Using HC-08 bluetooth module with arduino
void setup(){
  //Initialize Serial Monitor
  Serial.begin(9600);
  Serial.println(&quot;ENTER AT Commands:&quot;);
  //Initialize Bluetooth Serial Port
  Serial3.begin(9600);
}

void loop(){
  //Write data from HC08 to Serial Monitor
  if (Serial3.available()){
    Serial.println(&quot;Reading from bluetooth&quot;);
    Serial.write(Serial3.read());
  }
  
  //Write from Serial Monitor to HC08
  if (Serial.available()){
    Serial.println(&quot;Writing to bluetooth&quot;);
    Serial3.write(Serial.read());
  }  
}