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Author Topic: Button to turn on LED sequence not working?  (Read 682 times)
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Im trying to program an arduino uno to turn an LED sequence on and off by the push of a button.
This is the code i am working with:
 Turns on and off a light emitting diode(LED) connected to digital 
 pin 10, when pressing a pushbutton attached to pin 2.
 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: LED is external
 created 2005
 by DojoDave <>
 modified 30 Aug 2011
 by Tom Igoe
 This example code is in the public domain.

// 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);
But only the led on the arduino chip connected to pin 13 reacts to the button even though i have an external LED connected.
any help?

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Maybe you have the external LED in back-to-front?

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To check the obvious
1. Is the LED in the right way around?
2. You have downloaded the new softeare to the Arduino board?
3. Have you tried some other pin (8, 9, 7) in case you pin 10 is damaged?

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