Circuit Documentation

Summary of the Circuit

This circuit is designed to monitor soil moisture levels and activate a buzzer and relay based on the moisture content. It features an Arduino UNO as the central microcontroller, interfaced with a 16x2 I2C LCD for display, a soil moisture module paired with a SparkFun Soil Moisture Sensor for detecting moisture levels, a 5V relay to control power to the buzzer, and a buzzer for audible alerts. The system is powered by two 9V batteries, with a rocker switch to control the power supply to the Arduino.

Component List

Arduino UNO

• Microcontroller board based on the ATmega328P
• Features digital and analog I/O pins
• Provides 5V and 3.3V power outputs

16x2 I2C LCD

• Alphanumeric liquid crystal display
• I2C communication interface
• Displays information such as system status and moisture levels

5V Relay

• Electromechanical switch with a coil rated at 5V
• Has Normally Open (NO) and Normally Closed (NC) contacts
• Controls the buzzer activation

Buzzer

• An audible signaling device
• Activates to alert when soil moisture is low

Rocker Switch

• A simple on/off switch
• Controls the power supply to the Arduino

9V Batteries (x2)

• Provide power to the circuit
• One battery powers the Arduino, and the other powers the relay and buzzer

Soil Moisture Module

• Interfaces with the soil moisture sensor
• Provides analog output corresponding to the moisture level

SparkFun Soil Moisture Sensor

• Detects the moisture content in the soil
• Outputs an analog signal to the soil moisture module

Wiring Details

Arduino UNO

• 5V to Soil Moisture Module VCC, 5V Relay VCC, and 16x2 I2C LCD VCC
• GND to Soil Moisture Module Ground, 16x2 I2C LCD GND, and 5V Relay GND
• Vin connected through Rocker Switch to 9V battery
• A0 to Soil Moisture Module Analog
• A4 (SDA) to 16x2 I2C LCD SDA
• A5 (SCL) to 16x2 I2C LCD SCL
• D2 to 5V Relay In

16x2 I2C LCD

• GND to Arduino UNO GND
• VCC to Arduino UNO 5V
• SDA to Arduino UNO A4
• SCL to Arduino UNO A5

5V Relay

• VCC to Arduino UNO 5V
• GND to Arduino UNO GND
• In to Arduino UNO D2
• Normally Open to Buzzer POSITIVE
• Common terminal to 9V battery +

Buzzer

• POSITIVE to 5V Relay Normally Open
• NEGATIVE to 9V battery -

Rocker Switch

• One terminal to 9V battery +
• Other terminal to Arduino UNO Vin

Soil Moisture Module

• VCC to Arduino UNO 5V
• Ground to Arduino UNO GND
• Analog to Arduino UNO A0
• positive to SparkFun Soil Moisture Sensor VCC
• negative to SparkFun Soil Moisture Sensor GND

SparkFun Soil Moisture Sensor

• VCC to Soil Moisture Module positive
• GND to Soil Moisture Module negative

Documented Code

#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
  lcd.clear();
  pinMode(2, OUTPUT);
  digitalWrite(2, HIGH);
  delay(1000);
  lcd.setCursor(0, 0);
  lcd.print("IRRIGATION");
  lcd.setCursor(0, 1);
  lcd.print("SYSTEM IS ON ");
  lcd.print("");
  delay(3000);
  lcd.clear();
}

void loop() {
  int value = analogRead(A0);
  Serial.println(value);
  if (value > 950) {
    digitalWrite(2, HIGH);
    lcd.setCursor(0, 0);
    lcd.print("BUZZER is OFF ");
  } else {
    digitalWrite(2, LOW);
    lcd.setCursor(0, 0);
    lcd.print("BUZZER is ON");
  }

  if (value < 500) {
    lcd.setCursor(0, 1);
    lcd.print("Moisture : HIGH");
  } else if (value > 500 && value < 950) {
    lcd.setCursor(0, 1);
    lcd.print("Moisture : MID ");
  } else if (value > 950) {
    lcd.setCursor(0, 1);
    lcd.print("Moisture : LOW ");
  }
}

This code initializes the LCD and sets up the Arduino to read the analog value from the soil moisture sensor. Depending on the moisture level, it activates or deactivates the relay (which controls the buzzer) and updates the display with the moisture status.