In the case of a basic ATR, whether a character exists and the allowed range of values ​​(if any) is indicated by its "basic response" message. There is no conflict between the basic response description and other extensions that may exist. For example, if an IC card supports multiple transport protocols and multiple transmission parameter values, it can return additional characters, but only if the IC card returns a basic ATR, or returns an ATR supported by the terminal that meets the minimum functional requirements. The correct exchange of characters follows.
If the terminal does not support other transport protocols supported by the IC card and the transmission parameter values, the IC card should have the ability to interact with the terminal using the mode defined by the basic ATR.
The maximum number of echoed characters (including historical characters but not TS) in the reset response is 32.
If the terminal cannot meet the transmission mode defined in the IC card return ATR, it will send a warm reset signal or put the IC card in a stationary state to end the card operation process.
1, TS - initial character
The start character TS has two functions: one is to provide the terminal with a known bit pattern for bit synchronization, and the other is to specify a logical convention for interpreting subsequent characters.
When using the reverse logic convention, the low state of the I/O is equivalent to logic 1, and the least significant bit of the data byte is sent after the start bit, and the first nibble LHHL is used for bit synchronization (where L represents Low level, H means high level).
Basic response: The TS that the IC card will return is one of the following two values.
* (H) LHHLLLLLLH indicates a reverse convention with a value of 0x3F.
* (H) LHHLHHHLLH indicates a forward convention with a value of 0x3B.
Terminals generally support forward conventions and reflection conventions, and receive any one of 0x3F and 0x3B returned by the IC card, which will be rejected for other values. At present, the cards in the reverse agreement mode are used less and less, and may be eliminated in the future card specifications and application specification versions. Therefore, in our design, it is recommended that everyone use 0x3B, that is, a forward agreement.
2, T0--format characters
The format character T0 is composed of two parts. The high nibble (b5~b8) indicates whether the subsequent characters TA1 to TD1 exist, and the b5-b8 bit is set to logic "1" to indicate that TA1 to TD1 exist, correspondingly, the lower nibble (b1~b4) indicates the number of optional history characters (0~15), as shown below:
[b]T0 basic response code[/b]
[b] b8 b7 b6 b5 b4 b3 b2 b1 [/b]
T=0 0 1 1 0 xxxx
T=1 1 1 1 0 xxxx
Basic response:
* When T=0 is selected, the IC card should send back T0=0x6X, indicating that the characters TB1 and TC1 exist.
* When T=1 is selected, the IC card should return T0=0xEX, indicating that the characters TB1, TC1 and TD1 exist.
Where X represents the number of historical characters.
A compatible terminal can receive all values ​​that satisfy the above conditions.
3, TA1 ~ TC3--interface characters
During the terminal and IC card information exchange after the reset response, TA1 to TC3 indicate the values ​​of the control parameters F, D, I, P, N, IFSC, BW1, and CW1. These parameters are used for the T=1 protocol, and the information transmitted by TA1 to TC1 and TC2 will be used for subsequent data exchanges regardless of the type of protocol used. The specific meaning of these parameters is given below.
(1) TA1
TA1 transmits the values ​​of FI and DI, where:
* FI is used to determine the value of F. F is the clock rate conversion factor used to modify the clock frequency provided by the terminal after the reset response.
* DI is used to determine the value of D. D is a bit rate adjustment factor. Used to adjust the bit duration used after the reset response.
The default values ​​FI=1 and DI=1 used when transmitting the ATR during the reset response indicate F=372 and D=1, respectively.
Basic response: If the IC card does not return the TA1 value, it means that the IC card uses the default parameters and continues to use the default values ​​F=372 and D=1 throughout the subsequent information exchange.
The compatible terminal receives the default TA1 value (0x11)
In order to improve the data transfer rate between the terminal and the IC card, some IC cards may choose to use the high speed mode by using other TA1 values ​​when the terminal supports.
(2) TB1
TB1 transmits PI1 and II values, where:
* PI1 is defined in bits b1 to b5 to determine the P voltage value required for the IC card. PI1 = 0 indicates that the IC card does not require the programming voltage VPP.
* II is defined in bits b6 to b7 and is used to determine the maximum programming current I value required for the IC card. This parameter is not used when PI1=0.
* The b8 bit is not used and the bit logic is set to 0.
Basic response: Most IC card chips currently in use do not require programming voltage support. Therefore, the IC card returns TB1=0x00, indicating that the IC card does not use VPP.
The terminal accepts any TB1 that satisfies the above definition. If VPP is not required, the terminal will keep VPP in a stationary state during card use.
(3) TC1
TC1 transmits an N value, N is used to indicate an additional guard time added to the minimum duration, where the minimum duration represents the rising edge of the start bit of two consecutive characters transmitted from the terminal to the IC card as a subsequent information exchange. Time between. N is binary coded at bits b1 to b8 of TC1, and its value as an additional guard time indicates the number of increased etu, and its value may be selected between 0 and 255. N=255 has a special meaning, indicating that the minimum delay time between the rising edges of the start bits of two consecutive characters can be reduced to 12 etu when using the T=0 protocol, and can be reduced to 12 when using the T=1 protocol. 11 etu.
The parameter defined by the value of TC1 is only applicable to the interval between two consecutive characters sent by the terminal to the IC card. It is not applicable to the case where the IC card sends characters to the terminal, nor does it apply to the case where two characters are sent in the opposite direction.
If the TC1 value is between 0x00 and 0xFE, the extra guard time added to the minimum duration between characters is 0 to 254 etu, which means that the additional protection time will be between 12 and 266 etu for subsequent transmissions.
If the TC1 value is 0xFF, the minimum duration of characters for subsequent transmissions is 12 etu when using the T=0 protocol, and 11 etu when using the T=1 protocol.
Basic response: According to the processing of I/O in the chip, the IC card returns any value between 0x00 and 0xFF.
The terminal can receive any TC1 value that satisfies the above conditions.
In the implementation process, we can calculate the minimum duration that a specific chip can receive. It is recommended that TC1 be set to this minimum time. Otherwise, if TC1 is too large, the communication between the terminal and the IC card may be slow, and the transaction time will be extended. If TC1 passes If the chip is small, the data coming from the I/O port cannot be processed in time, which will result in data loss.
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