Reading data from Mifare Ultralight NFC Tag

Question

I've extracted the following data from a Mifare Ultralight tag :

[ 05:7E:EF:1C ] Addr. 00 : DATA
[ 6E:51:64:E9 ] Addr. 01 : DATA
[ B2:15:00:00 ] Addr. 02 : DATA
[ 00:00:00:00 ] Addr. 03 : DATA
[ 65:33:ED:7A ] Addr. 04 : DATA
[ A2:00:00:5A ] Addr. 05 : DATA
[ A5:5A:12:34 ] Addr. 06 : DATA
[ 00:00:00:00 ] Addr. 07 : DATA
[ 00:00:00:00 ] Addr. 08 : DATA
[ 00:00:00:00 ] Addr. 09 : DATA
[ 00:00:00:00 ] Addr. 0A : DATA
[ 00:00:00:00 ] Addr. 0B : DATA
[ 00:00:00:00 ] Addr. 0C : DATA
[ 00:00:00:00 ] Addr. 0D : DATA
[ 00:00:00:00 ] Addr. 0E : DATA
[ 00:00:00:00 ] Addr. 0F : DATA

This doesn't seem to follow TLV message types starting at page 4 and I want to make sense of it.

I suppose there might be a value for 17.5, or maybe 1750 somewhere.

Any idea how to figure this out?

Answer 1

I don't think this is a Mifare Ultralight tag for 2 reasons

1. Mifare Ultralight are NFC Type 2 compliant Tags.

   Type 2 tags block 3 must be the Capability Container (CC) and byte 0 must be the E1h magic number. As this Tag has 00h in this byte address it cannot be a Type 2 compliant Tag

2. The byte 0 of page zero is the first byte of the UID, which should be the manufacturers identifier. NXP's who make Mifare Ultralight Tags ID is 04h

   05h is assigned to Infineon Technologies AG (DE)

But you are right that the data is not in the Ndef TLV format but as it does not have the Capability Container set then it cannot store Ndef data anyway.

But also I cannot see how any of the bytes via straight hex to asci or hex to decimal will give 17.5 or 1750