The connected trash can

by José, Hardware Manager

#Prototype 1

Once our idea had been determined and studied, it was time to bring it to life and to build our first prototype – from cardboard. Cardboard was easy to find and above all was easy to handle, so we were able to test the triangular shape and all the dimensions of our trash can. With a bit of DIY, lots of reusable cardboard, a bit of tape & scissors our first prototype was born! We presented it to various experts and employees and received lots of helpful feedback, however then an acquaintance inadvertently put his entire weight on the bin, forgetting that it was only made of cardboard despite the design and sturdy appearance. Our first prototype then unfortunately became just a piece of garbage to put in our next trash can!


#Prototype 2

After the destruction of our cardboard prototype, we had to get back on track as fast as possible. The very next morning, therefore we visited a cabinetmaker who helped us make our second prototype, which, as you’ll have guessed, was made of wood, for obvious reasons of solidity. This second prototype was placed in a company and allowed us to test the whole hardware aspect of our trash can to validate its function.


#Prototype 3

The question now was should we continue with the design wood idea or opt for another material? This dilemma encouraged us to research the alternatives extensively to compare all the pros and cons. We contacted various suppliers and, thanks to their valuable advice, we completed our V3 prototype in a combination of wood and metal. Our analyses and meetings with suppliers enabled us to draw up plans and discover new technologies, for example, we learnt about laser cutting when cutting parts of our trash can in a Belgian “fablab”, the Makilab. To really differentiate ourselves, we wanted our third prototype to be as advanced as possible in terms of design while guaranteeing support for all the hardware.


When we went to buy no less than 130 kg of metal bars, we quickly realized that not only was the metal was very dirty but that cutting it to a size to facilitate transport would result in considerable extra cost. We therefore quickly found a solution: buy the bars from one company and negotiate with a neighbouring company to use their premises and power to cut all the bars ourselves with a circular saw! After negotiating this strategic solution, we nevertheless had to deal with the physical challenge of carrying all the metal, on foot, from one company to another. At our meeting with TRP Design experts the same afternoon, we still had the traces of this exploit on our hands.

#MVP Hardware

During one of our usual meetings at The Space, we met Laurent, the manager of Skirmysh, a prototyping company. After an extremely constructive exchange, Laurent was very taken with our project and suggested a partnership. Skirmysh would work on the development of our technology, installing the sensors in our trash can and making sure that the data could be sent to FireBase. New features such as the NFC drive were later added thanks to our collaboration with Skirmysh. In exchange, we would promote their services to our customers, contacts and of course, Skirmysh could use us as a use case. After weeks of work and lots of forward-thinking, our partnership with Skirmysh ensured that the different functionalities and data extraction worked perfectly in our trash can.


#MVP Design

As far as the appearance, layout, ergonomics and individual components of the trash are concerned, we initially wanted to work with RAAK Design. Our goal was also to achieve a product ready for mass production and therefore quickly reproducible. Following our crowdfunding though, TRP design contacted us as they saw potential in our project. On March 11th, we held our first meeting to determine how to incorporate the different features in our design and to perform a series of performance and user-friendliness tests. Due to the critical Covid 19 situation, we have kept in touch with the designers virtually and have yet to determine with which partner we will proceed. Since competition is often a source of innovation and improvement, we intend to make the most of this competition and take our time to evaluate the different possibilities and advantages that each partner offers to determine whether RAAK or TRP Design best corresponds to our needs.


Initially, after lots of research and analysis, I took care of creating the first designs for our trash can. I am very proud that real industrial engineers are taking these first plans forward and improving them as they see them as a good basis for their work. Being able to discuss with them and participate in the development is very beneficial for me.


  • NFC module constantly sends radio waves to NFC (Near Field Communication) chips in phones or bank cards that act as antennas. When the NFC module has detected a chip in the vicinity, it will send a stronger signal to be able to identify that chip. If the chip is encoded, it will activate the motion sensor to open the trash can.

