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RFID is a conveninent technology for access control and authentication. In this project, I connected an RC522 RFID reader to an ESP32 in order to use it for IoT applications. Additionally, to provide feedback to the user, the ESP32 is also connected to an SSD1306 OLED display and a buzzer. I chose an ESP32 over an ESP8266 simply because of the amount of GPIOs required.

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.

RFID tags come in various forms and sizes, from standard plastic cards to chips that can be implanted in one's hand. I got particularly interested in RFID rings, which can be purchased online for less than USD 20$. Those are based on EM4305 chips, which require a compatible reader. Thus, I designed an IoT EM4305 reader that can exchange data over MQTT with other devices.

This headset enables the overlay of information on top of its user's field of view. The field of view of the user is captured by a camera and then fed to video goggles, while a MAX7456 OSD chip overlays text on the video feed.

Have you ever left your apartment and couldn't remember if you locked your front door or not? Sadly, if it is unlocked, there is not much you can do about it until you get back home. This system is an attempt to solve the problem. Simply put, it consists of attaching an actuator to the door's original locking mechanism control it with through WiFi.

Mosquitto is usually the first candidate to come to mind when looking for an MQTT broker. However, by default, Mosquitto manages users using a password file. This makes it difficult to easily add or remove users, especially when the broker is deployed in Kubernetes.

Wifi controlled smart light bulbs can now be purchased from less than USD 10. However, those can often only be used by a specific application provided by the vendor and can involve exchanging data with a third party server. I wanted a solution to use my own software while benefiting from the cheap hardware so I replaced the wifi module of a a cheap Wifi light bulb my own electronics.

Air conditioners consume a fair amount of electricity. As such, forgetting to turn one off before leaving one's home can result in an expensive electricity bill. This is a Wi-Fi enabled controller for air condtioners, which can turn the unit on or off according to MQTT messages. It is built around an Wemos D1 mini and interfaces with the AC using an IR LED.

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.

Modules like the Wemos D1 mini are a relatively cheap and easy way to integrate an ESP8266 in a project. However, one would sometimes require to have more freedom over the electronics, especially when it comes to PCB layout. For this purpose, the ESP8266 can be used in a form factor closer to its raw form, the ESP12-F module.