Introducing passive, active, and smart sensors

As we discussed in Chapter 1, Architecting High-Performance Embedded Systems, the basic sequence of processing in a simple embedded system consists of reading inputs, computing outputs, writing outputs, and waiting until either it is time to start the next processing loop or the next triggering event occurs. This chapter will look in more depth at the first of these steps: reading inputs. The inputs used by a particular system depend, obviously, on what the system does. In embedded systems, the inputs generally consist of commands entered by a user, commands received from other sources such as a network server controlling the system, and sensor measurements. Our focus here is on inputs collected using sensors.

In the context of embedded systems, a sensor is an electrical or electronic component that is sensitive to some property of its environment and produces an output corresponding to the measured property. To make this abstract description...