WO2001099039A1 - Method for selecting an operating mode for a chip card and card therefor - Google Patents

Abstract

The invention concerns a method for selecting an operating mode for a smart card (10), said card having an assembly (E) of electronic microcircuits communicating with outside through at least a standardised contact interface (l1) whereof some are dedicated to the input of specific electrical signals, in particular an electric supply voltage signal (VCC), a sequencing or clock signal (CLK) and a reset signal (RST), said card being also capable of having a contact-free interface of acoustic and/or radiofrequency type (13). The invention is characterised in that it consists in internally selecting the operating mode of the card with its associated interface corresponding to the environment wherein the card is placed, using at least one of said signals, in the present case the reset signal (RST).

Description

 METHOD FOR SELECTING A MODE OF OPERATION OF A CHIP CARD, AND CARD FOR THE IMPLEMENTATION OF THE

PROCESS

The subject of the invention is a method for selecting an operating mode of a smart card, this card having a set of electronic microcircuits which communicate with the outside by at least one standardized communication interface with contacts.

Generally, the contact communication interface is used in a card reader environment with a synchronous or asynchronous operating mode depending on the type of reader. When this interface meets the ISO 7816 standard, certain contacts are dedicated to specific electrical signals.

Furthermore, portable objects and / or smart cards are known which are equipped with a communication interface of acoustic or radiofrequency type.

The invention applies to smart cards having several operating modes, and the aim is in particular to select the operating mode which corresponds to the environment in which the card is used, without modifying or altering the mode operating mode selected.

To this end, the invention proposes a method for selecting an operating mode of a smart card, said card having a set of electronic microcircuits which communicate with the outside by at least one standardized interface with contacts some of which are dedicated to the input of determined electrical signals, in particular of a supply voltage signal, of a sequencing or clock signal and of a reset signal, said card possibly also having a contactless interface for acoustic type and / or radio frequency type, characterized in that it consists in internally selecting the operating mode of the card with its associated interface corresponding to the environment in which is placed the card, using at least one of the above electrical signals, in this case the reset signal.

According to a preferred version, the method consists in using in combination two of the signals of the standard interface with contacts, namely the supply voltage signal and the reset signal.

More specifically, the method consists in testing the presence or absence of the supply voltage signal to determine first of all whether the card is placed in an environment with or without contact card reader. In a contact reader environment, the method consists in selecting the asynchronous operating mode if the reset signal is at a low level and the synchronous operating mode if it is at a high level.

In an environment outside of the contact reader and when the card also includes an acoustic type interface, the method consists in selecting this interface if the reset signal is at a low level, knowing that the method also consists in keeping this signal at a high level by means of an internal "pull up" circuit, and to force this signal to a low level to activate the acoustic operating mode by means of a tactile key which can advantageously be constituted by the reset contact and the ground contact of the standard contact interface.

When the card includes an interface of radio frequency type in addition to the acoustic interface or not, the method consists in selecting this interface as a priority, and in validating this operating mode only as a result of a voluntary action by the user of the card, this action consisting in activating the aforementioned touch key for example.

According to an important advantage of the invention, the selection of the operating mode of the card is based on the combination of the predetermined signal levels on the standardized communication interface with contacts, which makes it possible to completely overcome the problems. that could arise from the subsequent adaptation of the card to new standards.

According to another advantage of the invention, the microcircuits of the card remain the same whatever the interfaces which will be mounted on the card.

Other advantages, characteristics and details of the invention will emerge from the additional description which follows with reference to the appended drawings, given solely by way of example and in which:

- Figure 1 is a schematic view in the form of a block diagram of a first embodiment of a smart card having a standardized communication interface with contacts and capable of operating in a synchronous or asynchronous operating mode in a environment with contact card reader,

FIG. 2 is a time diagram for explaining the selection of the asynchronous operating mode for the card illustrated in FIG. 1,

- Figure 3 is a timing diagram to explain the selection of the synchronous operating mode for the card illustrated in Figure 1, and - Figure 4 is a schematic view in the form of a block diagram of a second mode of realization of a smart card having in addition a contactless interface of acoustic and / or radiofrequency type.

The smart card 10 illustrated in FIG. 1 comprises a set E of electronic microcircuits and at least one standardized communication interface 11 with contacts. According to ISO 7816, these contacts are eight in number and some of them are dedicated to the input of determined signals, in particular a VCC signal or supply voltage, a sequencing signal or d CLK and a reset signal RST. The interface 11 also includes a GND ground contact and an I / O input / output contact. This smart card 10 is intended for use in an environment with a contact card reader with synchronous or asynchronous operation depending on the type of reader.

The selection of the operating mode is ensured by a logic L which is in particular connected to the contacts dedicated to the signals VCC, CLK and RST on the one hand, and to the set E of electronic microcircuits on the other hand.

The selection of the asynchronous operating mode is described below with reference to FIG. 2. Suppose that the time to corresponds to the time when the card is physically connected to the contact reader.

Then, the power-up process of the card 10 is started:

- at time t1, after having forced the reset signal RST to a low level, the reader forces the signal RST to a low level and raises the signal VCC to the high level which corresponds to the input of a voltage to supply all of the electronic microcircuits of the card,

- at time t2, the reader sends a clock signal CLK, greater than 1 MHz in a standard operating mode, - at time t3, the reader raises the signal RST to level 1, and

- at time t4, the card responds according to an asynchronous operating mode using the I / O contact of the interface 11.

