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Power Management Mechanisms in Embedded Systems

In today’s digital world, people are using applications in daily use which are not available few years back. In fact, what was termed as science fiction just a decade ago is becoming reality today. Increase in the density of electronic circuits, shrinking the size, and decreasing costs have all facilitated easy computing through mobile and embedded electronic devices that are used daily. However, these devices are also becoming power hungry by the day and the ability to deliver viable power for long-term in such applications remains a major challenge. There is a tremendous increase observed in the computing power of hardware and the relatively slow growth in the energy densities of the battery technologies and that remains a concern for system designers. Analyzing the sources of power consumption in electronic devices along with the development of dynamic energy management and energy harvesting techniques are solutions for autonomous operations of embedded systems.
Power Consumption by Embedded Systems 
An embedded system is a computing system that is specifically built to complete a certain task. Its applications range from consumer, aviation, and space equipment etc. These systems are completely or partially isolated from human interaction. Moreover, sometimes they may be expected to continue operating in such a state for many years. A major constraint in the design of mobile embedded systems today is the low capacity of the battery for a given size and weight. The problem is to integrate variety of power reducing methods proposed in the designs. These designs need to be based on a notion that power consumption is as important as performance. Popular peripherals, components and microcontrollers are used in variable combinations or may not be used in all systems. Performance issues are frequently observed by incorrect handling, inefficient configuration and unused components resulting in system instability.
Mechanisms for Power Management
A set of mechanisms enable designers to directly influence, or even control, the power management strategy for a system. These mechanisms have been modeled around typical embedded system requirements, including small footprint, little overhead, and noninterference with real-time constraints. The primary mechanisms for power management are having an autonomous power manager, whose policies can be configured. The decisions outputs of these power managers are given due weightage in the interactions between applications and system.  The management API can be enabled for applications to override specific policies. Another mechanism could be a power management infrastructure for system components, with accounting, auto-suspend, and auto-resume tools. At the level of user-visible system components like files, sockets, and processes that supports semantic energy modes arbitrary energy modes. The hardware features are supportive to implement power management strategies that are aware of the context. Power management mechanisms can also benefit from device drivers for the operating systems. Applications must run with platform-specific operatives by themselves without the need for separate commands.
Secondary Peripheral Mechanisms 
Power management architecture supported by android systems framework can be used along with methods like using the proximity sensors of the mobile or any other device to adjust the illumination of LCD to reduce battery consumption. An external power management chip can also be used to reduce the voltage level of peripherals based on the CPU state. For example, if the CPU is no longer active, then reduce the voltage levels of peripherals interfaced to it. Another example could be of using a core regulator for the processor when CPU is in the idle state so that it reduces the voltage level required for core and memory process and restoring the voltage levels when CPU is active. There are innovative tools to monitor applications for their power consumptions and a user can see the report and close down such applications. Applications like gaming and network leaded services which consume a high portion of power are controlled by implementing sophisticated algorithms which can reduce the battery usage in such as Wi-Fi, GPS on devices.
Diverse Fields of Knowledge
Two of the upcoming technologies have been in the forefront against the power consumption. The techniques are fuel cells and Micro-Electro-Mechanical Systems (MEMS) systems. The researchers believe that these technologies will eventually resolve the energy constraints by improving energy efficiency. Researchers from such a diverse area as physics, mechanical engineering, electrical engineering, design automation are coming together to solve problems in power and energy management. Their efforts are further augmented by scientists from areas like logic and high-level synthesis, computer architecture, operating systems, compiler design, and application development to make it a multidimensional work.
Solutions at Software Front
Additional power savings can be applied through algorithmic and at architectural level changes but it has its own limitation with respect to voltage scaling. System loading and processing requirements techniques are useful for dynamic voltage scaling. Clock power optimizations will remain a challenge as higher frequencies and increased pipelining are applied to extract increased performance. Parallelism must be efficiently extracted without sacrificing the goal of low power. Software generation strategies that are based on cost functions will be increasingly common in these future systems.
Integrated System of Hardware and Software
Designing an embedded system comprises management of complex interactions between hardware and software. The hardware and software development processes are becoming more integrated to achieve the best results in power consumption. Power management is directed by major commercial technologies and other emerging technologies that may affect it. As the field of embedded systems is still active, hence researchers are continually developing new algorithms. They are exploring how to integrate algorithms along with multiple levels of heuristics hardware techniques. It is desirable to overcome the limits imposed by high power consumption and continue to build processors offering greater levels of performance. The wide variety of micro-architectural and software techniques are available today. Intelligent techniques can be designed to manage power consumption of embedded systems such as using the microcontrollers with on-chip peripherals.
Critical Areas of Utility
Embedded systems have the advantage of being isolated from the hacking hence they are used in transportation, fire safety, medical applications and life-critical systems. The implementation of an application using Power Management (PM) may differ with each case of usage where the PM software takes care of selecting the operating points and resource availability. These systems functions and estimation of its power consumption are a key issue in designing battery-powered devices. It will continue to functioning longer without recharging or changing the battery if less power is consumed. Development of ultra-low power consuming electronics has created a possibility of receiving necessary energy for their operation from the environment. These sources of energy are convenient for device use from ecological point of view.
Broader Perspectives on Future
Global warming and environmental concerns are also major contributing factors to attract the attention of consumers, industries, and governments into give serious considerations to the energy crisis. The world economy is changing and the balance in the supply and demand equation for energy suppliers will also be fluctuating. There will be an uncertainty of non-renewable energy sources oil and gas supplies in the world. In upcoming years, the impact of insecurity on the energy market will become a delicate issue. Therefore, the technology which helps in energy efficiency will be in high demand. Consequently, the energy efficient technologies will see a high demand in the forthcoming years.