Due to Covid19, the NFC module took a long time to arrive. So as not to be stuck, we used an RFID (Radio-Frequency IDentification) sensor. The use of RFID radio technology permits the reading of the UUID on the RFID cards. The sensor is activated as soon as the card is inserted into the slot. The microcontroller then checks that this UUID corresponds to a known user UUID in our database. If this is the case, it grants access to the trash can, starts a check of the weight of the waste, the degree of fullness of the trash can and sends this data to FireBase and BLynk. RFID cards are blank cards with a unique UUID. They can be linked to employees and to visitors. Testing with RFID technology allowed us to test an alternative for one-day visitors. This solution can be offered to companies.

  • PIR motion detector (Passive Infrared Sensor) is a motion detector placed on the lid of the trash can. It works with infrared lights, like the time of flight sensor that will be outlined below. This detector detects the passage of the user’s hand. It only turns on if the NFC module detects a recognizable chip in the vicinity. The motor opening the trash can is activated when the motion detector is activated.
  • Servo micro 9g is a mini motor used to open and close the lid of the bin. You can easily define the angles you want the trash can lid to open at, for example that the lid only opens 90 degrees and no more. We use mini motors because they are powerful enough to lift the lid but not too powerful to prevent manual lifting of the lid (in case of malfunction) (1.5kg/cm of resistance). Servos operate at 4.8V.
  • M5 stack microcontroller collects all the data from the different sensors and sends them to the application thanks to the Wifi module. This microcontroller is based on ESP that allows easy access to the communication protocols related to it, such as I2C, GPIO, UART. It allows the reading of all the sensors (TOF, RFID, weight) and permits real-time communication with the FireBase database and the Blynk Server.

At the beginning of the year, we initially preferred the ease of an open-source system, namely an Arduino, to act as a controller and conductor of the hardware. However, we encountered problems in the collection and transfer of data with this system. Thanks to Skyrmish’s knowledgeable advice, we switched to the M5 stack microcontroller. In the near future, probably when we start mass producing our bins, we will move to a more personalized and certainly even better adapted, unique PCB created by a Belgian (ideal!) electronics company. This idea came to us while attending a conference organized by the company CowBoy.

  • Weight sensor is based on a HX711 card in combination with a 20 kg load cell positioned at the bottom of the trash can. It is a weight sensor that is activated once the Motion detector has recognized that someone is moving his or her hand over the sensor. Otherwise the weight sensor is normally in deep sleep mode to conserve battery power. When it activates and identifies a weight change, this value is added to what was previously measured, and the data is sent to the microcontroller (by wire). It has been noticed that the weight sensor we use has difficulty in accurately measuring waste weighing less than 3 grams, probably due to the change in temperature and humidity. We are exploring 2 options: the first is to buy a more expensive and more accurate weight sensor for 40€; the second option is to keep this weight sensor and install a humidity and temperature sensor (if we can prove a correlation). All three sensors would cost less than 30€ and would provide additional data.
  • Time of flight sensor (ToF) is a fast and accurate distance sensor based on a laser placed on the ceiling of the trash can. The sensor sends out a light wave and calculates the time it takes for the wave to return, obtaining the distance from the lid to the waste layer and thus the fullness level of the trash can. The data are sent to the microcontroller. This laser sensor is activated only after the trash can has been opened, 15min after calculating the level of waste mass in a previous opening, all to save battery power and avoid incessant and unnecessary measurements. The distance of the light wave will be at least 3 cm and at most 200 cm.
  • 20 000 mAh BatteryPack is an energy bank that provides a stable and reliable power source with a month’s autonomy for the microcontroller. The powerbank system was chosen specifically because there are safety measures already in place in the battery to prevent it from overcharging, and the voltage levels are already regulated. By using the deep sleep capabilities of the M5 stack microcontroller, the device can be put into standby mode to consume less energy. This way, the device is only switched on during the trash can openings for 30 seconds. This operation consumes 300mAh of battery power. In this way, we reach an average consumption of about 20mAh.


At our prototyping stage, we bought our materials in Belgium and mainly in Brussels.


  • Prototype 1: reused pieces of cardboard, assembled with glue and tape.
  • Prototype 2: MDF, wood reconstituted from wood waste. It was recovered, in a workshop, assembled and cut in a local woodworking shop.
  • Prototype 3: metal from the company Sobemetal in Brussels, of the “treated steel” type. Wood from the company Bois Watteau.
  • Tech test materials: recovered from the tests of other tech projects at The Space.

