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<html>
<head>
<title>NuttX</title>
</head>
<body background="backgd.gif">
<hr><hr>
<table width ="100%">
  <tr align="center" bgcolor="#e4e4e4">
    <td>
      <h1><big><font color="#3c34ec"><i>NuttX RTOS</i></font></big></h1>
      <p>Last Updated: May 19, 2007</p>
    </td>
  </tr>
</table>
<hr><hr>
<table width ="100%">
  <tr bgcolor="#e4e4e4">
    <td>
  <h1>Table of Contents</h1>
    </td>
  </tr>
</table>

<center><table width ="80%">
<tr>
<td>
<table>
<tr>
  <td><img src="favicon.ico"></td>
  <td><a href="#overview">Overview</a></td>
</tr>
<tr>
  <td><img src="favicon.ico"></td>
  <td><a href="#downloads">Downloads</a></td>
</tr>
<tr>
  <td><img src="favicon.ico"></td>
  <td><a href="#platforms">Supported Platforms</a></td>
</tr>
<tr>
  <td><img src="favicon.ico"></td>
  <td><a href="#footprint">Memory Footprint</a></td>
</tr>
<tr>
  <td><img src="favicon.ico"></td>
  <td><a href="#licensing">Licensing</a></td>
</tr>
<tr>
  <td><img src="favicon.ico"></td>
  <td><a href="#history">Release History</a></td>
</tr>
<tr>
  <td><img src="favicon.ico"></td>
  <td><a href="#documentation">Other Documentation</a></td>
</tr>
</table>
</td>
</td>
</table></center>

<table width ="100%">
  <tr bgcolor="#e4e4e4">
  <td>
    <a name="overview"><h1>Overview</h1></a>
  </td>
  </tr>
</table>

<p>
  <b>Goals</b>.
  Nuttx is a real timed embedded operating system (RTOS).
  Its goals are:
<p>
<center><table width="90%">
<tr>
  <td valign="top"><img src="favicon.ico"></td>
  <td bgcolor="#5eaee1">
    <b>Small Footprint</b>
  </td>
</tr>
<tr>
  <td><br></td>
  <td>
    <p>
      Usable in all but the tightest micro-controller environments,
      The focus is on the tiny-to-small, deeply embedded environment.
    </p>
</tr>
<tr>
  <td valign="top"><img src="favicon.ico"></td>
  <td bgcolor="#5eaee1">
    <b>Rich Feature OS Set</b>
  </td>
</tr>
<tr>
  <td><br></td>
  <td>
    <p>
      The goal is to provide most standard POSIX OS interfaces to support
      a rich, multi-threaded development environment for deeply embedded
      processors.
    </p>
      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>
</tr>
<tr>
  <td valign="top"><img src="favicon.ico"></td>
  <td bgcolor="#5eaee1">
    <b>Highly Scalable</b>
  </td>
</tr>
<tr>
  <td><br></td>
  <td>
    <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>
</tr>
<tr>
  <td valign="top"><img src="favicon.ico"></td>
  <td bgcolor="#5eaee1">
    <b>Standards Compliance</b>
  </td>
</tr>
<tr>
  <td><br></td>
  <td>
    <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>).
    </p>
    <p>
      Because of this standards conformance, software developed under other
      standard OSs (such as Linux) should port easily to NuttX.
    </p>
</tr>
<tr>
  <td valign="top"><img src="favicon.ico"></td>
  <td bgcolor="#5eaee1">
    <b>Real-Time</b>
  </td>
</tr>
<tr>
  <td><br></td>
  <td>
    <p>
      Fully pre-emptible, fixed priority and round-robin scheduling.
    </p>
</tr>
<tr>
  <td valign="top"><img src="favicon.ico"></td>
  <td bgcolor="#5eaee1">
    <b>Totally Open</b>
  </td>
</tr>
<tr>
  <td><br></td>
  <td>
    <p>
      Non-restrictive BSD license.
    </p>
</tr>
</table></center>

<table width ="100%">
  <tr bgcolor="#e4e4e4">
  <td>
    <a name="downloads"><h1>Downloads</h1></a>
  </td>
  </tr>
</table>

<p>
   The 8th release of NuttX (nuttx-0.2.5) is available for download
   from the <a href="http://sourceforge.net/project/showfiles.php?group_id=189573">SourceForge</a>
   website.
</p>

<table width ="100%">
  <tr bgcolor="#e4e4e4">
  <td>
    <a name="platforms"><h1>Supported Platforms</h1></a>
  </td>
  </tr>
</table>

