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Arduino-Based Smart Soil Moisture and Air Quality Monitoring System with LED Indicators and Motor Control

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Circuit Documentation

Summary

This circuit is designed to monitor soil moisture and air quality, and control a DC motor based on the readings. It uses an Arduino UNO microcontroller to interface with various sensors and actuators, including a soil moisture sensor, an air quality sensor (SGP30), a relay, a toggle switch, and multiple LEDs. The circuit also includes resistors to limit current to the LEDs.

Component List

  1. Adafruit SGP30

    • Description: Air quality sensor
    • Pins: VCC, 3.3V, GND, SCL, SDA

  2. SparkFun Soil Moisture Sensor

    • Description: Measures soil moisture levels
    • Pins: VCC, GND, SIG

  3. Adafruit STEMMA Non-Latching Relay Breakout

    • Description: Controls the DC motor
    • Pins: 1, 2, 3, GND, VIN, SIGNAL, NC, COM, NO

  4. Toggle Switch

    • Description: Used to start/stop the system
    • Pins: L1, COM, L2

  5. Arduino UNO

    • Description: Microcontroller
    • Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

  6. DC Motor

    • Description: Actuator controlled by the relay
    • Pins: pin 1, pin 2

  7. Resistors

    • Description: Current limiting resistors for LEDs
    • Pins: pin1, pin2
    • Properties: Various resistances (560 Ohms, 1000 Ohms)

  8. LEDs (Red, Yellow, Green)

    • Description: Indicate system status
    • Pins: cathode, anode

  9. Power Supply Bench

    • Description: Provides power to the circuit
    • Pins: -12V, GND, +12V, +5V, +3.3V

Wiring Details

Adafruit SGP30

SparkFun Soil Moisture Sensor

Adafruit STEMMA Non-Latching Relay Breakout

Toggle Switch

Arduino UNO

DC Motor

Resistors

LEDs

Power Supply Bench

Code Documentation

//****************************************************************************************************************
const int Grn1 = 2; const int Yel1 = 3; const int Red1 = 4; // Use digital I/O pin 2,3,4
const int Grn2 = 5; const int Yel2 = 6; const int Red2 = 7; // Use digital I/O pin 5,6,7

const int Switch = 8; // Use digital I/O pin 8
const int Motor = 9; // Use digital I/O pin 9

int SysState = 0; // Initial value for reading the button status 

int H2O = 0; //value for storing moisture value 
int H2OPin = A0;//Declare a variable for the soil moisture sensor 

//This is a function used to get the soil moisture content
int readH2O(){
  delay(10);//wait 10 milliseconds 
  H2O = analogRead(H2OPin);//Read the SIG value form sensor 
  return H2O;//send current moisture value
}

#include "SparkFun_SGP30_Arduino_Library.h" // Click here to get the library: http://librarymanager/All#SparkFun_SGP30
#include <Wire.h>
SGP30 mySensor; //create an object of the SGP30 class

//******************************************************************************************************************
void setup() {
  // put your setup code here, to run once
  Serial.begin(9600);   // open serial over USB

  pinMode(Grn1, OUTPUT); pinMode(Yel1, OUTPUT); pinMode(Red1, OUTPUT); // Sets Green, Yellow, and Red Light 1 as Output
  pinMode(Grn2, OUTPUT); pinMode(Yel2, OUTPUT); pinMode(Red2, OUTPUT); // Sets Green, Yellow, and Red Light 2 as Output
  
  pinMode(Motor, OUTPUT); // Sets Motor as Output
  pinMode(Switch, INPUT); // Sets Start button as Input

  // Sets value for inital light outputs to off (LOW)
  digitalWrite(Grn1,LOW); digitalWrite(Yel1,LOW); digitalWrite(Red1,LOW); 
  digitalWrite(Grn2,LOW); digitalWrite(Yel2,LOW); digitalWrite(Red2,LOW);

  Wire.begin();
  //Initialize sensor
  if (mySensor.begin() == false) {
    Serial.println("No SGP30 Detected. Check connections.");
    while (1);
  }
  //Initializes sensor for air quality readings
  //measureAirQuality should be called in one second increments after a call to initAirQuality
  mySensor.initAirQuality();
}
//******************************************************************************************************************
void loop() {
  // Main code here, to run repeatedly

  delay(1000);//take a reading every half second
  SysState = digitalRead(Switch); //Sets the Start button as system state
  
  // Turn on sampling system and read moisture
    if(SysState == HIGH