const int buttonPin = 2; // 按鈕接在Arduino的2號腳位
const int relayPin = 3;  // 繼電器接在Arduino的3號腳位
int buttonState = 0;     // 按鈕當前狀態
int lastButtonState = 0; // 按鈕前一次狀態
bool relayState = false; // 繼電器狀態 (false = 關閉, true = 開啟)

void setup() {
  pinMode(buttonPin, INPUT_PULLUP); 
  pinMode(relayPin, OUTPUT);        
  digitalWrite(relayPin, LOW);      
}

void loop() {
  buttonState = digitalRead(buttonPin); 

  if (buttonState != lastButtonState) {
    if (buttonState == LOW) { 
      relayState = !relayState; 
      digitalWrite(relayPin, relayState ? HIGH : LOW); 
    }
    delay(50); 
  }
  lastButtonState = buttonState; 
}