Method and apparatus for communicating with a host
First Claim
1. An apparatus for communicating with a host, comprising:
- a card;
an integrated circuit (“
IC”
) affixed to the card, wherein the IC is coupled to a number of contacts, including a first output of the IC being coupled to a first one of the contacts, wherein a resistor of the IC is coupled to the first one of the contacts, and the IC includes voltage conditioning circuitry coupled to a second one of the contacts to receive a voltage supply, wherein the voltage conditioning circuitry is capable of generating an output voltage selectively coupled to the first contact, to selectively pull up the first contact to the output voltage through the resistor, so that attachment of the apparatus is capable of being detected, by the host detecting the output voltage on the first contact.
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Accused Products
Abstract
A method and apparatus is disclosed for communicating with a host. In one embodiment, a smart card has an IC with voltage conditioning circuitry and a pull-up resistor. The smart card, when inserted in a smart card reader coupled to the host, is capable of signaling the host over a bus using the pull-up resistor selectively coupled to a voltage output of the voltage conditioning circuitry and a first output of the smart card. The voltage conditioning circuitry output is selectively coupled to the first output through the resistor, responsive to the device being powered by the bus but not transmitting. This tends to pull up the first output to the voltage level of the voltage source, which makes the smart card capable of being properly detected by the host upon the bus being driven by a host. Selectively disconnecting the pull-up resistor while the smart card is transmitting or receiving results in a more balanced differential output signal. Since the pull-up resistor and voltage conditioning circuitry supplying the proper voltage to the pull-up resistor are an integrated part of the IC, no separate contact is required to supply voltage to the resistor. This permits the smart card to be compatible with the contact configuration of certain existing smart cards, and eliminates a need for the pull-up resistor or voltage conditioning circuitry to be included in the smart card reader.
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Citations
27 Claims
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1. An apparatus for communicating with a host, comprising:
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a card;
an integrated circuit (“
IC”
) affixed to the card, wherein the IC is coupled to a number of contacts, including a first output of the IC being coupled to a first one of the contacts, wherein a resistor of the IC is coupled to the first one of the contacts, and the IC includes voltage conditioning circuitry coupled to a second one of the contacts to receive a voltage supply, wherein the voltage conditioning circuitry is capable of generating an output voltage selectively coupled to the first contact, to selectively pull up the first contact to the output voltage through the resistor, so that attachment of the apparatus is capable of being detected, by the host detecting the output voltage on the first contact. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for communicating with a host, comprising:
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a card;
an integrated circuit (“
IC”
) affixed to the card, wherein the IC is coupled to a number of contacts, including a first output of the IC being coupled to a first one of the contacts, wherein a resistor of the IC is coupled to the first one of the contacts, and the IC includes voltage conditioning circuitry coupled to a second one of the contacts for receiving a voltage supply from the host, and wherein the voltage conditioning circuitry has an output coupled to the resistor, so that attachment of the apparatus is capable of being detected by the host;
wherein a switch on the IC is coupled in a series circuit, the series circuit including the voltage conditioning circuitry output, the resistor and the first contact, and wherein the IC comprises;
control circuitry for selectively pulling up or not pulling up the first contact to the output of the voltage conditioning circuitry through the resistor and the switch; and
wherein the apparatus further comprises;
a reader, having a connector for connection to a port, and a passthrough connector for receiving the card and coupling to the contacts, wherein electrical components of the reader consist solely of passive components. - View Dependent Claims (11, 12, 13, 15, 16, 17, 18, 19)
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14. A method for communicating with a host, comprising the steps of:
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a) receiving a voltage at a first voltage level, on a first contact of a number of contacts coupled to an integrated circuit (“
IC”
), wherein the voltage is conditioned, by voltage conditioning circuitry of the IC to generate an output voltage at a second voltage level; and
b) pulling up the second contact to the second voltage level, through a resistor of the IC coupled to the voltage conditioning circuitry output voltage and the second contact, so that attachment of an apparatus that includes the IC is capable of being detected by the host.
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20. An apparatus for communicating with a host comprising:
an integrated circuit (“
IC”
) coupled to a first contact and having a first driver and a first receiver, so that the IC is capable of generating a first output signal to and receiving a first input signal from the first contact for communicating with a host, wherein the IC has a voltage reference, an integrated resistor and a switch coupled in series with the first contact, and the switch is capable of coupling the first voltage reference to the first contact responsive to the apparatus being powered, in order to signal attachment to the host.- View Dependent Claims (21, 22, 23, 24, 26, 27)
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25. A method for communicating between an apparatus and a host comprising the steps of:
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coupling a voltage reference by a switch through a resistor in an integrated circuit (“
IC”
) of the apparatus to a first contact coupled to the IC, so that the host can detect attachment of the apparatus, wherein the coupling is responsive to the IC being powered;
asserting first and second output signals by the IC, for transmitting to the host, the first signal being asserted on the first contact and the second signal being asserted on a second contact coupled to the IC; and
decoupling the voltage reference of the IC from the first contact, by the switch in the IC, wherein the decoupling is responsive to the IC transmitting or receiving.
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Specification