Arduino Simple Counter

counter.ino

/* Simple Counter
* ——————
*
* This is a simple counter that takes a digital input
*
*/
int ledPin = 13; // choose the pin for the LED
int switchPin =2; // choose the input pin (for a pushbutton)
int val = 0; // variable for reading the pin status
int counter = 0;
int currentState = 0;
int previousState = 0;

void setup() {
    pinMode(ledPin, OUTPUT); // declare LED as output
    pinMode(switchPin, INPUT); // declare pushbutton as input
    Serial.begin(9600);
}

void loop() {
    val = digitalRead(switchPin); // read input value
    if (val == HIGH) { // check if the input is HIGH (button released)
        digitalWrite(ledPin, HIGH); // turn LED on
        currentState = 1;
    }
    else {
        digitalWrite(ledPin, LOW); // turn LED off
        currentState = 0;
    }
    if(currentState != previousState){
        if(currentState == 1){
            counter = counter + 1;
            Serial.println(counter);
        }
    }
    previousState = currentState;
    delay(250);
}