New version, still under construction, is available here :  https://github.com/lepton-distribution/lepton-root.scions.
Legacy version available on this github depot: https://github.com/lepton-distribution/lepton

LEPTON/TAUON OPERATING SYSTEM
Lepton/Tauon is an open source POSIX "compliant" Operating System for 
deeply embedded devices. It tries to bring PSE-53 POSIX capabilities 
to embedded world (including multiprocess, filesystems, messages 
queues, ... BUT currently no asynchronous I/O support). 
The system implementation follows an UNIX approach.

The aim of this project, it's not to develop another operating system 
like GNU/Linux, but an human understandable operating system that provides 
more services than a realtime kernel, while keeping a reasonable footprint 
for deeply embedded system. 

We hope Lepton/Tauon will be able to help anybody to develop their personal,
school or professional projects easily and quickly.

We are ready to accommodate contributions to improve Lepton/Tauon and support 
new features.

Supported platforms:
   -. ARM7: AT91M55800A (Atmel)
   -. ARM9: AT91SAM9261-EK (Atmel)
   -. ARM9: AT91SAM9260-EK (Atmel)
   -. ARM Cortex-M4: TWR-K60N512 (Freescale)
   -. PC (32bits simulation for GNU/Linux and MS Windows)

Initial version of Lepton/Tauon is 4.0.0.0.

Lepton/Tauon provides more than 150 POSIX functions over a real-time
operating system that can be:
   -. Proprietary embOS from Segger (original Lepton)
   -. Open source eCos community (Tauon)
Lepton/Tauon offers the ability to use other real-time operating system (closed 
or open source) like FreeRTOS by using a simple abstraction layer. 

Lepton/Tauon uses some parts of underlying real-time operating system:
   -. board startup (HAL)
   -. basic synchronization functions (semaphore, mutex, ...)
   -. task sheduler
   -. ISR mechanisms
   -. some libraries (math.h, stdlib.h, ...)

In addition Lepton/Tauon offers:
   -. more than 150 functions from POSIX standard (IEEE Std 1003.1a), 
   realtime extension (1003.1b) and threads extension (1003.1c)
   -. simple model for device drivers
   -. UNIX stream to improve "reuse"
   -. support lwip stack (1.3.2)
   -. support uip stack (1.0) (Lepton only)
   -. support rootfs, ufs, fat16 (msdos and vfat) filesystem
   -. VFS layer to brings new and custom file systems 
   -. USB devices stack and profils CDC-ACM, MSD and Ethernet-ECM (tested
   only on AT91SAM9261-EK)
   -. NanoX and FLTK support (FLNX exactly)
   -. Mongoose WEB server, FTP server (from trollFTPD) and mini shell
   -. simulation process under GNU/Linux (Tauon) and Windows (Lepton)

To install Lepton/Tauon and launch a sample application see docs/INSTALL.
To see what is Lepton/Tauon, installation are tested on:
   -. Debian Squeeze and Wheezy
   -. Ubuntu 11.10
To create your application, see docs/START.
To see all available function, see docs/AVAILABLE_POSIX

Changes made in version 4.0.0.0 are documented in the ChangeLog file.

Directories and/or files in this distribution:
   -. tools : tools to build a Lepton/Tauon application
   
   -. sys/user : part for user application sources, libraries and
   binaries
   
   -. sys/root/lib/arch : install path for all supported eCos HAL
   -. sys/root/prj/scons : general compilations files for arch supported
   by Lepton/Tauon.
   
   -. sys/root/prj/config : a pkg-config files use for compilation and a
   minicom configuration file for simulation
   
   -. sys/root/src/sbin : source files for general utilities (mini
   shell aka lsh, mkfs, ls, uname, ...)
   -. sys/root/src/bin/net : source files for high level networking
   utilities like web server or telnet server.
   -. sys/root/src/lib : source files for all common libraries (libc, 
   pthread, ..)
   
   -. sys/root/src/kernel/core : source files for all kernel functions
   -. sys/root/src/kernel/core/core-ecos : source files for kernel
   functions that use underlying real-time os functions
   -. sys/root/src/kernel/fs : source files for supported filesystems.
   -. sys/root/src/kernel/net : source files for supported net stack.
   Currently, Tauon only supports lwip.
   -. sys/root/src/kernel/dev : source files for device drivers.
   

Send comments/corrections/improvements to [email protected].

The Lepton/Tauon home page is http://code.google.com/p/lepton/.

Thanks to:
   * eCos: http://ecos.sourceware.org/
   * lwip: http://savannah.nongnu.org/projects/lwip/
   * nano-X: http://www.microwindows.org/
   * fltk: http://www.fltk.org/
   * openOCD: http://openocd.sourceforge.net/
   * all BSD and GNU tools...
   

Philippe Le Boulanger (original author of Lepton and maintainer)
<[email protected]>

Jean-Jacques Pitrolle (maintainer)
<[email protected]>