NuttX RTOS

Last Updated: November 5, 2012

	Overview. What is NuttX? Look at all those files and features... How can it be a tiny OS?
	NuttX Discussion Group. Do you want to talk about NuttX features? Do you need some help? Problems? Bugs?
	Downloads. Where can I get NuttX? What is the current development status?
	Supported Platforms. What target platforms has NuttX been ported to?
	Development Environments. What kinds of host cross-development platforms can be used with NuttX?
	Memory Footprint. Just how big is it? Do I have enough memory to use NuttX?
	Licensing. Are there any licensing restrictions for the use of NuttX? (Almost none) Will there be problems if I link my proprietary code with NuttX? (No)
	Release History What has changed in the last release of NuttX? What unreleased changes are pending in SVN?
	Bugs, Issues, Things-To-Do. Software is never finished nor ever tested well enough. (Do you want to help develop NuttX? If so, send me an email).
	Other Documentation. What other NuttX documentation is available?
	Trademarks. Some of the words used in this document belong to other people.

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 level of OS features like those provided by Linux. In order to work with smaller MCUs, small footprint must be more important than an extensive feature set. But standard compliance is more important than small footprint. Surely a smaller RTOS could be produced by ignoring standards. Think of NuttX is a tiny Linux work-alike with a much reduced feature set. (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 functionality 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.
	GNU Toolchains
	Compatible GNU toolchains based on buildroot available for download to provide a complete development environment for many architectures.

Feature Set. Key features of NuttX include:

	Standards Compliant Core Task Management
	Fully pre-emptible.
	Naturally scalable.
	Highly configurable.
	Easily extensible to new processor architectures, SoC architecture, or board architectures. A Porting Guide is available.
	FIFO and round-robin scheduling.
	Realtime, deterministic, with support for priority inheritance
	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.
	Inheritable "controlling terminals" and I/O re-direction.
	On-demand paging.
	System logging.
	May be built either as an open, flat embedded RTOS or as a separtely built, secure micro-kernel with a system call interface.
	Well documented in the NuttX User Guide.
	File system
	Tiny, in-memory, root pseudo-file-system.
	Virtual file system supports drivers and mountpoints.
	Mount-able volumes. Bind mountpoint, filesystem, and block device driver.
	Generic system logging (SYSLOG) support.
	FAT12/16/32 filesystem support with optional FAT long file name support¹.
	NFS Client. Client side support for a Network File System (NFS, version 3, UDP).
	NXFFS. The tiny NuttX wear-leveling FLASH file system.
	ROMFS filesystem support.
	A binary loader with support for the following formats: Separately linked ELF modules. Separately linked NXFLAT modules. NXFLAT is a binary format that can be XIP from a file system.
	¹ FAT long file name support may be subject to certain Microsoft patent restrictions if enabled. See the top-level `COPYING` file for details.
	Device Drivers
	Supports character and block drivers as well as specialized driver interfaces.
	Network, USB (host), USB (device), serial, CAN, ADC, DAC, PWM, Quadrature Encoder, and watchdog timer driver architectures.
	RAMDISK, pipes, FIFO, `/dev/null`, `/dev/zero`, `/dev/random`, and loop drivers.
	Generic driver for SPI-based or SDIO-based MMC/SD/SDH cards.
	Power management sub-system.
	ModBus support provided by built-in FreeModBus version 1.5.0.
	C/C++ Libraries
	Standard C Library Fully integrated into the OS.
	Includes floating point support via a Standard Math Library.
	Add-on uClibc++ module provides Standard C++ Library (LGPL).
	Networking
	TCP/IP, UDP, ICMP, IGMPv2 (client) stacks.
	SLIP
	A port cJSON
	Small footprint (based on uIP).
	BSD compatible socket layer.
	Networking utilities (DHCP server and client, SMTP client, TELNET client, FTP server and client, TFTP client, HTTP server and client). Inheritable TELNET sessions (as "controlling terminal")
	NFS Client. Client side support for a Network File System (NFS, version 3, UDP).
	A NuttX port of Jeff Poskanzer's THTTPD HTTP server integrated with the NuttX binary loader to provide true, embedded CGI.
	UDP Network Discover (Contributed by Richard Cochran).
	XML RPC Server (Contributed by Richard Cochran).
	FLASH Support
	MTD-inspired interface for Memory Technology Devices.
	FTL. Simple Flash Translation Layer support file systems on FLASH.
	NXFFS. the NuttX wear-leveling FLASH file system.
	Support for SPI-based FLASH and FRAM devices.
	USB Host Support
	USB host architecture for USB host controller drivers and device-dependent USB class drivers.
	USB host controller drivers available for the NXP LPC17xx.
	Device-dependent USB class drivers available for USB mass storage and HID keyboard.
	USB Device Support
	Gadget-like architecture for USB device controller drivers and device-dependent USB class drivers.
	USB device controller drivers available for the PIC32, NXP LPC17xx, LPC214x, LPC313x, LPC43xx, STMicro STM32 and TI DM320.
	Device-dependent USB class drivers available for USB serial (CDC/ACM and a PL2303 emulation), for USB mass storage, and for a composite CDC/ACM and mass storage device.
	Built-in USB trace functionality for USB debug.
	Graphics Support
	Framebuffer drivers.
	LCD drivers for both parallel and SPI LCDs and OLEDs.
	NX: A graphics library, tiny windowing system and tiny font support that works with either framebuffer or LCD drivers. Documented in the NX Graphics Subsystem manual.
	Font management sub-system.
	NxWidgets: NXWidgets is library of graphic objects, or "widgets," (labels, buttons, text boxes, images, sliders, progress bars, etc.). NXWidgets is written in C++ and integrates seamlessly with the NuttX NX graphics and font management subsystems.
	NxWM: NxWM is the tiny NuttX window manager based on NX and NxWidgets.
	Input Devices
	Touchscreen, USB keyboard, GPIO-based buttons and keypads.
	Analog Devices
	Support for Analog-to-Digital conversion (ADC), Digital-to-Analog conversion (DAC), multiplexers, and amplifiers.
	Motor Control
	Pulse width modulation (PWM) / Pulse count modulation.

NuttX Add-Ons. The following packages are available to extend the basic NuttX feature set:

	NuttShell (NSH)
	A small, scalable, bash-like shell for NuttX with rich feature set and small footprint. See the NuttShell User Guide.
	Pascal Compiler with NuttX runtime P-Code interpreter add-on
	The Pascal add-on is available for download from the SourceForge website.

Look at all those files and features... How can it be a tiny OS?. The NuttX feature list (above) is fairly long and if you look at the NuttX source tree, you will see that there are hundreds of source files comprising NuttX. How can NuttX be a tiny OS with all of that?

	Lots of Features -- More can be smaller!
	The philosophy behind that NuttX is that lots of features are great... BUT also that if you don't use those features, then you should not have to pay a penalty for the unused features. And, with NuttX, you don't! If you don't use a feature, it will not be included in the final executable binary. You only have to pay the penalty of increased footprint for the features that you actually use. Using a variety of technologies, NuttX can scale from the very tiny to the moderate-size system. I have executed NuttX with some simple applications in as little as 32K total memory (code and data). On the other hand, typical, richly featured NuttX builds require more like 64K (and if all of the features are used, this can push 100K).
	Many, many files -- More really is smaller!
	One may be intimidated by the size NuttX source tree. There are hundreds of source files! How can that be a tiny OS? Actually, the large number of files is one of the tricks to keep NuttX small and as scalable as possible. Most files contain only a single function. Sometimes just one tiny function with only a few lines of code. Why? Static Libraries. Because in the NuttX build processed, objects are compiled and saved into static libraries (archives). Then, when the file executable is linked, only the object files that are needed are extracted from the archive and added to the final executable. By having many, many tiny source files, you can assure that no code that you do not execute is ever included in the link. And by having many, tiny source files you have better granularity -- if you don't use that tiny function of even just a few lines of code, it will not be included in the binary.
	Other Tricks
	As mentioned above, the use of many, tiny source files and linking from static libraries keeps the size of NuttX down. Other tricks used in NuttX include: Configuration Files. Before you build NuttX, you must provide a configuration file that specifies what features you plan to use and which features you do not. This configuration file contains a long list of settings that control what is built into NuttX and what is not. There are hundreds of such settings (see the NuttX Porting Guide for a partial list that excludes platform specific settings). These many, many configuration options allow NuttX to be highly tuned to meet size requirements. The downside to all of these configuration options is that it greatly complicates the maintenance of NuttX -- but that is my problem, not yours. Weak Symbols The GNU toolchain supports weak symbols and these also help to keep the size of NuttX down. Weak symbols prevent object files from being drawn into the link even if they are accessed from source code. Careful use of weak symbols is another trick for keep unused code out of the final binary.

