AN2284 datasheet(18/40 Pages) STMICROELECTRONICS

18 / 40 page

7 ISO 7816-3 - Electronic Signal and Transmission Protocol

AN2284

18/40

The historical characters can be defined at the discretion of the card manufacturer or the card

issuer. These characters are typically used to convey some type of designation of the type,

model, and use of this specific card. When used in this way, the historical characters provide a

modest mechanism through which systems can automatically detect the use of an inserted

card (within that system) and can initiate other actions (or software) accordingly. The check

character provides a mechanism through which the integrity of the ATR can be measured; that

is, whether a transmission error has occurred in sending the characters from the card to the

reader.

The structure of the ATR is illustrated in Table 4. As discussed previously, the initial TS

character is used to establish the bit-signaling and bit-ordering conventions between the reader

and the card. The T0 character is used to signal the presence or absence of subsequent

interface characters or historical characters. The interface characters are used to tailor the

characteristics of the I/O channel, including the specific protocol used by the card and reader

during subsequent exchange of commands (from the reader to the card) and responses (from

the card to the reader). The historical characters, if present, are used to convey card-

manufacturer-specific information from the card to the read, and hence to the application

system being served by the reader. There is really no established standard for the information

presented in the historical bits.

The total length of the ATR sequence is limited to 33 bytes and must adhere to the following

format:

Table 4.

The Answer-to-Reset Structure

Character ID

Definition

Initial Character Section

Mandatory initial character

Format Character Section

Indicator for presence of interface characters

Interface Character Section

TA1

Global, codes F1 and D1

TB1

Global, codes 11 and Pl1

TC1

Global, code N

TD1

Codes Y2 and T

TA2

Specific

TB2

Global, code Pl2

TC2

Specific

TD2

Codes Y3 and T

TA3

TAi, TBi and TCi are specific

...TDi

Codes Yi+1 and T

Historical Character Section

Card specific information

...TK

(Maximum of 15 characters)

Check Character Section

TCK2

Optional check character

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