Lepton is an POSIX operation system that targets deeply embedded system and platform like cortex-M. Lightweight is greek translation of lepton. It brings modularity and "application" process development for limited resources system (few hundred of Kio FLASH and few dozens of Kio RAM).

The aim of this project is not to develop an another operating system like GNU/Linux but an human undestandable OS that provides more services than a realtime kernel, while keeeping a reasonable footprint for deeply embedded system.

Lepton eases portability of UNIX-like programs and libraries with providing a POSIX layer that gives application programer most common syscalls like vfork and exec.

Lepton is not only a POSIX layer, it takes some concepts from UNIX "philosophy": - Modularity and reusability - Everything is file. Everything is a stream of bytes. - Standard input/output

In fact more than 150 functions of POSIX standard are available for : - process and thread creation/synchronisation - standard peripherals abstraction layer like Linux kernel modules - UNIX stream mechanism. - network support though LWIP or uIP from contiki. - VFS virtual file system layer to add any type of file system (FAT, YAFFS ...). - gui libraries (nanoX and FLNX) - network standard services like webserver and FTP server

Lepton is already use in industrial products like oscilloscopes and electrical installation testers.

Some demonstrations will be showed with AT91SAMD20 (cortex-M0+) and STM32-nucleo (cortex-M4).