Designing Embedded Hardware

Chapter 8. DSP-Based Controllers

. . . the uniformity of the world, that everything which happens is connected, that the great and the small things are all encompassed by the same forces of time . . . this unity and necessary sequence of all things is nevertheless broken in one place, through a small gap, this world of unity is invaded by something alien, something new . . .

—Hermann Hesse, Siddhartha

This chapter takes a look at Digital Signal Processors , or DSPs, which are special-purpose processors designed for executing mathematically intensive algorithms. They first appeared in the early 1980s and since then have expanded into a wide range of devices used in a variety of applications. These processors are characterized by their ability to quickly move data in and out of memory (or a peripheral), and their architectures are optimized for mathematical processing of that data.

The basic purpose of a DSP is to rapidly read in some data, perform a complex algorithm on it, then move the result out. Many DSPs have dual data spaces, known as X and Y. They are able to access both data spaces simultaneously, retrieving two operands at once for processing. As well, many DSPs are also Harvard architecture, and so have three separate address spaces, one for code and two for data, all of which can be accessed concurrently. That ability, combined with very sophisticated ALUs, gives DSPs their advanced data-processing prowess.

DSPs are commonly used in audio processing, video or image processing, ...