After all, it's also the flexibler mode in terms of the pins you can use to connect the RFID Reader. From that standpoint, UART might be the safer, easier and better to understand mode for the Library. I've spent more time playing with the UART code than with the Wiegand variant. UART mode, on the other hand, can use any two digital pins that are available and leave thus more freedom in implementing complex or fancy Arduino setups, possibly adding other sensors and tools to the mix as well. On an Arduino UNO, the only option are thus PIN 2 and PIN 3 (Interrupts INT0 and INT1, respectively). Wiegand mode is limited to pins that can generate an interrupt on falling/rising signals. Depending on your needs, having access to the whole ID might be necessary.

Wiegand is limited to 24bit (3 bytes) and will thus only return the card's ID value. UART mode will return the complete RFID's ID value, including the manufacturer/facility code. Wiegand mode has a smaller code footprint than UART as well, so resource and power wise, Wiegand might be the better choice. UART, on the other hand, uses Software Serial, which is quite a resource intensive beast. That means that it should be possible to put your Arduino to sleep and to wait until an interrupt wakes it up. Wiegand Mode uses interrupts to 'read' the data in. Here's a few points that illustrate the differences.

No writing: The SeedStudio RFID Reader does not have the capability to write to RFID tags so no write methods were added to the Libraryīesides the fact that there are two different interface methods, you might yourself ask: Why choose UART over Wiegand or vice versa.

No 'Facility' code in Wiegand mode: In Wiegand mode, only the 3 bytes of the card's ID (often printed on the tag) are available from the reader.

The following limitations apply to the RFIDLib, mainly because of the limitations of the underlying Hardware:

In Wiegand Mode, we only get the card code DATA1 of the RFID Reader must be connected DATA0 of the RFID Reader must be connected If you use the Library in Wiegand Mode, then the compiler SoftwareSerial must be included because the library depends on it

Rfid reader proteus library