ESP8266 - Irrigation

This tutorial instructs you how to use ESP8266, soil moisture sensor, relay, and pump to build an automatic irrigation system for the garden with. Specifically:

Hardware Preparation

1×ESP8266 NodeMCU
1×Micro USB Cable
1×Capacitive Soil Moisture Sensor
1×Relay
1×12V Pump
1×Vinyl Tube
1×12V Power Adapter
1×DC Power Jack
1×Jumper Wires
1×(Optional) 5V Power Adapter for ESP8266
1×(Optional) ESP8266 Screw Terminal Adapter

Or you can buy the following sensor kit:

1×DIYables Sensor Kit 30 types, 69 units
Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you. We appreciate your support.

Buy Note: Many soil moisture sensors available in the market are unreliable, regardless of their version. We strongly recommend buying the sensor from the DIYables brand using the link provided above. We tested it, and it worked reliably.

Overview of soil moisture sensor and Pump

If you are not familiar with pump and soil moisture sensor (including pinout, functioning, programming, etc.), the following tutorials will be helpful:

Wiring Diagram

The wiring diagram between ESP8266 NodeMCU and soil moisture sensor Pump

This image is created using Fritzing. Click to enlarge image

See more in ESP8266's pinout and how to supply power to the ESP8266 and other components.

ESP8266 Code

/* * This ESP8266 NodeMCU code was developed by newbiely.com * * This ESP8266 NodeMCU code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/esp8266/esp8266-irrigation */ #define RELAY_PIN D7 // The ESP8266 pin D7 that connects to relay #define MOISTURE_PIN A0 // The ESP8266 pin ADC0 that connects to AOUT pin of moisture sensor #define THRESHOLD 530 // 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); }

Detailed Instructions

To get started with ESP8266 on Arduino IDE, follow these steps:

  • Check out the how to setup environment for ESP8266 on Arduino IDE tutorial if this is your first time using ESP8266.
  • Wire the components as shown in the diagram.
  • Connect the ESP8266 board to your computer using a USB cable.
  • Open Arduino IDE on your computer.
  • Choose the correct ESP8266 board, such as (e.g. NodeMCU 1.0 (ESP-12E Module)), and its respective COM port.
  • Perform calibration to identify the wet-dry THRESHOLD, as outlined in ESP8266 - Calibrates Soil Moisture Sensor.
  • Insert the calibrated THRESHOLD value into the code.
  • Launch Serial Monitor on Arduino IDE.
  • Upload the code to ESP8266.
  • View the result on Serial Monitor.
COM6
Send
The soil is DRY => turn pump ON The soil is DRY => turn pump ON The soil is DRY => turn pump ON The soil is DRY => turn pump ON The soil is WET => turn pump OFF The soil is WET => turn pump OFF The soil is WET => turn pump OFF The soil is WET => turn pump OFF
Autoscroll Show timestamp
Clear output
9600 baud  
Newline  

Code Explanation

Check out the line-by-line explanation contained in the comments of the source code!

Video Tutorial