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Global warming and the COVID-19 pandemic are some the many challenges humanity is having to face. However, I somehow decided that the problem I was going to solve is having to take my keys out of my pocket whenever I lock or unlock my front door.

I wanted my home automation system to detect when I arrive home so as to unlock my door automatically or let me know if I leave the apartment without turning the A/C off. I figured my smartphone could be used to achieve this since it is equipped with a vast array of sensors and connectivity options. For example, I could use an app like OwnTracks which would send an MQTT message once I enter a certain perimeter around my apartment. However, constantly monitoring one's GPS location is wasteful in terms of battery life. Another option would be to ping my phone's IP address to check if it is connected to the WiFi, but smartphones can sometimes take a while to connect. So, I decided to use BLE advertising, which does not use too much battery while still remaining constantly active.

One of the companies I used to work for had a serious bathroom issue: My floor had only three toilet stalls for about 200 employees. There were countless times when I would walk all the way to the bathroom only to find all stalls occupied. I built this simple system to quickly identify whether one or more stall were. It consists of an IoT sensor installed on the bathroom stalls' door and an indicator placed somewhere easily visible.

A company I worked for had a coffee machine for which employees could purchase coffee. However, the payment was done by putting coins in a jar. Not only did this present the obvious risk of theft, this system was also impractical for people not carrying spare change at all time. I decided to solve this issue by designing this cashless payment system.

Smartwatches can be rather expensive and tend to be known for their poor battery life. On the other hand, Xiaomi's Mi band 2 is cheap and its battery lasts for up to 20 days. However, the Mi band 2 is mainly limited to fitness tracking functions, at least without the appropriate apps.

This project consists of an HC-SR501 PIR motion sensor and a DHT22 temperature and humidity sensor connected to a Wemos D1 mini, an ESP8266 breakout board.

I am not much of a cook so salads are usually one of my favorite options for a healthy meal. So, just like for everything else, I started wondering if I could make my own. However, I don't have access to a garden so I started looking into solutions to grow vegetables indoors. I settled for hydroponics, which seemed to provide a good balance between yield and operational hassle. Specifically, I went for a Deep Water Culture type of hydroponic system as it is usually considered easy for beginners to setup.

Earlier this year, a friend of mine was organizing an event to promote eco-friendly behaviors. She wanted someone to talk about our relationship with energy and asked me to give a presentation on the topic, which I agreed to. I wanted the presentation to be entertaining so I designed a set of hardware demonstrations aimed at explaining physical concepts related to energy.

Over the years, I have built multiple IoT devices ranging from AC controllers to ceiling lights. Usually, I would control those devices using my smartphone or computer but sometimes a physical button can be more convenient. Thus, I designed this simple IoT button which publishes MQTT messages when pressed.

Few would argue that having lights turned on in a room without occupant is a waste of electricity. Ideally, lights and other appliances like air conditioners would only be turned on when someone is around. This project is a NodeJS application that gathers data about the occupancy of an apartment and manages appliances accordingly.