🌱 Smart Plant Monitoring + Automatic Watering System

Using ESP32 + Soil Moisture Sensor + Relay + Water Pump

ESP32 Wifi Terminal Code + VERY detailed line-by-line explanation.

✅ ESP32 creates Hotspot (Access Point)
✅ Mobile connects to ESP32 WiFi
✅ Open WiFi Terminal app
✅ ESP32 sends live text like Serial Monitor
✅ Moisture < 10% → Pump ON
✅ Moisture ≥ 10% → Pump OFF

✅ 1) Best WiFi Terminal App (Android)

Use this app:

📱 “TCP Telnet Terminal”
or
📱 “WiFi Telnet Terminal”

(Any app that supports TCP Client / Telnet will work)

✅ 2) ESP32 Hotspot WiFi Terminal Code

⚡ Connections:

• Soil Sensor AO → GPIO34

• Relay IN → GPIO26

This code makes ESP32 act as:

✅ Hotspot
✅ TCP Server (like WiFi Serial terminal)

/************************************************************
SMART PLANT MONITORING + AUTO WATERING SYSTEM (WiFi Terminal)
Board: ESP32
Sensor: Soil Moisture Sensor (Analog)
Relay: 1 Channel Relay
Pump: DC Water Pump

Condition:
Moisture < 10% -> Pump ON
Moisture >= 10% -> Pump OFF

Output:
Serial Monitor + WiFi Terminal App (TCP)
************************************************************/

#include <WiFi.h>

// ----------- Hotspot WiFi Details -----------
const char* ssid = "ESP32_PLANT_WIFI";
const char* password = "12345678";

// ----------- TCP Server Port -----------
WiFiServer server(23); // Port 23 (Telnet)

WiFiClient client;

// ----------- Pin Definitions -----------
#define SOIL_SENSOR_PIN 34
#define RELAY_PIN 26

// ----------- Moisture Calibration Values -----------
int dryValue = 3500;
int wetValue = 1500;

// ----------- Moisture Threshold -----------
int pumpThreshold = 10;

// ----------- Variables -----------
int sensorValue = 0;
int moisturePercent = 0;
String soilStatus = "";
String pumpStatus = "";

void setup()
{
Serial.begin(115200);

pinMode(RELAY_PIN, OUTPUT);

// Pump OFF initially
digitalWrite(RELAY_PIN, HIGH);

// ----------- Start ESP32 Hotspot -----------
WiFi.softAP(ssid, password);

Serial.println("=======================================");
Serial.println("ESP32 WiFi Terminal Started!");
Serial.print("Hotspot SSID: ");
Serial.println(ssid);
Serial.print("Hotspot Password: ");
Serial.println(password);
Serial.print("ESP32 IP Address: ");
Serial.println(WiFi.softAPIP());
Serial.println("TCP Port: 23");
Serial.println("=======================================");

// ----------- Start TCP Server -----------
server.begin();
server.setNoDelay(true);
}

// ----------- Function: Read sensor + control pump -----------
void readSensorAndControlPump()
{
sensorValue = analogRead(SOIL_SENSOR_PIN);

moisturePercent = map(sensorValue, dryValue, wetValue, 0, 100);

if (moisturePercent > 100) moisturePercent = 100;
if (moisturePercent < 0) moisturePercent = 0;

if (moisturePercent < pumpThreshold)
{
// Soil dry -> Pump ON
digitalWrite(RELAY_PIN, LOW);
soilStatus = "DRY";
pumpStatus = "ON";
}
else
{
// Soil ok -> Pump OFF
digitalWrite(RELAY_PIN, HIGH);
soilStatus = "OK";
pumpStatus = "OFF";
}
}

void loop()
{
// ----------- Step 1: Check if client connected -----------
if (!client || !client.connected())
{
client = server.available();

if (client)
{
Serial.println("New WiFi Terminal Client Connected!");

client.println("=======================================");
client.println("SMART PLANT MONITORING + AUTO WATERING");
client.println("WiFi Terminal Connected Successfully!");
client.println("Condition: Moisture < 10% => Pump ON");
client.println("=======================================");
}
}

// ----------- Step 2: Read sensor + control pump -----------
readSensorAndControlPump();

// ----------- Step 3: Create terminal message -----------
String message = "";
message += "ADC: ";
message += sensorValue;
message += " | Moisture: ";
message += moisturePercent;
message += "%";
message += " | Soil: ";
message += soilStatus;
message += " | Pump: ";
message += pumpStatus;

// ----------- Step 4: Print to Serial Monitor -----------
Serial.println(message);

// ----------- Step 5: Send to WiFi Terminal App -----------
if (client && client.connected())
{
client.println(message);
}

// ----------- Step 6: Delay -----------
delay(1000);
}

✅ 3) How to Use WiFi Terminal App (Step-by-Step)

✅ Step 1: Upload Code

Upload this code to ESP32.

✅ Step 2: Connect Mobile to ESP32 WiFi

Go to mobile WiFi settings and connect:

📶 SSID: ESP32_PLANT_WIFI
🔐 Password: 12345678

✅ Step 3: Open WiFi Terminal App

In the app set:

• Mode: TCP Client / Telnet

• IP Address: 192.168.4.1

• Port: 23

Then press Connect.

✅ Step 4: Result

You will see output like:

✅ 4) FULL CODE EXPLANATION (Line-by-Line)

Now deep explanation.

✅ A) WiFi Library

This library provides ESP32 WiFi features.

✅ B) Hotspot Name and Password

ESP32 will create WiFi hotspot with these details.

✅ C) TCP Server Creation

This makes ESP32 act like a server.

Port 23 is standard for Telnet terminal.

✅ D) WiFi Client Object

This stores the connected mobile device.

✅ E) Pin Setup

• Soil sensor analog output on GPIO34

• Relay control on GPIO26

✅ F) Calibration Values

Used for converting sensor ADC to moisture %.

✅ G) Threshold

Main logic:

• <10% → Pump ON

• =10% → Pump OFF

✅ setup() Explanation

1) Serial Monitor Start

Starts Serial Monitor.

2) Relay Output Pin

Relay needs output.

3) Pump OFF Initially

Active LOW relay:

• HIGH = OFF

4) Start Hotspot

ESP32 starts WiFi Access Point mode.

5) Print IP Address

Shows ESP32 IP address.

Default is:
192.168.4.1

6) Start TCP Server

Starts the terminal server.

✅ loop() Explanation

Step 1: Client Connection Check

Means:

• If no phone connected, wait for new client.

Accept new client

If phone connects, this returns client object.

Welcome message

Shows message on WiFi terminal app.

Step 2: Read sensor + control pump

This function does:

• read sensor ADC

• convert to moisture %

• pump ON/OFF

Step 3: Create output message

This builds one line message.

Step 4: Print Serial

So you also see output on laptop.

Step 5: Send to WiFi Terminal App

Sends message to mobile app only if connected.

Step 6: Delay

Updates every 1 second.

✅ 5) Final Result (You Will Get)

On WiFi Terminal app you will see:

• ADC value

• Moisture %

• Soil status

• Pump status

And pump will automatically ON/OFF.