Toilet light wall

LED screen made of empty toilet rolls

Why ?

The first idea was to reuse empty toilet rolls and make some fun with arduino and some LEDs. After gluing first block (4x3 LEDs connected to Arduino Nano), I've decided that it would be cool to control it right from the android. So I've added one BT adapter and created an android app. As the time went by, another empty toilet roll appeared. So I've built one block after another... After some time I've set my goal to have 4x4 blocks all together (192 LEDs). As the blocks were adding, the functionality of android app was also rising.

first 6 blocks

What it can do ?

Because it is quite straightforward from the video below, let's just briefly list the features from an android app:
  • draw (real-time)
  • toggle random LED (screen saver)
  • animation (includes also editor for key-frame animation)
  • font loop
  • incoming sound
  • simple game using accelerometer

front view 

Was there something interesting ?

Aside from the gluing, soldering and programming, I've come across few interesting things:
  • I needed to create a protocol so the lights will be showing in real-time. I ended up with 2 bytes for each block. 12 bits for the light and the rest 4 bits as an identifier in the grid.
  • I've never used multiple bluetooth devices before. In this setup, my power resource was not sufficient enough so i needed to split the screen and use multiple bluetooth adapters.

view from the back


To sum it up, I've made quite a large screen (76x60cm) with a horribly small resolution (16x12px) that can be controlled only via bluetooth with a custom protocol. The possible use-case might be as some sort of art exhibition object or as a domestic screen saver.


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