Graduation Cap Shows Us What It’s Got!

A high school graduation ceremony is well due the pomp and circumstance for making it through one of life’s many milestones. To commemorate the event with their own flair, redditor [PM_(cough)_FOR_KITTENS] hid a 32 x 32 GIF-playing LED matrix in their graduation cap!

The board is controlled by a Teensy hosting a SmartMatrix shield. With the shield’s assistance, the matrix enables scrolling text and GIFs to play across the LEDs, as well as an SD card slot to load up your favourites. Currently, it’s set to a 50-50 chance of playing a gif — one of sixty — or one of the twenty scrolling text lines loaded onto the SD card. [PM_(ahem)_FOR_KITTENS] co-opted his friend’s expertise to write the code — available here — while he designed the circuit and handled the assembly.

Carefully unwrapping his cap, [PM_(yep)_FOR_KITTENS] reinforced it with thinner and stronger cardboard, cutting slots into it, allowing the boards and wires to — barely — fit inside. A hole in the side of the cap is enough for a barely noticeable USB cable to run down his neck to a 2000 mAh battery which can power the cap for over five hours at 5V and 2A. Check out a demo video after the break!

We’ve previously featured a similar bid to mess with school administrators, as well as an infrared option.

[Thanks for the tip, Nikropht!]

15 thoughts on “Graduation Cap Shows Us What It’s Got!

  1. That is a great grad cap. Would be super cool if it responded to sound like clapping or something.
    Also I assume [PM_(ahem)_FOR_KITTENS] is writing “code” not “cold”.

  2. Sure beats the blinking red LEDs I put into my cap! But that was 35 years ago when my TRS-80 was hi-tech. I might have done something similar had microcontrollers and LED matrixes been available to me then. Kudos to PM_FOR_KITTENS! You have an illustrious career ahead of you! (My hat was upstaged by someone who released 3 piglets, with ‘Pig #1’, ‘Pig #2’, and ‘Pig #4’ painted on their sides. They spent hours trying to find ‘Pig #3’.)

    1. SmartMatrix author here – SmartMatrix includes color correction tables, which could be adjusted. Color correction is turned on by default. It’s possible to adjust the tables:

      https://github.com/pixelmatix/SmartMatrix/blob/master/src/MatrixCommon.h#L125

      The “adafruit utility” referenced in the comment (I’ll add an actual link to this in the code):
      https://github.com/adafruit/RGB-matrix-Panel/blob/master/extras/gamma.c

      It’s quite possible that the panel looks just fine (e.g. doesn’t need color correction adjustment) in person, it’s really hard to capture these panels on camera.

  3. Hi! Creator of this graduation cap here,

    I thought I’d just let you know that the battery pack was rated 20000 mAh, not 2000 (I tried to get the biggest I could at the time to prevent it from dying in the middle of the ceremony). I was a little surprised that I wasn’t informed my project was written about here, but I guess it made it that much more exciting to stumble upon it, haha.

    Great short read! If you have any questions about the process (even this late), I don’t mind answering them.

    Have a great day!

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.