CR95HF Anticollision ISO14443A Select 2: How to formulate the select cascade level 2 command?

[DRich.1]

Some info:

Working with the CR95HF NFC Reader/writer. NFC tag is a Mifare Ultralight EV1, ISO14443A type 2 tag..

My current anticollision sequence is as following (I send the commands with sendreceive of the CR95HF library):

REQA "2607"

ATQA "80054400280000"

Anticollision 1 "932008"

Answer anticollision 1 "800888044AE422280000"

Select 1 "937088044AE42228"

Select 1 Acknowledgement "800604DA17080000"

Anticollision 2 "952008"

Answer anticollision 2 "80085A734D81E5280000"

So at this point you know the ID of my tag, in this case its: 044AE45A734D81

However, to ''confirm'' to the reader that this is the whole tag, the select 2 step needs to be executed. I try the following:

"9570" + part of ID retrieved during Anticollision 2 step + "52" (also from anticollision 2 answer) + "28" = "95705A734D815228"

This results in not finding any tags. How does this work? From what parts is the Select 2 statement built?

[Ulysses HERNIOSUS · Accepted solution]

Hi,

the strings don't look right to me:

5A734D81E5 : received

5A734D8152 : sent

I think you shifted by one nibble and instead you need to send:

95705A734D81E528

Regards, Ulysses