I've read several documents about ATR and I found that before I get ATR, there is another four bytes which called ATR header, so I'm curious how can I get this ATR header?
many thanks for your attention
I'm curious about your documents !?
There is no such thing as an atr header
the atr is the string of the first bytes emitted by a contact card following an activation sequence. In an ATR, you have a variable number of interface bytes, then a variable number of historical bytes.
contactless cards don't have ATRs.
ISO 14443-B cards have a PUPI (4 bytes)
ISO 14443-A cards have an UID (4,7 or 10 bytes)
this value is exchanged before the reader reports a fake-ATR.