Tilt sensor module, SW-520D, 3.3-5V

// SW-520D vibration/tilt module with Serial monitoring + software delay (debounce filter)
// D0: HIGH at rest, LOW when triggered

const int PIN_SENSOR = 3;     // D0 connected to digital pin 3
const int PIN_LED    = 13;    // onboard LED

const unsigned long FILTER_MS = 80;   // software delay for filtering
const unsigned long REPORT_MS = 150;  // serial print rate limit

bool stableState = HIGH;              // current filtered state
bool lastRawState = HIGH;             // last raw read
unsigned long lastChangeMs = 0;       // last time raw state changed
unsigned long lastReportMs = 0;       // last time we printed to Serial

void setup() {
  pinMode(PIN_SENSOR, INPUT);
  pinMode(PIN_LED, OUTPUT);

  Serial.begin(115200);
  delay(200);

  Serial.println("SW-520D monitoring started");
  Serial.println("RAW: direct read, STABLE: filtered read, TRIGGER: LOW");
}

void loop() {
  // Raw read
  bool raw = digitalRead(PIN_SENSOR);

  // If raw state changed, start (or restart) the filter timer
  if (raw != lastRawState) {
    lastRawState = raw;
    lastChangeMs = millis();
  }

  // If raw state has been stable long enough, accept it as the new stable state
  if ((millis() - lastChangeMs) >= FILTER_MS && stableState != lastRawState) {
    stableState = lastRawState;

    // Act on stable state change
    if (stableState == LOW) {
      digitalWrite(PIN_LED, HIGH);
      Serial.println("STABLE: LOW  TRIGGER: YES");
    } else {
      digitalWrite(PIN_LED, LOW);
      Serial.println("STABLE: HIGH TRIGGER: NO");
    }
  }

  // Periodic Serial monitoring without spamming
  if (millis() - lastReportMs >= REPORT_MS) {
    lastReportMs = millis();
    Serial.print("RAW: ");
    Serial.print(raw == LOW ? "LOW" : "HIGH");
    Serial.print("  STABLE: ");
    Serial.println(stableState == LOW ? "LOW" : "HIGH");
  }
}