#define BUTTON_PIN 21 // GPIO21 pin connected to button

// Variables will change:
int lastState = HIGH; // the previous state from the input pin
int currentState;     // the current reading from the input pin

void setup() {
  // initialize the pushbutton pin as an pull-up input
  pinMode(BUTTON_PIN, INPUT_PULLUP);

  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, ESP32!");
}

void loop() {

  // read the state of the switch/button:
  //currentState = digitalRead(BUTTON_PIN);

  //if(lastState == LOW && currentState == HIGH)
  //  Serial.println("The state changed from LOW to HIGH");

  // save the last state
  //lastState = currentState;

  // read the state of the switch/button:
  int buttonState = digitalRead(BUTTON_PIN);

  // print out the button's state
  Serial.println(buttonState);

}