Sensors

Sensors

Turbidity Sensor Tested

The project uses the LGZD Sensor V1.1 turbidity sensor, powered at 5 V DC with a current consumption of up to 30 mA, making it suitable for direct connection to a microcontroller system. It measures water clarity by providing either an analog output (0–4.5 V) or a digital signal (0–5 V), with a fast response time of less than 500 ms, allowing the system to quickly detect changes in water quality. This sensor is chosen because it enables real-time monitoring of turbidity levels, so the system can automatically trigger actions such as activating the solenoid valve to stop or allow flow and controlling the pump, ensuring only clean water passes through the system while maintaining reliable and responsive automated operation.

const int turbidityPin = A0;

float V_clean = 2.77;
float V_dirty = 0.90;

int getAverage() {
  int sum = 0;
  for (int i = 0; i < 20; i++) {
    sum += analogRead(turbidityPin);
    delay(5);
  }
  return sum / 20;
}

void setup() {
  Serial.begin(115200);
  Serial.println("=== TURBIDITY MONITOR ===");
}

void loop() {
  int raw = getAverage();
  float voltage = raw * (3.3 / 4095.0);

  float turbidity = ((V_clean - voltage) / (V_clean - V_dirty)) * 100.0;

  // Clamp values
  if (turbidity < 0) turbidity = 0;
  if (turbidity > 100) turbidity = 100;

  // Classification
  String status;
  if (turbidity < 20) {
    status = "CLEAN 💧";
  } 
  else if (turbidity < 50) {
    status = "SLIGHTLY DIRTY 🌫️";
  } 
  else if (turbidity < 80) {
    status = "DIRTY 🟤";
  } 
  else {
    status = "VERY DIRTY 🚫";
  }

  // Print everything nicely
  Serial.print("Raw: ");
  Serial.print(raw);

  Serial.print(" | Voltage: ");
  Serial.print(voltage, 2);

  Serial.print(" V | Turbidity: ");
  Serial.print(turbidity, 1);
  Serial.print(" %");

  Serial.print(" | Status: ");
  Serial.println(status);

  delay(1000);
}

Results

SEN0189  Sensor  with Xiao Esp32-C3

New sensor readings
clean water 
Raw: 3435 Voltage: 2.77 V
Raw: 3438  Voltage: 2.77 V
Raw: 3432  Voltage: 2.77 V
Raw: 3434  Voltage: 2.77 V
Raw: 3432  Voltage: 2.77 V
Raw: 3422  Voltage: 2.76 V





Dirty Water
Raw: 1176  Voltage: 0.95 V
Raw: 1163  Voltage: 0.94 V
Raw: 1161  Voltage: 0.94 V
Raw: 1199  Voltage: 0.97 V
Raw: 1126  Voltage: 0.91 V
Raw: 1097  Voltage: 0.88 V
Raw: 1095  Voltage: 0.88 V
Raw: 1095  Voltage: 0.88 V
Raw: 1070  Voltage: 0.86 V
Raw: 1069  Voltage: 0.86 V

My averages
 float V_clean = 2.77;
float V_dirty = 0.90;

with very consistent readings now with new sensor

old sensor readings

Clean Water
Raw: 2029  Voltage: 1.64 V
Raw: 2029  Voltage: 1.64 V
Raw: 2030  Voltage: 1.64 V
Raw: 2037  Voltage: 1.64 V
Raw: 2041  Voltage: 1.64 V
Raw: 2039  Voltage: 1.64 V
Raw: 2040  Voltage: 1.64 V
Raw: 2044  Voltage: 1.65 V
Raw: 2044  Voltage: 1.65 V
Raw: 2043  Voltage: 1.65 V

Average Raw Value: 2037.6
Average Voltage: 1.643 V

dirty Water
Raw: 2139  Voltage: 1.72 V
Raw: 2139  Voltage: 1.72 V
Raw: 2141  Voltage: 1.73 V
Raw: 2151  Voltage: 1.73 V
Raw: 2153  Voltage: 1.74 V
Raw: 2152  Voltage: 1.73 V
Raw: 2152  Voltage: 1.73 V
Raw: 2154  Voltage: 1.74 V
Raw: 2154  Voltage: 1.74 V
Raw: 2152  Voltage: 1.73 V
Raw: 2166  Voltage: 1.75 V

Average Raw Value: 2150.27
Average Voltage: 1.733 V

Flow Sensor

Flow Rate: 0.00 L/min
Flow Rate: 0.00 L/min
Flow Rate: 0.00 L/min
Flow Rate: 0.27 L/min
Flow Rate: 0.27 L/min
Flow Rate: 0.67 L/min
Flow Rate: 0.93 L/min
Flow Rate: 0.93 L/min
Flow Rate: 0.93 L/min
Flow Rate: 1.07 L/min
Flow Rate: 0.93 L/min
Flow Rate: 1.07 L/min

I tested the sensor using xiao esp 32-c3, and connected with MQTT, and got the followng readings:

#include <WiFi.h>
#include <PubSubClient.h>

// WiFi
const char* ssid = "MT";
const char* password = "#@Innovate";

// MQTT
const char* mqtt_server = "broker.emqx.io";

WiFiClient espClient;
PubSubClient client(espClient);

// Flow sensor
const int flowPin = D2; // D2 (change if needed)
volatile int pulseCount = 0;

float flowRate = 0.0;
float totalLiters = 0.0;

unsigned long previousMillis = 0;

// Interrupt
void IRAM_ATTR pulseCounter() {
  pulseCount++;
}

// Connect WiFi
void setup_wifi() {
  delay(10);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("\nWiFi connected");
}

// Reconnect MQTT
void reconnect() {
  while (!client.connected()) {
    if (client.connect("ESP32FlowClient")) {
      Serial.println("MQTT connected");
    } else {
      delay(2000);
    }
  }
}

void setup() {
  Serial.begin(115200);

  pinMode(flowPin, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(flowPin), pulseCounter, FALLING);

  setup_wifi();
  client.setServer(mqtt_server, 1883);
}

void loop() {
  if (!client.connected()) reconnect();
  client.loop();

  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= 1000) { // every 1 sec
    previousMillis = currentMillis;

    // Calculate flow rate (L/min)
    flowRate = pulseCount / 7.5;

    // Convert to liters per second and accumulate
    float litersThisSecond = flowRate / 60.0;
    totalLiters += litersThisSecond;

    pulseCount = 0;

    // Convert to string
    char flowMsg[20];
    char totalMsg[20];

    sprintf(flowMsg, "%.2f", flowRate);
    sprintf(totalMsg, "%.2f", totalLiters);

    // Publish to MQTT
    client.publish("water/flow", flowMsg);
    client.publish("water/total", totalMsg);

    // Debug
    Serial.print("Flow: ");
    Serial.print(flowRate);
    Serial.print(" L/min | Total: ");
    Serial.println(totalLiters);
  }
}