<center><table width="90%">
<tr>
  <td valign="top"><img src="favicon.ico"></td>
  <td bgcolor="#5eaee1">
    <b>Linux User Mode</b>
  </td>
</tr>
<tr>
  <td><br></td>
  <td>
    <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 developement.
    </p>
    <p>
      <b>STATUS:</b>
      Does not support interrupts but is otherwise fully functional.
    </p>
   </td>
</tr>
<tr>
  <td valign="top"><img src="favicon.ico"></td>
  <td bgcolor="#5eaee1">
    <b>ARM7TDMI</b>.
  </td>
</tr>
<tr>
  <td><br></td>
  <td>
    <p>
      <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*.
    </p>
    <p>
      <b>STATUS:</b>
      This port is complete, verified, and included in the initial NuttX release.
    </p>
   </td>
</tr>
<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-eld toolchain*.
    </p>
    <p>
      <b>STATUS:</b>
        This port is in progress and should be available in the nuttx-0.2.6 release.
    </p>
  </td>
</tr>
<tr>
  <td valign="top"><img src="favicon.ico"></td>
  <td bgcolor="#5eaee1">
    <b>ARM9EJS</b>.
  </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>
      with a GNU arm-elf toolchain*.
    </p>
    <p>
      <b>STATUS:</b>
      This port is code complete but totally untested due to hardware issues with my OSD.
    </p>
   </td>
</tr>
<tr>
  <td valign="top"><img src="favicon.ico"></td>
  <td bgcolor="#5eaee1">
    <b>8052 Microcontroller</b>
  </td>
</tr>
<tr>
  <td><br></td>
  <td>
    <p>
      <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.
    </p>
    <p>
     <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.
    </p>
   </td>
</tr>
<tr>
  <td valign="top"><img src="favicon.ico"></td>
  <td bgcolor="#5eaee1">
    <b>Other ports</b>
  </td>
</tr>
<tr>
  <td><br></td>
  <td>
    <p>
      There are partial ports for the TI TMS320DM270 and for MIPS.
    </p>
   </td>
</tr>
</table></center>

<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>

<table width ="100%">
  <tr bgcolor="#e4e4e4">
  <td>
    <a name="footprint"><h1>Memory Footprint</h1></a>
  </td>
  </tr>
</table>

<ul>
<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:
</p>
<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>
</ul>

<table width ="100%">
  <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>.
  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.
</p>
</ul>

<table width ="100%">
  <tr bgcolor="#e4e4e4">
  <td>
    <a name="history"><h1>Release History</h1></a>
  </td>
  </tr>
</table>

<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 2007-03-26 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();
	* Added pthread barrier test
	* Added protection so that errno cannot be modified from
	  interrupt handling.
	* sched_setparam(), sched_setscheduler() now correctly set
	  errno; pthread_setscheduler() now returns the correct errno.
	* Added pthread_setschedprio().
	* Added directories to hold board-specific header files
	* Added directories to hold board-specific drivers

0.2.3 2007-03-29 Gregory Nutt <spudmonkey@racsa.co.cr>

	* mq_receive and mq_send now return errno's appropriately
	* mq_receive and mq_send are now correctly awakened by signals.
	* Fixed an unmatched sched_lock/unlock pair in task_delete().
	* sched_lock must be called in _exit() because operation of
	  task_delete() can cause pending tasks to be merged and a
	  context switch to occur.
	* Added mq_timedreceive() and mq_timedsend()
	* signal mask is now inherited by both child tasks and threads.
	* Improved sharebility of stdout among pthreads (only).  Nothing
	  was broken, but by moving the mutual exclusion logic to a
	  higher level, the printf output is more readable.
	* Fixed a bug in file system cleanup:  A list was being deleted
	  before the buffers contained in the list.
	* Fixed a bug in the wait-for-message-queue-not-empty logic.
	* Added a test of timed mqueue operations; detected and corrected
	  some mqueue errors.
	* Identified and corrected a race condition associated with
	  pthread_join.  In the failure condition, memory was being
	  deallocated while still in use.

0.2.4 2007-04-28 Gregory Nutt <spudmonkey@racsa.co.cr>

	* Verfied c5471 build under Cygwin on WinXP
	* Makesystem changes to better support different SoCs.
	* Made arch/c5471/include and arch/dm320/include identical in
	  preparation for merging into arch/arm
	* Logic from arch/c5471 and arch/dm320 combined into arch/arm.
	  arch/c5471 and arch/dm320 are deprecated and will be removed
	  when the new c5471 and dm320 logic is verified.

0.2.5 2007-05-19 Gregory Nutt <spudmonkey@racsa.co.cr>

	* Corrected some build/configuration issues introduced with the
	  last release.
	* Added support for the NXP 214x processor on the mcu123.com lpc214x
	  development board (untested)
	* Added support for block devices.
	* Simulated target now exports a VFAT filesystem
	* Begin support for VFAT filesystem (missing functionalit)
	* Added mount() and umount()
	* Fix bug in memcmp return value
	* Fix errors in timeslice calculation (several places)
	* Added missing irqrestore() in timer_deletall().
	* close() was not closing the underlying device.
	* Added fsync()
	* Added strspn() and strcspn()

0.2.6 2007-xx-xx Gregory Nutt <spudmonkey@racsa.co.cr>

	* Started m68322
</pre></ul>

<table width ="100%">
  <tr bgcolor="#e4e4e4">
  <td>
    <a name="documentation"><h1>Other Documentation</h1></a>
  </td>
  </tr>
</table>

<ul><table>
<tr>
  <td><img src="favicon.ico"></td>
  <td><a href="NuttxUserGuide.html">User Guide</td>
</tr>
<tr>
  <td><img src="favicon.ico"></td>
  <td><a href="NuttxPortingGuide.html">Porting Guide</td>
</tr>
</center></ul>

</body>
</html>