Sensors are devices that measure a physical property, such as temperature, humidity, stress, and so on. As this is an electronics book, we are concerned with converting such measurements into electrical signals. We have also stretched the definition of a sensor a little to include things such as global positioning systems (GPSs) that locate your position in space.
Many sensors will provide an output signal that is simply a voltage proportional to the property being measured. Others are digital devices that provide digital data about the property. In both cases, these measurements will often be the input to a microcontroller.
6.1 General Principles
Before we look at some of the vast array of sensors that are available, we ...