Problem with NFC shield v 2.0

Hello everybody, this is my first post on the forum, so please forgive me if i’ll do some errors :slight_smile:
I’ve bought an NFC shield v 2.0 (the black one) and i’ve attached it to my arduino uno board. Everything is fine, i connect the board to the pc, and then run up one sample (readMifarMemory as well as the others ones…), suddenly i get “Found chip PN532, Firmware ver. 1.6, Supports 7” and when i put in contact my tag (mifare 1k card) with the antenna i get nothing but: “Found 1 tags, Sens Response: 0x4, Sel Response: 0x8, 0x94 0x6F 0xFB 0xA6, Read card #2490366886” and then anything else…
i’ve made some basic debugging and found out that the problem is with the function “nfc.authenticateBlock(1, id ,0x08,KEY_A,keys)” that never returns true…so i tried to avoid the use of the function, and put a “nfc.readMemoryBlock(1,0x8,block)”, but it also return always false…
so what may be my problem? ayone knows? pls i’m really stuck with this stuff :frowning:

Thanks in advance!


Hi Mirco,

It’s likely that your tag’s keys are changed (default is { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF }).
The library on the wiki is a little old:(. To get the newest library, please go to and search “NFC”.

Hi Yihui,
What do you mean by tag keys changed?
Mine has the same problem. And if the tag keys changed, how can we read/write data since I cannot do it. I’m new with NFC here :slight_smile: