Embedded Systems Power Consumption Measurement Methods Overview

Estimation of embedded systems (ES) power consumption is becoming a standard step in the development cycle of battery powered equipment. The importance of the power consumption is well realized by the vendors of integrated circuits, especially microprocessors and filed programmable gate arrays (FPGA). The issue is also targeted by the designers of ES development tools. It is also covered in the research publications. Power consumption and therefore its estimation is a key issue in designing battery powered devices in the field of wireless, medical, utility metering, etc., applications. The less power is consumed by the electronics the longer it will continue functioning without recharging or changing the battery. This is not only improves convenience of device use but is also important from the ecology point of view. Development of ultra-low power electronics opened a possibility to create absolutely new class of ES scavenging a necessary energy for their operation from the ambience [1]. In the larger energy sector the key issue is the energy dissipation of the integrated circuits that leads to the need of cooling equipment and expensive packages. The key component of today’s ES is microcontroller and/or FPGA. Both are user programmable units and their power consumption depends upon the executed program and data processed. Therefore, so called software related power is widely considered [2−4]. Having in mind that most of modern microcontrollers and FPGAs are designed for run time switching between active and low power modes, the software related power is the part of overall power consumption budget that can be optimized during development of a system. To be able to minimize power consumption methods and tools for its estimation are needed. There exist two main approaches towards estimation of the power consumption of ES containing programmable unit: simulation based and measurement based. The simulation based approach uses models relating power consumption and programming instructions. This type of tools are becoming a standard utility in the FPGA design packages like Altera PowerPlay or Synopsys Power Compiler. The second approach is based on physical measurements of power consumption while running the system under development. While the measurement based approach requires measurement instruments and in most of the cases special setups inside the ES, it does not suffer from the inadequacy or even absence of reliable models. To add more, measurement approach is the only way to verify correctness of simulation based approach. Therefore measurement is important to validate the power consumption models. The goal of this paper is to give an overview of the current status of ESs power consumption measurement problems, methods and instrumentation.