at83c26 ATMEL Corporation, at83c26 Datasheet - Page 19

• Manufacturer Part Number: at83c26
• Description: Multiple Smart Card Reader Interface With Power Management
• Manufacturer: ATMEL Corporation

Card Presence Detection
Card presence detection for SC1 interface
Card Presence Detection for SC2 interface
7511D–SCR–02/07
VSS
VSS
Card
Presence
Contact
VCC
Card
Presence
Contact
VCC
External
Pull-up
Resistor
External
Pull-up
Resistor
VSS
VSS
External
Pull-down
Resistor
VCC
External
Pull-down
Resistor
VCC
Card
Presence
Contact
The card presence signal is connected on the CPRES1 pin. The polarity of card presence con-
tact is selected with the CARDDET1 bit (see SC1_CFG1 register). A programmable filtering is
controlled with the CDS1[2-0] bits.
The internal pull-up on the CPRES1 pin can be disconnected in order to reduce the consump-
tion. An external pull-up must be connected to Vcc. The PULLUP1 bit (see SC1_CFG1 register)
controls this feature.
If the card presence contact is connected to Vcc, the internal pull-up must be disconnected and
an external pull-down must be connected to the CPRES1 pin.
An interrupt can be generated if a card is inserted or extracted (see Section “Interrupts”,
page 30).
Card
Presence
Contact
CPRES1
CPRES2
INT
INT
VCC
VCC
Figure 12. SC1 presence Input
Figure 13. SC2 presence Input
VCC
VCC
INT_PULLUP Bit
INT_PULLUP Bit
= 1 Closed
= 0 Open
= 1 Closed
= 0 Open
PULLUP1 Bit
PULLUP2 Bit
= 1 Closed
= 0 Open
= 1 Closed
= 0 Open
= 0 Closed
= 1 Open
ITDIS2 Bit
CARDDET1 Bit
CARDDET2 Bit
= 1 No Card if CPRES1 = 0
= 0 No Card if CPRES1 = 1
= 1 No Card if CPRES2 = 0
= 0 No Card if CPRES2 = 1
FILTERING
FILTERING
CDS1[2-0]
CDS2[2-0]
AT83C26
= 1 Card Inserted
= 0 No Card
= 1 Card Inserted
= 0 No Card
CARDIN1 bit
CARDIN2 bit
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