Usable in all but the tightest micro-controller environments, The focus is on the tiny-to-small, deeply embedded environment.

The goal is to provide implementations of most standard POSIX OS interfaces to support a rich, multi-threaded development environment for deeply embedded processors.

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.

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.

Fully pre-emptible, fixed priority and round-robin scheduling.

Non-restrictive BSD license.

Compatible GNU toolchains based on buildroot available for download to provide a complete development environment for many architectures.

¹ FAT long file name support may be subject to certain Microsoft patent restrictions if enabled. See the top-level COPYING file for details.

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).

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.

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 Configuration Variable Documentation 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.

• STMicro STM32F303x (STM32 F3 family, ARM Cortex-M4).
• STMicro STM32F401x (STM32 F4 family, ARM Cortex-M4)
• STMicro STM32F407x (STM32 F4 family, ARM Cortex-M4)
• STMicro STM32 F427/437 (STM32 F4 family, ARM Cortex-M4)
• STMicro STM32 F429 (STM32 F4 family, ARM Cortex-M4)

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. Refer to the NuttX README file for further information.

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. Refer to the NuttX board README file for further information.

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. Board support is available for the Motorola C139, C155 and W220 phones and for the Pirelli DP-L10 phone.

STATUS: This port was contributed by Denis Carilki and includes the work of Denis Carikli, Alan Carvalho de Assis, and Stefan Richter. Calypso support first appeared in NuttX-6.17 with LCD drivers. Support for the Calypso keyboard was added in NuttX-6.24 by Denis Carilki. Refer to the NuttX board README files for the Compal E88, Compal E99 and Pirelli DP-L10 phones for further information.

NXP LPC214x. Support is provided for the NXP LPC214x family of processors. In particular, support is provided for (1) the mcu123.com lpc214x evaluation board (LPC2148) and (1) the The0.net ZPA213X/4XPA development board (with the The0.net UG-2864AMBAG01 OLED) 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. Refer to the NuttX board README files for the mcu123.com and for the ZPA213X/4XPA boards for further information.

Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin/MSYS with Cygwin GNU toolchain, 3) Cygwin/MSYS with Windows native toolchain (CodeSourcery or devkitARM), or 4) Native Windows. 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 included only basic timer interrupts and serial console support. In NuttX 7.1, Lizhuoyi contributed additional I2C and SPI drivers. Refer to the NuttX board README file for further information.

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). Refer to the NuttX board README file for further information.

Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin/MSYS with Cygwin GNU toolchain, 3) Cygwin/MSYS with Windows native toolchain (CodeSourcery or devkitARM), or 4) Native Windows. A DIY toolchain for Linux or Cygwin is provided by the NuttX buildroot package.

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). Refer to the NuttX board README file for further information.

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. Refer to the NuttX board README file for further information.

NXP LPC3131. Two boards based on the NXP LPC3131 are supported:

• First, a port for the NXP LPC3131 on the Embedded Artists EA3131 development board was first released in NuttX-5.1 (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.

  Refer to the Embedded Artists EA3131 board README file for further information.

• A second port to the NXP LPC3131 on the Olimex LPC-H3131 development board was added in NuttX-6.32.

  STATUS: The basic H3131 port is complete and verified in NuttX-6.3. It is similar to the EA3131 port except: (1) I have not yet gotten the SDRAM to work, and (2) this board was used to develop and verify the USB 2.0, low-/full-/high-speed EHCI host controller driver. NOTE: That driver should work on the EA3131 as well. However, the EA3131 uses a PCA9532 PWM part to controller the port power so the it would not quite be a simple drop-in.

  Refer to the Olimex LPC-H3131 board README file for further information.

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. Refer to the NuttX board README file for further information.

Atmel SAMA5D3. There are ports to two Atmel SAMA5D3 boards:

• Atmel SAMA5D3x-EK development boards This is the port of NuttX to the Atmel SAMA5D3x-EK development boards (where x=1,3,4, or 5). These boards feature the Atmel SAMA5D3x microprocessors. Four different SAMA5D3x-EK kits are available

  • SAMA5D31-EK with the ATSAMA5D31
  • SAMA5D33-EK with the ATSAMA5D33
  • SAMA5D34-EK with the ATSAMA5D34
  • SAMA5D35-EK with the ATSAMA5D35

  The each kit consist of an identical base board with different plug-in modules for each CPU. All four boards are supported by NuttX with a simple reconfiguration of the processor type.

  STATUS. Initial support for the SAMA5D3x-EK was released in NuttX-6.29. That initial support was minimal: There are simple test configurations that run out of internal SRAM and extended configurations that run out of the on-board NOR FLASH:

  • A barebones NuttShell (NSH) configuration that can be used as the basis for further application development.
  • A full-loaded NuttShell (NSH) configuration that demonstrates all of the SAMA5D3x features.

  The following support was added in Nuttx 6.30:

  • DMA support, and
  • PIO interrupts,

  And drivers for

  • SPI (with DMA support),
  • AT25 Serial Flash,
  • Two Wire Interface (TWI), and
  • HSMCI memory cards.

  NuttX-6.30 also introduces full USB support:

  • High speed device controller driver,
  • OHCI (low- and full-speed) and
  • EHCI (high-speed) host controller driver support.

  With NuttX-6.31, these additional drivers were added:

  • A 10/100Base-T Ethernet (EMAC) driver,
  • A 1000Base-T Ethernet (GMAC) driver,
  • A Real Time Clock (RTC) driver and integrated with the NuttX system time logic
  • /dev/random using the SAMA5D3x True Random Number Generator (TRNG),
  • A Watchdog Timer (WDT) driver,
  • A Timer/Counter (TC) library with interface that make be used by other drivers that need timer support,
  • An ADC driver that can collect multiple samples using the sequencer, can be trigger by a timer/counter, and supports DMA data transfers,
  • A touchscreen driver based on the special features of the SAMA5D3 ADC peripheral, An LCD controller (LCDC) frame buffer driver, and
  • A CAN driver (Testing of the CAN has been delayed because of cabling issues).

