An RFID ring as a front door key

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.

Instead of a literal key, I would ideally have some form of access token that stays within hands reach and can unlock my door. In fact, I figured that it could actually be on my hand and thus went shopping for an RFID ring on AliExpress.

It turns out that RFID rings are easy to get and come in two variants: 125kHz or 13.5 kHz. I went with the 125kHz variant as it can be read from a further distance.

I've been using a DIY IoT lock for a while now so, I simply installed a Wifi enabled RFID reader on the outside of my door and made it trigger the lock when the reading a ring containing the right data.

The hardware is pretty straightforward. It simply consists of a Wemos D1 mini and a generic EM4305 reader breakout board. I settled on this chipset because RFID rings often use it. The Wemos D1 mini communicates with the reader using software serial.

The source code for the firmware is available on GitHub: