[ESP32-C3] esp-rfid-bridge -- RFID reader that talks JSON over USB Serial

[AlwizBA]

Hi, just dropped a small firmware project on GitHub that I've been sitting on for a while.

esp32c3-supermini.jpeg (148.17 KiB) Viewed 180 times

Basic idea: ESP32-C3 + RC522 module, plugged into USB, and it just sends card scan events as JSON over serial. Your host (whatever it is -- Python script, Node, a Rust binary, doesn't matter) is the one that decides if the card gets access or not. The firmware doesn't know and doesn't care about your access list.

So when someone taps a card you get:

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{"event": "card", "uid": "HE:LL:O6:67"}

You reply with:

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{"method": "POST", "resource": "access", "data": {"access": true}}

LED blinks, done. If you don't reply in time it blinks a different pattern and moves on.

There's also a handful of other endpoints -- GET /status, PUT /config for tweaking debounce and timeouts at runtime, PUT /led if you want to drive the LED yourself, POST /reset, etc. All single-line JSON over USB CDC at 115200.

Hardware side is pretty cheap. ESP32-C3 Super Mini is like $2 shipped, RC522 is another $1-2. Five SPI (+one more for 3.3v) wires plus one LED pin and you're done.

Built with PlatformIO. GitHub Actions handles CI and spits out a merged .bin (bootloader + partitions + firmware all in one) so if you just want to flash and not deal with the build toolchain, grab it from Releases and use esptool or the browser-based esptool-js.

Repo: https://github.com/lenzarchive/esp-rfid-bridge

Let me know if anything's broken or if the protocol is missing something obvious.