Project 1.02 Blink x2

In this project, we bring a second LED, LED3, into the mix.  Upload this project and watch the LEDs blink in a pattern.

 Concepts: setup(), loop(), declare variables, set pin modes, digitalWrite, delay.

Circuits: 

Circuit 1

Select Sketch

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

int LED1 = 13;

int LED3 = 7;

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

  pinMode(LED1,OUTPUT);

  pinMode(LED3,OUTPUT);

In the loop() block 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); 

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

  digitalWrite(LED1,LOW);

  digitalWrite(LED3,LOW);

  delay(1000);

Next, we turn only LED1 on:

  digitalWrite(LED1,HIGH);

  digitalWrite(LED3,LOW);

  delay(1000);

And then switch so that only LED3 is on:

  digitalWrite(LED1,LOW);

  digitalWrite(LED3,HIGH);

  delay(1000);

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

  digitalWrite(LED1,LOW);

  digitalWrite(LED3,LOW);

  delay(1000);

}

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