The Rickrolling Toilet

The Idea

In 2015, my church decided to revive their Fun Fair event.  They encouraged folks to take a look at some of the old games and refurbish them if they were interested.  I found an old game called “Dunk It”.  It consisted of a toilet seat bolted to a green wooden frame.  The goal was to toss a roll of toilet paper through the hole of the toilet seat to win a prize.

My inner 5yo. thought this would be my game.  But, I couldn’t just leave it as is.  I needed to make some… improvements.  The premise of the game was simple, but it lacked something.  There was no feedback for the player.  So, I set out to give it a voice.

My first inclination was to use an Arduino with an audio shield.  However, I was trying to minimize the cost, so I thought I’d use something I  already had on hand, a Rapsberry Pi A+.  This would handle the audio, and the programming would be relatively simple.

Alpha/Beta Version

To prove the concept, I thought I would wire up a light sensor (Light-dependent Resistor) to the Raspberry Pi.  This was not as straightforward as I’d hoped, since LDRs are analog devices and the RPi only has digital I/O pins.  So, after a bit of searching, I found a technique to read analog values from a digital I/O pin using a simple circuit.

Once I got this wired up, I stole some code to make the LDR reading work.  I combined that with some code to play back audio and the alpha version was working…

Version 1.0

I foolishly ignored the advice to always put a resistor in series with an LED.  And it bit me in the behind.  An hour before the fun fair, the LED blew out, and I wasn’t able to leave and get a replacement.  Lesson learned.

Version 2.0

For Version 2.0, I wanted to make some significant improvements.  First, I wanted to make a more realistic “experience” for the players.  I was able to secure a toilet on freecycle (I love freecycle).  After sanitizing it, I set to work wiring up the LED in the bottom of the bowl.  This had the added benefit of making the code simpler.

I also wanted to improve the sound for the game, so I got an inexpensive power amp and car speakers.  I mounted the speakers on the snazzy new platform with locking casters.  This made the whole thing much easier to move around.

Version 3.0

For version 3.0, I wanted to clean things up significantly, and make it easier to assemble/disassemble.  I mounted the amp and Raspberry Pi on a board, that attaches to the inside of the tank with Velcro.  I also used a connector for the sensor instead of being wired to the board.

all components mounted to a single board
I wired up the circuit on a proto hat and added a connector for the LDR so that it was easier to connect/disconnect
Debug mode with monitor and keyboard
What toilet wouldn’t benefit from a debug monitor and keyboard?

Version 3.1

I added a shutdown button for the system so the SD card doesn’t get trashed, and the Pi shuts down gracefully. and covered the wires with some flexible split tubing.  I also added some code to avoid repeating the audio if the sensor detected darkness at the end of the previous audio playback.  Finally, I added some other… apropos sounds.

I bet this is the first time the words “graceful” and “toilet” appear in the same context.

Shutdown button on the Pi Hat
I added a shutdown button. This puts my mind at ease by gracefully shutting down the Pi.

Possible Improvements:

  • I’d like to use the flush handle to perform the shutdown/recalibration