PushButtonControl

// Example 02: Turn on LED while the button is pressed

const int LED = 9;   // the pin for the LED
const int BUTTON = 7; // the pin for the BUTTON
int val = 0; // val is the state of the input pin
int old_val = 0; // the previous value
int state = 0; // tells arduino 0 = off and 1 = on
 
void setup() 
{
  pinMode(LED, OUTPUT); // LED is the output
  pinMode(BUTTON, INPUT); // BUTTON is input
}
void loop()
{
  val = digitalRead(BUTTON); // read button value and store it
  
  if ((val == HIGH) && (old_val == LOW))
  {
    state = 1 - state; // changes state of button from on to off or v.v.
    delay(30); // 30 millisecond delay since last time button pressed.
  }
  
  old_val = val;    //stores old value
  
  if (state == 1){
    digitalWrite(LED, HIGH); // Writes ON to the LED
  }
  else 
  {
    digitalWrite(LED, LOW);    // Writes off to the LED
  }
}