NuttX RTOS

Last Updated: December 18, 2007



Table of Contents

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

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 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.
  • Downloads

    The 17th release of NuttX (nuttx-0.3.5) 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 0.3.5 is the 6th 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 and intended to synchronize with the current CVS contents. See the ChangeLog for a detailed list of changes and fixes.

    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.

    This release was verified only on the Spectrum Digital C5471 EVM using the C5471 Ethernet driver. Any feedback about bugsor suggestions for improvement would be greatly appreciated.

    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 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.

    Memory Footprint

    Licensing

    Release History

    Change Logs for all releases
    ChangeLog for Current Release
    Unreleased Changes
    ChangeLog for Current Release
    Unreleased Changes

    Bugs, Issues, Things-To-Do

    Other Documentation