#define BUTTON_PIN 25  // ESP32 pin GPIO25, which connected to button
#define LED_PIN    2  // ESP32 pin GPIO18, which connected to led

// variables will change:
int led_state = LOW;    // the current state of LED
int button_state;       // the current state of button
int last_button_state;  // the previous state of button

void setup() {
    // put your setup code here, to run once:
    Serial.begin(115200);
    Serial.println("Hello, ESP32!");
    pinMode(LED_PIN, OUTPUT);
    pinMode(BUTTON_PIN, INPUT_PULLUP);
    button_state = digitalRead(BUTTON_PIN);
}

void loop() {
    last_button_state = button_state;      // save the last state
    button_state = digitalRead(BUTTON_PIN); // read new state
    delay(10);
    if (last_button_state == HIGH && button_state == LOW) {
        Serial.println("The button is pressed");
        // toggle state of LED
        led_state = !led_state;
        // control LED arccoding to the toggled state
        digitalWrite(LED_PIN, led_state);
  }
}