Home Automation – ESP32 + Android App

#include <WiFi.h>
 
// Replace with your network credentials
const char* ssid     = "your ssid";
const char* password = "your password";
 
WiFiServer server(80);                                     // Set web server port number to 80
 
String header;                                             // Variable to store the HTTP request
 
const int relay1 = 19;                                     
const int relay2 = 21;
const int relay3 = 22;                                     
const int relay4 = 23;
const int LED = 2;
 
 
void setup() 
{
  Serial.begin(115200);
 
  pinMode(relay1, OUTPUT);                               // Initialize the output variables as outputs
  digitalWrite(relay1, LOW);                             // Set outputs to LOW
 
  pinMode(relay2, OUTPUT);                               // Initialize the output variables as outputs
  digitalWrite(relay2, LOW);                             // Set outputs to LOW
 
  pinMode(relay3, OUTPUT);                               // Initialize the output variables as outputs
  digitalWrite(relay3, LOW);                             // Set outputs to LOW
 
  pinMode(relay4, OUTPUT);                               // Initialize the output variables as outputs
  digitalWrite(relay4, LOW);                             // Set outputs to LOW
 
  pinMode(LED,OUTPUT);
  digitalWrite(LED,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
    while (client.connected()) // loop while the client's connected
    {            
      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();
            
            // Relay 1 GPIO control
            if (header.indexOf("GET /1") >= 0) 
            {
              if(digitalRead(relay1)== LOW)
              {
                Serial.println("Relay 1 ON");
                digitalWrite(relay1, HIGH);
                client.print("Relay 1 ON");
              }
              else
              {
                Serial.println("Relay 1 OFF");
                digitalWrite(relay1, LOW);
                client.print("Relay 1 OFF");
              }
            }
 
              // Relay 2 GPIO control
 
              else if (header.indexOf("GET /2") >= 0) 
            {
              if(digitalRead(relay2)== LOW)
              {
                Serial.println("Relay 2 ON");
                digitalWrite(relay2, HIGH);
                client.print("Relay 2 ON");
              }
              else
              {
                Serial.println("Relay 2 OFF");
                
                digitalWrite(relay2, LOW);
                client.print("Relay 2 OFF");
              }
            }
 
              // Relay 3 GPIO control
 
             else if (header.indexOf("GET /3") >= 0) 
            {
              if(digitalRead(relay3)== LOW)
              {
                Serial.println("Relay 3 ON");
                digitalWrite(relay3, HIGH);
                client.print("Relay 3 ON");
              }
              else
              {
                Serial.println("Relay 3 OFF");
                digitalWrite(relay3, LOW);
                client.print("Relay 3 OFF");
              }
            }
 
              // Relay 4 GPIO control
 
              else if (header.indexOf("GET /4") >= 0) 
            {
              if(digitalRead(relay4)== LOW)
              {
                Serial.println("Relay 4 ON");
                digitalWrite(relay4, HIGH);
                client.print("Relay 4 ON");
              }
              else
              {
                Serial.println("Relay 4 OFF");
                digitalWrite(relay4, LOW);
                client.print("Relay 4 OFF");
              } 
            }
 
            // LED GPIO control
 
             else if (header.indexOf("GET /9") >= 0) 
            {
              if(digitalRead(LED)== LOW)
              {
                Serial.println("LED ON");
                
                digitalWrite(LED, HIGH);
                client.print("LED ON");
              }
              else
              {
                Serial.println("LED OFF");
                digitalWrite(LED, LOW);
                client.print("LED OFF");
              } 
            }
            client.stop();
            header = "";
          }
        }
      }    
    }
  }
}