Code

The following is the code for the projects in this chapter:

#define RELAY 3 

void setup() {
  pinMode(RELAY, OUTPUT);
}

void loop() {
  digitalWrite(RELAY, HIGH);
  delay(3000);
  digitalWrite(RELAY, LOW);
  delay(3000);
}

This code should look pretty familiar by now. This code starts off by defining that the relay is connected to the digital 3 pin on the Arduino. In the setup() function, we enable the relay pin for output because we want to use the digitalWrite() function to turn the relay on and off.

In the loop() function, we use the digitalWrite() function to set the relay pin to high, pause three seconds, use the digitalWrite() function again to set the relay pin to low and finally pause three seconds again. This will turn the components connected to the relay on and off every three seconds. This code will work with either the AC circuit or the DC circuit shown previously...