DEW2023 - Hamburg

XXL Can count

Team 8 – The Fistels


Our school, as well as some others in northern Germany, got the so called XXL Can from another school to collect deposit cans and bottles to raise donations for sustainability and climate protection purposes. It is a huge can with a whole in which you can easily throw your cans and bottles.

The Problem

As a Team we dove into the problem of not being able to keep track on the impact of the XXL Can. In addition to that, it was not possible to tell when to empty out the can. These things made working with the can less sustainable and intuitive.

Our Solution

Our main focus was to find a solution that is easily scalable and implementable at a low cost. This way, it can be added to all of the cans in northern Germany. We decided to try and connect a motion detector to a Raspberry Pi Pico (micro controller) and place it inside the Can to detect the incoming deposit bottles. These should then be counted and the data should be available for different purposes.

XXL Can prototype

We managed to build a prototype that is able to detect incoming objects via an infrared sensor. The green light indicates that the Can is ready to receive new deposit, as soon as it detects one the light turns red because the motion detector needs some seconds to cool down. Our python software on the controller increases the count by one for each movement detected.

Pin placement on the board with the motion detector

Our suggestion for implementing the counter is to use a micro controller that is able to connect to the internet. This way, it can call an endpoint on an API we created and increment the bottle count by one. The data is then available in the endpoint.

Further, we would move away from using the infrared detector and rather choose a photoelectric barrier (like the KY 010) and test it further.


When multiple school implement the detector in their XXL Cans, the data can be displayed in a sort of Leaderboard to introduce a competitive aspect into the collection and keep track of the donation progress. This page might also be used to advertise the projects and organizations supported with the money.