*/ The circuit:

• pushbutton attached to pin 2 from +5V
• 10 kilohm resistor attached to pin 2 from ground
• LED attached from pin 13 to ground (or use the built-in LED on most Arduino boards)

*/

// this constant won't change: const int buttonPin = 2; // the pin that the pushbutton is attached to const int ledPin = 8; // the pin that the LED is attached to

// Variables will change: int buttonPushCounter = 0; // counter for the number of button presses int buttonState = 0; // current state of the button int lastButtonState = 0; // previous state of the button

void setup() { // initialize the button pin as a input: pinMode(buttonPin, INPUT); // initialize the LED as an output: pinMode(ledPin, OUTPUT); // initialize serial communication: Serial.begin(9600); }

void loop() { // read the pushbutton input pin: buttonState = digitalRead(buttonPin);

// compare the buttonState to its previous state if (buttonState != lastButtonState) { // if the state has changed, increment the counter if (buttonState == HIGH) { // if the current state is HIGH then the button went from off to on: buttonPushCounter++; Serial.println("on"); Serial.print("number of button pushes: "); Serial.println(buttonPushCounter); } else { // if the current state is LOW then the button went from on to off: Serial.println("off"); } // Delay a little bit to avoid bouncing delay(10); } // save the current state as the last state, for next time through the loop lastButtonState = buttonState;

// turns on the LED every four button pushes by checking the modulo of the // button push counter. the modulo function gives you the remainder of the // division of two numbers: if (buttonPushCounter % 2 == 0) { digitalWrite(ledPin, LOW); } else { digitalWrite(ledPin, HIGH); }

}

/*  The circuit:
  - pushbutton attached to pin 2 from +5V
  - 10 kilohm resistor attached to pin 2 from ground
  - LED attached from pin 13 to ground (or use the built-in LED on most
    Arduino boards)
*/

// this constant won't change:
const int  buttonPin = 2;    // the pin that the pushbutton is attached to
const int ledPin = 8;       // the pin that the LED is attached to

// Variables will change:
int buttonPushCounter = 0;   // counter for the number of button presses
int buttonState = 0;         // current state of the button
int lastButtonState = 0;     // previous state of the button

void setup() {
  // initialize the button pin as a input:
  pinMode(buttonPin, INPUT);
  // initialize the LED as an output:
  pinMode(ledPin, OUTPUT);
  // initialize serial communication:
  Serial.begin(9600);
}

void loop() {
  // read the pushbutton input pin:
  buttonState = digitalRead(buttonPin);

  // compare the buttonState to its previous state
  if (buttonState != lastButtonState) {
    // if the state has changed, increment the counter
    if (buttonState == HIGH) {
      // if the current state is HIGH then the button went from off to on:
      buttonPushCounter++;
      Serial.println("on");
      Serial.print("number of button pushes: ");
      Serial.println(buttonPushCounter);
    } else {
      // if the current state is LOW then the button went from on to off:
      Serial.println("off");
    }
    // Delay a little bit to avoid bouncing
    delay(10);
  }
  // save the current state as the last state, for next time through the loop
  lastButtonState = buttonState;


  // turns on the LED every four button pushes by checking the modulo of the
  // button push counter. the modulo function gives you the remainder of the
  // division of two numbers:
  if (buttonPushCounter % 2 == 0) {
    digitalWrite(ledPin, LOW);
  } else {
    digitalWrite(ledPin, HIGH);
  }
}