#include <WiFi.h> 
#include <PubSubClient.h>

// Wi-Fi Credentials 
const char* ssid = "Wokwi-GUEST"; 
const char* password = ""; 

// MQTT Broker Settings 
const char* mqtt_server = "broker.hivemq.com"; // Example public  
const char* mqtt_topic = "Money";   // Topic to subscribe to 
WiFiClient espClient; 
PubSubClient client(espClient); 

// Function to connect to Wi-Fi 
void connectWiFi() { 
WiFi.begin(ssid, password); 
while (WiFi.status() != WL_CONNECTED) { 
delay(1000); 
Serial.println("Connecting to WiFi..."); 
} 
Serial.println("WiFi Connected"); 
} 

// Function to connect to the MQTT broker 
void connectMQTT() { 
while (!client.connected()) { 
Serial.print("Attempting MQTT connection..."); 

// Create a unique client ID 
String clientId = "ESP32Client-" + String(random(0xffff), HEX); 
if (client.connect(clientId.c_str())) { 
Serial.println("Connected to MQTT broker"); 
} else { 
Serial.print("Failed to connect, state "); 
Serial.println(client.state()); 
delay(5000); 
} 
} 
} 
void setup() { 
Serial.begin(115200);  // Initialize Serial Monitor 
connectWiFi();         

// Connect to Wi-Fi 
client.setServer(mqtt_server, 1883);  // Set MQTT broker address and 
connectMQTT();   
} 
void loop() { 
if (!client.connected()) { 
connectMQTT();  // Reconnect if the connection is lost 
} 
client.loop();  // Keep the connection alive 

// Publish a test message every 5 seconds 
String payload = "Hello from ESP32"; 
client.publish(mqtt_topic, payload.c_str()); 
Serial.println("Published: " + payload); 
delay(5000);  // Delay for 5 seconds before sending the next message 
}