Electrical computers and digital processing systems: support – Clock – pulse – or timing signal generation or analysis
Reexamination Certificate
2000-07-13
2002-01-29
Butler, Dennis M. (Department: 2182)
Electrical computers and digital processing systems: support
Clock, pulse, or timing signal generation or analysis
C713S503000
Reexamination Certificate
active
06343364
ABSTRACT:
BACKGROUND
The invention relates generally to Integrated Circuit (IC) cards or smart cards used in processing transactions involving goods and services. Smart cards are plastic cards having microprocessor and memory circuits attached to the front or back side that connect to electrical contacts located on a front side of the card. The circuits are activated and data accessed from the card by inserting the card into a reader device that makes connections to the electrical contacts. More particularly, the invention relates to a device and method for connecting a smart card to smart card reader devices that have different interface characteristics. Furthermore, the invention relates to a novel method and device for generating an internal clock signal that is synchronized by an externally applied signal.
Smart cards are a class of data cards. Data cards used in processing transactions are either passive or active in nature. Passive data cards include traditional credit, debit and ATM cards that make use of stored data on a magnetic strip on the back of the card. When a transaction is processed using a passive data card, transaction verification is generally required via a reader device connected to a remote computer over a telephone network. During a transaction, data may be written and read from the magnetic strip. Active data cards or smart cards make use of processor and memory circuits embedded on the card that are activated when the card is connected to a reader device. Since smart cards may contain the intelligence required to complete a transaction, the transaction may be completed locally without resorting to a telephone connection to a remote transaction verification facility. In addition to storing data related to the owner's account such as identification number and account balance, the circuits also contain encryption for security purposes. Smart cards are used in many applications, including Subscriber Identification Module (SIM) in Global System for Mobile (GSM) telephones, TV satellite receivers, banking, health care programs, parking and highway toll payment, etc. Smart cards are expected to find increasingly wider application, eventually replacing magnetic strip type data cards.
The basic smart card standard is the International Standard ISO 7816, which provides detailed requirements for the physical, electrical, mechanical, and application programming interface for IC cards with contacts. In particular, International Standard ISO 7816-1 Physical Characteristics, International Standard 7816-2 Dimension and Location of the Contacts, and International Standard ISO 7816-3 Electronic Signals and Transmission Protocols are incorporated herein by reference. This standard provides for a serial interface connection to the smart card. In a great majority of cases, these cards are used in a reader connected to a computer. The reader contains electronic circuits that enable communication between the card and the computer. The reader is connected to a computer by means of a serial or parallel port on the computer.
The Universal Serial Bus (USB) has recently become firmly established and has gained wide acceptance in the Personal Computer (PC) marketplace. The USB was developed in response to a need for a standard interface that extends the concept of “plug and play” to devices external to a PC, and enables users to install and remove external peripheral devices without having to open the PC case or to remove power from the PC. The USB provides a low-cost, half-duplex serial interface that is easy to use and readily expandable. The USB also supplies up to 500 mA of current at 5 volts to interconnected devices. The USB is currently defined by the Universal Serial Bus Specification written and controlled by USB Implementers Forum, Inc., a non-profit corporation founded by the group of companies that developed the USB Specification. In particular, Chapter 5 USB Data Flow Model, Chapter 7 Electrical, and Chapter 8 Protocol Layer of Universal Serial Bus Specification are incorporated herein by reference. The increasingly widespread use of the USB in computers has led smart card reader manufacturers to develop USB interfaces for connection of their products to computers to complement the existing serial and parallel interfaces. However, because of the differences between the serial interface defined by ISO 7816 and the serial interface defined by the USB specification, smart cards have not been directly compatible with the USB specification. And different card reader configurations have been required due to incompatibility constraints between the various computer interface standards.
The USB Specification version 1.1 defines two theoretical data transfer speed rates. A low-speed at 1.5 megabits per second and a full-speed at 12 megabits per second are provided. A high-speed data transfer rate greater than 480 megabits per second is anticipated for high data throughput application such as video or mass storage. The present invention preferably makes use of the low-speed implementation of packet transactions. When taking into account the different overheads and protocols, the effective USB low speed data rate varies between 50 kilobits per second and 400 kilobits per second depending of the available bandwidth. This data rate outperforms the data rate achieved by use of the ISO 7816 Standard. The higher data rate makes possible a reduction in smart card customizing time, and increases possible applications.
A hub provides USB attachment points. Attachment points are referred to as ports. The host has an embedded hub called the root hub that provides one or more attachment points. A USB device provides additional functionality to the host and is connected to one of the ports of any hub. The host, embedded in a PC, masters the USB. Each device reacts in a master-slave relationship. Every transaction starts by a host request. The USB does not have any dedicated clock signal lines. Each hub and each USB device has its own reference clock. The hub supports both low speed and full speed data signaling rates. The hub clock generator uses a crystal to provide the ±0.25% timing accuracy required for full speed transactions. A low speed device clock generator tolerance of ±1.5% is compatible with the use of a cheaper resonator. All USB transactions, downstream and upstream, begin with a Synchronization Pattern (SP) signal that allows the device and the hub clocks to lock in phase. Because of the lack of space and limited contact pin availability, neither a crystal nor a resonator is practical solutions for clocking USB circuitry on a smart card.
For the foregoing reasons, there is a need to provide a smart card with a capability for local clock generation using the SP and Packet Identifier (PID) signals, without the use of crystals, resonators or other components external to an integrated circuit. There is a further need to connect a smart card to an USB port without the need for any interposing electronic circuitry.
SUMMARY
The present invention is directed towards a device and method for providing a smart card with the capability of supporting the serial interface defined by the USB specification without adding any additional complexity to the smart card or reader.
The present invention is also directed towards a device and method for generating a USB device clock signal synchronized with a USB signal, without the need for a crystal or resonator. Furthermore, the present invention is also directed towards a device and method for connecting a smart card to a USB port with a simple connector without the need for any interposing electronic circuitry.
The present invention relates to a physical link between a USB port and a smart card. It describes a solution to generate a USB low speed device clock without using any external components.
When a hub sends information to an Integrated Circuit Module (ICM) on a smart card, the ICM is in a reception mode. This is referred to as a downstream transaction. When the ICM sends information to the hub, the hub is in reception mode. This
Leydier Robert A.
Pomet Alain C.
Butler Dennis M.
Schlumberger Malco Inc.
Taylor Russell & Russell P.C.
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