Can I read the blue tags also?

[MerlinGuy]

I have this library example working for the white cards but it does not detect the blue tag. Can anyone tell me if this is possible and if so what do I need to do. Thanks.

[alastaira]

"Fobs" / "cards" are just differently shaped plastic cases to contain an RFID PICC (the "tag") - what matters is not the shape of the plastic hardware, but the protocol of the RFID tag inside.
The PN5180 hardware supports several different RFID protocols, but this library currently only supports the ISO15693 interface.
From your description I would assume that your card uses ISO15693 (so works correctly with this library), but your blue tag uses the ISO14443 interface instead (you could verify this by trying to read the blue fob on one of the common MFRC-522 ISO14442 readers).

There is already an open issue to introduce ISO14443 support - fortunately it's a well-documented standard: #6