NuttX Discussion Group

Most NuttX-related discussion occurs on the Yahoo! NuttX group. You are cordially invited to join. I make a special effort to answer any questions and provide any help that I can.

Downloads

NuttX-6.23 Release Notes

The 90^th release of NuttX, Version 6.23, was made on November 5, 2012, and is available for download from the SourceForge website. Note that the release consists of two tarballs: nuttx-6.23.tar.gz and apps-6.23.tar.gz. Both may be needed (see the top-level nuttx/README.txt file for build information) The change log associated with the release is available here. Unreleased changes after this release are available in SVN. These unreleased changes are also listed here.

This release corresponds with SVN release number: r5313, Note that all SVN information has been stripped from the tarballs. If you need the SVN configuration, you should check out directly from SVN. Revision r5313 should equivalent to release 6.23 of NuttX:

svn checkout -r5313 svn://svn.code.sf.net/p/nuttx/code/trunk nuttx-code

svn checkout -r5313 http://svn.code.sf.net/p/nuttx/code/trunk nuttx-code

Additional new features and extended functionality

RTOS: If both atexit() and on_exit() are enabled, use on_exit() to implement atexit(). Updates for RGMP 4.0.
Binfmt: Add support for loading and executing ELF binary modules from a file system.
Drivers: Maxim MAX11802 touchscreen controller (Petteri Aimonen)
STM32 Driver: Implementation of /dev/random using the STM32 Random Number Generator (RNG).
STM32 Boards: ADC support for the Shenzhou IV board. Relay support for the Shenzhou IV board (both by Darcy Gong).
C++ Standard Library: Support is now included for the add-on uClibc++ C++ standard library support. This includes support for iostreams, strings, STL, RTTI, exceptions -- the complete C++ environment. uClibc++ is provided as a separate add-on package due to licensing issues. Contributed by Qiang Yu and David of the RGMP team.

Add support for __cxa_atexit().
C Standard Library:
Optimized generic and ARM-specific memcpy() function. Optimized memset() function.

Add support for ferror()), feof()), and clearerror()).
Standard Math Library:
Port of the math library from Rhombus OS by Nick Johnson (Darcy Gong).
Applications: New NSH commands: ifup, ifdown, urlencode, urldecode, base64enc, bas64dec, and md5 (Darcy Gong). Extensions to the ifconfig command (Darcy Gong), Add support for NSH telnet login (Darcy Gong). Enancements to NSH ping command to support pinging hosts with very long round-trip times.

Many extensions to the webclient/wget and DNS resolver logic from Darcy Gong. SON, Base64, URL encoding, and MD5 libraries contributed by Darcy Gong.

New examples: ELF loader, JSON, wgetjson, cxxtest, relays.

Bugfixes (see the change log for details) Some of these are very important (marked critical):

Drivers: W25 SPI FLASH
STM32 Drivers: ADC reset
Fraphics: Missing implementation of the blocked method (*critical*, Petteri Aimonen).
C Library: Floating point numbers in printf and related formatting functions (Mike Smith), cf[get|set]speed() (Mike Smith)

As well as other, less critical bugs. See the ChangeLog for additional, detailed changes.

Supported Platforms

The short story (Number of ports follow in parentheses). The state of the various ports vary from board-to-board. Follow the links for the details:

Linux user mode simulation (1)

ARM

ARM7TDMI (5)
ARM920T (1)
ARM926EJS (3)
ARM Cortex-M3 (16)
ARM Cortex-M4 (5)

Atmel AVR

Atmel 8-bit AVR (3)
Atmel AVR32 (1)

Freescale M68HCS12 (2)

Intel

Intel 8052 Microcontroller (1)
Intel 80x86 (2)

MicroChip PIC32MX (MIPS) (4)

Renesas/Hitachi:

Renesas/Hitachi SuperH (1/2)
Renesas M16C/26 (1/2)

Zilog

Zilog Z16F (1)
Zilog eZ80 Acclaim! (1)
Zilog Z8Encore! (2)
Zilog Z80 (2)

The details, caveats and fine print follow:

	Linux User Mode.
	A user-mode port of NuttX to the x86 Linux/Cygwin platform is available. The purpose of this port is primarily to support OS feature development. 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-nuttx-elf toolchain* under Linux or Cygwin. STATUS: This port is complete, verified, and included in the initial NuttX release.

	TI Calypso. This port supports the TI "Calypso" MCU used in various cell phones (and, in particular, by the Osmocom-bb project). Like the c5471, NuttX operates on the ARM7 of this dual core processor. STATUS: This port was contributed by Denis Carilki and includes the work of Denis, Alan Carvalho de Assis, and Stefan Richter. Calypso support first appeared in NuttX-6.17.

	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-nuttx-elf toolchain* under Linux or Cygwin. STATUS: This port boots and passes the OS test (apps/examples/ostest). The port is complete and verified. As of NuttX 0.3.17, the port includes: timer interrupts, serial console, USB driver, and SPI-based MMC/SD card support. A verified NuttShell (NSH) configuration is also available. Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin with Cygwin GNU toolchain, or 3) Cygwin with Windows native toolchain (CodeSourcery or devkitARM). A DIY toolchain for Linux or Cygwin is provided by the NuttX buildroot package.

	NXP LPC2378. Support is provided for the NXP LPC2378 MCU. In particular, support is provided for the Olimex-LPC2378 development board. This port was contributed by Rommel Marcelo is was first released in NuttX-5.3. This port also used the GNU arm-nuttx-elf toolchain* under Linux or Cygwin. STATUS: This port boots and passes the OS test (apps/examples/ostest) and includes a working implementation of the NuttShell (NSH). The port is complete and verified. As of NuttX 5.3, the port includes only basic timer interrupts and serial console support. Development Environments: (Same as for the NXP LPC214x).

	STMicro STR71x. Support is provided for the STMicro STR71x family of processors. In particular, support is provided for the Olimex STR-P711 evaluation board. This port also used the GNU arm-nuttx-elf toolchain* under Linux or Cygwin. STATUS: Integration is complete on the basic port (boot logic, system time, serial console). Two configurations have been verified: (1) The board boots and passes the OS test with console output visible on UART0, and the NuttShell (NSH) is fully functional with interrupt driven serial console. An SPI driver is available but only partially tested. Additional features are needed: USB driver, MMC integration, to name two (the slot on the board appears to accept on MMC card dimensions; I have only SD cards). An SPI-based ENC28J60 Ethernet driver for add-on hardware is available and but has not been fully verified on the Olimex board (due to issues powering the ENC28J60 add-on board). Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin with Cygwin GNU toolchain, or 3) Cygwin with Windows native toolchain (CodeSourcery or devkitARM). A DIY toolchain for Linux or Cygwin is provided by the NuttX buildroot package.
	ARM920T.
	Freescale MC9328MX1 or i.MX1. This port uses the Freescale MX1ADS development board with a GNU arm-nuttx-elf toolchain* under either Linux or Cygwin. STATUS: This port has stalled due to development tool issues. Coding is complete on the basic port (timer, serial console, SPI).
	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-nuttx-elf toolchain* under Linux or Cygwin. The port was performed using the OSD v1.0, development board. STATUS: The basic port (timer interrupts, serial ports, network, framebuffer, etc.) is complete. All implemented features have been verified with the exception of the USB device-side driver; that implementation is complete but untested.

	NXP LPC3131. The port for the NXP LPC3131 on the Embedded Artists EA3131 development board was first released in NuttX-5.1 with a GNU arm-nuttx-elf or arm-eabi toolchain* under Linux or Cygwin (but was not functional until NuttX-5.2). STATUS: The basic EA3131 port is complete and verified in NuttX-5.2 This basic port includes basic boot-up, serial console, and timer interrupts. This port was extended in NuttX 5.3 with a USB high speed driver contributed by David Hewson. David also contributed I2C and SPI drivers plus several important LPC313x USB bug fixes that appear in the NuttX 5.6 release. This port has been verified using the NuttX OS test, USB serial and mass storage tests and includes a working implementation of the NuttShell (NSH). Support for on-demand paging has been developed for the EA3131. That support would all execute of a program in SPI FLASH by paging code sections out of SPI flash as needed. However, as of this writing, I have not had the opportunity to verify this new feature.

