Introduction

No embedded multimedia design is complete without a thorough analysis of the power supply architecture. This goes without saying for battery-operated devices, but it also holds true for wired systems that have a constant supply of energy, because there are thermal, volumetric, and financial impacts to the power requirements of a system. The media processor and its surrounding hardware ecosystem usually consume a significant share of power, since that's where all the "heavy lifting" occurs.

There are a number of ways to tune the power profile of a system to meet application requirements. As we've done throughout the book, we will discuss concepts generically, but when we discuss specific processor features, these will be derived from Blackfin processor elements in this case, from Blackfin's Dynamic Power Management subsystem.

This subsystem refers to a collection of architectural traits and features that allow manipulations in clock rates and voltages in order to optimize a system's power pro-file for a given activity level. These features include:

• A facility for dynamically changing frequency and voltage

• Flexible power management modes

• Separate power domains

• Efficient architectural constructs

• Software profiling tools

• Intelligent voltage regulation

In this chapter, we'll consider power from these angles and others, like battery choices, regulator architectures, system power dissipators, and so on. But first, let's start by studying the important relationships between frequency, voltage and power in an embedded processor.

A Processor's View of Power

Before we go any further, a discussion of terminology is in order. "Energy" relates the total amount of...