#include <WiFi.h>

#define WATER_SENSOR 34
#define RELAY_PIN 26

const char* ssid = "Water_System_AP";
const char* password = "12345678";

WiFiServer server(23); // Telnet port

int waterValue = 0;

bool autoMode = true;
bool motorState = false;

int lowLevel = 1000;
int fullLevel = 3000;

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

pinMode(RELAY_PIN, OUTPUT);
digitalWrite(RELAY_PIN, HIGH); // Motor OFF

// Start Access Point
WiFi.softAP(ssid, password);

Serial.println("Access Point Started");
Serial.print("AP IP Address: ");
Serial.println(WiFi.softAPIP());

server.begin();
Serial.println("Server Started on Port 23");
}

void loop() {

WiFiClient client = server.available();

if (client) {
Serial.println("Client Connected");

client.println("=== Smart Water Management ===");
client.println("Commands: AUTO, MANUAL, ON, OFF");

while (client.connected()) {

waterValue = analogRead(WATER_SENSOR);

client.print("Water Level: ");
client.println(waterValue);

if (client.available()) {

String command = client.readStringUntil('\n');
command.trim();

if (command.equalsIgnoreCase("AUTO")) {
autoMode = true;
client.println("Switched to AUTO Mode");
}

else if (command.equalsIgnoreCase("MANUAL")) {
autoMode = false;
client.println("Switched to MANUAL Mode");
}

else if (command.equalsIgnoreCase("ON") && !autoMode) {
turnMotorOn(client);
}

else if (command.equalsIgnoreCase("OFF") && !autoMode) {
turnMotorOff(client);
}

else {
client.println("Invalid Command!");
}
}

// AUTO MODE LOGIC
if (autoMode) {

if (waterValue < lowLevel && !motorState) {
client.println("Water LOW -> Motor ON");
turnMotorOn(client);
}

if (waterValue > fullLevel && motorState) {
client.println("Tank FULL -> Motor OFF");
turnMotorOff(client);
client.println("WARNING: Tank Full!");
}
}

delay(2000);
}

client.stop();
Serial.println("Client Disconnected");
}
}

void turnMotorOn(WiFiClient client) {
digitalWrite(RELAY_PIN, LOW);
motorState = true;
client.println("Motor is ON");
}

void turnMotorOff(WiFiClient client) {
digitalWrite(RELAY_PIN, HIGH);
motorState = false;
client.println("Motor is OFF");
}

🧠 CODE EXPLANATION (Step-by-Step)

1️⃣ Create Hotspot (Access Point Mode)

ESP32 becomes a WiFi router.

Mobile connects to:

2️⃣ Get ESP32 IP Address

Default IP:

You use this in mobile app.

3️⃣ Create TCP Server

Port 23 is Telnet communication port.

4️⃣ Read Water Sensor

Reads water level (0–4095).

5️⃣ Auto Mode Logic

If:

→ Tank LOW → Motor ON

If:

→ Tank FULL → Motor OFF + Warning

6️⃣ Manual Mode Logic

Manual works only if:

Commands:

7️⃣ Relay Control

Relay Active LOW:

📱 How To Use Mobile App

Step 1

Upload code

Step 2

Open Serial Monitor
You will see:

Step 3

Mobile WiFi → Connect to:

Step 4

Open TCP Client App

Enter:

• Host: 192.168.4.1

• Port: 23

Click Connect

Step 5

Send commands:

📟 Example Output in App

🎯 What Students Learn

• Access Point Mode

• TCP Client-Server communication

• Analog sensor reading

• Relay motor control

• Auto + Manual system design

• Embedded networking