// Code written By: Chinmay Kolhatkar (IOT EMBEDDED ENGINEER)
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
 
// Connect to the WiFi
const char* ssid = "******";                 //add your wifi Name
const char* password = "*****";             //Add your wifi password here
const char* mqtt_server = "192.168.43.69"; //add the ip address of your raspberry pi you can get the ip address of your Pi by typing ifconfig in terminal
 
WiFiClient espClient;
PubSubClient client(espClient);
 
const byte relay=12; 
const byte led_pin=13;
 
void callback(char* topic, byte* payload, unsigned int length) {
 Serial.print("Message arrived [");
 Serial.print(topic);
 Serial.print("] ");
 for (int i=0;i<length;i++) {
  char receivedChar = (char)payload[i];
  Serial.print(receivedChar);
  if (receivedChar == '1')
  digitalWrite(relay, LOW);
  if (receivedChar == '0')
   digitalWrite(relay, HIGH);
  }
  Serial.println();
}
 
 
void reconnect() {
 // Loop until we're reconnected
 while (!client.connected()) {
 Serial.print("Attempting MQTT connection...");
 // Attempt to connect
 if (client.connect("Client")) {
  Serial.println("connected");
  // ... and subscribe to topic
  client.subscribe("led");             // led is the topic which we are going to add in rapberry pi
 } else {
  Serial.print("failed, rc=");
  Serial.print(client.state());
  Serial.println(" try again in 5 seconds");
  // Wait 5 seconds before retrying
  delay(5000);
  }
 }
}
 
void setup()
{
 Serial.begin(9600);
 
 client.setServer(mqtt_server, 1883);
 client.setCallback(callback);
 
 pinMode(led_pin, OUTPUT);
 pinMode(relay,OUTPUT);
 digitalWrite(led_pin, HIGH);
 digitalWrite(relay, HIGH);
for(int h=0;h<5;h++)
{
 digitalWrite(led_pin,LOW);
 delay(200);
 digitalWrite(led_pin,HIGH);
 delay(100);
}
}
 
void loop()
{
 if (!client.connected()) {
  reconnect();
 }
 client.loop();
}