Sensors and Actuators

Sensors and actuators are electronic components that allow a piece of electronics to interact with the world.

As the microcontroller is a very simple computer, it can process only electric signals (a bit like the electric pulses that are sent between neurons in our brains). For it to sense light, temperature, or other physical quantities, it needs something that can convert them into electricity. In our body, for example, the eye converts light into signals that get sent to the brain using nerves. In electronics, we can use a simple device called a light-dependent resistor (LDR), also known as a photoresistor, that can measure the amount of light that hits it and report it as a signal that can be understood by the microcontroller.

Once the sensors have been read, the device has the information needed to decide how to react. The decision-making process is handled by the microcontroller, and the reaction is performed by actuators. In our bodies, for example, muscles receive electric signals from the brain and convert them into a movement. In the electronic world, these functions could be performed by a light or an electric motor.

In the following sections, you will learn how to read sensors of different types and control different kinds of actuators.