  Additional board configurations were added to test and demonstrate these new drivers including new graphics and NxWM configurations.

  These drivers were added in NuttX-6.32:

  • A PWM driver with DMA support
  • An SSC-based I2S driver
  • Support for Programmable clock outputs
  • NAND support including support for the PMECC hardware ECC and for DMA transfers.

  DBGU support was added in NuttX-7.2 (primarily for the SAMA5D3 Xplained board).

  NuttX-7.4 added support for the on-board WM8904 CODEC chip and for Tickless operation.

  Refer to the NuttX board README file for further information.

• Atmel SAMA5D3 Xplained development board This is the port of NuttX to the Atmel SAMA5D3 Xplained development board. The board features the Atmel SAMA5D36 microprocessor. See the Atmel Website for additional information about this board.

  STATUS. This port is complete as of this writing and ready for general use. The basic port is expected to be simple because of the similarity to the SAMAD3x-EK boards and is available in the NuttX 7.2 release.

  Most of the drivers and capabilities of the SAMA5D3x-EK boards can be used with the SAMA5D3 Xplained board. The primary difference between the ports is that the SAMA5D3x-EK supports NOR FLASH and NuttX can be configured to boot directly from NOR FLASH. The SAMA5D3 Xplained board does not have NOR FLASH and, as a consequence NuttX must boot into SDRAM with the help of U-Boot.

  Refer to the NuttX board README file for further information.

Atmel SAMA5D4. There is a port in progress on one Atmel SAMA5D4 board:

• Atmel SAMA5D4-EK/MB development boards This is the port of NuttX to the Atmel SAMA5D4-MB Rev C. development board (which should be compatible with the SAMA5D4-EK). These boards feature the Atmel SAMA5D44 microprocessors with compatibility with most of the SAMA5D3 peripherals.

  STATUS. At the time of the release of NuttX-7.3, the basic port for the SAMA5D4-MB was complete. The board had basic functionality. But full functionality was not available until NuttX-7.4. In NuttX-7.4 support was added for the L2 cache, many security features, XDMAC, HSMCI and Ethernet integrated with XDMAC, the LCDC, TWI, SSC, and most of the existing SAMA5 drivers. Timers were added to support Tickless operation. The TM7000 LCDC with the maXTouch multi-touch controller are also fully support in a special NxWM configuration for that larger display. Support for a graphics media player is included (although there were issues with the WM8904 audio CODEC on my board). An SRAM bootloader was also included. Refer to the NuttX board README file for current status.

Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin/MSYS with Cygwin GNU toolchain, 3) Cygwin/MSYS with Windows native toolchain, or 4) Native Windows. All testing has been performed with the CodeSourcery toolchain (GCC version 4.7.3) in the Cygwin environment under Windows.

Allwinner A10. These following boards are based on the Allwinner A10 have are supported by NuttX:

• pcDuino v1. A port of NuttX to the pcDuino v1 board was first released in NuttX-6.33. See http://www.pcduino.com/ for information about pcDuino Lite, v1, and v2 boards. These boards are based around the Allwinner A10 Cortex-A8 CPU. This port was developed on the v1 board, but the others may be compatible:

  Refer to the NuttX board README file for further information.

  STATUS. This port was an experiment was was not completely developed. This configuration builds and runs an NuttShell (NSH), but only if a patch to work around some issues is applied. While not ready for "prime time", the pcDuino port is functional and could the basis for a more extensive development. There is, at present, no work in progress to extend this port, however.

nuvoTon NUC120. This is a port of NuttX to the nuvoTon NuTiny-SDK-NUC120 that features the NUC120LE3AN MCU.

STATUS. Initial support for the NUC120 was released in NuttX-6.26. This initial support is very minimal: There is a NuttShell (NSH) configuration that might be the basis for an application development. As of this writing, more device drivers are needed to make this a more complete port. Refer to the NuttX board README file for further information.

Memory Usage. For a full-featured RTOS such as NuttX, providing support in a usable and meaningful way within the tiny memories of the NUC120 demonstrates the scalability of NuttX. The NUC120LE2AN comes in a 48-pin package and has 128KB FLASH and 16KB of SRAM. When running the NSH configuration (itself a full up application), there is still more than 90KB of FLASH and 10KB or SRAM available for further application development).

Static memory usage can be shown with size command:

$ size nuttx
   text    data     bss     dec     hex filename
  35037     106    1092   36235    8d8b nuttx

NuttX, the NSH application, and GCC libraries use 34.2KB of FLASH leaving 93.8KB of FLASH (72%) free from additional application development. Static SRAM usage is about 1.2KB (<4%) and leaves 14.8KB (86%) available for heap at runtime. SRAM usage at run-time can be shown with the NSH free command:

NuttShell (NSH) NuttX-6.26
nsh> free
             total       used       free    largest
Mem:         14160       3944      10216       10216
nsh>

You can see that 10.0KB (62%) is available for further application development.

Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin/MSYS with Cygwin GNU toolchain, 3) Cygwin/MSYS with Windows native toolchain, or 4) Native Windows. A DIY toolchain for Linux or Cygwin is provided by the NuttX buildroot package.

FreeScale Freedom KL25Z. This is a port of NuttX to the Freedom KL25Z board that features the MKL25Z128 Cortex-M0+ MCU, 128KB of FLASH and 16KB of SRAM. See the Freescale website for further information about this board.

