/*
  On / Off buzzer 
  Turns on an LED on for one second, then off for one second, repeatedly.

  Most Arduinos have an on-board LED you can control. On the UNO, MEGA and ZERO 
  it is attached to digital pin 13, on MKR1000 on pin 6. LED_BUILTIN is set to
  the correct LED pin independent of which board is used.
  If you want to know what pin the on-board LED is connected to on your Arduino model, check
  the Technical Specs of your board  at https://www.arduino.cc/en/Main/Products
  
  This example code is in the public domain.
 
*/

#define BUZZER_PIN 9
#define BUTTON_PIN 12

// why do we define these variables here and not insode the loop() function? 
int cnt=0;
int baseFrequency = 440;
int buttonState = 0;
bool soundOn = false;


// the setup function runs once when you press reset or power the board
void setup() {
  Serial.begin(9600);
  
  // initialize digital pin for buzzer as an output, and button  as an input. 
  pinMode(LED_BUILTIN , OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT);
  
}

// the loop function runs over and over again forever
void loop() {

   int buttonNewState;
   
   buttonNewState = digitalRead(BUTTON_PIN);

   // this code detects the change in the state of the button 
   if (buttonNewState != buttonState && buttonNewState == 1) {
       cnt = cnt + 1; 
       Serial.println(cnt);
       soundOn = ! soundOn;
       digitalWrite(LED_BUILTIN , soundOn);
   }
   buttonState = buttonNewState;
   Serial.println(soundOn);

   if ( soundOn ) {
    // output signal that to the buzzer. 
    tone(BUZZER_PIN, baseFrequency, 200);
   }
   delay(500);       // wait for a short while
  
}
// End!