Data Acquisition and Signal Processing for Smart Sensors

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SMART SENSOR BUSES AND INTERFACE CIRCUITS

In large measurement and control systems (modern cars, for example), which include hundreds of sensors, communication between a central computer and the smart sensors, which are widely scattered, is difficult. It is probable that the sensors are produced by different manufacturers, and that the sensors’ outputs have different formats. In order to design efficient sensor systems the data transfer must ideally be organized in an orderly and reliable fashion. Such systems are called bus systems or networks. In general a bus system consists of a central computer that is connected by a number of wires to a large number of sensors. When a sensor is activated to send information into the central computer, the sensor's address is selected and the sensor will be switched to the digital data line. The central computer can initiate different kinds of tests and recalibrations. Every sensor is connected to the same wires. A dedicated transmission protocol is applied to allow a flexible and an undisturbed data flow.

There are many buses now available and it is still difficult to find the one to suit smart sensors’ requirements. We do not intend to describe in detail all existing sensor buses and network protocols in this book. For more detailed information we recommend references [8] and [178]. The mission of this last chapter is to show the most applicable digital bus interfaces for smart sensor applications as well as to answer what is expedient ...