STATUS. This is the work of Alan Carvalho de Assis. Verified, initial, minimal support for the Freedom KL25Z is in place in NuttX 6.27 and 6.28: There is a working NuttShell (NSH) configuration that might be the basis for an application development. As of NuttX-6.28 more device driver development would be needed to make this a complete port, particularly to support USB OTG. A TSI and a SPI driver were added in NuttX-6.29. Alan contributed a PWM driver in NuttX-6.32. Refer to the Freedom KL25Z board README file for further information.

Atmel SAMD20. The port of NuttX to the Atmel SAMD20-Xplained Pro development board. This board features the ATSAMD20J18A MCU (Cortex-M0+ with 256KB of FLASH and 32KB of SRAM).

STATUS. The initial SAMD20 Xplained Pro release (NuttX 7.1) included a functional NuttShell (NSH) configuration. An SPI driver was also included to support the OLED1 and I/O1 modules. That SPI driver, however, was not completed verified due to higher priority tasks that came up (I hope to get back to this later). Refer to the SAMD20 Explained Pro board README file for further information.

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).

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. A configuration is available 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 was released in NuttX 6.14. Refer to the NuttX board README file for further information.

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 to run the NuttShell (NSH), the NuttX networking test, and the uIP web server. Refer to the NuttX board README file for further information.

Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin/MSYS with Cygwin GNU toolchain, 3) Cygwin/MSYS with Windows native toolchain (CodeSourcery or devkitARM), or 4) Native Windows. A DIY toolchain for Linux or Cygwin is provided by the NuttX buildroot package.

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. Refer to the NuttX board README file for further information.

Development Environments: See the Eagle-100 LM3S6918 above.

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. Refer to the NuttX board README file for further information.

TI/Stellaris LM3S9B96. Header file support was contributed by Tiago Maluta for this part. Jose Pablo Rojas V. is used those header file changes to port NuttX to the TI/Stellaris EKK-LM3S9B96. That port was available in the NuttX-6.20 release. Refer to the NuttX board README file for further information.

SiLabs EFM32 Gecko. This is a port for the Silicon Laboraties EFM32 Gecko family. Board support is available for the following:

1. SiLabs EFM32 Gecko Starter Kit t (EFM32-G8XX-STK). The Gecko Starter Kit features:

   • EFM32G890F128 MCU with 128 kB flash and 16 kB RAM
   • 32.768 kHz crystal (LXFO) and 32 MHz crystal (HXFO)
   • Advanced Energy Monitoring
   • Touch slider
   • 4x40 LCD
   • 4 User LEDs
   • 2 pushbutton switches
   • Reset button and a switch to disconnect the battery.
   • On-board SEGGER J-Link USB emulator
   • ARM 20 pin JTAG/SWD standard Debug in/out connector

   STATUS. The basic port is verified and available now. This includes on-board LED and button support and a serial console available on LEUART0. A single configuration is available using the NuttShell NSH and the LEUART0 serial console.

   Refer to the EFM32 Gecko Starter Kit README.txt file for further information.

2. Olimex EFM32G880F120-STK. This board features:

   • EFM32G880F128 with 128 kB flash and 16 kB RAM
   • 32.768 kHz crystal (LXFO) and 32 MHz crystal (HXFO)
   • LCD custom display
   • DEBUG connector with ARM 2x10 pin layout for programming/debugging with ARM-JTAG-EW
   • UEXT connector
   • EXT extension connector
   • RS232 connector and driver
   • Four user buttons
   • Buzzer

   STATUS. The board suppport is complete but untested because of tool-related issues. An OpenOCD compatible, SWD debugger would be required to make further progress in testing.

   Refer to the Olimex EFM32G880F120-STK README.txt for further information.

SiLabs EFM32 Giant Gecko. This is a port for the Silicon Laboraties EFM32 Giant Gecko family.

STATUS. At this time there are no board support packages for the Giant Gecko in the NuttX source tree (there are ports to proprietary Giant Gecko hardware, howevever).

STMicro STM32L152 (STM32L "EnergyLite" Line). This is a port of NuttX to the STMicro STM32L-Discovery development board. The STM32L-Discovery board is based on the STM32L152RBT6 MCU (128KB FLASH and 16KB of SRAM).

The STM32L-Discovery and 32L152CDISCOVERY kits are functionally equivalent. The difference is the internal Flash memory size (STM32L152RBT6 with 128 Kbytes or STM32L152RCT6 with 256 Kbytes). Both boards feature:

• An ST-LINK/V2 embedded debug tool interface,
• LCD (24 segments, 4 commons),
• LEDs,
• Pushbuttons,
• A linear touch sensor, and
• Four touchkeys.

STATUS. Initial support for the STM32L-Discovery was released in NuttX-6.28. This initial support includes a configuration using the NuttShell (NSH) that might be the basis for an application development. A driver for the on-board segment LCD is included as well as an option to drive the segment LCD from an NSH "built-in" command. As of this writing, a few more things are needed to make this a more complete port: 1) Verfication of more device drivers (timers, quadrature encoders, PWM, etc.), and 2) logic that actually uses the low-power consumption modes of the EnergyLite part. Refer to the NuttX board README file for further information.

Memory Usage. For a full-featured RTOS such as NuttX, providing support in a usable and meaningful way within the tiny memories of the STM32L152RBT6 demonstrates the scalability of NuttX. The STM32L152RBT6 comes in a 64-pin package and has 128KB FLASH and 16KB of SRAM.