	NXP LPC315x. Support for the NXP LPC315x family has been incorporated into the code base as of NuttX-6.4. Support has added for the Embedded Artists EA3152 board in NuttX-6.11. STATUS: Basic support is in place for both the LPC3152 MCU and the EA3152 board. Verification of the port was deferred due to tool issues However, because of the high degree of compatibility between the LPC313x and LPC315x family, it is very likely that the support is in place (or at least very close). At this point, verification of the EA3152 port has been overcome by events and may never happen. However, the port is available for anyone who may want to use it.
	ARM Cortex-M3.
	TI Stellaris LM3S6432. This is a port of NuttX to the Stellaris RDK-S2E Reference Design Kit and the MDL-S2E Ethernet to Serial module (contributed by Mike Smith).

	Luminary/TI Stellaris LM3S6918. This port uses the Micromint Eagle-100 development board with a GNU arm-nuttx-elf toolchain* under either Linux or Cygwin. STATUS: The initial, release of this port was included in NuttX version 0.4.6. The current port includes timer, serial console, Ethernet, SSI, and microSD support. There are working configurations the NuttX OS test, to run the NuttShell (NSH), the NuttX networking test, and the uIP web server. Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin with Cygwin GNU toolchain, or 3) Cygwin with Windows native toolchain (CodeSourcery or devkitARM). A DIY toolchain for Linux or Cygwin is provided by the NuttX buildroot package.

	Luminary/TI Stellaris LM3S6965. This port uses the Stellaris LM3S6965 Ethernet Evalution Kit with a GNU arm-nuttx-elf toolchain* under either Linux or Cygwin. STATUS: This port was released in NuttX 5.5. Features are the same as with the Eagle-100 LM3S6918 described above. The apps/examples/ostest configuration has been successfully verified and an NSH configuration with Telnet support is available. MMC/SD and Networking support was not been thoroughly verified: Current development efforts are focused on porting the NuttX window system (NX) to work with the Evaluation Kits OLED display. NOTE: As it is configured now, you MUST have a network connected. Otherwise, the NSH prompt will not come up because the Ethernet driver is waiting for the network to come up. Development Environments: See the Eagle-100 LM3S6918 above.

	Luminary/TI Stellaris LM3S8962. This port uses the Stellaris EKC-LM3S8962 Ethernet+CAN Evalution Kit with a GNU arm-nuttx-elf toolchain* under either Linux or Cygwin. Contributed by Larry Arnold. STATUS: This port was released in NuttX 5.10. Features are the same as with the Eagle-100 LM3S6918 described above.

	Luminary/TI Stellaris LM3S9B96. Header file support was contributed by Tiago Maluta for this part. Jose Pablo Rojas V. is currently using those header file changes to port NuttX to the TI/Stellaris EKK-LM3S9B96. With any luck, that port should be working and available in the NuttX-6.20 release.

	TI Stellaris LM3S6432S2E. This port uses Serial-to-Ethernet Reference Design Kit (RDK-S2E) and has similar support as for the other Stellaris family members. Configurations are available for the OS test and for the NuttShell (NSH) (see the NSH User Guide). The NSH configuration including networking support with a Telnet NSH console. This port was contributed by Mike Smith. STATUS: This port was will be released in NuttX 6.14.

	STMicro STM32F100x. Chip support for these STM32 "Value Line" family was contributed by Mike Smith and users have reported that they have successful brought up NuttX on there proprietary boards using this logic. However, there is no specific board support for this chip families in the NuttX source tree.

	STMicro STM32F103x. Support for four MCUs and four board configurations are available. MCU support includes all of the high density and connectivity line families. Board supported is available specifically for: STM32F103ZET6, STM32F103RET6, STM32F103VCT, and STM32F103VET6. Boards supported include: A port for the STMicro STM3210E-EVAL development board that features the STM32F103ZET6 MCU. The ISOTEL NetClamps VSN V1.2 ready2go sensor network platform based on the STMicro STM32F103RET6. Contributed by Uros Platise. A port for the HY-Mini STM32v board. This board is based on the STM32F103VCT chip. Contributed by Laurent Latil. The M3 Wildfire development board (STM32F103VET6), version 2. See http://firestm32.taobao.com (the current board is version 3). These ports uses a GNU arm-nuttx-elf toolchain* under either Linux or Cygwin (with native Windows GNU tools or Cygwin-based GNU tools). STATUS: Basic Support/Drivers. The basic STM32 port was released in NuttX version 0.4.12. The basic port includes boot-up logic, interrupt driven serial console, and system timer interrupts. The 0.4.13 release added support for SPI, serial FLASH, and USB device.; The 4.14 release added support for buttons and SDIO-based MMC/SD and verifed DMA support. Verified configurations are available for NuttX OS test, the NuttShell (NSH) example, the USB serial device class, and the USB mass storage device class example. NetClamps VSN. Support for the NetClamps VSN was included in version 5.18 of NuttX. Uros Platise added support for timers, RTC, I2C, FLASH, extended power management and other features. Additional Drivers. Additional drivers and configurations were added in NuttX 6.13 and later releases for the STM32 F1 and F4. F1 compatible drivers include an Ethernet driver, ADC driver, DAC driver, PWM driver, IWDG, WWDG, and CAN drivers. M3 Wildfire. Support for the Wildfire board was included in version 6.22 of NuttX. The board port is basically functional. Not all features have been verified. Support for FAT file system on an an SD card had been verified. The ENC28J60 network is functional (but required lifting the chip select pin on the W25x16 part). Customizations for the v3 version of the Wildfire board are selectable (but untested). Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin with Cygwin GNU toolchain, or 3) Cygwin with Windows native toolchain (RIDE7, CodeSourcery or devkitARM). A DIY toolchain for Linux or Cygwin is provided by the NuttX buildroot package.

	STMicro STM32F107x. Chip support for the STM32 F1 "Connectivity Line" family has been present in NuttX for some time and users have reported that they have successful brought up NuttX on there proprietary boards using this logic. Olimex STM32-P107 Support for the Olimex STM32-P107 was contributed by Max Holtzberg and first appeared in NuttX-6.21. That port features the STMicro STM32F107VC MCU. STATUS: Configurations for the basic OS test and NSH are available and verified. Networking is functional. Shenzhou IV Work is underway as of this writing to port NuttX to the Shenzhou IV development board (See www.armjishu.com) featuring the STMicro STM32F107VCT MCU. If all goes according to plan, this port should be verified and available in NuttX-6.22. STATUS: In progress. The following have been verified: (1) Basic Cortex-M3 port, (2) Ethernet, (3) On-board LEDs

	STMicro STM32F207IG. Support for the STMicro STM3220G-EVAL development board was contributed by Gary Teravskis and first released in NuttX-6.16. STATUS: The peripherals of the STM32 F2 family are compatible with the STM32 F4 family. See discussion of the STM3240G-EVAL board below for further information.

	Atmel AT91SAM3U. This port uses the Atmel SAM3U-EK development board that features the AT91SAM3U4E MCU. This port uses a GNU arm-nuttx-elf or arm-eabi toolchain* under either Linux or Cygwin (with native Windows GNU tools or Cygwin-based GNU tools). STATUS: The basic SAM3U-EK port was released in NuttX version 5.1. The basic port includes boot-up logic, interrupt driven serial console, and system timer interrupts. That release passes the NuttX OS test and is proven to have a valid OS implementation. A configuration to support the NuttShell is also included. NuttX version 5.4 adds support for the HX8347 LCD on the SAM3U-EK board. This LCD support includes an example using the NX graphics system. NuttX version 6.10 adds SPI support. Subsequent NuttX releases will extend this port and add support for SDIO-based SD cards and USB device (and possible LCD support). These extensions may or may not happen soon as my plate is kind of full now. Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin with Cygwin GNU toolchain, or 3) Cygwin with Windows native toolchain (CodeSourcery or devkitARM). A DIY toolchain for Linux or Cygwin is provided by the NuttX buildroot package.

