IoT Physical Layer: Sensors, Actuators, Controllers and Programming

Abstract

The physical layer is the most detailed level of abstraction in IoT. It mainly consists of sensors that acquire information for the system and actuators that do actions in response to instructions from the system. To imagine how they both, actuators and sensors, act together in a system, a smart house is considered for example. The actuators here are used to lock and unlock doors, switch on/off the lights and alert users of any warnings or control the temperature of a room or the whole house. The sensors are used to send feedback to the controller of each small system of those systems mentioned above. For example, they send feedback about the condition of the rooms and whether there are any people in the rooms or not, and accordingly, the controller sends its signals to the actuators to turn off unnecessary working devices such as the lights and the air conditioner. Transducer terminology is used for both sensors and actuators. It means a device that converts energy form to another. In this chapter, different types of sensors and actuators are thoughtfully presented and discussed. Actuators may be written, sensors may be read. Moreover, different controllers used in IoT are discussed with its programming methods.