1. Prerequisites

To program the Tello drone, you will need a few key pieces of software.

• Adobe Air

• Scratch

• NodeJS

• Tello Extension

You will need to install these software in the order given above. Note the following.

• Adobe Air is required by Scratch to work.

• The offline version of Scratch 2.0 is required (the latest is Scratch 3.0). Scratch is the Integrated Development Environment (IDE) that you will use to program behavior and fligt paths into the Tello drone.

• NodeJS version 12 or higher should work. NodeJS may be looked as simply a JavaScript runtime.

• The Tello Extension contains files that has a plugin for Scratch and a NodeJS script that enables your program/Scratch to connect to the drone. The Tello Extension is wrapped in a file called Scratch.zip that you must unzip. Please make note of where you downloaded and unzipped Scratch.zip as you will need to access the contents later.

After you have successfully installed the software above, you will need to load up Scratch and start the NodeJS program to connect to the Tello drone.

1.1. Scratch

After you start the Scratch IDE, you should see the application as follows.

The Scratch version 2.0 Offline IDE.

The next thing to do is to import the Tello Scratch Extension, which is a file named Tello.s2e. What you will need to do is to hold the Shift key and use your mouse to click on the File menu. If you do not hold the Shift key, you will not see the menu item Import experimental HTTP extension. Instead, you will only see the normal menu subitems as follows.

Selecting the File menu without holding the Shift key.

If you press and hold the Shift key and then use the mouse to select the File menu, you will see the following.

Selecting the File menu while holding the Shift key. Move your mouse and click on Import experimental HTTP extension.

Now, navigate to where you downloaded and unzipped the Tello Extension zip file and select Tello.s2e.

Selecting the Tello.s2e extension.

In the Code Block area, under the Scripts tab, click on More Blocks. You should see the following.

The code blocks for Tello programming via Scratch. Note the red dot indicates that the Scratch IDE is not connected to a Tello drone.

1.2. NodeJS

To connect to the Tello drone, you will need to run the Tello.js program as follows. Note that you will first need to change directory, cd, to where you unzipped Scratch.zip.

node Tello.js

Your output on the console should look like the following.

---------------------------------------
Tello Scratch Ext running at http://127.0.0.1:8001/
---------------------------------------

You will then need to connect your computer to the Tello drone’s WiFi.

Connect to the Tello drone’s WiFi.

After you connect to the Tello drone’s WiFi, look at the Scratch IDE. You will notice that the red dot is now green indicating that the Scratch IDE is connected to the Tello drone.

The Scratch IDE is now connected to a Tello drone.

After a certain time period of inactivity, where you are not sending commands to the Tello drone from Scratch anymore, the WiFi connection will disconnect and you will have to repeat the WiFi connection steps.