	NXP LPC1766, LPC1768, and LPC1769. Drivers are available for CAN, DAC, Ethernet, GPIO, GPIO interrupts, I2C, UARTs, SPI, SSP, USB host, and USB device. Verified LPC17xx onfigurations are available for three boards. The Nucleus 2G board from 2G Engineering (LPC1768), The mbed board from mbed.org (LPC1768, Contributed by Dave Marples), and The LPC1766-STK board from Olimex (LPC1766). The Embedded Artists base board with NXP LPCXpresso LPC1768. The Micromint Lincoln60 board with an NXP LPC1769. The Nucleus 2G board, the mbed board, and the LPCXpresso all feature the NXP LPC1768 MCU; the Olimex LPC1766-STK board features an LPC1766. All use a GNU arm-nuttx-elf or arm-eabi toolchain* under either Linux or Cygwin (with native Windows GNU tools or Cygwin-based GNU tools). STATUS: The following summarizes the features that has been developed and verified on individual LPC17xx-based boards. These features should, however, be common and available for all LPC17xx-based boards. Nucleus2G LPC1768 Some initial files for the LPC17xx family were released in NuttX 5.6, but The first functional release for the NXP LPC1768/Nucleus2G occured with NuttX 5.7 with Some additional enhancements through NuttX-5.9. That initial, 5.6, basic release included timer interrupts and a serial console and was verified using the NuttX OS test (`apps/examples/ostest`). Configurations available include include a verified NuttShell (NSH) configuration (see the NSH User Guide). The NSH configuration supports the Nucleus2G's microSD slot and additional configurations are available to exercise the the USB serial and USB mass storage devices. However, due to some technical reasons, neither the SPI nor the USB device drivers are fully verified. (Although they have since been verfiied on other platforms; this needs to be revisited on the Nucleus2G). mbed LPC1768 Support for the mbed board was contributed by Dave Marples and released in NuttX-5.11. This port includes a NuttX OS test configuration (see `apps/examples/ostest`). Olimex LPC1766-STK Support for that Olimex-LPC1766-STK board was added to NuttX 5.13. The NuttX-5.14 release extended that support with an Ethernet driver. The NuttX-5.15 release further extended the support with a functional USB device driver and SPI-based micro-SD. The NuttX-5.16 release added a functional USB host controller driver and USB host mass storage class driver. The NuttX-5.17 released added support for low-speed USB devicers, interrupt endpoints, and a USB host HID keyboard class driver. Verified configurations are now available for the NuttX OS test, for the NuttShell with networking and microSD support(NSH, see the NSH User Guide), for the NuttX network test, for the THTTPD webserver, for USB serial deive and USB storage devices examples, and for the USB host HID keyboard driver. Support for the USB host mass storage device can optionally be configured for the NSH example. A driver for the Nokia 6100 LCD and an NX graphics configuration for the Olimex LPC1766-STK have been added. However, neither the LCD driver nor the NX configuration have been verified as of the the NuttX-5.17 release. Embedded Artists base board with NXP LPCXpresso LPC1768 An fully verified board configuration is included in NuttX-6.2. The Code Red toolchain is supported under either Linux or Windows. Verifed configurations include DHCPD, the NuttShell (NSH), NuttX graphis (NX), the NuttX OS test, THTTPD, and USB mass storage device. Micromint Lincoln60 board with an NXP LPC1769 This board configuration was contributed and made available in NuttX-6.20. As contributed board support, I am unsure of what all has been verfied and what has not. See the Microment website for more information about the Lincoln60 board. More to come. Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin with Cygwin GNU toolchain, or 3) Cygwin with Windows native toolchain (CodeSourcery devkitARM or Code Red). A DIY toolchain for Linux or Cygwin is provided by the NuttX buildroot package.
	ARM Cortex-M4.
	FreeScale Kinetis K40. This port uses the Freescale Kinetis KwikStik K40. Refer to the Freescale web site for further information about this board. The Kwikstik is used with the FreeScale Tower System (mostly just to provide a simple UART connection) STATUS: The unverified KwikStik K40 first appeared in NuttX-6.8 As of this writing, the basic port is complete but I accidentally locked my board during the initial bringup. Further development is stalled unless I learn how to unlock the device (or until I get another K40). Additional work remaining includes, among other things: (1) complete the basic bring-up, (2) bring up the NuttShell NSH, (3) develop support for the SDHC-based SD card, (4) develop support for USB host and device, and (2) develop an LCD driver. NOTE: Some of these remaining tasks are shared with the K60 work described below.

	FreeScale Kinetis K60. This port uses the Freescale Kinetis TWR-K60N512 tower system. Refer to the Freescale web site for further information about this board. The TWR-K60N51 includes with the FreeScale Tower System which provides (among other things) a DBP UART connection. STATUS: As of this writing, the basic port is complete and passes the NuttX OS test. An additional, validated configuration exists for the NuttShell (NSH, see the NSH User Guide). This basic TWR-K60N512 first appeared in NuttX-6.8. Ethernet and SD card (SDHC) drivers also exist: The SDHC driver is partially integrated in to the NSH configuration but has some outstanding issues; the Ethernet driver is completely untested. Additional work remaining includes: (1) integrate the Ethernet and SDHC drivers, and (2) develop support for USB host and device. NOTE: Most of these remaining tasks (excluding the Ethernet driver) are the same as the pending K40 tasks described above.

	STMicro STM3240G-EVAL. This port uses the STMicro STM3240G-EVAL board featuring the STM32F407IGH6 MCU. Refer to the STMicro web site for further information about this board. STATUS: NuttX-6.12 The basic port is complete and first appeared in NuttX-6.12. The initial port passes the NuttX OS test and includes a validated configuration for the NuttShell (NSH, see the NSH User Guide) as well as several other configurations. NuttX-6.13-6.16 Additional drivers and configurations were added in NuttX 6.13-6.16. Drivers include an Ethernet driver, ADC driver, DAC driver, PWM driver, CAN driver, F4 RTC driver, Quadrature Encoder, DMA, SDIO with DMA (these should all be compatible with the STM32 F2 family and many should also be compatible with the STM32 F1 family as well). NuttX-6.16 The NuttX 6.16 release also includes and logic for saving/restoring F4 FPU registers in context switches. Networking intensions include support for Telnet NSH sessions and new configurations for DHPCD and the networking test (nettest). NuttX-6.17 The USB OTG device controller driver, and LCD driver and a function I2C driver were added in NuttX 6.17. NuttX-6.18 STM32 IWDG and WWDG watchdog timer drivers were added in NuttX 6.18 (should be compatible with F1 and F2). An LCD driver and a touchscreen driver for the STM3240G-EVAL based on the STMPE811 I/O expander were also added in NuttX 6.18. NuttX-6.21 A USB OTG host controller driver was added in NuttX 6.21.

	STMicro STM32F4-Discovery. This port uses the STMicro STM32F4-Discovery board featuring the STM32F407VGT6 MCU. Refer to the STMicro web site for further information about this board. STATUS: The basic port for the STM32F4-Discovery was contributed by Mike Smith and was first released in NuttX-6.14. Drivers listed for the STM3240G-EVAL may be usable on this plaform as well.

	NXG Technologies LPC4330-Xplorer. This NuttX port is for the LPC4330-Xplorer board from NGX Technologies featuring the NXP LPC4330FET100 MCU. See the NXG website for further information about this board. STATUS: NuttX-6.20 The basic port is complete. The OS test configuration and the basic NSH configurations are present and fully verified. This includes verified support for: SYSTICK system time, pin and GPIO configuration, and a serial console. Several drivers have been copied from the related LPC17xx port but require integration into the LPC43xx: ADC, DAC, GPDMA, I2C, SPI, and SSP. The registers for these blocks are the same in both the LPC43xx and the LPC17xx and they should integrate into the LPC43xx very easily by simply adapting the clocking and pin configuration logic. Other LPC17xx drivers were not brought into the LPC43xx port because these peripherals have been completely redesigned: CAN, Ethernet, USB device, and USB host. So then there is no support for the following LPC43xx peripherals: SD/MMC, EMC, USB0,USB1, Ethernet, LCD, SCT, Timers 0-3, MCPWM, QEI, Alarm timer, WWDT, RTC, Event monitor, and CAN. Some of these can be leveraged from other MCUs that appear to support the same peripheral IP: The LPC43xx USB0 peripheral appears to be the same as the USB OTG peripheral for the LPC31xx. The LPC31xx USB0 device-side driver has been copied from the LPC31xx port but also integration into the LPC43xx (clocking and pin configuration). It should be possible to complete poriting of this LPC31xx driver with a small porting effort. The Ethernet block looks to be based on the same IP as the STM32 Ethernet and, as a result, it should be possible to leverage the NuttX STM32 Ethernet driver with a little more effort. NuttX-6.21 Added support for a SPIFI block driver and for RS-485 option to the serial driver.

	Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin with Cygwin GNU Cortex-M3 or 4toolchain, or 3) Cygwin with Windows native GNU Cortex-M3 or M4 toolchain (CodeSourcery or devkitARM). A DIY toolchain for Linux or Cygwin is provided by the NuttX buildroot package. I use FreeScale's CodeWarrior IDE only to work with the JTAG debugger built into the Kinetis boards. I use the Code Red IDE with the some of the NXP parts and the Atollic toolchain with some of the STMicroelectronics parts.
	Atmel AVR.
	SoC Robotics ATMega128. This port of NuttX to the Amber Web Server from SoC Robotics is partially completed. The Amber Web Server is based on an Atmel ATMega128. STATUS: Work on this port has stalled due to toolchain issues. Complete, but untested code for this port appears in the NuttX 6.5 release.

