💧 Smart Irrigation System - Complete Code Tutorial

📋 System Overview

This smart irrigation system monitors soil moisture and rain, then automatically waters your crops when needed. It sends data to the cloud every 15 minutes and runs on batteries for months!

Component	Function
Soil Moisture Sensor	Measures water content (0-100%)
Rain Sensor	Detects rainfall to skip watering
Relay Module	Controls water pump (on/off)
ESP32	Brain of the system - reads sensors, controls pump, sends data

🔌 Wiring Diagram

ESP32 Connections:
├── Soil Moisture Sensor
│   ├── VCC  → 3.3V
│   ├── GND  → GND
│   └── AO   → GPIO32 (ADC)
│
├── Rain Sensor
│   ├── VCC  → 3.3V
│   ├── GND  → GND
│   └── DO   → GPIO33 (Digital)
│
└── Relay Module (Water Pump)
    ├── VCC  → 3.3V
    ├── GND  → GND
    └── IN   → GPIO4
    

📖 Complete Code with Line-by-Line Explanation

/*
 * Smart Irrigation System for ESP32
 * Automatically waters crops based on soil moisture
 * Sends data to OceanRemote cloud every 15 minutes
 * 
 * Components Required:
 * - ESP32 board
 * - Capacitive soil moisture sensor
 * - Rain sensor (optional but recommended)
 * - 5V relay module
 * - 12V water pump
 * - 12V power supply
 */

#include       // For internet connectivity
#include  // For sending data to cloud

// ========== PIN DEFINITIONS ==========
#define SOIL_PIN 32     // GPIO32 - Reads soil moisture (ADC)
#define PUMP_RELAY 4    // GPIO4 - Controls water pump relay
#define RAIN_PIN 33     // GPIO33 - Reads rain sensor (digital)

// ========== WIFI CONFIGURATION ==========
const char* ssid = "YOUR_WIFI";        // Replace with your WiFi name
const char* password = "YOUR_PASSWORD"; // Replace with your WiFi password

// ========== OCEANREMOTE CONFIGURATION ==========
const char* token = "YOUR_TOKEN";      // Replace with your OceanRemote device token

// ========== SOIL MOISTURE CALIBRATION ==========
const int DRY_VALUE = 3800;   // Reading when sensor is in dry air
const int WET_VALUE = 1500;   // Reading when sensor is in water
const int WATER_THRESHOLD = 30; // Water when moisture drops below 30%

void setup() {
    // ---------- STEP 1: CONFIGURE PINS ----------
    pinMode(PUMP_RELAY, OUTPUT);      // Set pump relay as output
    pinMode(RAIN_PIN, INPUT_PULLUP);  // Set rain sensor with internal pull-up
    digitalWrite(PUMP_RELAY, HIGH);   // Start with pump OFF (active LOW relay)
    
    // ---------- STEP 2: READ SENSORS ----------
    // Read soil moisture from analog pin (0-4095 on ESP32)
    int raw = analogRead(SOIL_PIN);
    
    // Convert raw value to percentage (0-100%)
    int moisture = map(raw, DRY_VALUE, WET_VALUE, 0, 100);
    moisture = constrain(moisture, 0, 100); // Keep within 0-100%
    
    // Read rain sensor (LOW = raining, HIGH = dry)
    int raining = digitalRead(RAIN_PIN);
    
    // ---------- STEP 3: DECIDE TO WATER OR NOT ----------
    // Condition: Soil is dry (below 30%) AND it's NOT raining
    if (moisture < WATER_THRESHOLD && raining == HIGH) {
        digitalWrite(PUMP_RELAY, LOW);   // Turn pump ON (active LOW relay)
        delay(60000);                     // Water for 60 seconds
        digitalWrite(PUMP_RELAY, HIGH);  // Turn pump OFF
    }
    
    // ---------- STEP 4: SEND DATA TO OCEANREMOTE ----------
    // Connect to WiFi
    WiFi.begin(ssid, password);
    while (WiFi.status() != WL_CONNECTED) {
        delay(500);
    }
    
