Abstract
Enix is a lightweight dynamic operating system for tightly constrained platforms for wireless sensor networks (WSN). Enix provides a cooperative threading model, which is applicable to event-based WSN applications with little run-time overhead. Virtual memory is supported with the assistance of the compiler, so that the sensor platforms can execute code larger than the physical code memory they have. To enable firmware update for deployed sensor nodes, Enix supports remote reprogramming. The commonly used library and the main logical structure are separated; each sensor device has a copy of the dynamic loading library in the Micro-SD card, and therefore only the main function and user-defined subroutines should be updated through RF. A lightweight, efficient file system named EcoFS is also included in Enix. The code size and data size of Enix with full-function including EcoFS are 8 KB and 512 bytes, respectively, enabling Enix to run on many RF-enabled systems-on-chip that cannot run most other WSN OSs. Copyright 2010 ACM.