MO3 / MO4 Water Level Sensor

				
					// M03 Non-Contact Water Level Sensor - Basic Test (Push-Pull Output / Direct Connection)
// Compatible with: Arduino UNO / Nano / ESP32 / ESP8266 (just rename pins as needed)

const int PIN_SENSOR = 2;      // Sensor OUT connected to D2
const int SAMPLE_N   = 10;     // Debounce sample count
const int SAMPLE_US  = 1000;   // Sampling interval (microseconds) 1ms

// Define the "trigger level" according to your module
// Most M03 modules: liquid detected or close → OUT = HIGH; no liquid → LOW
const int TRIGGER_LEVEL = HIGH;

void setup() {
  Serial.begin(115200);
  pinMode(PIN_SENSOR, INPUT);  // Push-pull output, just use INPUT
  // If you find signal floating/noise, you may try INPUT_PULLDOWN/INPUT_PULLUP (supported on ESP32);
  // UNO has no PULLDOWN option.
  Serial.println(F("M03 Water Level Sensor Test (digital)"));
}

bool readDebounced(int pin) {
  int ones = 0;
  for (int i = 0; i < SAMPLE_N; i++) {
    ones += digitalRead(pin);
    delayMicroseconds(SAMPLE_US);
  }
  // Majority voting: if HIGH counts exceed half, treat as HIGH
  return (ones >= (SAMPLE_N + 1) / 2);
}

void loop() {
  bool level = readDebounced(PIN_SENSOR);

  if (level == (TRIGGER_LEVEL == HIGH)) {
    Serial.println(F("DETECTED: Water level / liquid detected ✔"));
  } else {
    Serial.println(F("CLEAR: No liquid detected ✖"));
  }

  delay(200);
}