Project 1.01 Blink x2

In this project, we bring a second LED, LED3, into the mix. We are essentially doing the same thing as the last project, but this time we are using two LEDs.

Project Code:

///////////////////////////////////////////////////
//Project 1.01 Blink x 2 
byte LED1 = 13;
byte LED3 = 7;

void setup(){
  pinMode(LED1,OUTPUT);
  pinMode(LED3,OUTPUT);
}

void loop(){ 
  digitalWrite(LED1,HIGH);
  digitalWrite(LED3,HIGH);
  delay(1000);
  digitalWrite(LED1,LOW);
  digitalWrite(LED3,LOW);
  delay(1000);
  digitalWrite(LED1,HIGH);
  digitalWrite(LED3,LOW);
  delay(1000);
  digitalWrite(LED1,LOW);
  digitalWrite(LED3,HIGH);
  delay(1000);
  digitalWrite(LED1,LOW);
  digitalWrite(LED3,LOW);
  delay(1000);
}
///////////////////////////////////////////////////

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*If you’re copying and pasting the code, or typing from scratch, delete everything out of a new Arduino sketch and paste / type in the above text.

Like all sketches, this simple sketch includes a setup() and a loop() function. Before the setup() function, we declare two variables that refer to the pin numbers for LED1 and LED3:

byte LED1 = 13; 
byte LED3 = 7;

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In the setup() function, we set both pins to OUTPUT using two pinMode statements:

pinMode(LED1,OUTPUT);
pinMode(LED3,OUTPUT);

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In the loop() function, we first switch both LEDs on by setting the pins to HIGH using two digitalWrite statements:

void loop(){ 
  digitalWrite(LED1,HIGH); 
  digitalWrite(LED3,HIGH); 
  delay(1000);

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After a 1-second delay, we turn both LEDs off:

digitalWrite(LED1,LOW);
digitalWrite(LED3,LOW); 
delay(1000);

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Next, we turn only LED1 on:

digitalWrite(LED1,HIGH); 
digitalWrite(LED3,LOW); 
delay(1000);

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And then switch so that only LED3 is on:

digitalWrite(LED1,LOW); 
digitalWrite(LED3,HIGH); 
delay(1000);

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Finally, we turn both LEDs off for 1 second before the loop() function reaches its closing bracket } and begins again at the top:

  digitalWrite(LED1,LOW); 
  digitalWrite(LED3,LOW); 
  delay(1000);
}

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