Question regarding RFID and 134.2K animal tags

[Nicba1010]

Hey, since I'm an idiot when it comes to electronics, can you tell me if this project works with standard 134.2K tags? And second question, what is the detection distance for the chip. I was looking to buy some boards on AliExpress that have the capability of scanning the tags, but they are super expensive, and I don't know if it's for a good reason.

[Alex-ala]

Hey
This project is not functional or optimised yet. The current state is hardware that is ok-ish for a first version but the software is not functional as a cat flap yet. I struggled with the logic and hadn't had the energy to deepdive into it again yet.

The hardware as specified is built for 134.2Khz tags. The circuitry is built to have the antennas resonate with 134.2Khz if the antenna is built correctly (0.5mm enlamelled copper wire, 38 turns around the antenna rim). This means in theory it could ready any 134.2Khz RFID, but the code currently is written to only decode ISO 11784 which is the standard pet implant "chip" in Europe.

With a different antenna composition and some changed capacitors/resitors, the circuitry should also be able to relatively easily be adapted to like 125khz.

Reading distance currently is around 2-5cm for glass capsule chips. This is mainly due to my current PCB using terrible tolerance parts making the frequency be quite off. I think I already updated the KiCAD files to use better parts for RFID and IR frequency tuning.

When I started this project, I used "134.2Khz animal tag reader module ISO11784" from Aliexpress (search for WL-134). There are multiple offers using the same layout that offer a serial interface for ~20$ per module. This was quite expensive when using two sensors in one flap and using both serial interfaces on the ESP32 was not ideal.
This project now uses an EM4095 directly hooked up to the ESP32. So the EM4095 takes care of RF and ESP32 decodes the DEMOD output.