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Controlling Led through Server.


Build an ESP8266 Web Server – Code and Schematics (NodeMCU)

This tutorial is a step-by-step guide that shows how to build a standalone ESP8266 Web Server that controls two outputs (two LEDs). This ESP8266 NodeMCU Web Server is mobile responsive and it can be accessed with any device with a browser in your local network.


Prepare the Arduino IDE

Step 1. Download and install the Arduino IDE on your operating system (some older versions won’t work).
Step2. Then, you need to install the ESP8266 add-on for the Arduino IDE. For that, go to File > Preferences.
Step3. Enter into the “Additional Board Manager URLs” field as shown in the figure below. Then, click the “OK” button.

Step 4. Go to Tools > Board > Boards Manager…

Step 5. Select the “ESP8266 by esp8266 by ESP8266 Community”, as shown in the figure below.

Step 6. Go to Tools > Board and choose your ESP8266 board. Then, re-open your Arduino IDE.


Copy the following code to your Arduino IDE, but don’t upload it yet. You need to make some changes to make it work for you

#include < ESP8266WiFi.h >

// Replace with your network credentials
const char* ssid = “REPLACE_WITH_YOUR_SSID”;
const char* password = “REPLACE_WITH_YOUR_PASSWORD”;

// Set web server port number to 80
WiFiServer server(80);

// Variable to store the HTTP request
String header;

// Auxiliar variables to store the current output state
String output5State = “off”;
String output4State = “off”;

// Assign output variables to GPIO pins
const int output5 = 5;
const int output4 = 4;

// Current time
unsigned long currentTime = millis();
// Previous time
unsigned long previousTime = 0;
// Define timeout time in milliseconds (example: 2000ms = 2s)
const long timeoutTime = 2000;

void setup() {
// Initialize the output variables as outputs
pinMode(output5, OUTPUT);
pinMode(output4, OUTPUT);
// Set outputs to LOW
digitalWrite(output5, LOW);
digitalWrite(output4, LOW);

// Connect to Wi-Fi network with SSID and password
Serial.print(“Connecting to “);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
// Print local IP address and start web server
Serial.println(“WiFi connected.”);
Serial.println(“IP address: “);

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

if (client) {
// If a new client connects,
Serial.println(“New Client.”);
// print a message out in the serial port
String currentLine = “”;
// make a String to hold incoming data from the client
currentTime = millis();
previousTime = currentTime;
while (client.connected() && currentTime – previousTime <= timeoutTime)
{ // loop while the client’s connected
currentTime = millis();
if (client.available()) {
// if there’s bytes to read from the client,
char c =;
// read a byte, then
// print it out the serial monitor
header += c;
if (c == ‘\n’) {
// if the byte is a newline character
// if the current line is blank, you got two newline characters in a row.
// that’s the end of the client HTTP request, so send a response:
if (currentLine.length() == 0) {
// HTTP headers always start with a response code (e.g. HTTP/1.1 200 OK)
// and a content-type so the client knows what’s coming, then a blank line:
client.println(“HTTP/1.1 200 OK”);

client.println(“Connection: close”);

// turns the GPIOs on and off
if (header.indexOf(“GET /5/on”) >= 0) {
Serial.println(“GPIO 5 on”);
output5State = “on”;
digitalWrite(output5, HIGH);
} else if (header.indexOf(“GET /5/off”) >= 0) {
Serial.println(“GPIO 5 off”);
output5State = “off”;
digitalWrite(output5, LOW);
} else if (header.indexOf(“GET /4/on”) >= 0) {
Serial.println(“GPIO 4 on”);
output4State = “on”;
digitalWrite(output4, HIGH);
} else if (header.indexOf(“GET /4/off”) >= 0) {
Serial.println(“GPIO 4 off”);
output4State = “off”;
digitalWrite(output4, LOW);

// Display the HTML web page
client.println(“<!DOCTYPE html><html>”);
client.println(“<head><meta name=\”viewport\” content=\”width=device-width, initial-scale=1\”>”);
client.println(“<link rel=\”icon\” href=\”data:,\”>”);
// CSS to style the on/off buttons
// Feel free to change the background-color and font-size attributes to fit your preferences
client.println(“<style>html { font-family: Helvetica; display: inline-block; margin: 0px auto; text-align: center;}”);
client.println(“.button { background-color: #195B6A; border: none; color: white; padding: 16px 40px;”);
client.println(“text-decoration: none; font-size: 30px; margin: 2px; cursor: pointer;}”);
client.println(“.button2 {background-color: #77878A;}<style><head>”);

// Web Page Heading
client.println(“<body><h1>ESP8266 Web Server<h1>”);

// Display current state, and ON/OFF buttons for GPIO 5
client.println(“<p>GPIO 5 – State ” + output5State + “<p>”);
// If the output5State is off, it displays the ON button
if (output5State==”off”) {
client.println(“<p><a href=\”/5/on\”><button class=\”button\”>ON<button><a><p>”);
} else {
client.println(“<p><a href=\”/5/off\”><button class=\”button button2\”>OFF<button><a><p>”);

// Display current state, and ON/OFF buttons for GPIO 4
client.println(“<p>GPIO 4 – State ” + output4State + “<p>”);
// If the output4State is off, it displays the ON button
if (output4State==”off”) {
client.println(“<p><a href=\”/4/on\”><button class=\”button\”>ON<button><a><p>”);
} else {
client.println(“<p><a href=\”/4/off\”><button class=\”button button2\”>OFF<button><a><p>”);

// The HTTP response ends with another blank line
// Break out of the while loop
} else { // if you got a newline, then clear currentLine
currentLine = “”;
} else if (c != ‘\r’) { // if you got anything else but a carriage return character,
currentLine += c; // add it to the end of the currentLine
// Clear the header variable
header = “”;
// Close the connection
Serial.println(“Client disconnected.”);

You need to modify the following two variables with your network credentials, so that your ESP8266 can establish a connection with your router.

// Replace with your network credentials
const char* ssid = “”;
const char* password = “”;

Uploading the Sketch

Uploading the Sketch to the ESP-12E

If you’re using an ESP-12E NodeMCU Kit, uploading the sketch is very simple, since it has built-in programmer. Plug your board to your computer. Make sure you have the right board and COM port selected.

Then, click the Upload button in the Arduino IDE and wait a few seconds until you see the message “Done uploading.” in the bottom left corner.

Connect two LEDs to your ESP8266 as shown in the following schematic diagram – with one LED connected to GPIO 4 (D2), and another to GPIO 5 (D1).

Testing the Web Server

Now, you can upload the code, and it will work straight away. Don’t forget to check if you have the right board and COM port selected, otherwise you’ll get an error when trying to upload. Open the Serial Monitor at a baud rate of 115200.

Finding the ESP IP Address

Press the ESP8266 RESET button, and it will output the ESP IP address on the Serial Monitor

Copy that IP address, because you need it to access the web server.

Accessing the Web Server

Open your browser, type the ESP IP address, and you’ll see the following page. This page is sent by the ESP8266 when you make a request on the ESP IP address.

OUTPUT: You will see output like this.


You-Tube Video :

NOTE: If you find any Error go through this STEPS AGAIN.If you still find any problem than you are not worth it for doing IOT project.KINDLY QUIT and do favour on internet.QUIT…!!


Published by Gnd_To_Vcc

Here to spread my knowledge . Knowledge should always be spread not stored.

14 thoughts on “Controlling Led through Server.

  1. Pingback: What is IoT?

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