Static memory usage can be shown with size command:

$ size nuttx
   text    data     bss     dec     hex filename
  39664     132    1124   40920    9fd8 nuttx

NuttX, the NSH application, and GCC libraries use 38.7KB of FLASH leaving 89.3B of FLASH (70%) free from additional application development. Static SRAM usage is about 1.2KB (<4%) and leaves 14.8KB (86%) available for heap at runtime.

SRAM usage at run-time can be shown with the NSH free command:

NuttShell (NSH) NuttX-6.27
nsh> free
             total       used       free    largest
Mem:         14096       3928      10168      10168
nsh>

You can see that 9.9KB (62%) of SRAM heap is staill available for further application development while NSH is running.

STMicro STM32F152x/162x(STM32 F1 "EnergyLite" Medium+ Density Family). Support for the STM32152 and STM32162 Medium+ density parts from Jussi Kivilinna and Sami Pelkonen was included in NuttX-7.3, extending the basic STM32F152x support. This is architecture-only support, meaning that support for the boards with these chips is available, but not support for any publicly available boards is included.

STMicro STM32F100x (STM32 F1 "Value Line"Family).

• Proprietary Boards 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 their proprietary boards using this logic.

• Generic Board Support This logic was extended to support the high density STM32F100RC chips by Freddie Chopin There is generic support for STM32F100RC boards. Refer to the NuttX board README file for further information.

• STM32VL-Discovery. In NuttX-6.33, support for the STMicro STM32VL-Discovery board was contributed by Alan Carvalho de Assis. The STM32VL-Discovery board features an STM32F100RB MCU. Refer to the NuttX board README file for further information.

STMicro STM32F103C4/8 (STM32 F1 Low- and Medium-Density Family). This port is for "STM32 Tiny" development board. This board is available from several vendors on the net, and may be sold under different names. It is based on a STM32 F103C8T6 MCU, and is bundled with a nRF24L01 wireless communication module.

STATUS: The basic STM32F103C8 port was released in NuttX version 6.28. This work was contributed by Laurent Latil. Refer to the NuttX board README file for further information.

STMicro STM32F103x (STM32 F1 Family). 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, STM32F103VET6, STM32F103RBT6, and STM32103CBT6. Boards supported include:

1. STM3210E-EVAL. A port for the STMicro STM3210E-EVAL development board that features the STM32F103ZET6 MCU. Refer to the NuttX board README file for further information.

2. ISOTEL NetClamps VSN. The ISOTEL NetClamps VSN V1.2 ready2go sensor network platform based on the STMicro STM32F103RET6. Contributed by Uros Platise. Refer to the NuttX board README file for further information.

3. HY-Mini STM32v board. This board is based on the STM32F103VCT chip. Port contributed by Laurent Latil. Refer to the NuttX board README file.

4. The M3 Wildfire development board (STM32F103VET6), version 2. See http://firestm32.taobao.com (the current board is version 3). Refer to the NuttX board README file for further information.

5. LeafLab's Maple and Maple Mini boards. These boards are based on the STM32F103RBT6 chip for the standard version and on the STM32F103CBT6 for the mini version. See the LeafLabs web site for hardware information; see the NuttX board README file for further information about the NuttX port.

6. Spark (and emulated Spark). The Spark boards are based on the STM32F103CBT6 chip and feature wireless networking using the TI CC3000 WLAN module. See the Spark web site for hardware information; The emulated Spark is a base board for the Maple Mini board (see above) developed by David Sidrane that supports Spark development while we all way breathlessly for or Spark boards. see the NuttX board README file for further information about the NuttX port.

   Initially Spark support was introduced in NuttX 6.31 and completed in NuttX 6.32. Most of this work is the result of the effort of David Sidrane.

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 verified DMA support. Verified configurations are available for 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).

• Maple. Support for the Maple boards was contributed by Yiran Liao and first appear in NuttX 6-30.

• Spark. David Sidrane has the emulated Spark board up-and-running with a functional CC3000 network, SST25 FAT file system, an NSH shell, and a composite USB CDC/ACM and USBMSC devices. This configuration is was first available NuttX 6.31 and completed in NuttX 6.32. That is really quite a lot of high end functionality on an STM32 that only has 20KB of RAM! I am impressed!

Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin/MSYS with Cygwin GNU toolchain, 3) Cygwin/MSYS with Windows native toolchain (RIDE7, CodeSourcery or devkitARM), or 4) Native Windows. A DIY toolchain or Linux or Cygwin is provided by the NuttX buildroot package.

STMicro STM32F107x (STM32 F1 "Connectivity Line" family). 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: A configuration for the NuttShell (NSH) is available and verified. Networking is functional. Support for an external ENCX24J600 network was added in NuttX 6.30.

• Shenzhou IV A port of NuttX to the Shenzhou IV development board (See www.armjishu.com) featuring the STMicro STM32F107VCT MCU was added in NuttX-6.22.

  STATUS: In progress. The following have been verified: (1) Basic Cortex-M3 port, (2) Ethernet, (3) On-board LEDs. Refer to the NuttX board README file for further information.

• ViewTool STM32F103/F107 Support for the Viewtool STM32F103/F107 board was added in NuttX-6.32. That board features the STMicro STM32F107VCT6 MCU. Networking, LCD, and touchscreen support were added in NuttX-6.33.

  Three configurations are available:

  1. A standard NuttShell (NSH) configuration that will work with either the STM32F103 or STM32F107 part.
  2. A network-enabled NuttShell (NSH) configuration that will work only with the STM32F107 part.
  3. The configuration that was used to verify the Nuttx high-priority, nested interrupt feature.

  STATUS: Networking and touchscreen support are well test. But, at present, neither USB nor LCD functionality have been verified. Refer to the SViewtool STM32F103/F107 README file for further information.

