릴레이 타이머 스위치

const int RELAY = 7;
const int BTN_START = 2;
const int BTN_SET = 3;
const int LED_PIN = 13;
const int BUZZER = 8;

int timerSeconds = 10;  // 기본 10초
bool timerRunning = false;
unsigned long timerStart = 0;

void setup() {
  pinMode(RELAY, OUTPUT);
  pinMode(BTN_START, INPUT);
  pinMode(BTN_SET, INPUT);
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  digitalWrite(RELAY, LOW);
  Serial.begin(9600);
  Serial.println("Timer Switch Ready");
  Serial.print("Time: ");
  Serial.print(timerSeconds);
  Serial.println("s");
}

void loop() {
  // 시간 설정 버튼: 10초씩 증가 (최대 60초)
  if (digitalRead(BTN_SET) == HIGH && !timerRunning) {
    timerSeconds += 10;
    if (timerSeconds > 60) timerSeconds = 10;
    Serial.print("Time set: ");
    Serial.print(timerSeconds);
    Serial.println("s");
    tone(BUZZER, 2000, 50);
    delay(300);
  }

  // 시작 버튼
  if (digitalRead(BTN_START) == HIGH && !timerRunning) {
    timerRunning = true;
    timerStart = millis();
    digitalWrite(RELAY, HIGH);
    digitalWrite(LED_PIN, HIGH);
    tone(BUZZER, 1000, 200);
    Serial.println("Timer ON!");
  }

  // 타이머 종료 체크
  if (timerRunning) {
    unsigned long elapsed = (millis() - timerStart) / 1000;
    if (elapsed >= (unsigned long)timerSeconds) {
      timerRunning = false;
      digitalWrite(RELAY, LOW);
      digitalWrite(LED_PIN, LOW);
      // 종료 알림음
      for (int i = 0; i < 3; i++) {
        tone(BUZZER, 1500, 150);
        delay(250);
      }
      Serial.println("Timer OFF!");
    }
  }

  delay(50);
}