 is complete but not stable
when the timer interrupt is enabled. Seems to be an
issue when SP enters indirect address space.
* Documentation updates
0.1.2 2007-03-19 Gregory Nutt <spudmonkey@racsa.co.cr>
* Add dirent.h, opendir(), readdir(), closedir(), etc.
* Add strerror()
* Added 'ls' command to nsh
* Added C5471 watchdog driver
* Fixed another bug where free() is called from IDLE task.
Can't do this; the caller must be able to wait for access
to memory.
* Fixed bugs associated with debug output:
Cannot do dbg() in middle of context switch logic.
because it may require use of semaphores and cause
additional context switches. lldbg() is safe.
* Interrupt must be disabled throughout all context switches.
* Separated C5471 serial driver; a shareable part is
in drivers/. ; the C5471 specific part is in arch/C5471.
serial.h defines the interface.
* Fixed mq_receive() and mq_send() -- bad memcpy()
* Fixed C5471 signal deliver logic: use of dbg() and
other actions by use signal handler can alter errno.
need to protect errno during signal handling.
* Fixed uninitialized variable in filesystem that could
cause various problems
* Added a test for roundrobin scheduler.
0.2.1 2007-03-22 Gregory Nutt <spudmonkey@racsa.co.cr>
* Fix error in handing signed decimal in vsprintf().
* Major restructuring of header files to get closer to
POSIX compliance.
* Eliminate compilation warnings that that crept into
recent check-ins
* Add kill()
* Added support for POSIX timers
* Some Documentation updates
* Added support for the Neuros OSD / DM320
0.2.2 2007-xx-xx Gregory Nutt <spudmonkey@racsa.co.cr>
* Created the configs/ directory; separated board configuration
from processor architecture logic
* Add memory leak detection test to examples/ostest
* Corrected memory leak in OS pthread join logic
* Corrected memory leaks in examples/ostest due to failures
to join or detach from pthreads.
* added pthread_once(), pthread_kill(), pthread_sigmask()
* added pthread_barrierattr_*() APIs
* added pthread_barrier_init(), pthread_barrier_destroy(), and
pthread_barrier_wait();
* Started m68322
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<a name="documentation"><h1>Other Documentation</h1></a>
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<td><a href="NuttxUserGuide.html">User Guide</td>
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<td><a href="NuttxPortingGuide.html">Porting Guide</td>
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