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Intro
ESP became very popular as an Arduino compatible board.
In this post we are going to use the ESP01 Module in a useful application that implements WIFI properties of the ESP01 module.
This is a small webserver that runs HTML code on the ESP01 Module and can be controlled from any browser as control interface.
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The HTML code generates two software buttons that can control LEDs, Relays or Motors from WIFI connection.
Components
You need ESP8266-01 and USB to Serial converter for programming.
You need a smartphone, tablet or computer with a web browser to open the interface on the ESP test circuit.
You may also like this other post about RemoteXY App
Software Code
// Load Wi-Fi library
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() {
Serial.begin(115200);
// 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 “);
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(“.”);
}
// Print local IP address and start web server
Serial.println(“”);
Serial.println(“WiFi connected.”);
Serial.println(“IP address: “);
Serial.println(WiFi.localIP());
server.begin();
}
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 = client.read(); // read a byte, then
Serial.write(c); // 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(“Content-type:text/html”);
client.println(“Connection: close”);
client.println();
// 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>");
}
client.println("</body></html>");
// The HTTP response ends with another blank line
client.println();
// Break out of the while loop
break;
} 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
client.stop();
Serial.println("Client disconnected.");
Serial.println("");
}
}
Here is the software that starts by defining the SSID and password of your wifi network.
Note:
This network data is the data of your WIFI router not of the ESP01 module.
Then the ESP module connects to the WIFI network and prints it connection data on Arduino Serial Monitor.
It also prints its IP so we use it on the browser address bar later.
Programming
We use Arduino IDE to program ESP01 module
Circuit Connection
Application Circuit Test
Now you can start to power up the ESP01 application circuit and test it to see the webserver running on the module.
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On your web browser address bar, type the following address:
http://192.168.4.1
Then you get the web page containing the two software buttons both labeled ON and has its status above it.
When you press each button, the LED light , the button toggles to OFF and its status change to reflect the LED status.