Building a Smart Farm with Arduino and ESP32: A Comprehensive Guide from Temperature and Humidity Monitoring to Automated Irrigation

🛠️ Low-Cost Agricultural IoT Solution | 💡 A Greenhouse Control System for Beginners

🌟 I. Project Background and System Value

🌱 Pain Points in Traditional Agriculture:

Manual inspections are time-consuming and labor-intensive
Difficulty in responding to fluctuations in environmental parameters
Severe waste of water resources

🚀 Core Functions of the Smart System:

Real-time monitoring of temperature, humidity, light intensity, and soil moisture
Automatic adjustment of shading curtains and irrigation systems
Remote control and alerts via mobile APP

🔧 II. Hardware List and Cost Budget

📦 Essential Materials (Total Budget Approximately 300 Yuan)

Module Type	Recommended Model	Unit Price	Function Description
Main Control	ESP32 NodeMCU	50 Yuan	Integrated Wi-Fi / Bluetooth
Sensor	DHT11 (Temperature and Humidity)	10 Yuan	Detects air temperature and humidity
BH1750 (Light)	20 Yuan	Measures light intensity
FC-28 (Soil Moisture)	30 Yuan	Monitors soil moisture
Actuator	Relay Module	15 Yuan	Controls water pump / shading curtain
Display	OLED Screen	25 Yuan	Local data display
Power Supply	Solar Panel + Lithium Battery	150 Yuan	Outdoor power supply solution

🚀 III. Comprehensive Development Process

📝 Four Key Steps from Hardware to Software

Circuit Construction (Breadboard Connection)

Wiring Diagram

ESP32

├── GPIO4 → DHT11 Data  
├── GPIO5 → Relay Control  
├── SDA → OLED Data  
├── SCL → OLED Clock  
├── A0 → BH1750 Analog Output  
└── A1 → FC-28 Analog Output

Code Writing (Arduino IDE)

Core Code for Temperature and Humidity Monitoring

#include <WiFi.h>

#include &lt;PubSubClient.h&gt;  
#include &lt;DHT.h&gt;  
#define DHT_PIN 4  
DHT dht(DHT_PIN, DHT11);

const char* ssid ="YourWiFi";
const char* password ="YourPassword";
const char* mqtt_server ="mqtt.eclipseprojects.io";

void setup(){
  dht.begin();
  WiFi.begin(ssid, password);
  while(WiFi.status()!= WL_CONNECTED) delay(1000);
}

void loop(){
  float h = dht.readHumidity();
  float t = dht.readTemperature();
  client.publish("farm/temp", String(t).c_str());
  delay(5000);
}

Mobile APP Configuration (Blynk Platform)

Step-by-Step Guide

Register a Blynk account and create a new project
Configure virtual pins V0 to display temperature and V1 to control irrigation
Insert the authorization code into the Arduino code

🎯 IV. Core Function Implementation

1. Real-time Monitoring of Environmental Parameters

Data Collection Logic
int light = analogRead(A0); // Read light intensity
```
int soil = analogRead(A1);   // Read soil moisture  
```
Threshold Alarmif (t > 30) client.publish(“alert”, “High Temperature Warning!”);

2. Automation Control

Automatic Irrigation System

if (soil < 300 && h < 60) {

  digitalWrite(5, HIGH); // Turn on water pump  
  client.publish("irrigation", "Automatic watering in progress");  
}

Smart Shading Curtainif (light > 800) digitalWrite(6, HIGH); // Pull up shading curtain

3. Local Data Visualization

OLED Display Code

display.clearDisplay();

display.setTextSize(1);  
display.setCursor(0,0);  
display.print("T: "); display.print(t);  
display.print(" H: "); display.print(h);  
display.display();

🔐 V. Advanced Function Development

🚀 Three Directions to Enhance System Intelligence

Low Power Design

Use <span>ESP.deepSleep()</span> to enter sleep mode, waking up every 30 minutes
Turn off unused peripherals (e.g., Bluetooth, ADC)

Cloud Data Analysis

Upload data to the ThingSpeak platform to generate historical trend charts
Implementation Code:
client.publish(“channels/123456/feeds/field1”, String(t).c_str());

Video Surveillance Integration

Connect the ESP32-CAM module for real-time transmission of greenhouse images
Example command: “View real-time greenhouse images”

⚠️ VI. Pitfall Guide

🔥 Common Problem Solutions During Development

Abnormal Sensor Data

Check for loose connections and avoid strong electrical interference (e.g., from water pump motors)

Automatic Irrigation False Trigger

Add debounce logic:
if (soil < 300 && lastSoil > 300) digitalWrite(5, HIGH);

Unstable Outdoor Power Supply

Use a solar charging controller to ensure the lithium battery voltage remains stable at 5V

📢 ConclusionThe combination of Arduino and ESP32 provides a low-cost, easily expandable solution for smart agriculture. From greenhouses to fields, you can easily achieve intelligent environmental control. Start building your smart farm now!