Using UART with Arduino UNO and RFID RS522

Projects General Guidance
1

Hello,

I am using an Arduino UNO board and I am trying to get an RFID-RC522 setup. The RFID is set up out of the box to work with SPI. I read the datasheet and other forum posts and found that to get the RFID to run UART you need to tie pin 32(EA) to GND instead of 3.3V. I have done that and confirmed the connection.

I then found this GITHUB repo with an example project using RFID and UART.GitHub - MakerSpaceLeiden/rfid: Arduino RFID Library for MFRC522
I ran the code and cannot seem to get any reading when I scan my card. I got the card ID from a different RC522 module using SPI, so I know I have the right ID, but the LED never toggles ON/OFF when it reads a card.

My current wiring setup is
RFID TX->UNO PIN 0
RFID RX-> UNO PIN 1
RST -> UNO PIN 2
3V3 -> UNO 3V3
GND -> UNO GND

Has anyone got this RFID module to work with UART before? I appreciate all help and feedback. Thanks!

2

Kindly read the pinned post re 'How to get the most from the forum'

3

There is a UART example in the link you posted. rfid/examples/rfid_uart/rfid_uart.ino at master · MakerSpaceLeiden/rfid · GitHub

5

Yes I ran that Uart example hoping it would just work. However, when I ran the code it never read the card ID and toggled an LED like it was supposed to.

6

Most of the internet gets this wrong, but this is the way the wires should be connected.

RFID reader to Arduino
RFID reader to Arduino735×775 34.6 KB

The 5V signals output from an Arduino need to be attenuated to avoid frying the RFID reader. Where as signals from the RFID reader to the Arduino do not need attenuation.