    // Prepare and send HTTP POST request
    HTTPClient http;
    http.begin("https://api.oceanremote.net/device/state");
    http.addHeader("Content-Type", "application/x-www-form-urlencoded");
    
    String data = "token=" + String(token);
    data += "&soil_moisture=" + String(moisture);
    data += "&irrigation=" + (moisture < WATER_THRESHOLD ? "ON" : "OFF");
    data += "&raining=" + (raining == LOW ? "YES" : "NO");
    
    http.POST(data);
    http.end(); // Close connection
    
    // ---------- STEP 5: DEEP SLEEP TO SAVE POWER ----------
    // Sleep for 15 minutes (15 * 60 * 1,000,000 microseconds)
    esp_sleep_enable_timer_wakeup(15 * 60 * 1000000ULL);
    esp_deep_sleep_start(); // ESP32 goes to sleep here
}

// The loop is empty because the ESP32 sleeps after each cycle
void loop() {
    // This function never runs due to deep sleep
}
    

📊 Code Breakdown: Understanding Each Part

🔧 1. Pin Definitions

#define SOIL_PIN 32     // Soil moisture sensor (analog)
#define PUMP_RELAY 4    // Water pump control (digital output)
#define RAIN_PIN 33     // Rain sensor (digital input)

These constants make your code easier to read and modify. Change the pin numbers here if you use different GPIO pins.

📡 2. WiFi Connection

WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
    delay(500);
}

Attempts to connect to your WiFi network. The loop waits until connection is established before proceeding.

💧 3. Reading Soil Moisture

int raw = analogRead(SOIL_PIN);           // 0-4095 reading
int moisture = map(raw, DRY_VALUE, WET_VALUE, 0, 100);
moisture = constrain(moisture, 0, 100);

• analogRead() - Reads 0-3.3V → 0-4095 on ESP32
• map() - Converts raw reading to percentage (dry→0%, wet→100%)
• constrain() - Ensures value never goes below 0% or above 100%

☔ 4. Rain Detection

int raining = digitalRead(RAIN_PIN);

Digital rain sensor outputs LOW when water is detected, HIGH when dry. We use INPUT_PULLUP so the pin reads HIGH normally and goes LOW when rain bridges the contacts.

🚰 5. Pump Control Logic

if (moisture < WATER_THRESHOLD && raining == HIGH) {
    digitalWrite(PUMP_RELAY, LOW);   // Pump ON
    delay(60000);                     // Run for 60 seconds
    digitalWrite(PUMP_RELAY, HIGH);  // Pump OFF
}

• Condition 1: Soil is too dry (moisture < 30%)
• Condition 2: It's NOT raining (raining == HIGH)
• Action: Turn pump ON for 60 seconds, then OFF

☁️ 6. Sending Data to OceanRemote

HTTPClient http;
http.begin("https://api.oceanremote.net/device/state");
http.addHeader("Content-Type", "application/x-www-form-urlencoded");

String data = "token=" + String(token);
data += "&soil_moisture=" + String(moisture);
data += "&irrigation=" + (moisture < WATER_THRESHOLD ? "ON" : "OFF");

http.POST(data);
http.end();

This sends your sensor readings to OceanRemote so you can monitor soil moisture and irrigation status from anywhere in the world!

🔋 7. Deep Sleep (Power Saving)

esp_sleep_enable_timer_wakeup(15 * 60 * 1000000ULL);
esp_deep_sleep_start();

Puts the ESP32 into deep sleep for 15 minutes. During sleep, power consumption drops to ~2.5μA! This allows your sensor to run on batteries for months.

🎯 Customizing for Your Farm

Adjust Watering Duration

delay(60000);  // Change this value (milliseconds)
// 30000 = 30 seconds
// 120000 = 2 minutes
// 300000 = 5 minutes

Change Soil Moisture Threshold

const int WATER_THRESHOLD = 30; // Water when below 30%
// Tomatoes: 50%
// Maize: 40%
// Succulents: 20%

Adjust Sleep Interval

// 15 minutes = 15 * 60 * 1000000
// 5 minutes = 5 * 60 * 1000000
// 1 hour = 60 * 60 * 1000000