The Microcontroller Idea Book - Jan Axelson's Lakeview Research

Using Sensors to Detect and Measure
9
Using Sensors to Detect and
Measure
With your 8052-BASIC system and some sensors, you can detect and measure properties
such as temperature, light, chemical composition, motion, and more. This chapter focuses
on how to use sensors in an 8052-BASIC or other microcontroller system.
Sensor Basics
A sensor is a device that responds to a physical property or condition. Other terms for sensor
are detector and transducer. Sensors enable a circuit to learn about the world outside of
itself, much as humans use the senses of sight, hearing, touch, smell, and taste.
A sensor may respond in any of a number of ways. For example, litmus paper is a sensor
that responds to acidity by changing color. For interfacing to the 8052-BASIC, we’re
interested in sensors that respond electrically, by varying in voltage, current, or resistance,
since these are easily interfaced to electronic circuits.
One obvious use for sensors is in environmental monitoring, including detecting and
measuring temperature, light, wind speed and direction, humidity, and so on. But all kinds
of electronic devices use sensors, even when sensing isn’t the primary purpose. For example,
computer printers have sensors that detect when the printer is out of paper. Many cameras
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