Overview Downloads Supported Platforms Memory Footprint Licensing Release History Bugs, Issues, Things-To-Do Other Documentation Trademarks

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 implementations of 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.

Feature Set. Key features of NuttX include:

	Standards Compliant Core Task Management
	Modular, micro-kernel
	Fully pre-emptible.
	Naturally scalable.
	Easily extensible to new processor architectures, SoC architecture, or board architectures. A Porting Guide is in development.
	FIFO and round-robin scheduling.
	Realtime, deterministic.
	POSIX/ANSI-like task controls, named message queues, counting semaphores, clocks/timers, signals, pthreads, environment variables, filesystem.
	VxWorks-like task management and watchdog timers.
	BSD socket interface.
	Extensions to manage pre-emption.
	Well documented in the NuttX User Guide.
	File system
	Tiny in-memory, root pseudo-file-system.
	Supports character and block drivers.
	Network and serial driver architecture.
	Mount-able volumes. Bind mountpoint, filesystem, and block device driver.
	VFAT filesystem support.
	C Library
	Fully integrated into the OS.
	Networking
	TCP/IP, UDP, ICMP stacks.
	Small footprint (based on uIP).
	BSD compatible socket layer.
	Networking utilities.

The 16th release of NuttX (nuttx-0.3.4) 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.

NuttX 0.3.4 is the 5th release containing the integration of a network subsystem and the uIP TCP/IP, UDP, and ICMP stacks based on uIP into NuttX.

This release is primarily a bug-fix release. New features include only:

• TELNET front-end to NSH,
• DHCPC server functionality, and
• C5471 Ethernet driver.

Numerous network related problems were fixed related to DHCPC, UDP input processing, UDP broadcast, send timeouts, and bad compilation when uIP is compiled at high levels of optimizatin.

The level of network reliability is at a strong beta release level. The baseline functionality of NuttX continues to mature and remains at post-beta or production level.

Parts of this release were verified only on the Neuros OSD (DM320 ARM9) platform using the DM90x0 Ethernet driver and other parts on the Spectrum Digital C5471 EVM using the C5471 Ethernet driver. Any feedback about bugs or suggestions for mproving the network reliability/performance would be greatly appreciated.

	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 C5471 or TMS320DA180 or DA180). 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: Initial coding of this port code complete but has not yet been verified.
	ARM926EJS.
	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 complete and verified.
	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. This architecture has not been built in some time will likely have some compilation problems because of SDCC compiler differences.
	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.

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

DM320 (ARM9) This build for the ARM9 target includes a significant subset of OS features, a filesystem, Ethernet driver, full TCP/IP, UDP and (minimal) ICMP stacks (via uIP) and a small network test application: (11/8/07, configuration netconfig, examples/nettest)

   text    data     bss     dec     hex filename
  49472     296    3972   53740    d1ec nuttx

Another build for the ARM9 target includes a minimal OS feature set, Ethernet driver, full TCP/IP and (minimal) ICMP stacks, and a small webserver: (11/20/07, configuration uipconfig, examples/uip)

   text    data     bss     dec     hex filename
  52040      72    4148   56260    dbc4 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

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.

The current NuttX Change Log is available in CVS here. ChangeLog snapshots associated with the current release are available below.

	Change Logs for all releases
	ChangeLog for Current Release
	Unreleased Changes

0.3.4 2007-12-10 Gregory Nutt 

	* Added and partially verified DHCP server logic (netutils/dhcpd)
	* Fix BROADCAST=y compilation problems
	* Fix UDP recvfrom timeout bug
	* Correct processing of input UDP broadcast packets.
	* Verfied basic DHCP client functionality (netutils/dhcpc)
	* Implemented send() timeout logic
	* Added and verifed a TELNETD front end to NSH (examples/nsh)
	* Add a skeleton Ethernet device driver (drivers/net/skeleton.c)
	* Added C5471 Ethernet device driver (arch/arm/src/c5471/c5471_ethernet.c)
	* Found and fixed several problems in uIP when compiled for ARM with optimization.

0.3.5 2007-xx-xx Gregory Nutt 

	* Added inet_ntoa() and ether_ntoa()
	* Added netdev_foreach() to support traversal of registered network devices
	* Added support for 'ifconfig' command to NSH (examples/nsh)
	* Moved MAC and ethernet definitions to net/ethernet.h
	* Fix sim and DM90x0 compilation errors introduced in 0.3.4
	* Fixed errors in C5471 configuration files for examples/uip
	* Modified DHCPC (netutils/dhcpc) so that it should work in environments where
	  there are more than one DHCPD server.
	* NSH ifconfig command now shows uIP status was well (examples/nsh)

The current list of NuttX Things-To-Do in CVS here. A snapshot of the To-Do list associated with the current release are available here.

	User Guide
	Porting Guide
	Change Log
	To-Do List

Trademarks

• ARM, ARM7 ARM7TDMI, ARM9, ARM926EJS are trademarks of Advanced RISC Machines, Limited.
• Cygwin is a trademark of Red Hat, Incorporated.
• Linux is a registered trademark of Linus Torvalds.
• LPC2148 is a trademark of NXP Semiconductors.
• TI is a tradename of Texas Instruments Incorporated.
• UNIX is a registered trademark of The Open Group.
• VxWorks is a registered trademark of Wind River Systems, Incorporated.

NOTE: NuttX is not licensed to use the POSIX trademark. NuttX uses the POSIX standard as a development guideline only.