ATR (Answer to Reset) : Information presented by the SIM to the ME at the beginning of the card session and gives operational requirements. It consists of at most 33 characters.
Initial Character : TS Set up the convention to decode every subsequent character.
Format Character: T0. Mandatory. Announce the first interface characters and all historical characters.
Interface Character: TA(i), TB(i), TC(i), TD(i). Optional. Indicate a bit map technique initiated by the format character.
Historical Character: T1, T2… TK. Optional. Indicate a number coded in the format character.
Check Character: TCK. Conditional. Depend on the value of parameter T in some interface bytes.
Parameter T : Refer to transmission protocol and/or qualify interface bytes. In every byte TD(i), TA2 or PPSO, the bits b4 to b1 code is a value of T ATR (Answer to Reset) - Continue Parameter Protocol Parameter Protocol T=0 Half duplex trans. Asynchronous char. T=5~13 Reserved for future use T=1 Half duplex trans. Asynchronous block T=14 ISO/IEC JTC 1 SC 17 T=2, T=3 Future full duplex T=15 Qualify global interface T=4 Reserved enhance T=0
TS T0 TA1 TB1 TC1 TD1 TA2 TB2 TC2 TDi TAi, TBi, TCi T1 TK TCK Coding convention for all subsequent characters (direct or inverse convention) Subsequent interface characters, number of historical characters Parameters to calculate the work etu Parameters to calculate the programming voltage and current Parameters to calculate the extra guardtime requested by the card; no extra guardtime is used to send characters from the card to the ME Protocol type; indicator for the presence of interface characters, Specifying rules to be used for transmissions with the given protocol type not used for protocol T=0 Parameter to calculate the programming voltage Parameters to calculate the work waiting time Protocol type; indicator for the presence of interface characters, specifying rules to be used for transmissions with the given protocol type Characters which contain interface characters for other transmission protocols. General Information (Card manufacturer, Chip inserted in card, state of life of card) Check byte (exclusive ‑ORing: T0~TCKinclusive) ATR (Answer to Reset) - Continue
ATR(cont.) : After the answer to reset, the card is in one of the following two modes of operation:
- Specific mode if TA2 is present,
- Negotiable mode if TA2 is absent.
Specific mode : Directly after the answer to reset, the protocol indicated by
TA(2) shall apply using for F and D
Negotiable mode : Implicit selection is possible as long as the first byte sent by the interface device to the card allows an unambiguous distinction between a PPS request and a command of the protocol.
TA2 is not used for protocol T=0, the card is in Negotiable mode.
ATR (Answer to Reset) - Continue
PPS procedure: Speed Setting between ME and SIM.
The PPS request and PPS response each consist of one initial byte PPSS, followed by a format byte PPSO, three optional parameter bytes PPS1, PPS2,PPS3 and a check byte PCK as the last byte
For MEs only supporting default speed(F=372, D=1)
For MEs only supporting enhanced speed(F=512, D=8)
If PPS procedure is not initiated, SIM use default value.
If SIM does not support the values requested by the ME, the SIM respond to the PPS request indicating the use of default values.