RFID reader not working with Ethernet Shield

Hi Everyone,

I am developing a payment system (with Arduino MEGA) that uses RFID readers and posts data to a server using an ethernet shield.

Although the Ethernet works well, the RFID reader does not. It seems to initialize (Firmware Version: 0x92 = v2.0 in the serial monitor), but it is unresponsive to any cards).

I have read that this is caused by the fact that they share the SPI bus, but I have not managed to find a good way to fix this.

Also, should I change my SS pin for the RFID reader?

Thanks in advance for your help :slight_smile:

Kind regards,

p.s. here is my code:

Payment_system_-_no_credentials.ino (25.6 KB)

separate Slave Select (SS) should solve your problem. You might post a schematic to help validate what I am saying.

I think You should change SS pin in RFID reader. If you use RFID-RC522, you should change SS pin in: MFRC522 rfid(SS_PIN, RST_PIN);

See more in RFID-RC522 tutorial

Hi everyone, thank you for your fast replies!

I changed the SS pin to 53, and although it initializes well, it does not read any card.

Is this is a code problem then?

Is this is a code problem then?

My crystal ball is not working. You'll have to post the code for anyone to answer that.

My philosophy is that if you need WiFi, then use a board with WiFi already built in. I did a project about a year ago for an escape room game where the player would put a stuffed bunny on an item to examine, which was really an RFID card reader in the butt of the bunny and the tag in the item to be examined. The bunny would send the tag number by MQTT over WiFi to a game controller which would decide on the appropriate response, then send the voice response back to the bunny.

All this was done using a Wemos D1 Mini

My crystal ball is not working. You’ll have to post the code for anyone to answer that.

I already uploaded the code in my first post, but here is the updated version (it’s an attachment because it’s quite long).
Also, I managed to get the reader working yesterday by changing the USB cable, but now it has stopped working and I’m facing the same issue :confused:

Updated_Payment_system_-_no_credentials.ino (25.5 KB)