This is the story of Occu-Pi, or how a magnet, a Raspberry Pi, and a barrel bolt saved an office team from queuing for the toilet.

The toil of toilet queuing

When Brian W. Wolter’s employer moved premises, the staff’s main concern as the dearth of toilets at the new office, and the increased queuing time this would lead to:

Our previous office had long been plagued by unreasonably long bathroom lines. At several high-demand periods throughout the day we’d be forced to wait three, four, five people deep while complaining bitterly to each other until our turn to use the facilities arrived. With even fewer bathrooms in our new office, concern about timely access was naturally high.

Faced with this problem, the in-house engineers decided to find a technological solution.

Occu-Pi

The main thing the engineers had to figure out was just how to determine the difference between a closed door and an occupied stall. Brian explains in his write-up:

There is one notable wrinkle: it’s not enough to know the door is closed, you need to know if the bathroom is actually in use — that is, locked from the inside. After considering and discarding a variety of ‘creative’ solutions (no thank you, motion sensors and facial recognition), we landed on a straightforward and reliable approach.

The team ended up using a magnet attached to the door’s barrel bolt to trigger a notification. Simply shutting the door doesn’t act as a trigger — the bolt needs to lock the door to set off a magnetic switch. That switch then triggers both LED notifications and updates to a dedicated Slack channel.

For the technically-minded, Occu-Pi is a pretty straightforward build. And those wanting to learn more about it can find a full write-up in Brian’s Medium post.

We’ve seen a few different toilet notification projects over the years, for example this project from DIY Tryin’ using a similar trigger plus a website. What’s nice about Occu-Pi, however, is the simplicity of its design and the subtle use of Slack — Pi Tower’s favoured platform for office shenanigans.