why when I touch the input cable or put my hand near it the LED comes on?

Question

I am a beginner at electronics and recently got an arduino and the Arduino Project Handbook and I am having trouble with the push button led project.

I have followed the directions and have the correct resistors but every time I go to press the button the led stay on and if I touch the cable or put my hand near the cable the led comes on.

am I missing something?

Below is the Circuit and Code I am using....

const int buttonPin = 2;
const int ledPin = 13;
int buttonState = 0;

void setup(){
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT);
}

void loop(){

  buttonState = digitalRead(buttonPin);

  if(buttonState == HIGH){
     digitalWrite(ledPin, HIGH); 
  }
  else{
    digitalWrite(ledPin, LOW);
  }

}

Answer 1

It's because your button pin is floating (susceptible to ambient electromagnetic interference). When you wave your hand or touch the power, the button pin might sense random voltage that could be in the "high" range.

Think about how the button is connected internally:

So in your schematic, all that second resistor is doing is draining a little current from power to ground, when it actually should be functioning as the pull-down resistor for the button pin.

Solution: If you move the right leg of that resistor over two holes to the other side of the button, it should work.

Answer 2

I am a beginner also and I tried the same code a few days ago.

So try connect the button like this:

Also at is mentioned in the site of Energia:

"External pushbuttons can be connected either through PULL-UP or PULL-DOWN resistors to any Digital I/0 pins."

So modify your code like this:

pinMode(buttonPin, INPUT_PULLUP);

Hope it works!