12/4/2025 - Getting some clear ground on what to build

Wrote out the goal, its objectives, went over methodologies and techinques to achieve them.

So the main goal is to construct a model which demonstrates countries involved in G20 as a interactive 3d infographic.
The crux is to make a levitating globe (cause why not) which continuously spins, has an RGB lighting system, and connects to a mobile app, and the user can select a country and the globe will spin and stop such that the selected country faces the user.

12/5/2025 1:08 AM - Created a working plan on how to build and implement.

Made all the requried calculations, went through all the planning and sketching of the model, and the required techonologies to use.

At the core, the globe will have a magnetic dipole facing outward, which will lock into another dipole placed above the globe spereated by air, which is connected to a servo through the length of the arch, down to the microcontrolelr (An Uno). So essentially, the globe will lock into the place and rotate, without physical contact.

The servo is controlled by the Arduino Uno which via a bluetooth module connects to a phone app I shall make to send commands and rotate the servo to a particular longitude to show the country. It shall also have an RGB led beneath it which shows the dominant color of that country's flag.

12/5/2025 1:48 AM - Created the globe and the stand.

Crafted a wooden stand with a slideable lid and slots for components. (This took time, well cause I'm not a woodworker XD) Created and painted a thermocol globe, and infused a dipole conected to the bottom through a string for strength.

12/5/2025 7 PM - Worked extensively on the electronics and code.

Connected a HC-05 bluetooth module to the arduino uno, a 360 servo on the top of the globe ring.

After this, was extremely difficult.
Problem 1: The 360 servo does not have a positional system, it cannot be put to a certain degree like a 180 servo. (Why did I pick a 360 then? Because I wanted it to spin all around resembling the actual motion of the earth.)
Problem 2: There is no built in way to move the servo by certain degrees and also no way to read the current state to change it.

So I spent hours and hours trying to find a way out, and I came out with:

Basically I created a thin flap with tape at the servo's staff at one end and ran it on 255 PWM, kept a beam adjacent so that it would hit the beam every time it revolves. (PS I also had to deal with the magnetic bar fixed on the servo)
Then, I recorded this audio and analysed its RPM.

Once I got the RPM, I did quite a bit of math, trignometry and geolocation to create a map of longitudes to the time needed to power to servo that it moves by a certain degree. Thus, only the initial calibration was required via bluetooth, to set the 0th longitude.

And the extensive list of maps corresponding to countries and commands recived via bluetooth, while ensuring the minimal amount of data transfer for optimal speeds.

And for graduating the RGB:

12/5/2025 10 PM - Built the control app

Here I designed the application in figma, all the assets for every country and exported it.

And then went on to build the application in flutter.
This again took quite a lot of time, as there were a few issuies in connecting the bluetooth module and transmitting data reliably.

The app allows one to connect to the HC05 module, displays whether its status, allows controlling the spin, and then most importantly, allows the user to select a country, display's its flag's custom designed asset, and then send the command via bluetooth so that the globe spins to show the particular country.

12/5/2025 11:21 PM - Assembling, debugging and finishing.

Put togeather the software and the hardware,
fixed the woodworking,
packed everything and some decorative finishing.

And after some resolving of errors and bug fixing, here comes the beauty: Maglev Globe

Maglev Globe

12/5/2025 11:50 PM - Source code and files

Arduino Code (C++)
Android APK for Control App