STMicro STM32F207 (STM32 F2 family).

• Support for the STMicro STM3220G-EVAL development board was contributed by Gary Teravskis and first released in NuttX-6.16. This board uses the STM32F207IG.
• Martin Lederhilger contributed support for the Olimex STM32 P207 board using the STM32F207ZE MCU.

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. Refer also to the NuttX board README file for further information.

Atmel SAM3U. This port uses the Atmel SAM3U-EK development board that features the SAM3U4E MCU. This port uses a GNU arm-nuttx-elf or arm-nuttx-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. Touchscreen support was added in NuttX-6.29.

Subsequent NuttX releases will extend this port and add support for the SDIO-based SD cards and USB device. Refer to the NuttX board README file for further information about this port.

Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin/MSYS with Cygwin GNU toolchain, 3) Cygwin/MSYS with Windows native toolchain (CodeSourcery or devkitARM), or 4) Native Windows. A DIY toolchain for inux or Cygwin is provided by the NuttX buildroot package.

Atmel SAM3X. This port uses the Arduino Due development board that features the ATSAM3X8E MCU running at 84MHz. See the Arduino Due page for more information.

STATUS: As of this writing, the basic port is code complete and a fully verified configuration exists for the NuttShell NSH). The first fully functional Arduino Due port was released in NuttX-6.29. Refer to the NuttX board README file for further information.

Development Environments: See the Atmel SAM3U discussion above.

NXP LPC1766, LPC1768, and LPC1769. Drivers are available for CAN, DAC, Ethernet, GPIO, GPIO interrupts, I2C, UARTs, SPI, SSP, USB host, and USB device. Additional drivers for the RTC, ADC, DAC, Timers, PWM and MCPWM were contributed by Max (himax) in NuttX-7.3. Verified LPC17xx configurations 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.
• Zilogic's ZKIT-ARM-1769 board.
• 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.

1. 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. Refer to the NuttX board README file for further information.

   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 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 verified on other platforms; this needs to be revisited on the Nucleus2G).

2. mbed LPC1768

   • Support for the mbed board was contributed by Dave Marples and released in NuttX-5.11. Refer to the NuttX board README file for further information.

3. 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 devices, interrupt endpoints, and a USB host HID keyboard class driver.
   • Refer to the NuttX board README file for further information.

   Verified configurations are now available 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 NuttX-5.17 release.

4. 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. Verified configurations include DHCPD, the NuttShell (NSH), NuttX graphis (NX), THTTPD, and USB mass storage device. Refer to the NuttX board README file for further information.

5. Zilogic's ZKIT-ARM-1769 board

   Zilogic System's ARM development Kit, ZKIT-ARM-1769. This board is based on the NXP LPC1769. The initial release was included NuttX-6.26. The Nuttx Buildroot toolchain is used by default. Verifed configurations include the "Hello, World!" example application and a THTTPD demonstration. Refer to the NuttX board README file for further information.

6. 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 Lincoln60 board and the NuttX board README file for further information about the Lincoln board.

Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin/MSYS with Cygwin GNU toolchain, 3) Cygwin/MSYS with Windows native toolchain (CodeSourcery devkitARM or Code Red), or 4) Native Windows. A DIY toolchain for Linux or Cygwin is provided by the NuttX buildroot package.

NXP LPC1788. The port of NuttX to the WaveShare Open1788 is a collaborative effort between Rommel Marcelo and myself (with Rommel being the leading contributor and I claiming only a support role). You can get more information at the Open1788 board from the WaveShare website.

STATUS: Initial Open1788 support appeared in NuttX-6.26 with the first verified configurations in NuttX-6.27. In NuttX-6.27 there is a working basic port with OS verification, Nuttshell (NSH) configurations, and a graphics test configuration. SDRAM and GPDMA are working. The NSH configuration includes verified support for a DMA-based SD card interface. The frame-buffer LCD driver is functional and uses the SDRAM for frame-buffer memory. A touchscreen interface has been developed but there appears to be a hardware issue with the WaveShare implementation of the XPT2046 touchscreen controller. Refer to the NuttX board README file for further information.

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. Refer to the NuttX board README file for further information.

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. Refer to the NuttX board README file for further information.

STMicro STM32F3-Discovery (STM32 F3 family). This port uses the STMicro STM32F3-Discovery board featuring the STM32F303VCT6 MCU (STM32 F3 family). Refer to the STMicro web site for further information about this board.

STATUS: The basic port for the STM32F3-Discover was first released in NuttX-6.26. Many of the drivers previously released for the STM32 F1, Value Line, and F2 and F4 may be usable on this platform as well. New drivers will be required for ADC and I2C which are very different on this platform. Refer to the NuttX board README file for further information.

STMicro STM32401x (STM32 F4 family).

Nucleo F401RE. This port uses the STMicro Nucleo F401RE board featuring the STM32F104RE MCU. Refer to the STMicro web site for further information about this board.

STATUS:

• NuttX-7.2 The basic port for STMicro Nucleo F401RE board was contributed by Frank Bennett.
• Refer to the NuttX board README file for further information.

STMicro STM32407x (STM32 F4 family).

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.
• NuttX-7.3 Support for the Olimex STM32 H405 board was added in NuttX-7.3.
• Refer to the NuttX board README file for further information.

STMicro STM32F4-Discovery. This port uses the STMicro STM32F4-Discovery board featuring the STM32F407VGT6 MCU. The STM32F407VGT6 is a 168MHz Cortex-M4 operation with 1Mbit Flash memory and 128kbytes. The board features:

• On-board ST-LINK/V2 for programming and debugging,
• LIS302DL, ST MEMS motion sensor, 3-axis digital output accelerometer,
• MP45DT02, ST MEMS audio sensor, omni-directional digital microphone,
• CS43L22, audio DAC with integrated class D speaker driver,
• Eight LEDs and two push-buttons,
• USB OTG FS with micro-AB connector, and
• Easy access to most MCU pins.