	Micropendous 3 AT90USB64x and AT90USB6128x. This port of NuttX to the Opendous Micropendous 3 board. The Micropendous3 is may be populated with an AT90USB646, 647, 1286, or 1287. I have only the AT90USB647 version for testing. This version have very limited memory resources: 64K of FLASH and 4K of SRAM. STATUS: The basic port was released in NuttX-6.5. This basic port consists only of a "Hello, World!!" example that demonstrates initialization of the OS, creation of a simple task, and serial console output.

	PJRC Teensy++ 2.0 AT90USB1286. This is a port of NuttX to the PJRC Teensy++ 2.0 board. This board was developed by PJRC. The Teensy++ 2.0 is based on an Atmel AT90USB1286 MCU. STATUS: The basic port was released in NuttX-6.5. This basic port consists of a "Hello, World!!" example that demonstrates initialization of the OS, creation of a simple task, and serial console output as well as a somewhat simplified NuttShell (NSH) configuration (see the NSH User Guide). An SPI driver and a USB device driver exist for the AT90USB as well as a USB mass storage configureation. However, this configuration is not fully debugged as of the NuttX-6.5 release.

	AVR-Specific Issues. The basic AVR port is solid and biggest issue for using AVR is its tiny SRAM memory and its Harvard architecture. Because of the Harvard architecture, constant data that resides to flash is inaccessible using "normal" memory reads and writes (only SRAM data can be accessed "normally"). Special AVR instructions are available for accessing data in FLASH, but these have not been integrated into the normal, general purpose OS. Most NuttX test applications are console-oriented with lots of strings used for printf and debug output. These strings are all stored in SRAM now due to these data accessing issues and even the smallest console-oriented applications can quickly fill a 4-8K memory. So, in order for the AVR port to be useful, one of two things would need to be done: Don't use console applications that required lots of strings. The basic AVR port is solid and your typical deeply embedded application should work fine. Or, Create a special version of printf that knows how to access strings that reside in FLASH (or EEPROM).
	Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin with Cygwin GNU toolchain, or 3) Cygwin with Windows native toolchain. All testing, however, has been performed using the NuttX DIY toolchain for Linux or Cygwin is provided by the NuttX buildroot package. As a result, that toolchain is recommended.

	Atmel AVR32.
	AV32DEV1. This port uses the www.mcuzone.com AVRDEV1 board based on the Atmel AT32UC3B0256 MCU. This port requires a special GNU avr32 toolchain available from atmel.com website. This is a windows native toolchain and so can be used only under Cygwin on Windows. STATUS: This port is has completed all basic development, but there is more that needs to be done. All code is complete for the basic NuttX port including header files for all AT32UC3* peripherals. The untested AVR32 code was present in the 5.12 release of NuttX. Since then, the basic RTOS port has solidified: The port successfully passes the NuttX OS test (apps/examples/ostest). A NuttShell (NSH) configuration is in place (see the NSH User Guide). Testing of that configuration has been postponed (because it got bumped by the Olimex LPC1766-STK port). Current Status: I think I have a hardware problem with my serial port setup. There is a good chance that the NSH port is complete and functional, but I am not yet able to demonstrate that. At present, I get nothing coming in the serial RXD line (probably because the pins are configured wrong or I have the MAX232 connected wrong). The basic, port (including the verified apps/examples/ostest configuration) was be released in NuttX-5.13. A complete port will include drivers for additional AVR32 UC3 devices -- like SPI and USB --- and will be available in a later release, time permitting.
	Freescale M68HCS12.
	MC9S12NE64. Support for the MC9S12NE64 MCU and two boards are included: The Freescale DEMO9S12NE64 Evaluation Board, and The Future Electronics Group NE64 /PoE Badge board. Both use a GNU arm-nuttx-elf toolchain* under Linux or Cygwin. The NuttX buildroot provides a properly patched GCC 3.4.4 toolchain that is highly optimized for the m9s12x family. STATUS: Coding is complete for the MC9S12NE64 and for the NE64 Badge board. However, testing has not yet begun due to issues with BDMs, Code Warrior, and the paging in the build process. Progress is slow, but I hope to see a fully verified MC9S12NE64 port in the near future.
	Intel 8052 Microcontroller.
	PJRC 87C52 Development Board. This port uses the PJRC 87C52 development system and the SDCC toolchain under Linux or Cygwin. 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.
	Intel 80x86.
	QEMU/Bifferboard i486. This port uses the QEMU i486 and the native Linux, Cywgin, MinGW the GCC toolchain under Linux or Cygwin. STATUS: The basic port was code-complete in NuttX-5.19 and verifed in NuttX-6.0. The port was verified using the OS and NuttShell (NSH) examples under QEMU. The port is reported to be functional on the Bifferboard as well. This is a great, stable starting point for anyone interest in fleshing out the x86 port!

	RGMP. RGMP stands for RTOS and GPOS on Multi-Processor. RGMP is a project for running GPOS and RTOS simultaneously on multi-processor platforms You can port your favorite RTOS to RGMP together with an unmodified Linux to form a hybrid operating system. This makes your application able to use both RTOS and GPOS features. See the RGMP Wiki for further information about RGMP. STATUS: This initial port of NuttX to RGMP was provided in NuttX-6.3. This initial RGP port provides only minimal driver support and does not use the native NuttX interrupt system. This is a great, stable starting point for anyone interest in working with NuttX under RGMP!
	MicroChip PIC32 (MIPS).
	PIC32MX250F128D. A port is in progress from the DTX1-4000L "Mirtoo" module from Dimitech. This module uses MicroChip PIC32MX250F128D and the Dimitech DTX1-4000L EV-kit1 V2. See the Dimitech website for further information. STATUS: The basic port is code complete. Two configurations are available: (1) An OS test configuration and a (2) configuration that support the NuttShell (NSH). The OS test configuration is fully functional and proves that we have a basically healthy NuttX port to the Mirtoo. The NSH configuration includes support for a serial console and for the SST25 serial FLASH and the PGA117 amplifier/multiplexer on board the module. The NSH configuration is set up to use the NuttX wear-leveling FLASH file system (NXFFS). The PGA117, however, is not yet fully integrated to support ADC sampling. See the NSH User Guide for further information about NSH. The first verified port to the Mirtoo module was available with the NuttX 6.20 release.

	PIC32MX460F512L. There one two board ports using this chip: PIC32MX Board from PCB Logic Design Co. This port is for the PIC32MX board from PCB Logic Design Co. and used the PIC32MX460F512L. The board is a very simple -- little more than a carrier for the PIC32 MCU plus voltage regulation, debug interface, and an OTG connector. STATUS: The basic port is code complete and fully verified in NuttX 6.13. Available configurations include the OS test and the NuttShell (NSH - see the NSH User Guide). UBW32 Board from Sparkfun This is the port to the Sparkfun UBW32 board. This port uses the original v2.5 board which is based on the MicroChip PIC32MX460F512L. This older version has been replaced with this newer board. See also the UBW32 web site. STATUS: The basic port is code complete and fully verified in NuttX 6.18. Available configurations include the OS test and the NuttShell (NSH - see the NSH User Guide). USB has not yet been fully tested but on first pass appears to be functional.

	PIC32MX440F512H. This port uses the "Advanced USB Storage Demo Board," Model DB-DP11215, from Sure Electronics. This board features the MicroChip PIC32MX440F512H. See the Sure website for further information about the DB-DP11215 board. (I believe that that the DB-DP11215 may be obsoleted now but replaced with the very similar, DB-DP11212. The DB-DP11212 board differs, I believe, only in its serial port configuration.) STATUS: This NuttX port is code complete and has considerable test testing. The port for this board was completed in NuttX 6.11, but still required a few bug fixes before it will be ready for prime time. The fully verified port first appeared in NuttX 6.13. Available configurations include the OS test and the NuttShell (NSH - see the NSH User Guide). An untested USB device-side driver is available in the source tree. A more complete port would include support of the USB OTG port and of the LCD display on this board. Those drivers are not yet available as of this writing.

