Energy-aware HW/SW Co-modeling of Batteryless Wireless Sensor Nodes

Abstract

Energy harvesting wireless sensor nodes are sensitive to spatial and temporal fluctuations in energy availability. This issue is especially prevalent in batteryless systems, where devices are directly connected to power sources with little or no buffering. The strong coupling of energy supply and demand introduces a new dimension to the problem of designing robust networked sensing systems. We propose a modeling framework for this class of batteryless systems with an emphasis on the interactions between energy and function. The tool models energy harvesters, power management circuitry, energy storage, microcontrollers, sensors, radio modules, environmental models, and is fully extensible. The microcontroller model is based on cycle-accurate instruction set simulators from Fused, with various peripheral extensions to enable board-level functionality, such as SPI, DMA, hardware multiplier etc. The tool enables virtual prototyping of self-powered wireless sensor nodes, but is especially useful for studying intermittent operation and developing application specific software, hardware, or combined solutions. The simulator is capable of executing real workloads under realistic conditions and this is demonstrated through a case study where the same compiled binary is executed on a virtual prototype and its corresponding physical wireless sensor system to yield matching digital traces and current profiles