Support for the STM3F4DIS-BB base board was added in NuttX-7.5. This includes support for the serial communications via the on-board DB-9 connector, Networking, and the microSD card slot.

Refer to the STMicro web site for further information about this board and to

STATUS: The basic port for the STM32F4-Discovery was contributed by Mike Smith and was first released in NuttX-6.14. All drivers listed for the STM3240G-EVAL are usable on this platform as well. Refer to the NuttX board README file for further information.

MikroElektronika Mikromedia for STM32F4. This is another board supported by NuttX that uses the same STM32F407VGT6 MCU as does the STM32F4-Discovery board. This board, however, has very different on-board peripherals than does the STM32F4-Discovery:

• TFT display with touch panel,
• VS1053 stereo audio codec with headphone jack,
• SD card slot,
• Serial FLASH memory,
• USB OTG FS with micro-AB connector, and
• Battery connect and batter charger circuit.

See the Mikroelektronika website for more information about this board and the NuttX board README file for further information about the NuttX port.

STATUS: The basic port for the Mikromedia STM32 M4 was contributed by Ken Petit and was first released in NuttX-6.128. All drivers for the STM32 F4 family may be used with this board as well.

Olimex STM32 H405. Support for the Olimex STM32 H405 development board was contributed by Martin Lederhilger and appeared in NuttX-7.3. See the NuttX board README file for further information about the NuttX port.

STMicro STM32 F427/437. General architectural support was provided for the F427/437 family in NuttX 6.27. Specific support includes the STM32F427I, STM32F427Z, and STM32F427V chips. This is architecture-only support, meaning that support for the boards with these chips is available, but not support for any publicly available boards is included. This support was contributed by Mike Smith.

The F427/f37 port adds (1) additional SPI ports, (2) additional UART ports, (3) analog and digital noise filters on the I2C ports, (4) up to 2MB of flash, (5) an additional lower-power mode for the internal voltage regulator, (6) a new prescaling option for timer clock, (7) a larger FSMSC write FIFO, and (8) additional crypto modes (F437 only).

STMicro STM32 F429. Support for STMicro STM32F429I-Discovery development board featuring the STM32F429ZIT6 MCU was contributed in NuttX-6.32 by Ken Pettit. The F429 port adds support for the STM32F439 LCDC and OTG HS (in FS mode). The STM32F429ZIT6 is a 180MHz Cortex-M4 operation with 2Mbit Flash memory and 256kbytes. Refer to the STM32F429I-Discovery board README file for further information.

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: Refer to the NuttX board README file for more detailed information about this port.

• NuttX-6.20 The basic port is complete. The basic NuttShell (NSH) configuration is 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 porting 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.

TI Stellaris LM4F120. This port uses the TI Stellaris LM4F120 LaunchPad. Jose Pablo Carballo and I are doing this port.

STATUS: As of this writing, the basic port is code complete and a fully verified configuration exists for the NuttShell NSH). The first fully functional LM4F120 LaunchPad port was released in NuttX-6.27.

TI Tiva TM4C123G. This port uses the TI Tiva TM4C123G LaunchPad.

STATUS: This is very much a work in progress. As of this writing, full architectural support for the TI Tiva TM4C123G has been implemented and was released in NuttX 7.1. Basic board support is in place for the TM4C123G LaunchPad but is completely untested and possibly incomplete. This partial logic is also included int he NuttX 7.1 release. This basic board supprted includes an (un-verified) configuration for the NuttShell NSH). A fully verified port to the TM4C123G LaunchPad is expected in NuttX-7.2. The first fully functional LM4F120 LaunchPad port was released in NuttX-6.27. Refer to the TM4C123G LaunchPad board README file for more detailed information about this port.

TI/Tiva CC3200 Launchpad. TI/Tiva CC3200 Launchpad

STATUS: This is very much a work in progress. The basic port was released in NuttX-7.5. This basic board supprted includes an verified configuration for the NuttShell NSH). Key wireless networking capability is still missing. Refer to the CC3200 LaunchPad board README file for more detailed information about this port.

Atmel SAM4L. This port uses the Atmel SAM4L Xplained Pro development board. This board features the ATSAM4LC4C MCU running at 48MHz with 256KB of FLASH and 32KB of internal SRAM.

STATUS: As of this writing, the basic port is code complete and a fully verified configuration exists for the NuttShell NSH). The first fully functional SAM4L Xplained Pro port was released in NuttX-6.28. Support for the SAM4L Xplained modules was added in NuttX-6.29:

• Support for the SPI-based SD card on the I/O1 module.
• Driver for the LED1 segment LCD module.
• Support for the UG-2832HSWEG04 OLED on the SAM4L Xplained Pro's OLED1 module
Refer to the NuttX board README file for further information.

Memory Usage. The ATSAM4LC4C comes in a 100-pin package and has 256KB FLASH and 32KB of SRAM. Below is the current memory usage for the NSH configuration (June 9, 2013). This is not a minimal implementation, but a full-featured NSH configuration.

Static memory usage can be shown with size command:

$ size nuttx
   text    data     bss     dec     hex filename
  43572     122    2380   46074    b3fa nuttx

NuttX, the NSH application, and GCC libraries use 42.6KB of FLASH leaving 213.4B of FLASH (83.4%) free from additional application development. Static SRAM usage is about 2.3KB (<7%) and leaves 29.7KB (92.7%) available for heap at runtime.

