Control a DJI/Ryze Tello programmble drone with Makey Makey and Scratch. Requires the Tello drone, node.js (free), the Scratch 2 offline editor, and a computer with wifi. Chocolate controllers taste so better than plastic ones. Unfortunately, this guide doesn't work on Raspberry Pi (it does work on Windows and hasn't been tested on Mac). I'd suggest pretty close adult supervision on this one too - plus an awareness of drone sense and local laws (please only fly low/in safe places with it - it's not as reactive as a proper controller!)
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Step 1: Set Up Arrow Buttons
Break up your favourite pointy chocolate bar and arrange four pieces as arrows. Keep them wrapped in a bit of foil - that works better than trying to get the chocolate to conduct without melting it... Keep the pieces separate - don't let the foils touch, or you'll short circuit the buttons.
Step 2: Connect the Arrows
These should be straightforward to connect - use an alligator clip on each foil, and connect to the corresponding arrow keys. Using different colours helps - if you put green as the "forward" arrow, for example, make sure it matches the same arrow on your Makey Makey (or your drone might fly off in the wrong direction).
Use a conductive earth/grounding wrist strap as the Makey Makey's earth. Make sure the metal part inside touches skin. You must wear this while pressing the chocolate arrows.
Step 3: Set Up Node.js and Scratch
Using Scratch with the Tello drone is best described elsewhere.
In short, you need this zip file from the drone manufacturer. Extract the files. You will need node.js (free) and the Scratch 2 offline editor. Once you have these, open the Node.js command prompt, type cd to change the folder (see the screenshot) to where you've saved your downloaded files. Type node tello.js.
Once this is up and running, open Scratch. Hold down shift, and click File menu. Choose Import Experimental HTTP Extension. Choose the file Tello.s2e. If it's worked properly, you should see the Tello blocks in Scratch, and a green status light (see the last screenshot).
For more advice on getting the Tello working with Scratch, try reading around online.
Step 4: Write the Scratch Program
Using the Tello extension blocks, my program takes off when the flag is clicked (see the screenshots). My first step was to make an emergency landing mode (space key) that stops all other scripts and sends an instruction to land (more on this later).
Once that's in place, add when key pressed blocks for the four arrows (up/down/left/right) and Tello blocks to fly in that direction. A word to the wise - make sure you fly forward and back, not up and down. This caught me out first time when my drone landed instead of flying back!
I've attached a Scratch 2 file that you could also use.
Step 5: Test It Out (safety First!)
I suggest testing the Makey Makey connections before the drone is connected at all - check that the logic of the program works, and the blocks run (light up) when you expect. This makes it less likely the drone will be flying in the wrong direction when you start.
You can always press space to land. But I decided I wanted a physical control too. Hence, my safety banana. Grabbing the banana makes the drone land wherever it is - so don't try to land over, say, water. In fact, given it's a tiny "toy" drone being controlled by chocolate and Scratch, don't fly over water/people/buildings at all!!
More seriously - clear the area. Make sure you have a big space, and don't go high (using this program, the drone will fly at around 2m height and not climb any higher). Keep people and things well away!
Have an adult in charge!
Step 6: First Flight...
When you've taken safety steps and tested the connections, switch on the drone. As mentioned at the start, make sure your computer's using wifi. Connect to the Tello's network and startup node.js and the Scratch program.
My program takes off with the flag (yours might be different). Even once the drone is airborne, it won't move for the first few seconds. Give it time to orient itself before you try pressing the arrows. Try gently moving forward (one press) to get a feel for the controls, before you try anything more adventurous.
Step 7: Eat Your Controller
The major benefit over a conventional controller is that this one is also delicious.