Non-volatile memory Configuration Contactless CCID ATR rules

September 3, 2025 at 8:35 AM

Contactless ATR rules

Address : 0234 (bank 2, register 34)

Size : 1 byte

Default : 00

Description

Contactless cards don’t have an ATR. PC/SC specifies how a pseudo-ATR shall be constructed by the reader, with a few options.

Content

Bit    Role Values
7 RFU
6 RFU
5 RFU
4 RFU
3 RFU
2 RFU
1 Use Innovatron T=0 ATR 0 : Obey to PC/SC rule and construct a T=1 ATR, even for Innovatron Contactless cards
1 : For Innovatron Contactless cards, use the T=0 ATR supplied by the card
0 Control which values for NN are used in the ATR 0 : Use all NN entries defined by SpringCard to cover all Contactless memory cards
1 : Use only NN entries specified by PC/SC workgroup, return NN=0000 for non-PC/SC cards

Remarks

Bit 1: Use Innovatron T=0 ATR

Using this option is known to break the compatibility with some implementations of the PC/SC stack (the card has a T=0 ATR but uses T=1 Case 4 APDUs, which is considered as a protocol violation by the stack).

Bit 0: Control which values for NN are used in the ATR

The PC/SC workgroup maintains a list of Contactless memory cards, and defines a NN value for every registered card technology. Unfortunately, this list is not updated frequently and not exhaustive. The reader shall theoritically return NN=0000 for all the cards that are not in list, but, to help application developers discriminate among card technologies, SpringCard readers have a more complete list (non-PC/SC values being above F000).