DataCard CP60, Service Manual

Page: 42 / 212

2-30 Theory of Operation
HID Corporation and is shown here for educational purposes. The printed image
on the card is an artist’s rendering.
Contact Smart Cards
A contact smart card needs to connect to an external interface to provide the
processor with power and set up serial communication. The eight terminal
contacts are described in the table below. (Note that two contacts are reserved for
future use.)
There are two classes of contact smart cards: Type-A cards operate at 5 volts, and
Type-B cards operate at 3 volts.
Smart Card Contacts
No. Name Purpose No. Name Purpose
C1 VCC Supply voltage (3 or 5 V) C5 GND Ground
C2 RST Resets the processor C6 VPP Variable voltage for programming
C3 CLK Provides the timing (clock) signal C7 I/O Data line
C4 N/A Reserved for future use C8 N/A Reserved for future use
Initiating Communication
When the card is inserted into a reader, it needs to be initialized and
communication protocols defined. Note that steps 1 through 6 all occur while the
card is forced to remain in a reset state (no activity).
1.
The card reader senses that the card is in position under the contacts. In most
cases, this is a mechanical switch that detects the presence of a card (any type
of card).
2.
The Reset line (C2) is held low. (The active-low reset forces the card to remain
in the reset state until released.)
3.
Power is applied to the Vcc and Gnd contacts.
• A Type-A reader will apply 5 volts to the card. (Type-B cards must accept
the overvoltage, but are not allowed to respond.)
• A Type-B reader will apply 3 volts to the card.
• A Type-A/B reader will first apply 3 volts to the card. If no response is
received, it removes power, waits, and reapplies power at 5 volts.
4.
The I/O line is held in the Receive mode (high impedance).
5.
If the card is a Type-A card, the programming voltage (Vpp) is placed in the
pause value, which is equal to Vcc.