Energy-efficient design of battery-powered embedded systems

Energy-efficient design of battery-powered embedded systems demands optimizations in both hardware and software. In this work we leverage cycle-accurate energy consumption models to explore compiler and source code optimizations aimed at reducing energy consumption. In addition, we extend cycle-accurate architectural power simulation with battery models that provide battery lifetime estimates. The enhanced simulator and software optimizations are used to study and optimize the power dissipation of Smart-Badge, a wearable system based on the ARM microprocessor developed by HP Laboratories. We found that standard compiler optimizations give less than 1% energy savings. Source code optimizations are capable of up to 90% energy savings. In addition, our analysis of battery lifetime for the MPEG decoder implemented on the Smart-Badge shows that battery efficiency varies greatly with discharge currents on cycle-by-cycle basis and can cause up to 16% reduction in battery lifetime.