Rainbow Electronics AT83C26 - Manual (Page 46)

46
7511B–SCR–10/05
AT83C26
Reset value = 0x XX10 1010
Table 25. SC2_CFG1 ()
7 6 5 4 3 2 1 0
X X SC2_FULL CARDDET2 PULLUP2 CDS22 CDS21 CDS20
Bit Number Bit Mnemonic Description
7-6 X
5 SC2_FULL
Set this bit to activate full IO interface on Smart card 2:
• CIO3/CC42 is CC42 and CRST3/CC82 is CC82.
• Interface 3 LDO is disabled.
• CARDCK3 is reset and CKSTOP3 to stop CCLK on SC3.
• ITDIS3 is set to disable interrupts from SC3.
CVCC2 and CVCC3 shall be connected externally and SC2_FULL must be set before activating the LDO.
Clear this bit only to use only CIO on interface 2:
• CIO3/CC42 is CIO3 and CRST3/CC82 is CRST3.
• Interface 3 can then be used independently to connect a SIM/SAM card.
The reset value is 1.
4 CARDDET2
Card Presence Detection Polarity - Interface 2
Set this bit to indicate the card presence detector is closed when no card is inserted (CPRES2 is low).
Clear this bit to indicate the card presence detector is open when no card is inserted (CPRES2 is high).
The reset value is 0.
3 PULLUP2
Pull-up Enable
Set this bit to enable the internal pull-up on the CPRES2 pin. This allows to minimize the number of external
components.
Clear this bit to disable the internal pull-up and minimize the power consumption when the card detection contact is
on. Then an external pull-up must be connected to V
CC
(typically a 1 M Ω resistor).
The reset value is 1.
2-0 CDS2[2:0]
Card Detection filtering - Interface 2
CPRES2 is sampled by the master clock provided on CLK input. A change on CPRES2 is detected after:
CDS2[2-0] = 0: no sample (1)
CDS2[2-0] = 1: 4 identical samples
CDS2 [2-0] = 2: 8 identical samples (reset value)
CDS2[2-0] = 3: 16 identical samples
CDS2[2-0] = 4: 32 identical samples
CDS2[2-0] = 5: 64 identical samples
CDS2[2-0] = 6: 128 identical samples
CDS2[2-0] = 7: 256 identical samples
Note: 1. When CDS2[2-0] = 0 and ITDIS2 = 0, a card insertion (even if CLK is stopped) puts a low level on
INT pin. This can be used to wake up the external micro controller and restart CLK when a card is
inserted in the AT83C24.