SDREAM: A Super‐Small Distributed REAL‐Time Microkernel Dedicated to Wireless Sensors

Abstract

Traditional embedded operation systems are resource consuming multitask, thus they are not adapted for smart wireless sensors. This paper presents a super‐small distributed real‐time microkernel (SDREAM) dedicated to wireless sensors. SDREAM is a tuple‐based message‐driven real‐time kernel. It adopts a meta language: Kernel Modeling Language to define and describe the system primitives in abstract manner. The IPC and processes synchronization are based on the LINDA concept: the tuple model implemented by two light primitives (SND: OUT & RCV: IN). In SDREAM, tasks are classified into two categories: periodic and priority. The periodic task has the highest priority level and is responsible for capturing sensor signals or actuating control signals; the priority task has various priority levels and is suitable for time‐constraints applications. A two‐level task scheduling policy scheme, named priority‐based pre‐emptive scheduling, is used for task scheduling. SDREAM is simple and efficient. It has a flexible hardware abstraction capability that enables it to be rapidly ported into different WSN platforms and other tiny embedded devices. Currently, it has been ported and evaluated in several hardware platforms. The performance results show SDREAM requires tiny resource and is suitable and efficient for hard real‐time multitask WSN applications.