Introduction

In the Internet of Things (IoT), seamless communication between devices is key to building smart systems. The ESP8266, a popular Wi-Fi module, allows easy wireless interaction between devices. In this project, we’ll demonstrate how to send and receive messages between two ESP8266 modules on the same Wi-Fi network by setting up one as a server and the other as a client. This simple setup forms the foundation for more complex IoT applications

Parts Required

1. 2 x ESP8266 Modules (e.g., NodeMCU or ESP-01)
   • These will serve as the server and client for communication.
2. USB to Micro-USB Cables
   • For powering and programming the ESP8266 modules.

Set Up One ESP8266 as a Server

The first ESP8266 will act as a server, listening for incoming connections from the client (the second ESP8266).

Server Code (ESP8266 A):

#include <ESP8266WiFi.h>

const char* ssid = “your_SSID”; // Replace with your Wi-Fi SSID
const char* password = “your_PASSWORD”; // Replace with your Wi-Fi password

WiFiServer server(80); // Server on port 80

void setup() {
Serial.begin(115200);
WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.println(“Connecting to WiFi…”);
}

Serial.println(“Connected to WiFi”);
Serial.print(“IP Address: “);
Serial.println(WiFi.localIP());

server.begin(); // Start the server
Serial.println(“Server started”);
}

void loop() {
WiFiClient client = server.available(); // Check for incoming clients

if (client) {
Serial.println(“Client connected”);
while (client.connected()) {
if (client.available()) {
String message = client.readStringUntil(‘\n’); // Read incoming message
Serial.print(“Message received: “);
Serial.println(message);

// Respond to the client
client.println(“Hello from Server”);
}
}
client.stop();
Serial.println(“Client disconnected”);
}
}

2. Set Up the Second ESP8266 as a Client

The second ESP8266 will act as a client, connecting to the server and sending a “hi” message.

Client Code (ESP8266 B):

#include <ESP8266WiFi.h>

const char* ssid = “your_SSID”; // Replace with your Wi-Fi SSID
const char* password = “your_PASSWORD”; // Replace with your Wi-Fi password

const char* serverIP = “192.168.1.100”; // Replace with the server ESP8266’s IP address
const uint16_t serverPort = 80;

void setup() {
Serial.begin(115200);
WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.println(“Connecting to WiFi…”);
}

Serial.println(“Connected to WiFi”);
}

void loop() {
WiFiClient client;

if (client.connect(serverIP, serverPort)) {
Serial.println(“Connected to server”);

// Send a “hi” message to the server
client.println(“hi”);
Serial.println(“Message sent: hi”);

while (client.connected()) {
if (client.available()) {
String response = client.readStringUntil(‘\n’); // Read server’s response
Serial.print(“Response received: “);
Serial.println(response);
}
}

client.stop();
Serial.println(“Disconnected from server”);
} else {
Serial.println(“Connection to server failed”);
}

delay(5000); // Wait 5 seconds before sending the next message
}

Github link :  https://github.com/makertribe/IoT-Codes/blob/86256d11a19cd864dcd9033f4bbbcf5ccf8dca91/Seamless%20Communication%3A%20Sending%20Messages%20Between%20ESP8266%20Modules%20on%20a%20Shared%20Wi-Fi%20Network

Introduction

Gas sensors play a crucial role in detecting hazardous gases in the environment. The MQ-2 sensor is widely used for its sensitivity to gases like LPG, propane, methane, hydrogen, and smoke. By connecting this sensor to an Arduino Uno, you can create a system that monitors gas levels and triggers alerts when necessary.

Parts Required

Before you start, ensure you have the following components:

• MQ-2 Gas Sensor
• Arduino Uno
• Jumper Wires
• LED
• Bread Board

MQ-2 Gas Sensor Pinout

Understanding the pinout of the MQ-2 sensor is essential for making the right connections:

• VCC: Connects to the 5V power supply of the Arduino.
• GND: Connects to the ground (GND) on the Arduino.
• AO (Analog Output): Outputs an analog signal proportional to the concentration of gas. Connect this to an analog input pin on the Arduino.
• DO (Digital Output): Outputs a digital signal (high or low) when the gas concentration exceeds a certain threshold. This can be connected to a digital pin on the Arduino.
• D11 : Connects to the input for the Positive pin of the Red LED
• D12 : Connects to the positive pin of the  Green LED

CODE: