Project 1: ESP32 Wi‑Fi Web Server (Control LED from Browser)

Concept

The ESP32 can host its own mini‑web server. When you type the board’s IP address in your browser, you’ll see a page with ON/OFF options to control an LED.

This is the simplest demonstration of how ESP32 brings an ordinary circuit onto the web.

Wiring

• Use onboard LED at GPIO2 (or external LED connected to pin 2 via resistor to GND).

Code

C++

#include <WiFi.h>

#include <WebServer.h>

 

const char* ssid = “YourWiFiName”;

const char* password = “YourWiFiPassword”;

 

WebServer server(80);

int ledPin = 2; // Onboard LED

 

void handleRoot() {

String page = “<h1>ESP32 Web Server</h1>”;

page += “<p><a href=\”/on\”>Turn ON LED</a></p>”;

page += “<p><a href=\”/off\”>Turn OFF LED</a></p>”;

server.send(200, “text/html”, page);

}

 

void handleOn() {

digitalWrite(ledPin, HIGH);

server.send(200, “text/html”, “LED is ON<br><a href=\”/\”>Back</a>”);

}

 

void handleOff() {

digitalWrite(ledPin, LOW);

server.send(200, “text/html”, “LED is OFF<br><a href=\”/\”>Back</a>”);

}

 

void setup() {

pinMode(ledPin, OUTPUT);

Serial.begin(115200);

 

WiFi.begin(ssid, password);

Serial.print(“Connecting to WiFi”);

while (WiFi.status() != WL_CONNECTED) {

delay(500);

Serial.print(“.”);

}

Serial.println(“\nConnected! IP address: “);

Serial.println(WiFi.localIP());

 

server.on(“/”, handleRoot);

server.on(“/on”, handleOn);

server.on(“/off”, handleOff);

server.begin();

}

 

void loop() {

server.handleClient();

}

How It Works

1. ESP32 connects to your Wi‑Fi.
2. It starts a server on port 80 (like a website server).
3. When a browser requests /on or /off, it changes LED state.

🌐 Result: Your ESP32 is now acting as a web‑controlled IoT switch.

Project 2: ESP32 Bluetooth (Send Data to Phone)

Concept

The ESP32 supports Bluetooth Classic + BLE (Bluetooth Low Energy). This lets you pair your phone and exchange data wirelessly — without needing Wi‑Fi.

Perfect for short‑range projects like remote sensing, fitness trackers, or robot control.

Code

C++

#include “BluetoothSerial.h”

 

BluetoothSerial SerialBT;

 

int potPin = 34;

 

void setup() {

Serial.begin(115200);

SerialBT.begin(“ESP32_BT”); // Bluetooth device name

Serial.println(“Bluetooth started. Pair phone now!”);

}

 

void loop() {

int potValue = analogRead(potPin);

SerialBT.print(“Potentiometer Value: “);

SerialBT.println(potValue);

delay(1000);

}

How It Works

• ESP32 starts as a Bluetooth device named “ESP32_BT”.
• Pair with your phone (use an app like Serial Bluetooth Terminal).
• Every second, ESP32 reads voltage on pin 34 (potentiometer) and sends it to phone.

📱 Result: You can view live sensor data on your smartphone.

Project 3: ESP32 IoT Cloud – Log Data to Thingspeak

Concept

IoT = devices connected to the Internet + Cloud. ESP32 can read a sensor and push values to online platforms like Thingspeak or Arduino IoT Cloud.

This project shows how to stream live sensor data online.

Steps

1. Create a free account at Thingspeak.
2. Make a new Channel → copy its Channel ID + Write API Key.

Code

C++

#include <WiFi.h>

#include “ThingSpeak.h”

 

const char* ssid = “YourWiFiName”;

const char* password = “YourWiFiPassword”;

 

WiFiClient client;

unsigned long channelID = YOUR_CHANNEL_ID;

const char* writeAPIKey = “YOUR_WRITE_API_KEY”;

 

int sensorPin = 34;

 

void setup() {

Serial.begin(115200);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {

delay(500);

Serial.print(“.”);

}

Serial.println(“Connected to WiFi.”);

 

ThingSpeak.begin(client);

}

 

void loop() {

int sensorValue = analogRead(sensorPin);

Serial.println(sensorValue);

 

int status = ThingSpeak.writeField(channelID, 1, sensorValue, writeAPIKey);

if (status == 200) {

Serial.println(“Data sent successfully”);

} else {

Serial.println(“Error sending data”);

}

delay(20000); // Send updates every 20 seconds

}

How It Works

• ESP32 connects to Wi‑Fi.
• Reads an analog sensor (potentiometer/temperature).
• Uploads values every 20 seconds to Thingspeak.
• You see a live graph of sensor data in your Thingspeak channel.

☁️ Result: You’ve built your first internet‑connected data logger.

Why These 3 Projects Matter

• Project 1 (Wi‑Fi Server) → Basic home automation.
• Project 2 (Bluetooth) → Local wireless projects (no router needed).
• Project 3 (IoT Cloud) → Global connectivity + data logging.

Together, they show the breadth of ESP32’s capability.