The application

by Sébastien, Software Manager


Before coding our apps, we thought about a multitude of features that were quickly submitted to potential partners and customers to check their market appeal. After some upstream work, we finally did a big brainstorming, with members of The Space and other experts, to validate functionalities and think about new ones, including the leaderboards system. Overall, the UX Design process around the application spread over many weeks, in order to have exchanges and feedback at each key stage.

After our app design, the finishing touch was provided by Fayçal Nakach and David Theijs, two very experienced creative designers. Thanks to their valuable recommendations about the interface and the User Experience, we were able to arrive at the current result. They also advised us to use Figma as a design and prototyping tool, allowing us to rectify many details such as the intensity of the shadows of each button before coding.

For the coding, we are working with a team of student developers. This allows us to reduce development costs that would otherwise be several thousand euros and to work with people who share our vision.


The best moments in the development of the app were the numerous design sessions from 9pm until 5am, listening to podcasts. Developing the designs for the different graphs that we had to represent in the application was particularly difficult for me. I spent a lot of time asking people around me if our graphs were clear and easily understandable to keep getting an outside perspective.

I really took the development of this app to heart. Beyond Echooo, the “UX/UI” has become one of my interests. I started to read articles and follow webinars on the subject and I am now considering studying to become a visual designer.


At a meeting with experts from Deloitte, Robin Descamps, a cybersecurity consultant, stressed the importance of data protection in a project such as ours. We have kept this piece of advice in mind throughout the development of our app. Thus, since that day, all the data collected by the sensors in our trash can are stored in Firebase, Google’s secure database.


  • Firebase is a Platform-As-A-Service owned by Google that allows us to manage the databases, the users of the application and to host our application. This gives us access to a real-time database allowing users to always have live data from the trash can.
  • Ionic/Angular is the technology used for the development of our application. It allows us to create a progressive-web-app that works just as well on a browser as on iOS or Android, drastically reducing the implementation time.
  • Edge Computing allows us to lighten the back-end of our application, the calculations carried out by the different mobile phones. Once a mobile phone has calculated the total value of the week for a bin, it will store it in the cloud, making it accessible to other mobile phones. The calculation load is therefore distributed over the total number of users.

Our services

by Thomas, Quality Manager


Our audits, advice and workshops are given in partnership with Little Green Dots. Thanks to our presence at the “Zero Waste” exhibition at Tour&Taxi last November, we met Pierre Léonard, a coach in sustainable development and waste management. He was immediately impressed by our project. It seemed obvious to him as well as to us that we had to cooperate by becoming partners. Since then, every time there is a major step forward in the project, we discuss with him to gather his opinions and criticisms, which allows us to improve continually.

My first meeting with Pierre was very warm. I had mentally prepared myself for a very conventional meeting but, because of his kindness and his desire to help, we quickly developed a friendly collaboration. Since then, I have been in charge of communication with our different partners. Although I didn’t really feel ready for the responsibility of learning how to move people and entities forward towards a common goal while ensuring professional information exchange and planning but with the support of the coaches and the rest of the team, I finally got my bearings and managed to reap many benefits from our collaborations.


Our eco-responsible by-products, in addition to our various services for companies, are also an important means of raising awareness and supporting our clients’ zero-waste approach. Efficy CRM was the first company to contact us: they wanted to provide each of their employees with one of the personalized bamboo mugs available in our Zero Waste merchandising catalogue. Though the impact of the lockdown temporarily delayed delivery of the 180 mugs, the order proves that our by-products are an additional and indispensable aid in our 360 service.

To guarantee the success of our crowdfunding, some of our by-products also served as incentives for support and as thank you gifts to our contributors.

It was important to us to promote a product from another zero waste Mini-Company. The quality of Vrap’s packaging had already impressed us at the congress in February, so we contacted them for a win-win exchange. Thanks to this collaboration, Vrap acquired a certain visibility with a new public and several of our contributors were able to benefit from their product in return.

Continue reading the last step of this 3-part journey that explores step by step the construction of the Echooo project …