URL reader with RC522 + LCD 16/2 + Arduino Uno ... need help ;-)

Hi all,

I am looking to create a standalone prototype of an NFC reader with a Arduino.

This will be used to read the last 14 characters of an URL encoded into an NFC tag and print it on the LCD screen. (It will be a part of an industrial process but we are at the prototyping stage for the moment)

I am completely novice … for the moment i can read the UID of a tag and print it to the LCD but i want to read an other info on the tag …

Does anyone have an idea of how i can do that ?

I am pretty sure that my problem is here in the code :

//Show UID on serial monitor
Serial.print(“UID tag :”);
String content= “”;
byte letter;
for (byte i = 0; i < mfrc522.uid.size; i++)
Serial.print(mfrc522.uid.uidByte < 0x10 ? " 0" : " ");
_ Serial.print(mfrc522.uid.uidByte*, HEX);_
_ lcd.print(mfrc522.uid.uidByte < 0x10 ? " 0" : " ");
lcd.print(mfrc522.uid.uidByte, HEX);
content.concat(String(mfrc522.uid.uidByte < 0x10 ? " 0" : " "));
content.concat(String(mfrc522.uid.uidByte, HEX));*

But i don’t see how to ask to read the URL and print it on the serial … (and when i will have the URL i will see how to ask the ARDUINO to just display the last 14 characters of it).
Thanks for the help,

What kind of tags are we talking about? Are you producing the yourself or are they preprogrammed? Are you sure that these tags are compatible with the MFRC522 reader?

If you post code, always use code tags!

And post complete code, in most case the error is not in the posted code but in the code users are hiding from us.


We use NXP MIFARE Ultrlight (Ultralight C) - NTAG213 tags. We are buying it without info on it and we are encoding a unique URL on each tag. OUr tag are readable by any smartphone and goes directly to the right URL.

For the moment with the Arduino and the RC522 we are able to read the UID of our tag, that mean that the RC522 is compatible with our tag ... no ?

The problem is that we want to read the URL (in fact the 14 last characters of the URL) that is encoded on the tag. Do you have an idea of how we can ask this info through the RC522 ?

For the code tags, thanks for the reminder, i will use it next time !

Thanks in advance,


I would be going back to the supplier or manfacturer to find out how to instruct the tag to upload the URL.

It seems to me the RC552 is only asking for the ID.
How you ask for the URL, you will need the manufacturer specs to see that commands need to be sent.

How does the phone app do it?

Tom... :slight_smile:


Yes, our TAG could be read by any NFC reader with an iPhone or without a specific program with an Androïd smartphone. It open directly the browser and go to the right page.

Do you think that RC522 only read UID of the tag ? Do we need a PN532 ?



Have you tried the ReadAndWrite example? You might have to extend the type check as the read command seems to be supported by the Ultralight tags too.