SRAM usage at run-time can be shown with the NSH free command. This runtime memory usage includes the static memory usage plus all dynamic memory allocation for things like stacks and I/O buffers:

NuttShell (NSH) NuttX-6.28
nsh> free
             total       used       free    largest
Mem:         29232       5920      23312      23312

You can see that 22.8KB (71.1%) of the SRAM heap is staill available for further application development while NSH is running.

Atmel SAM4C. General architectural support was provided for SAM4CM family in NuttX 7.3 This was architecture-only support, meaning that support for the boards with these chips is available, but no support for any publicly available boards was included. The SAM4CM port should be compatible with most of the SAM3/4 drivers (like HSMCI, DMAC, etc.) but those have not be verified on hardware as of this writing. This support was contributed in part by Max Neklyudov.

Atmel SAM4E. General architectural support was provided for the SAM4E family in NuttX 6.32. This was architecture-only support, meaning that support for the boards with these chips is available, but no support for any publicly available boards was included. This support was contributed in part by Mitko.

Atmel SAM4E-EK. Board support was added for the SAM4E-EK development board in NuttX 7.1. A fully functional NuttShell (NSH) configuration is available (see the NSH User Guide). That NSH configuration includes networking support and support for an AT25 Serial FLASH file system.

STATUS. A new Ethernet MAC driver has been developed and is functional in the NSH configuration. A DMA-base SPI driver is supported and has been verified with the AT25 Serial FLASH. Touchscreen and LCD support was added in NuttX-7.3, but has not been fully integrated as of this writing. The SAM4E-EK should be compatible with most of the other SAM3/4 drivers (like HSMCI, DMAC, etc.) but those have not be verified on the SAM4E-EK as of this writing. Refer to the NuttX board README file for further information.

Atmel SAM4S. There are ports to two Atmel SAM4S board:

• There is a port the Atmel SAM4S Xplained development board. This board features the ATSAM4S16 MCU running at 120MHz with 1MB of FLASH and 128KB of internal SRAM.

  STATUS: As of this writing, the basic port is code complete and a fully verified configuration exists for the the NuttShell NSH). The first fully functional SAM4S Xplained port was released in NuttX-6.28. Support for the on-board 1MB SRAM was added in NuttX-6.29. An RTT driver was Bob Doiron in NuttX-7.3. Bob also added an high resolution RTC emulation using the RTT for the sub-second counter. Refer to the NuttX board README file for further information.

• There is also a port to the the Atmel SAM4S Xplained Pro development board. This board features the ATSAM4S32C MCU running at 120MHz with 2MB of FLASH and 160KB of internal SRAM.

  STATUS: As of this writing, the basic port is code complete and a fully verified configuration exists for the the NuttShell NSH). The first fully functional SAM4S Xplained Pro port was released in NuttX-7.2. This supported also added HSMCI, RTC, and watchdog and verified support for USB device. Refer to the NuttX board README file for further information.

Atmel SAM4E. General architectural support was provided for the SAM4E family in NuttX 6.32. This was architecture-only support, meaning that support for the boards with these chips is available, but no support for any publicly available boards was included. This support was contributed in part by Mitko.

Atmel SAM4E-EK. Board support was added for the SAM4E-EK development board in NuttX 7.1. A fully functional NuttShell (NSH) configuration is available (see the NSH User Guide). That NSH configuration includes networking support and support for an AT25 Serial FLASH file system.

STATUS. This is very much a work in progress. A new Ethernet MAC driver has been developed and is functional in the NSH configuration. A DMA-base SPI driver is supported and has been verified with the AT25 Serial FLASH. The SAM4E-EK should be compatible with most of the other SAM3/4 drivers (like HSMCI, DMAC, etc.) but those have not be verified on the SAM4E-EK as of this writing. Refer to the NuttX board README file for further information.

Development Environments: 1) Linux with native Linux GNU toolchain, 2) Cygwin/MSYS with Cygwin GNU Cortex-M3 or 4 toolchain, 3) Cygwin/MSYS with Windows native GNU Cortex-M3 or M4 toolchain (CodeSourcery or devkitARM), or 4) Native Windows. 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.

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. Refer to the NuttX board README file for further information.

AVR AT90USB64x and AT90USB6128x.

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. Refer to the NuttX board README file for further information.

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 configuration. However, this configuration is not fully debugged as of the NuttX-6.5 release. Refer to the NuttX board README file for further information.

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:

1. 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,
2. 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/MSYS with Cygwin GNU toolchain, 3) Cygwin/MSYS with Windows native toolchain, or 4) Native Windows. 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.

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 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. Refer to the NuttX board README file for further information.

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. Refer to the NuttX board README files for DEMO9S12NE64 and for the NE64 /PoE Badge for further information.

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. Refer to the NuttX board README file for further information.

Obsoleted. This architecture has been obsoleted. The code has been moved out of the NuttX source tree but can still be found be found in Obsoleted directory. This support was obsoleted because (1) the architecture limitations of the 8051 family make ongoing development of more advanced NuttX features too difficult, and (2) although the basic port was marginally functional, it has never really been demonstrated convincingly in any application.

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. In NuttX 7.1, Lizhuoyi contributed additional keyboard and VGA drivers. This is a great, stable starting point for anyone interest in fleshing out the x86 port! Refer to the NuttX README file for further information.

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! Refer to the NuttX README file for further information.

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. The OS test configuration is fully functional and proves that we have a basically healthy NuttX port to the Mirtoo. A configuration is available for the NuttShell (NSH). 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. Refer to the NuttX board README file for further information.

PIC32MX4xx Family.

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 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. Refer to the NuttX board README file for further information.

