void setup() { 
Serial.begin(115200); 
// UART2 (Zigbee simulation) 
Serial2.begin(9600, SERIAL_8N1, 16, 17); 
Serial.println("Zigbee Simulation Started");
void loop() { 

int data = random(10, 99);

// Send data 
Serial2.print(data); 
Serial2.print("\n"); 

Serial.print("Sent (IoT): "); 
Serial.println(data); 

delay(1000); 

// Receive data safely 
if (Serial2.available()) { 
     String msg = Serial2.readStringUntil('\n'); 

Serial.print("Received (Zigbee): "); 
Serial.println(msg); 
} 
}