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Chapter 6. How Microcomputers Work > Project 6.1. Use a Microcontroller - Pg. 145

Chapter | 6 How Microcomputers Work 145 Using a program called the fast Fourier transform (FFT), the DSP can analyze a signal and tell you exactly what frequency components are in it. It identifies the harmonic frequencies and their various amplitudes and phases just as in a frequency-domain plot. The big question is why use a complicated technique such as DSP when you can do it with simple analog/linear hardware? Probably the best answer is "just because we can." With cheap single-chip processors, DSP is often no more expensive than an equivalent analog circuit. Since everything else is dig- ital these days, it makes some sense to do as many analog functions digitally as well. But the best reason is that DSP provides superior results over analog methods. Filtering is substantially improved with better selectivity that was not possible with analog filters. While DSP can be programmed on any processor or controller, it is best done on special DSP chips designed for the purpose. They use special archi- tectures and processing schemes to speed up and improve the processing over standard conventional processors. A good example is that DSP chips imple- ment a multiply and add or accumulate function, called MAC, that is common to most DSP processes. The MAC has to be programmed in a standard proces- sor, but in a DSP chip it is implemented with special hardware that speeds up the process and simplifies programming. Some more conventional processors