Mifare Classic - Unknown Command

Question

I'm simulating a Mifare Classic (1K) tag, and following the o ISO/IEC 14443 Type A protocol.

I could not found any information about what should be a proper response in case of receiving an unknown command from the reader (the reader supports other protocols).

Should I respond with an invalid operation NAK? Should I just ignore the command?

Answer 1

Mifare Classic EV1 datasheet §9.3 suggests Invalid operations should return 4h as response. It's quite unclear to me wether undefined commmands should be considered Invalid operations. I don't have a MFC EV1 at hand to test on. In my experience older MFCs simply do not answer to erroneous commands, though.