Graduation Hat Decoration With Custom LED Matrix

Graduation day is coming up in few months and many students decorate their graduation hats creatively. For myself, I came up with an idea to make a LED matrix (7 LEDs on each side) to attach on top of the hat that would display patterns and texts. Without any further delay, let's get building!

1. 2m WS2813 LED Light Strip (I needed 49 LEDs, so I chose 30 LEDs/m) (or any other desired length)
2. 1 X IR Remote Control Kit (remote controller & receiver)
3. 1 X ESP32
4. 1 X Boost Converter (3.7V to 5V)
5. 1 X 3.7V 3300mAh 18650 Li-Ion Battery (make sure the battery can power the LED strip sufficiently)
6. 1 X 18650 Battery Case
7. Wires & Soldering Equipment

The circuit is pretty simple as the core features are: receive signal from IR remote control, then display image on the LED matrix accordingly.

I chose 3300mAh battery because the 49 LEDs on WS2813 will draw about 1.6A of current when it is at full brightness (white) and I want to make it run for a couple of hours. We have a boost converter to increase the voltage from 3.7V li-ion battery to 5V, which will power the ESP32 and WS2813.

The IR receiver will be powered by the ESP32 and its data pin is connected to D15.

WS2813 has 4 pins: VCC, GND, DO (D18) and BO (D19). DO pin stands for "Data Output" and it is the primary pin that outputs the data to LEDs. BO is a backup pin which allows WS2813 to run even if one LED is broken (if two or more LEDs are broken, then the rest of the LED strip would not work).

The graduation hat is 24cm by 24cm, so to solder seven strips that are 2.8cm apart from each other, I prepared the wires as the following:

Red Wire (5V): 3 of 8cm & 3 of 5cm

Yellow Wire (Data): 3 of 7cm & 3 of 6cm

Blue Wire (Backup): 3 of 6cm & 3 of 7cm

Black Wire (GND): 3 of 5cm & 3 of 8cm

When soldering, make sure the direction of current matches with the arrows indicated on WS2813.

You can solder IR receiver directly on to ESP32, but I used jumper wires.

Upload the following code and change the pin number on the second line to the pin you are using. If you check the serial monitor after clicking a button on the IR remote, you will see a 32-bit code that is designated to each button. Each IR remote has its own codes, so take note of the codes to use later in the project, where each button will have its own function.

This is the main code for the LED matrix. I commented on what each part does, so have a look at it and modify it as much as you would like. Make sure to change the IR codes to yours.

The two libraries I used are FastLED and Freenove IR Lib for ESP32.

Some of its modes are rainbow effect and text display. It can also change colors and brightness. Text function would only work on 7 by 7 LED matrix because I mapped the characters specifically to this size.

Now, it is time to decorate the LED matrix to blend in with the graduation hat. First, peel off the adhesive tape on the back of LED strips and attach it on a piece of cardboard. I attached a SVG file to guide where to attach the LED strips on a 24cm by 24cm cardboard. Then, place a white sheet of paper on top of the LED matrix to mark where the LED is exactly located. Cut out the squares and each LED should fit tightly into the openings.

This is the finished product! I haven't glued the battery and ESP32 on the graduation hat because this is my brother's and I have not received mine yet, but once I do, I would be able to hide the electronic under the brim. There are some improvements I can make like adding scrolling text to scroll and emojis. I will be keep improving it until the graduation date comes and if you have any questions or concerns, please comment down below. Thank you for reading my first Instructables!