As a proof of concept, I connected (3) RFID-RC522 readers in parallel to an Arduino Nano. These are the standard readers that come with any Arduino sensor kit. They are large, so I knew that I couldn’t put them in the middle of the face plate. Instead, I envisioned distributing them around the circumference of the face plate to make a better reading surface. I used 3 copies of this Arduino library (a very janky solution) to read each sensor subsequently. https://github.com/miguelbalboa/rfid.
This test mostly WORKED! It was amazing that my first attempt would read the presence of an RFID chip nearby and send that reading via Arduino TX to the Raspberry Pi which would either make the LEDs light up, or play a sound. I had no idea why one or the other worked, until much later in the project. Another struggle was that the range of the RC522 behind plastic was very poor. I could only obstruct it with 2 mm of PLA before it would stop reading the Magic Band. Coupled with its indirect placement, this was not acceptable as a final solution.
Working with RFID in the summer of 2024 at Sandia National Labs, I was familiarized with WIEGAND readers and their effectiveness in door access devices.
This was a perfect application of this device. All it needed was a boost converter (5 V → 12 V) and resistor voltage dividers for the signal lines.
This reader did not work at all. I have no idea what went wrong. The sensor is 13.56 MHz, but it is possible that it did not use a ISO/IEC 14443A reading standard.
Next, I tried using an m1-232-r chipset and tuned antenna to get the signal. With very limited documentation, this did not work either.