	PIC32MX795F512L. There one two board ports using this chip: Microchip PIC32 Ethernet Starter Kit. This port uses the Microchip PIC32 Ethernet Starter Kit (DM320004) with the Expansion I/O board. See the Microchip website for further information. STATUS: This port was started and then shelved for some time until I received the Expansion I/O board. The basic Starter Kit (even with the Multimedia Expansion Board, MEB, DM320005)) has no serial port and most NuttX test configurations depend heavily on console output. Verified configurations for the OS test and the NuttShel (NSH) appeared in NuttX-6.16. Board support includes a verified USB (device-side) driver. Also included are a a verified Ethernet driver, a partially verified USB device controller driver, and an unverifed SPI driver. Stay tuned for updates. Mikroelektronika PIC32MX7 Mulitmedia Board (MMB). A port has been completed for the Mikroelektronika PIC32MX7 Multimedia Board (MMB). See http://www.mikroe.com/ for further information about this board. STATUS: Two verified configurations are available: (1) The basic OS test configuration that verfies the correctness port of NuttX, and (2) an extensive NuttShell (NSH) configuration. The NSH configuration includes: (1) Full network support, (2) Verified SPI driver, (3) SPI-based SD Card support, (4) USB device support (including configuration options for the USB mass storage device and the CDC/ACM serial class), and (5) Support for the MIO873QT2 LCD on the PIC32MX7 MMB. The PIC32MX7 MMB's touchscreen is connected directly to the MCU via ADC pins. A touchscreen driver has been developed using the PIC32's ADC capabilities and can be enabled in the NSH configuration. However, additional verification and tuning of this driver is required. Further display/touchscreen verification would require C++ support (for NxWidgets and NxWM). Since I there is no PIC32 C++ is the free version of the MPLAB C32 toolchain, further graphics development is stalled.

	Development Environment: These ports uses either: The LITE version of the PIC32MX toolchain available for download from the MicroChip website, or The Pinguino MIPS ELF toolchain avaiable from the Pinquino website.

	Renesas/Hitachi SuperH.
	SH-1 SH7032. This port uses the Hitachi SH-1 Low-Cost Evaluation Board (SH1_LCEVB1), US7032EVB, with a GNU ELF toolchain* under Linux or Cygwin. STATUS: This port is available as of release 0.3.18 of NuttX. The port is basically complete and many examples run correctly. However, there are remaining instabilities that make the port un-usable. The nature of these is not understood; the behavior is that certain SH-1 instructions stop working as advertised. This could be a silicon problem, some pipeline issue that is not handled properly by the gcc 3.4.5 toolchain (which has very limit SH-1 support to begin with), or perhaps with the CMON debugger. At any rate, I have exhausted all of the energy that I am willing to put into this cool old processor for the time being.
	Renesas M16C/26.
	Renesas M16C/26 Microncontroller. This port uses the Renesas SKP16C26 Starter kit and the GNU M32C toolchain. The development environment is either Linux or Cygwin under WinXP. STATUS: Initial source files released in nuttx-0.4.2. At this point, the port has not been integrated; the target cannot be built because the GNU `m16c-nuttx-elf-ld` link fails with the following message: `m32c-nuttx-elf-ld: BFD (GNU Binutils) 2.19 assertion fail /home/Owner/projects/nuttx/buildroot/toolchain_build_m32c/binutils-2.19/bfd/elf32-m32c.c:482` Where the reference line is: /* If the symbol is out of range for a 16-bit address, we must have allocated a plt entry. / BFD_ASSERT (plt_offset != (bfd_vma) -1); No workaround is known at this time. This is a show stopper for M16C for the time being.
	Zilog Z16F.
	Zilog z16f Microncontroller. This port use the Zilog z16f2800100zcog development kit and the Zilog ZDS-II Windows command line tools. The development environment is Cygwin under WinXP. STATUS: The initial release of support for the z16f was made available in NuttX version 0.3.7.
	Zilog eZ80 Acclaim!.
	Zilog eZ80Acclaim! Microncontroller. There are two eZ80Acclaim! ports: One uses the ZiLOG ez80f0910200kitg development kit, and The other uses the ZiLOG ez80f0910200zcog-d development kit. Both boards are based on the eZ80F091 part and both use the Zilog ZDS-II Windows command line tools. The development environment is Cygwin under WinXP. STATUS: Integration and testing of NuttX on the ZiLOG ez80f0910200zcog-d is complete. The first integrated version was released in NuttX version 0.4.2 (with important early bugfixes in 0.4.3 and 0.4.4). As of this writing, that port provides basic board support with a serial console, SPI, and eZ80F91 EMAC driver.
	Zilog Z8Encore!.
	Zilog Z8Encore! Microncontroller. This port uses the either: Zilog z8encore000zco development kit, Z8F6403 part, or Zilog z8f64200100kit development kit, Z8F6423 part and the Zilog ZDS-II Windows command line tools. The development environment is Cygwin under WinXP. STATUS: This release has been verified only on the ZiLOG ZDS-II Z8Encore! chip simulation as of nuttx-0.3.9.
	Zilog Z80.
	Z80 Instruction Set Simulator. This port uses the SDCC toolchain under Linux or Cygwin (verified using version 2.6.0). This port has been verified using only a Z80 instruction simulator. That simulator can be found in the NuttX SVN here. STATUS: This port is complete and stable to the extent that it can be tested using an instruction set simulator.

	XTRS: TRS-80 Model I/III/4/4P Emulator for Unix. A very similar Z80 port is available for XTRS, the TRS-80 Model I/III/4/4P Emulator for Unix. That port also uses the SDCC toolchain under Linux or Cygwin (verified using version 2.6.0). STATUS: Basically the same as for the Z80 instruction set simulator. This port was contributed by Jacques Pelletier.

* A highly modified buildroot is available that may be used to build a NuttX-compatible ELF toolchain under Linux or Cygwin. Configurations are available in that buildroot to support ARM, Cortex-M3, avr, m68k, m68hc11, m68hc12, m9s12, blackfin, m32c, h8, and SuperH ports.

Development Environments

	Linux + GNU `make` + GCC/binutils
	The is the most natural development environment for NuttX. Any version of the GCC/binutils toolchain may be used. There is a highly modified buildroot available for download from the NuttX SourceForge page. This download may be used to build a NuttX-compatible ELF toolchain under Linux or Cygwin. That toolchain will support ARM, m68k, m68hc11, m68hc12, and SuperH ports. The buildroot SVN may be accessed in the NuttX SVN.
	Linux + GNU `make` + SDCC
	Also very usable is the Linux environment using the SDCC compiler. The SDCC compiler provides support for the 8051/2, z80, hc08, and other microcontrollers. The SDCC-based logic is less well exercised and you will likely find some compilation issues if you use parts of NuttX with SDCC that have not been well-tested.
	Cygwin + GNU `make` + GCC/binutils
	This combination works well too. It works just as well as the native Linux environment except that compilation and build times are a little longer. The custom NuttX buildroot referenced above may be build in the Cygwin environment as well.
	Cygwin + GNU `make` + SDCC
	I have never tried this combination, but it would probably work just fine.
	Cygwin + GNU `make` + Windows Native Toolchain
	This is a tougher environment. In this case, the Windows native toolchain is unaware of the Cygwin sandbox and, instead, operates in the native Windows environment. The primary difficulties with this are: Paths. Full paths for the native toolchain must follow Windows standards. For example, the path `/home/my\ name/nuttx/include` my have to be converted to something like `'C:\cygwin\home\my name\nuttx\include'` to be usable by the toolchain. Fortunately, this conversion is done simply using the `cygpath` utility. Symbolic Links NuttX depends on symbolic links to install platform-specific directories in the build system. On Linux, true symbolic links are used. On Cygwin, emulated symbolic links are used. Unfortunately, for native Windows applications that operate outside of the Cygwin sandbox, these symbolic links cannot be used. The NuttX make system works around this limitation by copying the platform specific directories in place. These copied directories make work a little more complex, but otherwise work well. NOTE: In this environment, it should be possible to use the NTFS `mklink` command to create links. This should only require a minor modification to the build scripts (see `tools/copydir.sh` script). Dependencies NuttX uses the GCC compiler's `-M` option to generate make dependencies. These dependencies are retained in files called `Make.deps` throughout the system. For compilers other than GCC, there is no support for making dependencies in this way. For Windows native GCC compilers, the generated dependencies are windows paths and not directly usable in the Cygwin make. By default, dependencies are surpressed for these compilers as well. NOTE: dependencies are suppress by setting the make variable `MKDEPS` to point to the do-nothing dependency script, `tools/mknulldeps.sh`. Supported Windows Native Toolchains. At present, only the Zilog Z16F, z8Encore, and eZ80Acclaim ports use a non-GCC native Windows toolchain(the Zilog ZDS-II toolchain). Support for Windows native GCC toolchains (CodeSourcery and devkitARM) is currently implemented for the NXP LPC214x, STMicro STR71x, and Luminary LMS6918 ARM ports. (but could easily be extended to any other GCC-based platform with a small effort).
	Wine + GNU `make` + Windows Native Toolchain
	I've never tried this one, but I off the following reported by an ez80 user using the ZiLOG ZDS-II Windows-native toolchain: "I've installed ZDS-II 5.1.1 (IDE for ez80-based boards) on wine (windows emulator for UNIX) and to my surprise, not many changes were needed to make SVN snapshot of NuttX buildable... I've tried nsh profile and build process completed successfully. One remark is necessary: NuttX makefiles for ez80 are referencing `cygpath` utility. Wine provides similar thing called `winepath` which is compatible and offers compatible syntax. To use that, `winepath` (which itself is a shell script) has to be copied as `cygpath` somewhere in `$PATH`, and edited as in following patch: # diff -u `which winepath` `which cygpath` --- /usr/bin/winepath 2011-05-02 16:00:40.000000000 +0200 +++ /usr/bin/cygpath 2011-06-22 20:57:27.199351255 +0200 @@ -20,7 +20,7 @@ # # determine the app Winelib library name -appname=`basename "$0" .exe`.exe +appname=winepath.exe # first try explicit WINELOADER if [ -x "$WINELOADER" ]; then exec "$WINELOADER" "$appname" "$@"; fi "Better solution would be replacing all `cygpath` references in `Makefiles` with `$(CONVPATH)` (or `${CONVPATH}` in shell scripts) and setting `CONVPATH` to `cygpath` or `winepath` regarding to currently used environment.
	Other Environments? Windows Native `make` + Windows Native Toolchain?
	Environment Dependencies. The primary environmental dependency of NuttX are (1) GNU make, (2) bash scripting, and (3) Linux utilities (such as cat, sed, etc.). If you have other platforms that support GNU make or make utilities that are compatible with GNU make, then it is very likely that NuttX would work in that environment as well (with some porting effort). If GNU make is not supported, then some significant modification of the Make system would be required. GNUWin32. For example, with suitable make system changes, it should be possible to use native GNU tools (such as those from GNUWin32) to build NuttX. However, that environment has not been used as of this writing. NOTE: One of the members on the NuttX forum reported that they successful built NuttX using such a GNUWin32-based, Windows native environment. They reported that the only necessary change was to the use the NTFS mklink command to create links (see `tools/copydir.sh` script).

