Rainbow Electronics AT89C5122 - Manual (Page 84)

84
AT8xC5122/23
4202E–SCR–06/06
Reset Value = X000 1000b
Reset Value = 0000 0000b
Table 49. Smart Card Selection Register - SCSR (S:ABh)
7 6 5 4 3 2 1 0
- BGTEN - CREPSEL ALTKPS1 ALTKPS0 SCCLK1 SCRS
Bit Number Bit Mnemonic Description
7 -
Reserved
The value read from this bit is indeterminate. Do not change this bit.
6 BGTEN
Block Guard Time Enable
Set this bit to select the minimum interval between the leading edge of the start bits of the last character
received from the ICC and the first character sent by the Terminal. The transfer of GT[8-0] value to the BGT
counter is done on the rising edge of the BGTEN.
Clear this bit to suppress the minimum time between reception and transmission.
5 -
Reserved
The value read from this bit is indeterminate. Do not change this bit.
4 CREPSEL
Character repetition selection
Clear this bit to select 5 times transmission (1 original + 4 repetitions) before parity error indication (conform to
EMV)
Set this bit to select 4 times transmission (1 original + 3 repetitions) before parity error indication
3-2 ALTKPS1:0
Alternate Card Clock prescaler factor
00 ALTKPS = 0: prescaler factor equals 1
01 ALTKPS = 1: prescaler factor equals 2
10 ALTKPS = 2: prescaler factor equals 4 (reset value)
11 ALTKPS = 3: prescaler factor equals 8
1 SCCLK1
Alternate card clock selection
Set to select the prescaled PR3 clock for CCLK1 (P1.7) pin
Clear to select P1.7 port bit
0 SCRS
Smart Card Register Selection
The SCRS bit selects which set of the SCIB registers is accessed.
Table 50. Smart Card Transmit / Receive Buffer - SCIBUF (S:AA)
7 6 5 4 3 2 1 0
- - - - - - - -
Bit Number Bit Mnemonic Description
- -
Smart Card Transmit / Receive Buffer
- A new byte can be written in the buffer to be transmitted on the I/O pin when SCTBE bit is set.
The bits are sorted and copied on the I/O pin versus the active convention.
- A new byte received from I/O pin is ready to be read when SCRI bit is set.
The bits are sorted versus the active convention.