#define BTN_PIN 4
#define LED_PIN 2
void setup() {
pinMode(BTN_PIN, INPUT);
pinMode(LED_PIN, OUTPUT);
Serial.begin(9600);
}
void loop() {
bool button = digitalRead(BTN_PIN);
bool led_on = digitalRead(LED_PIN);
digitalWrite(LED_PIN, button ? LOW : !led_on);
Serial.println("LED " + String(button ? "OFF" : (led_on ? "OFF" : "ON")));
delay(500);
}