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

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, apps/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, apps/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 18-19K:

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

ChangeLog snapshots associated with the previous, current, and future release are available below.

	Change logs for previous NuttX releases
	ChangeLog for the current NuttX releases
	Unreleased changes

ChangeLog for the Current Release

nuttx-6.23 2012-11-05 Gregory Nutt <gnutt@nuttx.org>

    * arch/arm/src/stm32/stm32_rng.c, chip/stm32_rng.h, and other files:
      Implementation of /dev/random using the STM32 Random Number
      Generator (RNG).
    * board.h file for shenzhou, fire-stm32v2, and olimex-stm32-p107:
      Add frequencies for HSE, HSI, LSE, and LSI.  These are needed
      by the STM32 watchdog driver.
    * CONFIG_EXAMPLES_*: To make things consistent, changed all occurrences
      of CONFIG_EXAMPLE_* to CONFIG_EXAMPLES_*.
    * drivers/mtd/w25.c and configs/*/src/up_w25.c:  Several fixes for the
      W25 SPI FLASH.
    * configs/*/Make.defs:  All buildroot tools now use the extension
      xxx-nuttx-elf- vs. xxx-elf-
    * configs/shenzhou/*/Make.defs:  Now uses the new buildroot 4.6.3
      EABI toolchain.
    * lib/stdio/lib_libdtoa.c:  Another dtoa() fix from Mike Smith.
    * configs/shenzhou/src/up_adc.c:  Add ADC support for the Shenzhou
      board (Darcy Gong).
    * configs/shenzhou/thttpd:  Add a THTTPD configuration for the
      Shenzhou board (Darcy Gong).
    * include/termios.h and lib/termios/libcf*speed.c: The non-standard,
      "hidden" c_speed cannot be type const or else static instantiations
      of termios will be required to initialize it (Mike Smith).
    * drivers/input/max11802.c/h, and include/nuttx/input max11802.h:  Adds
      support for the Maxim MAX11802 touchscreen controller (contributed by
      Petteri Aimonen).
    * graphics/nxtk/nxtk_events.c:  Missing implementatin of the blocked
      method.  This is a critical bugfix for graphics support (contributed
      by Petteri Aimonen).
    * drivers/usbdev/pl2303.c, drivers/usbdev/usbmsc.h, and
      include/nuttx/usb/cdcacm.h: USB_CONFIG_ATTR_SELFPOWER vs.
      USB_CONFIG_ATT_SELFPOWER (contributed by Petteri Aimonen).
    * arch/arm/src/armv7-m/up_memcpy.S:  An optimized memcpy() function for
      the ARMv7-M family contributed by Mike Smith.
    * lib/strings/lib_vikmemcpy.c:  As an option, the larger but faster
      implemementation of memcpy from Daniel Vik is now available (this is
      from http://www.danielvik.com/2010/02/fast-memcpy-in-c.html).
    * lib/strings/lib_memset.c: CONFIG_MEMSET_OPTSPEED will select a
      version of memset() optimized for speed.  By default, memset() is
      optimized for size.
    * lib/strings/lib_memset.c: CONFIG_MEMSET_64BIT will perform 64-bit
      aligned memset() operations.
    * arch/arm/src/stm32/stm32_adc.c:  Need to put the ADC back into the
      initial reset in the open/setup logic.  Opening the ADC driver works
      the first time, but not the second because the device is left in a
      powered down state on the last close.
    * configs/olimex-lpc1766stck/scripts:  Replace all of the identical
      ld.script files with the common one in this directory.
    * configs/stm3220g-eval/scripts:  Replace all of the identical
      ld.script files with the common one in this directory.
    * configs/hymini-stm32v/scripts:  Replace all of the identical
      ld.script files with the common one in this directory.
    * configs/lpcxpresso-lpc1768/scripts:  Replace all of the identical
      ld.script files with the common one in this directory.
    * binfmt/elf.c, binfmt/libelf, include/elf.h, include/nuttx/elf.h: Add
      basic framework for loadable ELF module support.  The initial check-
      in is non-functional and is simply the framework for ELF support.
    * include/nuttx/binfmt.h, nxflat.h, elf.h, and symtab.h:  Moved to
      include/nuttx/binfmt/.
    * arch/sim/src/up_elf.c and arch/x86/src/common/up_elf.c:  Add
      for ELF modules.
    * arch/arm/include/elf.h:  Added ARM ELF header file.
    * include/elf32.h:  Renamed elf.h to elf32.h.
    * configs/stm32f4discovery/ostest:  Converted to use the new
      Kconfig-based configuration system.
    * configs/stm32f4discovery/elf and configs/stm32f4discovery/scripts/gnu-elf.ld
      Add a configuration for testing the ARM ELF loader.
    * binfmt/libelf:  Can't use fstat(). NuttX does not yet support it.  Damn!
    * binfmt/libelf:  The basic ELF module execution appears fully functional.
    * configs/shenzhou/src/up_relays.c:  Add support for relays from the
      Shenzhou board.  Contributed by Darcy Gong.
    * lib/fixedmath: Moved the old lib/math to lib/fixedmath to make room for
      the math library from the Rhombus OS
    * lib/math: Now contains the math library from the Rhombus OS by Nick Johnson
      (submitted by Darcy Gong).
    * include/float.h:  Add a first cut at the float.h header file.  This
      really should be an architecture/toolchain-specific header file.  It
      is only used if CONFIG_ARCH_FLOAT_H is defined.
    * lib/math: Files now conform to coding standards.  Separated float,
      double, and long double versions of code into separate files so that
      they don't draw in so much un-necessary code when doing a dumb link.
    * binfmt/libelf:  The ELF loader is working correctly with C++ static
      constructors and destructors and all.
    * Documentation/NuttXBinfmt.html:  Add documentionof the binary loader.
    * configs/sim/ostest:  Converted to use the mconfig configuration tool.
    * configs/sim/cxxtest:  New test that will be used to verify the uClibc++
      port (eventually).
    * include/nuttx/fs/fs.h, lib/stdio/lib_libfread.c, lib_ferror.c,
      lib_feof.c, and lib_clearerr.c:  Add support for ferror(), feof(),
      and clearerror().  ferror() support is bogus at the moment (it
      is equivalent to !feof()); the others should be good.
    * configs/stm32f4discovery/include/board.h:  Correct timer 2-7
      base frequency (provided by Freddie Chopin).
    * include/nuttx/sched.h, sched/atexit.c, and sched/task_deletehook.c:
      If both atexit() and on_exit() are enabled, then implement atexit()
      as just a special caseof on_exit().  This assumes that the ABI can
      handle receipt of more call parameters than the receiving function
      expects.  That is usually the case if parameters are passed in
      registers.
    * libxx/libxx_cxa_atexit():  Implements __cxa_atexit()
    * configs/stm32f4discovery/cxxtest:  New test that will be used to
      verify the uClibc++ port (eventually).  The sim platform turned not
      to be a good platform for testing uClibc++.  The sim example will not
      run because the simulator will attempt to execute the static
      constructors before main() starts. BUT... NuttX is not initialized
      and this results in a crash.  On the STM324Discovery, I will have
      better control over when the static constructors run.
    * RGMP 4.0 updated from Qiany Yu.
    * configs/*/Make.defs and configs/*/ld.script:  Massive clean-up
      and standardization of linker scripts from Freddie Chopin.
    * net/netdev_ioctl.c:  Add interface state flags and ioctl calls
      to bring network interfaces up and down (from Darcy Gong).
    * config/stm32f4discovery: Enable C++ exceptions.  Now the entire
      apps/examples/cxxtest works -- meaning the the uClibc++ is
      complete and verified for the STM32 platform.

