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ESP32-Based Aquaponics Monitoring System with Relay Control

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Circuit Documentation

Summary

The circuit in question is designed to monitor various parameters of an aquaponics system, including water temperature, air temperature, humidity, total dissolved solids (TDS), pH level, and dissolved oxygen (DO). It utilizes an Arduino Nano ESP32 as the central microcontroller to read data from a suite of sensors and control a relay that can switch a water pump on or off based on the water temperature. The sensors include a TDS sensor, a PH Meter, a DO Sensor, a Temperature Sensor, and an AHT10 sensor for measuring air temperature and humidity. A buck converter is used to step down the voltage from a lipo battery to power the system, and a 1-Channel Relay is used to control the water pump.

Component List

Wiring Details

TDS Sensor

AHT10

Buck Converter

1-Channel Relay (5V 10A)

Arduino Nano ESP32

PH Meter

Lipo Battery 2200mAh 30C

DO Sensor

Temperature Sensor

Water Pump

Documented Code

#include <Wire.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#include <AHT10.h>
#include <DFRobot_ESP_PH.h>
#include <DFRobot_DO.h> // Added dissolved oxygen sensor library

// Pin Definitions
#define TDS_SENSOR_PIN A0
#define PH_SENSOR_PIN A3
#define DS18B20_PIN 5
#define RELAY_PIN 8
#define ONE_WIRE_BUS DS18B20_PIN
#define DO_SENSOR_PIN A1 // Added pin for dissolved oxygen sensor
#define SCL_PIN A5 // Typical SCL pin for I2C
#define SDA_PIN A4 // Typical SDA pin for I2C

// Sensor Objects
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature tempSensor(&oneWire);
AHT10 aht10;
DFRobot_ESP_PH ph;
DFRobot_DO do_sensor; // Dissolved oxygen sensor object
float tdsSensorValue = 0;
float phValue = 0;
float doValue = 0; // Dissolved oxygen value

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

    // Initialize I2C with specific SCL and SDA pins
    Wire.begin(SDA_PIN, SCL_PIN);

    // Initialize Sensors
    tempSensor.begin();

    // AHT10 Initialization
    if (!aht10.begin())
    {
        Serial.println("AHT10 not found. Check wiring!");
    }

    // PH Sensor Initialization
    ph.begin();

    // Dissolved Oxygen Sensor Initialization
    do_sensor.begin();

    // Relay Setup
    pinMode(RELAY_PIN, OUTPUT);
    digitalWrite(RELAY_PIN, LOW);
}

void loop()
{
    // Read Temperature Sensors
    tempSensor.requestTemperatures();
    float waterTemp = tempSensor.getTempCByIndex(0);

    // Read AHT10 (Humidity and Air Temperature)
    float humidity = aht10.readHumidity();
    float airTemp = aht10.readTemperature();

    // Read TDS Sensor
    tdsSensorValue = readTDSSensor();

    // Read PH Sensor
    phValue = readPHSensor();

    // Read Dissolved Oxygen Sensor
    doValue = readDOSensor(waterTemp);

    // Print Sensor Readings
    Serial.println("--- Aquaponics Sensor Readings ---");
    Serial.print("Water Temperature: ");
    Serial.print(waterTemp);
    Serial.println(" °C");

    Serial.print("Air Temperature: ");
    Serial.print(airTemp);
    Serial.println(" °C");

    Serial.print("Humidity: ");
    Serial.print(humidity);
    Serial.println(" %");

    Serial.print("TDS Value: ");
    Serial.print(tdsSensorValue);
    Serial.println(" ppm");

    Serial.print("PH Value: ");
    Serial.print(phValue);
    Serial.println("");

    Serial.print("Dissolved Oxygen: ");
    Serial.print(doValue);
    Serial.println(" mg/L");

    // Control Relay (example: turn on if water temp is below 20°C)
    if (waterTemp < 20.0)
    {
        digitalWrite(RELAY_PIN, HIGH);
    }
    else
    {
        digitalWrite(RELAY_PIN, LOW);
    }

    delay(5000); // Read sensors every 5 seconds
}

float readTDSSensor()
{
    int sensorValue = analogRead(TDS_SENSOR_PIN);
    float voltage = sensorValue * (3.3 / 4095.0);
    float tdsValue = (133.42 * voltage * voltage * voltage - 255.86 * voltage * voltage + 857.39 * voltage) * 0.5;
    return tdsValue;
}

float readPHSensor()
{
    static unsigned long samplingTime = millis();
    static unsigned long printTime = millis();
    static float pHValue, voltage;

    if (millis() - samplingTime > 20)
    {
        pHValue = ph.readPH(analogRead(PH_SENSOR_PIN), 25.0); // 25.0°C temperature compensation
        samplingTime = millis();
    }

    return pHValue;
}

float readDOSensor(float temperature)
{
    // Read dissolved oxygen sensor with temperature compensation
    float doValue = do_sensor.readDO(analogRead(DO_SENSOR_PIN), temperature);
    return doValue;
}

This code is responsible for initializing and reading from the various sensors connected to the Arduino Nano ESP32. It also controls the relay based on the water temperature. The code includes functions to read from the TDS, pH, and DO sensors, and it prints the sensor readings to the serial monitor. The relay is controlled in the loop() function, where it is turned on if the water temperature is below 20°C. The code is structured with clear definitions for pin assignments and sensor objects, making it easy to understand and maintain.