Delphi Cookbook - Third Edition

How it works...

Basically, the relay is nothing more than a switch that can be operated through a digital signal (high or low). There are two types of configuration: NO and NC. They stand for normally open and normally closed. This means that to pass a current in the first configuration, a low signal must be sent, while for the second configuration, it is the opposite.

From this explanation, it is very easy to understand the Arduino Sketch:

1. In the setup function, the different pins are configured, but I want to dwell on two initializations:
   • digitalWrite(relay_pin_1, HIGH); and digitalWrite(relay_pin_2, HIGH);
   • We are connecting to the relay in NO (normally open configuration), so the preceding lines ensure that the relay is initially ...