RFID keychain holder/reader

thingiverse

There's an updated version of this project available at https://www.thingiverse.com/thing:3970973. This new version has several improvements but also comes with its own set of issues. One problem is that it requires support during printing and cleaning can be quite a challenge. Additionally, the distance between the sensor and the RFID key tags is slightly too great, resulting in inconsistent on/off recognitions. To fix this, you'll need to use a knife to carefully trim some parts so the sensor can get closer to the key tags. Another issue is that without a display, it's impossible to determine if the tag has been recognized or not, or if it has switched back to not recognizing it anymore. If you plan on adding something like this to your home automation system, I highly recommend using the new version as the base case. However, the software and overall concept haven't changed much. I recently acquired an RC522 RFID reader with the intention of integrating it into my smart home IoT setup. Most projects involving these readers focus on access control, where a device with a reader is placed in front of a door and controls a lock. When a user approaches, they hold their key card at the reader, which then either grants or denies access before returning to its idle state. My use case is different, more similar to what you'd find in a hotel: the device with the reader is placed behind the door, and users are expected to insert their key cards into the reader and leave them there. The reader identifies the card and informs the smart home controller that the owner is at home, allowing it to turn on lights and other features. When the user removes their key card, these features are disabled again. To make this work, the RFID key card needs to be in close proximity to the reader in a stable position, essentially requiring some sort of pocket. After searching, I couldn't find any suitable designs, so I created my own based on a circular cutout at the top for easy insertion and removal of the key chain chip. One notable drawback is that this design requires extensive support during printing, making it a time-consuming process to remove without damaging the pocket. On the software side, many examples use sketches where the reader idles until a card is inserted, then analyzes it and returns to its idle state. However, there's no event generated when the card is removed. To address this, I had to write my own sketch for the Arduino clone (Nodemcu V2), which creates events when a known key card is entered or taken out. Since my smart home is controlled by openHab2 with its REST API, I also added some code to report these events to it, but you'll need to adapt this to fit your specific setup.