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 NuttShell (NSH - see the NSH User Guide). Refer to the NuttX board README file for further information.

• 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 the NuttShell (NSH - see the NSH User Guide). USB has not yet been fully tested but on first pass appears to be functional. Refer to the NuttX board README file for further information.

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.

A verified configuration is available for 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. Refer to the NuttX board README file for further information.

• 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: A verified configuration is available for 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 MIO283QT2 LCD on the PIC32MX7 MMB. (6) Support for the MIO283QT9A LCD used on later boards (NuttX 7.1).

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. Refer to the NuttX board README file for further information.

Development Environment: These ports uses either:

1. The LITE version of the PIC32MX toolchain available for download from the MicroChip website, or
2. The Pinguino MIPS ELF toolchain avaiable from the Pinquino website.

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. Refer to the NuttX board README file for further information.

Renesas M16C/26 Microcontroller. 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. Refer to the NuttX board README file for further information.

• Zilog z16f2800100zcog development kit. This port use the Zilog z16f2800100zcog development kit and the Zilog ZDS-II Windows command line tools. The development environment is either Windows native or Cygwin under Windows.

  STATUS: The initial release of support for the z16f was made available in NuttX version 0.3.7. A working NuttShell (NSH) configuration as added in NuttX-6.33 (although a patch is required to work around an issue with a ZDS-II 5.0.1 tool problem). An ESPI driver was added in NuttX-7.2. Refer to the NuttX board README file for further information.

• Toyaga 16z (obsoleted). This port if for the Toyaga 16z board that also use the Zilog ZNEOZ16F2811AL20EG microntroller with the Zilog ZDS-II Windows command line tools. The development environment is either Windows native or Cygwin under Windows.

  STATUS: The initial release of support for the 16z board was made available in NuttX version 6.33. Both the 16z board and the NuttX port are works in progress and are not ready for usage as of NuttX-7.2. Refer to the NuttX board README file for further information.

  Obsoleted. This architecture has been obsoleted. The code has been moved out of the NuttX source tree but can still be found be found in Obsoleted directory. This support was obsoleted because of technical issues that make NuttX unusable on the board at least in the short term. This configuration may return to the NuttX source tree at some time in the future.

Zilog eZ80Acclaim! Microcontroller. 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 either Windows native or Cygwin under Windows.

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. Refer to the NuttX board README files for the ez80f0910200kitg and ez80f910200zcofile for further information.

Zilog Z8Encore! Microcontroller. 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 either Windows native or Cygwin under Windows.

STATUS: This release has been verified only on the ZiLOG ZDS-II Z8Encore! chip simulation as of nuttx-0.3.9. Refer to the NuttX board README files for the z8encore000zco and for thez8f64200100kit for further information.

P112. The P112 is a hobbyist single board computer based on a 16MHz Z80182 with up to 1MB of memory, serial, parallel and diskette IO, and realtime clock, in a 3.5-inch drive form factor. The P112 computer originated as a commercial product of "D-X Designs Pty Ltd"[ of Australia.

STATUS: Most of the NuttX is in port for both the Z80182 and for the P112 board. Boards from Kickstarter project will not be available, however, until the third quarter of 2013. So it will be some time before this port is verified on hardware. Refer to the NuttX board README file for further information.

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 GIT here.

STATUS: This port is complete and stable to the extent that it can be tested using an instruction set simulator. Refer to the NuttX board README file for further information.

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. Refer to the NuttX board README file for further information.

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 GIT may be accessed in the NuttX GIT.

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.

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.

I have never tried this combination, but it would probably work just fine.

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 suppressed 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, the following Windows native toolchains are in use:

1. GCC built for Windows (such as CodeSourcery, Atollic, devkitARM, etc.),
2. SDCC built for Windows,
3. the ZiLOG XDS-II toolchain for Z16F, z8Encore, and eZ80Acclaim parts.

Build support has been added to support building natively in a Windows console rather than in a POSIX-like environment.

This build:

1. Uses all Windows style paths
2. Uses primarily Windows batch commands from cmd.exe, with
3. A few extensions from GNUWin32

This capability first appeared in NuttX-6.24 and should still be considered a work in progress because: (1) it has not been verfied on all targets and tools, and (2) still lacks some of the creature-comforts of the more mature environments. The windows native build logic initiated if CONFIG_WINDOWS_NATIVE=y is defined in the NuttX configuration file:

At present, this build environment also requires:

• Windows Console. The build must be performed in a Windows console window. This may be using the standard CMD.exe terminal that comes with Windows. I prefer the ConEmu terminal which can be downloaded from: http://code.google.com/p/conemu-maximus5/
• GNUWin32. The build still relies on some Unix-like commands. I usethe GNUWin32 tools that can be downloaded from http://gnuwin32.sourceforge.net/. See the top-level nuttx/README.txt file for some download, build, and installation notes.
• MinGW-GCC. MinGW-GCC is used to compiler the C tools in the nuttx/tools directory that are neede by the build. MinGW-GCC can be downloaded from http://www.mingw.org/. If you are using GNUWin32, then it is recommended that you not install the optional MSYS components as there may be conflicts.

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 GIT 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.

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.

MSYS. I have not used MSYS but what I gather from talking with NuttX users is that MSYS can be used as an alternative to Cygwin in any of the above Cygwin environments. This is not surprising since MSYS is based on an older version of Cygwin (cygwin-1.3). MSYS has been modified, however, to interoperate in the Windows environment better than Cygwin and that may be of value to some users.

MSYS, however, cannot be used with the native Windows NuttX build because it will invoke the MSYS bash shell instead of the CMD.exe shell. Use GNUWin32 in the native Windows build envionment.