As our team grows ever larger, we’ve had to face a dire, unforeseen side effect; inadequate bathroom capacity. With a team of nearly 40 and only two bathrooms, many of us have experienced the daily frustration known as the bathroom queue.
Thus, our DIY bathroom project was formed; a project born of necessity from the genius minds of our resident DIYers. Here to explain the background, steps and tools is Valentin, the team lead for this project and Dalia’s wiz at all things DIY.
Making the bathroom great again with Valentin Arkhipov
While discussing our upcoming plans for a team-wide DIY project, someone suggested we create an airplane-style bathroom sign to indicate when the stall is occupied or free. The idea immediately caught on due to our frustrations with the current bathroom situation.
I worked with Lucia on this challenge over a few weeks:
We kicked off with some brainstorming, working backwards from the outcome to figure out the steps we’d need to achieve our goal. We split the project into two main parts.
First, we’d need a sensor in the bathroom to indicate when the doors are locked. Second, we’d need an outside display that lets people know what the bathroom status is. The two parts would have to exist at some distance apart, so we’d need a wireless solution to connect them.
Part 1: From lasers to machine vision, we had a few ideas about how to develop the sensor. But in the end we went with hall effect sensors, which detect a magnetic force. Using this approach we planned to attach a tiny magnet to the bathroom lock mechanism to sense it at a short distance.
Part 2: For a fun and stylish solution for the occupied display we really wanted to use some actual pedestrian crossing lights! But, unfortunately the lights we wanted were only available as used items on eBay in the US and the long delivery times and the potentially poor condition of the lights made us choose another option in the end.
We decided to go with an LED array and emulate the pedestrian crossing light. After some initial prototyping, the LED array attracted a lot of attention and suggestions for new DIY projects involving cat gifs.
With our plan in place, we purchased the necessary parts. You can see the breakdown and costs here:
After we planned our approach and received all the deliveries with the different working parts, it was time to start setting everything up.
First off, we tested out our magnets on location to figure out how best to sense the locks. It was very helpful to try a few ideas as not all of them worked in practice.
For the communications, we took an example code for a radio system and customised it. The idea is for the display side to ask for lock status, while the sensor side would wait for these requests and reply. Another option we didn’t end up using would be for the sensor side to actively “push” lock state changes to the display side.
With the all the parts working, the time came to bring it all together.
The bathroom sensors went in first. Armed with a roll of sticky tape and a pair of scissors we routed wiring around the bathroom door frames and hid our arduino under the sink.
Excited to try it out the next day, we found our radio had stopped working due to some water damage. After some multimeter probing and youtube advice, we managed to fix the dead radio board. Not risking it again, we sealed everything in a plastic box before reinstalling it under the sink.
And for the finishing touches – software on raspberry pi – we combined the radio example and the display driver software into one c++ program. Then we added some code to load gif animations, a couple of threads and a check so that it only runs on weekday working hours.
Our project was finally complete! Here’s a quick demo:
The red light of the magnet lock sensor turns on when the door is locked. The signal is transported to the monitor.
When the bathroom door to the right stall locks, the right display changes to indicate it’s occupied:
DIY Teammates: Lucia & Valentin
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