ESP32 - Automatic Irrigation System

This tutorial instructs you how to make an automatic irrigation system for the garden using ESP32, a soil moisture sensor, relay, and pump. In detail:

Hardware Used In This Tutorial

1×ESP-WROOM-32 Dev Module
1×Micro USB Cable
1×Capacitive Soil Moisture Sensor
1×12V Pump
1×Vinyl Tube
1×12V Power Adapter
1×DC Power Jack
1×Jumper Wires
1×(Optional) 5V Power Adapter
1×(Optional) ESP32 Screw Terminal Adapter
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Introduction to Soil Moisture Sensor and Pump

We have specific tutorials about soil moisture sensor and pump. Each tutorial contains detailed information and step-by-step instructions about hardware pinout, working principle, wiring connection to ESP32, ESP32 code... Learn more about them at the following links:

Wiring Diagram

ESP32 Irrigation System Wiring Diagram

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ESP32 Code

/* * This ESP32 code is created by * * This ESP32 code is released in the public domain * * For more detail (instruction and wiring diagram), visit */ #define RELAY_PIN 17 // ESP32 pin GIOP17 that connects to relay #define MOISTURE_PIN 36 // ESP32 pin GIOP36 (ADC0) that connects to AOUT pin of moisture sensor #define THRESHOLD 1000 // CHANGE YOUR THRESHOLD HERE void setup() { Serial.begin(9600); pinMode(RELAY_PIN, OUTPUT); } void loop() { int value = analogRead(MOISTURE_PIN); // read the analog value from sensor if (value < THRESHOLD) { Serial.print("The soil is DRY => turn pump ON"); digitalWrite(RELAY_PIN, HIGH); } else { Serial.print("The soil is WET => turn pump OFF"); digitalWrite(RELAY_PIN, LOW); } Serial.print(" ("); Serial.print(value); Serial.println(")"); delay(200); }

Quick Instructions

  • Do calibration to determine the wet-dry THRESHOLD, see ESP32 - Calibrates Soil Moisture Sensor
  • Update the calibrated THRESHOLD value in the code
  • Open Serial Monitor on Arduino IDE
  • Upload the code to ESP32 board
  • See the result on Serial Monitor. It looks like the below:
The soil is DRY => turn pump ON (112) The soil is DRY => turn pump ON (321) The soil is DRY => turn pump ON (541) The soil is DRY => turn pump ON (745) The soil is DRY => turn pump ON (864) The soil is WET => turn pump OFF (1265) The soil is WET => turn pump OFF (2011) The soil is WET => turn pump OFF (2365) The soil is WET => turn pump OFF (3375) The soil is WET => turn pump OFF (3679)
Autoscroll Show timestamp
Clear output
9600 baud  

Code Explanation

Read the line-by-line explanation in the comment lines of the source code!

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