7 - Analog Interfacing

Abstract

This chapter discusses transducers and analog devices, A-to-D and D-to-A converters, and data acquisition systems. A good designer must be aware of the analog devices and circuits, and must be aware of the advantages of the different ways to implement some functions in analog or digital hardware, or in software. Analog circuits are commonly used to interconnect the I/O device and the outside world. Two kinds of analog signals are important, which correspond to AM and FM radio. The chapter considers analog signals whose amplitude carries the value, whether the signal is direct current or alternating current, as AM radios carry the sound. Amplitude analog signals are more pervasive in interface design. A basic theme of this chapter is that many functions can be done using digital or analog hardware, or using software. The smart designer determines the best technique from among many alternatives to implement a particular function. Thus, the designer should know a little about analog circuitry. On the one hand, a basic understanding of the operation and use of analog circuits is essential in making intelligent hardware/software trade-offs and is quite useful even for programmers who write code to interface to such devices.