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Arduino, LEDs, & Buttons

In this How-To Tuesday video they take a look at a simple button setup which lets you turn an LED on/off. This time we hook up an LED without using the build in resistor on pin 13.

Materials you’ll need:

  • Arduino Duemilanove
  • LED
  • 1K ohm resistor (brown, black, red)
  • 10K ohm resistor (brown, black, orange)
  • Push Button
  •  

    Arduino Sketch
    You can find this sketch under File > Examples > Digital > Button
    Note: I’ve made a slight change to the code on line 27, changing ledPin=13; to ledPin=10;

    /*
      Button
     
     Turns on and off a light emitting diode(LED) connected to digital  
     pin 13, when pressing a pushbutton attached to pin 7. 
     
     
     The circuit:
     * LED attached from pin 10 to ground 
     * pushbutton attached to pin 2 from +5V
     * 10K resistor attached to pin 2 from ground
     
     * Note: on most Arduinos there is already an LED on the board
     attached to pin 13.
     
     
     created 2005
     by DojoDave <http://www.0j0.org>
     modified 17 Jun 2009
     by Tom Igoe
     
      http://www.arduino.cc/en/Tutorial/Button
     */
    
    // constants won't change. They're used here to 
    // set pin numbers:
    const int buttonPin = 2;     // the number of the pushbutton pin
    const int ledPin =  10;      // the number of the LED pin
    
    // variables will change:
    int buttonState = 0;         // variable for reading the pushbutton status
    
    void setup() {
      // initialize the LED pin as an output:
      pinMode(ledPin, OUTPUT);      
      // initialize the pushbutton pin as an input:
      pinMode(buttonPin, INPUT);     
    }
    
    void loop(){
      // read the state of the pushbutton value:
      buttonState = digitalRead(buttonPin);
    
      // check if the pushbutton is pressed.
      // if it is, the buttonState is HIGH:
      if (buttonState == HIGH) {     
        // turn LED on:    
        digitalWrite(ledPin, HIGH);  
      } 
      else {
        // turn LED off:
        digitalWrite(ledPin, LOW); 
      }
    }
    

     

    LED/Button Schematic

     

    LED/Button Illustration

     

    Photos

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