The Arduino IDE has a feature that can be a great help in debugging sketches or controlling Arduino from your computer's keyboard.
The Serial Monitor is a separate pop-up window that acts as a separate terminal that communicates by receiving and sending Serial Data.
You will use the Serial Monitor to debug Arduino Software Sketches or to view data sent by a working Sketch.
Step 1: Requirements
You mustn't have an Arduino connected by USB to your computer to be able to activate the Serial Monitor but we use Bluetooth COM Port instead.
Step 2: Adding COM Port
First of all Open Bluetooth Setting on your PC
If you don't have a COM Port Click Add as in the first picture next choose Incoming As In The Second Picture Then Click OK.
Now you have a COM Port with number As In The third Picture.
Step 3: Configure Arduine IDE
First of All open Arduino IDE.
next go to tools << Port<<(your COM Port ).
Then Click on Serial Monitor.
After that , a COM Port Window appears
Finally make sure from baud rate is 9600 by default.
Step 4: Configure Bluetooth Connection
to begin with you have to turn on Bluetooth in both PC and Android Device .
Secondly Pair them with each other .
Next Open the Android App.
Then Connect Android App to your PC Bluetooth.
Lastly test your App .