apps-6.23 2012-11-05 Gregory Nutt <gnutt@nuttx.org>

    * vsn: Moved all NSH commands from vsn/ to system/.  Deleted the vsn/
      directory.
    * Makefile:  Change order of includes when CONFIG_NEWCONFIG=y.  In
      that case, namedapp must be included first so that the namedapp
      context is established first.  If the namedapp context is established
      later, it will overwrite any existing namedapp_list.h and nameapp_proto.h
      files.
    * CONFIG_EXAMPLES_*: To make things consistent, changed all occurrences
      of CONFIG_EXAMPLE_* to CONFIG_EXAMPLES_*.
    * Kconfig:  Fleshed out apps/examples/adc/Kconfig and apps/examples/wget/Kconfig.
      There are still a LOT of empty, stub Kconfig files.
    * Kconfig:  Fleshed out apps/examples/buttons/Kconfig. There are still a LOT
      of empty, stub Kconfig files.
    * apps/netutils/webserver/httpd.c:  Fix a bug that I introduced in
      recent check-ins (Darcy Gong).
    * apps/netutils/webclient/webclient.c:  Fix another but that I introduced
      when I was trying to add correct handling for loss of connection (Darcy Gong)
    * apps/nshlib/nsh_telnetd.c:  Add support for login to Telnet session via
      username and password (Darcy Gong).
    * apps/netutils/resolv/resolv.c (and files using the DNS resolver): Various
      DNS address resolution improvements from Darcy Gong.
    * apps/nshlib/nsh_netcmds.c:  The ping command now passes a maximum round
      trip time to uip_icmpping().  This allows pinging of hosts on complex
      networks where the ICMP ECHO round trip time may exceed the ping interval.
    * apps/examples/nxtext/nxtext_main.c:  Fix bad conditional compilation
      when CONFIG_NX_KBD is not defined.  Submitted by Petteri Aimonen.
    * apps/examples/nximage/nximage_main.c:  Add a 5 second delay after the
      NX logo is presented so that there is time for the image to be verified.
      Suggested by Petteri Aimonen.
    * apps/Makefile: Small change that reduces the number of shell invocations
      by one (Mike Smith).
    * apps/examples/elf:  Test example for the ELF loader.
    * apps/examples/elf:  The ELF module test example appears fully functional.
    * apps/netutils/json:  Add a snapshot of the cJSON project.  Contributed by
      Darcy Gong.
    * apps/examples/json:  Test example for cJSON from Darcy Gong
    * apps/nshlib/nsh_netinit.c: Fix static IP DNS problem (Darcy Gong)
    * apps/netutils/resolv/resolv.c: DNS fixes from Darcy Gong.
    * COPYING: Licensing information added.
    * apps/netutils/codec and include/netutils/urldecode.h, base64.h, and md5.h:
      A port of the BASE46, MD5 and URL CODEC library from Darcy Gong.
    * nsnlib/nsh_codeccmd.c:  NSH commands to use the CODEC library.
      Contributed by Darcy Gong.
    * apps/examples/wgetjson: Test example contributed by Darcy Gong
    * apps/examples/cxxtest:  A test for the uClibc++ library provided by
      Qiang Yu and the RGMP team.
    * apps/netutils/webclient, apps/netutils.codes, and apps/examples/wgetjson:
      Add support for wget POST interface.  Contributed by Darcy Gong.
    * apps/examples/relays:  A relay example contributed by Darcy Gong.
    * apps/nshlib/nsh_netcmds: Add ifup and ifdown commands (from Darcy
      Gong).
    * apps/nshlib/nsh_netcmds: Extend the ifconfig command so that it
      supports setting IP addresses, network masks, name server addresses,
      and hardware address (from Darcy Gong).

NxWidgets-1.3 2012-09-29 Gregory Nutt <gnutt@nuttx.org>

    * UnitTests/*/main.cxx:  Change entry point name to be consistent
      with with entry point naming conventions introduced in NuttX
      6.22.
    * Kconfig:  Added a mconfig configuration file.  Eventually, NxWidgets
      needs to get hooked into the NuttX mconf configuration.  Still not
      exactly sure how to do that.
    * libnxwidgets/Makefile and NxWidgets/nxwm/Makefile:  Need updates
      for consistency with recent changes to NuttX build system (>= 6.22)
    * Kconfig:  Add option to turn on the memory monitor feature of the
      NxWidgets/NxWM unit tests.

uClibc++-1.0 2011-11-05 <gnutt@nuttx.org>

    * The initial release of the uClibc++ implementation of the standard
      C++ library for NuttX.  This package was contributed ay Qiang Yu and
      David for the RGMP team.

buildroot-1.11 2011-11-05 <gnutt@nuttx.org>

    * configs/avr-defconfig-4.3.3 - Added --enable-long-long as a GCC
      option.
    * configs/avr-defconfig-4.5.2 - New configuration.
    * Config.in and almost all configurations in configs/ - Changed the
      default nuttx path to $(TOPDIR)/../../nuttx
    * Misc files.  Patch provided by Gerd v. Egidy that solves the following
      problems
      - binutils 2.21 is not available on the gnu servers anymore, they replaced
        it with 2.21.1
      - there is some assembler error when compiling gcc for arm, gcc bugzilla
        43999
      - you can't build nuttx for cortex m3/m4 because of a missing instruction
        in the assembler, binutils bugzilla 12296
    * Add support for binutils 2.22 and GCC 4.6.3.
    * Change name of all tools from xxx-elf to xxx-nuttx-elf
    * Added an ARM EABI GCC 4.6.3 configuration (tool name is arm-nuttx-eabi-).
    * ldnxflat: Add support for the R_ARM_REL32 relocation.  This relocation
      type was not generated by GCC/LD prior to gcc-4.6.3
    * R_ARM_REL32 logic is conditionally disabled because it has not been
      tested.
    * ldnxflat: Correct a memory allocation error that could cause written
      past the end of allocated memory.  Partial restoration of R_ARM_REL32
      logic.  There are lots of issues that I still do not understand here.

pascal-3.0 2011-05-15 Gregory Nutt <gnutt@nuttx.org>

    * nuttx/:  The Pascal add-on module now installs and builds under the
      apps/interpreters directory.  This means that the pascal-2.1 module is
      incompatible with will all releases of NuttX prior to nuttx-6.0 where the 
      apps/ module was introduced.

Unreleased Changes

nuttx-6.18. The ChangeLog for the not-yet-released version 6.18 is available at the bottom of the ChangeLog file that can viewed in the SourceForge SVN.
apps-6.18. The ChangeLog for the not-yet-released version 6.18 is available at the bottom of the ChangeLog file that can viewed in the SourceForge SVN.
NxWidgets-1.1. The ChangeLog for the not-yet-released version 1.1 is available at the bottom of the ChangeLog file that can viewed in the SourceForge SVN.
pascal-1.1. The ChangeLog for the not-yet-released version 1.1 is available at the bottom of the ChangeLog file that can viewed in the SourceForge SVN.
buildroot-1.11. The ChangeLog for the not-yet-released version 1.11 is available at the bottom of the ChangeLog file that can viewed in the SourceForge SVN.

Bugs, Issues, Things-To-Do

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

Trademarks

ARM, ARM7 ARM7TDMI, ARM9, ARM920T, ARM926EJS Cortex-M3 are trademarks of Advanced RISC Machines, Limited.
Cygwin is a trademark of Red Hat, Incorporated.
Linux is a registered trademark of Linus Torvalds.
Eagle-100 is a trademark of Micromint USA, LLC.
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.
ZDS, ZNEO, Z16F, Z80, and Zilog are a registered trademark of Zilog, Inc.

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

	Getting Started
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