#define LED 18
#define BUTTON 19

int button_state;
int ledState = LOW;
int last_button_state;

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

  pinMode(BUTTON, INPUT_PULLUP);
  pinMode(LED, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:

  delay(50);

  last_button_state = button_state;      
  button_state = digitalRead(BUTTON); 

  if (last_button_state == HIGH && button_state == LOW) {
    ledState = !ledState;

    digitalWrite(LED, ledState);
  }

}