at83c5122 ATMEL Corporation, at83c5122 Datasheet - Page 66

• Manufacturer Part Number: at83c5122
• Description: At83c5123 C51 Microcontroller With Usb And Smart Card Reader Interfaces
• Manufacturer: ATMEL Corporation

ATR
F and D
Guard Time
Extra Guard Time
Block Guard Time
Work Waiting Time (WWT)
Character Waiting Time (CWT) In T=1 protocol CWT is the interval between the leading edge of 2 consecutive charac-
Block Waiting Time (BWT)
Waiting Time Extention (WTX)
Parity error in T=0 protocol
66
AT8xC5122/23
Answer To Reset. Response from the ICC to a Reset initiated by the Terminal
F = Clock Rate Conversion Factor, D = Bit rate adjustment factor. ETU is defined as :
ETU = F/(D*f) with f = Card Clock frequency. If f is in Hertz, ETU is in second. F and D
are available in the ATR (byte TA1). The default values are F=372, D=1.
The time between 2 leading edges of the start bit of 2 consecutive characters is com-
prised of the character duration (10) plus the guard time. Be aware that the Guard Time
counter and the Guard Time registers in the AT8xC5122/23 consider the time between 2
consecutive characters. So the equation is Guard Time Counter = Guard Time + 10. In
other words, the Guard Time is the number of Stop Bits between 2 characters sent in
the same direction.
ISO IEC 7816-3 and EMV introduce the Extra Guard time to be added to the minimum
Guard Time. Extra Guard Time only apply to consecutive characters sent by the termi-
nal to the ICC. The TC1 byte in the ATR define the number N. For N=0 the character to
character duration is 12 ETUs. For N=254 the character to character duration is 266. For
N=255 (special case) The minimum character to character duration is to be used : 12 for
T=0 protocol and 11 for T=1 protocol.
The time between the leading edges of 2 consecutive characters sent in opposit direc-
tion. ISO IEC 7816-3 and EMV recommend a fixed Block Guard Time of 22 ETUs.
In T=0 protocol WWT is the interval between the leading edge of any character sent by
the ICC, and the leading edge of the previous character sent either by the ICC or the
Terminal. If no character is received by the terminal after WWTmax time, the Terminal
initiates a De-Activation Sequence.
ters sent by the ICC. If the next character is not received by the Terminal after CWTmax
time, the Terminal initiates a De-Activation Sequence.
In T=1 protocol BWT is the interval between the leading edge of the start bit of the last
character sent by the Terminal that gives the right to sent to the ICC, and the leading
edge of the start bit of the first character sent by the ICC. If the first character from the
ICC is not received by the Terminal after BWTmax time, the Terminal initiates a De-Acti-
vation Sequence.
In T=1 protocol the ICC can request a Waiting Time Extension with a S(WTX request)
request. The Terminal should acknowlege it. The Waiting time between the leading
edge of the start bit of the last character sent by the Terminal that gives the right to sent
to the ICC, and the leading edge of the start bit of the first character sent by the ICC will
be BWT*WTX ETUs.
In T=0 protocol, a Terminal (respectively an ICC) detecting a parity error while receiving
a character shall force the Card IO line at 0 starting at 10.5 ETUs, thus reducing the first
Guard bit by half the time. The Terminal (respectively an ICC) shall maintain a 0 for 1
ETU min and 2 ETUs max (according to ISO IEC) or to 2 ETUs (according to EMV). The
ICC (respectively a Terminal) shall monitor the Card IO to detect this error signal then
attempt to repeat the character. According to EMV, following a parity error the character
can be repeated one time, if parity error is detected again this procedure can be
repeated 3 more times. The same character can be transmitted 5 times in total. ISO
4202E–SCR–06/06