NuttX RTOS

Last Updated: May 26, 2007

	Overview
	Downloads
	Supported Platforms
	Memory Footprint
	Licensing
	Release History
	Other Documentation

Overview

Goals. Nuttx is a real timed embedded operating system (RTOS). Its goals are:

	Small Footprint
	Usable in all but the tightest micro-controller environments, The focus is on the tiny-to-small, deeply embedded environment.
	Rich Feature OS Set
	The goal is to provide most standard POSIX OS interfaces to support a rich, multi-threaded development environment for deeply embedded processors. 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.
	Highly Scalable
	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.
	Standards Compliance
	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 `fork()`). Because of this standards conformance, software developed under other standard OSs (such as Linux) should port easily to NuttX.
	Real-Time
	Fully pre-emptible, fixed priority and round-robin scheduling.
	Totally Open
	Non-restrictive BSD license.

Downloads

The 9th release of NuttX (nuttx-0.2.6) is available for download from the SourceForge website. The change log associated with the release is available here. Unreleased changes after this release are avalable in CVS. These unreleased changes are listed here.

Supported Platforms

	Linux User Mode
	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. STATUS: Does not support interrupts but is otherwise fully functional.
	ARM7TDMI.
	TI TMS320C5471 (also called a C5471 or TMS320DM180). NuttX operates on the ARM7 of this dual core processor. This port uses the Spectrum Digital evaluation board with a GNU arm-elf toolchain. STATUS:* This port is complete, verified, and included in the initial NuttX release.
	NXP LPC214x. 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. STATUS:* This port is in progress and should be available in the nuttx-0.2.7 release.
	ARM9EJS.
	TI TMS320DM320 (also called DM320). NuttX operates on the ARM9 of this dual core processor. This port uses the Neuros OSD with a GNU arm-elf toolchain. STATUS:* This port is code complete but totally untested due to hardware issues with my OSD.
	8052 Microcontroller
	PJRC 87C52 Development Board. This port uses the PJRC 87C52 development system and the SDCC toolchain. STATUS: 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.
	Other ports
	There are partial ports for the TI TMS320DM270 and for MIPS.

* A highly modified buildroot is available that be used to build a NuttX-compatible arm-elf toolchain.

Memory Footprint

C5471 (Arm7) 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 size command is (3/9/07):

   text    data     bss     dec     hex filename
  53272     428    3568   57268    dfb4 nuttx

87C52 A reduced functionality OS test for the 8052 target requires only about 18-19Kb:

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

Licensing

NuttX is available under the highly permissive BSD license. 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.

Release History

	Change Logs for Older Releases
	ChangeLog for Current Release
	Unreleased Changes

ChangeLog for Current Release


0.2.6 2007-05-26 Gregory Nutt 

	* Added unlink(), mkdir(), rmdir(), and rename()
	* Fixed several serious FAT errors with oflags handling (&& instead of &)
	* Added FAT support for unlink(), mkdir(), rmdir(), and rename
	* Added FAT support for opendir(), closedir(), readdir(), seekdir(),
	  telldir(), rewindir().
	* Fixed ARM compilation errors introduced in 0.2.5 (that is what I get
	  for only testing on the simulation).

Unreleased Changes



0.2.7 2007-xx-xx Gregory Nutt 

	* Started m68322