1. A Structured Hardware/Software Architecture for Embedded Sensor Nodes Joe A. Blogs*, Joe B. Blogs, Joe C. Blogs *email: @ecs.soton.ac.uk; web: http://www.ecs.soton.ac.uk/people/ ; tel. +44 (0)23 8059 ; fax. +44 (0)23 8059 Intelligence, Agents, Multimedia Group, School of Electronics and Computer Science, University of Southampton, SO17 1BJ, UK For further information, please visit http://www.wise.ecs.soton.ac.uk or email @ecs.soton.ac.uk Last updated 15 September 2008 Project AimsThe Energy and Sensing Stacks A Hardware/Software Architecture To develop and deploy a node hardware/software architecture that provides equal weighting to all node functions; for example, communications, energy management, intelligent sensing, locationing and actuation. This promotes modular design, code reuse, and protocol standardisation in the development of all node functions. Communication protocol stacks have been utilised for decades, aiming to formalise, structure and provide interoperability between the tasks of the networking system. The resource-constrained nature of nodes, and the fact that they are developed around radio transceivers, has given prominence to the communications stack. Other functions, such as intelligent sensing and energy management, are usually inelegantly appended to the communications software stack. This is not ideal for node functions that are arguably as important to the successful operation of a node. We propose an embedded system architecture to formally specify multiple interfaces on a sensor node. The architecture provides a sensor node with multiple stacks (which are derived from the same ‘basic template stack’), linked by a shared application layer; this forms a ‘unified’ stack, that can perform all functionality of the node. The structure of various protocol stacks A ‘unified’ stack for communication, energy & sensing The energy management stack contains the Physical Energy Layer (monitors sources/stores, and controls switching), Energy Analysis Layer (uses models to convert measured voltages into a residual energies or remaining lifetimes), and Energy Control Layer (controls energy aware operation, and manages flow between energy components). The intelligent sensing stack contains the Physical Sensing Layer (activates and samples sensors, and controls inputs), Sensor Processing Layer (converts samples into meaningful values, and calculates error), and Sensor Evaluation Layer (provides event detection, and local fusion). An energy-aware intelligent sensing node has been developed. It is powered from a solar cell, via two 1F supercapacitors. The node senses temperature, and reports based upon the data and node’s energy state. Energy management and intelligent sensing stacks The prototype energy- aware intelligent sensing node developed using the proposed architecture References 1.G.V. Merrett, A.S. Weddell, N.R. Harris, B.M. Al-Hashimi, N.M. White. A Structured Hardware/Software Architecture for Embedded Sensor Nodes, In Proceedings of 17th International Conf. Computer Communications and Networks (ICCCN’08) (In Press), 03-07 August 2008, St Thomas, Virgin Islands (USA). 2.A.S. Weddell, G.V. Merrett, N.R. Harris, B.M. Al-Hashimi. Energy Harvesting and Management for Wireless Autonomous Sensors. In Measurement + Control, vol 41 (4). pp. 104-108, 2008 Acknowledgments This work was supported in part by the Engineering and Physical Science Research Council (EPSRC) under grant number EP/D042917/1 PLATFORM: ‘New Directions for Intelligent Sensors’.