// One method of interrupt - Detect FALLING

// This does not allow for LONG PRESS. It generates TWO interrupts when held longer than debounce

volatile bool buttonPressed; // use "volatile" for variable INSIDE interrupt service routeine (ISR)
int buttonPin = 2; // interrupt pin INT0... also available is INT1, pin 3
int ledPin3 = 3; // red LED
int ledPin5 = 5; // white LED
int count; // a counter

void setup() {
  Serial.begin(9600); // start the serial monitor for text (for this demonstration)

  pinMode(ledPin3, OUTPUT);
  pinMode(ledPin5, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP); // button is wired to ground and signal pin, pulled HIGH internally

  attachInterrupt(digitalPinToInterrupt(buttonPin), buttonISR, FALLING); // PIN#, ISR, TRIGGER
  // digitalPinToInterrupt(buttonPin) - use the Arduino pin number, not the ATMega328 pin number
  // buttonISR - the function (also Interrupt Service Routine/Interrupt Handler) to be called
  // TRIGGER - run the ISR when the pin senses RISING, FALLING, ONCHANGE

  welcome(); // Send an introduction to the Serial Monitor (for this demonstration)
}

void loop() {
  // calling functions
  blockingCode(); // blink LED and delay
  checkButton();
}

int buttonISR() { // Interrupt Service Routine called on a button press
  noInterrupts(); // disable interrupts while in the ISR
  buttonPressed = true; // set the flag that the button was pressed
  interrupts(); // enable interrupts when leaving the ISR
}

void blockingCode() { // set both LEDs ON
  digitalWrite(ledPin5, !(digitalRead(ledPin5))); // read and toggle LED pin
  delay(250); // wait
}

void checkButton() {
  if (buttonPressed) { // check the buttonPressed flag always
    delay(150); // debounce the button press noise if the buttonPressed flag was set
    buttonPressed = false; // reset buttonPressed flag to prepare for the next interrupt
    digitalWrite(ledPin3, !(digitalRead(ledPin3))); // toggle LED pin
    count++; // increment the counter...
    Serial.print(" "); Serial.print(count); // ... show the number of button presses
  }
}

void welcome() {
  // a place to display instructions
  Serial.print("Button Press count: 0");
}