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  • Projects
    • Projects 1 >
      • 1.01: Blink
      • 1.02 Blink x2
      • 1.03 Blink Faster
      • 1.04 LED Chase!
      • 1.05 Wait To Blink
      • 1.06 Blink a Little Faster Now
      • 1.07 LED Fade
      • 1.08 RGB Blink
      • 1.09 Change RGB Color with SW1
      • 1.10 Fade RGB Colors
      • 1.11 Reaction Time Game
    • Projects 2 >
      • 2.01 Hello World
      • 2.02 Talk Back
      • 2.03 ASCII Values
      • 2.04 Ski Game
      • 2.05 Demonstration of the String Object
    • Projects 3 >
      • 3.01 Read the Potentiometer
      • 3.02 ASCIIbet Soup
      • 3.03 Potentiometer sets LED Brightness
      • 3.04 Potentiometer Sets Blink Rate
      • 3.05 LED Chase, Part II
    • Projects 4 >
      • 4.01 Bringing the Piezo to Life
      • 4.02 Controlling the Piezo with a Function
      • 4.03 Piezo C Major
      • 4.04 Piezo Greensleaves
      • 4.05 Piezo Metronome
      • 4.06 Piezo as an Input
      • 4.07 Piezo as an Input 2
      • 4.08 Metronome II
      • 4.09 Piezo Playback
      • 4.10 Piezo Fireworks
      • 4.11 Piezo Mosquito
    • Projects 5 >
      • 5.01 The Phototransistor
      • 5.02 Light and Sound
      • 5.03 Light and Sound II
    • Projects 6 >
      • 6.01 EEPROM
      • 6.02 I2C Address Scan
      • 6.03 Read the I2C Temperature Sensor
      • 6.04 High Temperature Alarm
    • Projects 7 >
      • 7.01 Arno Phone Home
      • 7.02 Keyboard Alphabet
      • 7.03 Move Mouse
      • 7.04 Draw Squares
    • Special Projects >
      • Bike Light Demo
  • References
    • Arno Pin Key
    • Arno Schematic
    • Project Index

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

    ///////////////////////////////////////////////////
    //Project 1.02 Blink x 2
    int LED1 = 13;
    int 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);
    }
    ///////////////////////////////////////////////////

    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);

    }

    Back to Projects 1

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