Thus, if the selection logic L detects the presence of the signal VCC (VCC = "1") and, on arrival of the clock signal CLK, samples the signal RST at a low level (RST = "0") on a rising edge of the clock signal between instants t2 and t3, it informs the assembly E of the electronic microcircuits that the operating mode is asynchronous. .

The asynchronous operating mode will then be maintained until the card is physically disconnected from the reader, that is to say as long as all of the electronic microcircuits are energized.

The selection of the synchronous operating mode is described below with reference to FIG. 3. Suppose also that the time to corresponds to the instant when the card is physically connected to the reader.

Then:

- at time t1, the reader raises the signal VCC and the signal RST to the high level, - at time t2, the reader sends a clock signal CLK, of the order of 100 KHz for example, and

- at time t3, the card responds according to a determined communication protocol and according to a synchronous operating mode using the I / O contact of the interface 11. Thus, if the selection logic L detects the presence of the VCC signal (VCC = "1") and, on arrival of the clock signal CLK, samples the signal RST at a high level (RST = "1") on a rising edge of the clock signal between times t2 and t3, it informs the set E of the electronic microcircuits that the operating mode is synchronous.

Furthermore, the card can switch to asynchronous operating mode at any time and remain there if the selection logic L samples the RST signal at a low level.

The smart card 10 can be equipped with an acoustic interface 12, known per se, to also be used in an environment outside the card reader, this interface 12 being connected to the selection logic L.

Such a smart card 10 is schematically illustrated in FIG. 4, knowing that the operation of the acoustic interface 12 requires an internal power supply by means of a battery P. In addition, the smart card 10 also includes a circuit 12 or "pull up" circuit which has the function of maintaining the RST signal at a high level, as long as the acoustic interface 12 is not activated or that the card 10 is not inserted in a contact card reader slot. The activation of the acoustic interface 12 is done by the user by means of a tactile key T which is advantageously constituted by the reset contact RST and the ground contact GND of the interface 11. A finger of the user on the RST and GND contacts has the effect of forcing the RST signal to a low level. Thus, after activation of the touch key T, if the selection logic L detects the absence of the VCC signal (VCC = "0") and a low level for the RST signal (RST - "0"), it informs the set E of electronic microcircuits that the operating mode is acoustic and selects the interface 12. Thus, when the smart card 10 comprises several communication interfaces, the logic L selects the operating mode of the card as well as the associated interface .

The smart card 10 can be equipped with an interface 13 of radio frequency type, known per se, which is illustrated in FIG. 4, knowing that the acoustic interface 12 may or may not be present. The radio frequency interface 13 is connected to the selection logic L and notably incorporates an antenna capable of detecting the presence of a determined electromagnetic field, knowing that this field can be radiated by a contactless card reader. The interface 13 is connected to the set E of electronic microcircuits by the selection logic L. When this electromagnetic field is detected by the card, the selection logic L selects in priority the radio frequency operating mode, which corresponds to the absence of the VCC signal (VCC = "0") and at a high level for the RST signal (RST = "1").

Indeed, if the smart card 10 is equipped with an acoustic interface 12, the circuit 12 or “pull up” circuit is supplied by the battery P for keep the RST signal high. On the other hand, if the smart card 10 is not equipped with an acoustic interface, it is the energy of the electromagnetic field which is used to power the circuit 12.

However, the detection of the electromagnetic field does not imply that the user is at this instant eager to use his card. Under these conditions, the validation of the radio frequency operating mode will be conditioned by a voluntary action by the user, namely the activation of the touch key T for example.

Claims

1. Method for selecting an operating mode of a smart card (10), said card having a set (E) of electronic microcircuits which communicate with the outside by at least one standardized interface with contacts (11) some of which are dedicated to the input of specific electrical signals, in particular an electrical supply voltage signal (VCC), a sequencing or clock signal (CLK) and a reset signal (RST ), said card possibly also having a contactless interface of acoustic type (12) and / or of radio frequency type (13), characterized in that it consists in internally selecting the operating mode of the card with its corresponding associated interface to the environment in which the card is placed, using at least one of the aforementioned electrical signals, in this case the reset signal (RST). 2. Method according to claim 1, characterized in that it consists in using in combination two of said determined electrical signals, in this case the supply voltage signal (VCC) and the reset signal (RST). 3. Method according to claim 2, characterized in that it consists in internally testing the presence or absence of the electrical supply voltage signal (VCC) on the contact interface (11) to determine whether the card is placed in an environment with or without contact card reader. 4. Method according to claim 3, characterized in that it consists, when the card is in an environment with contact reader, internally selecting a synchronous or asynchronous operating mode according to the level of the reset signal (RST ). 5. Method according to claim 4, characterized in that it consists in internally selecting an asynchronous operating mode by sampling the reset signal (RST) at least once at a low level. 6. Method according to claim 4, characterized in that it consists in internally selecting a synchronous operating mode by sampling the reset signal (RST) at a high level. 7. Method according to claim 3, characterized in that it consists, when the card is placed in an environment outside of contact reader and equipped with an acoustic interface, in internally selecting this interface when the reset signal ( RST) is at a low level. 8. Method according to claim 7, characterized in that it consists in maintaining the reset signal (RST) at a high level, and in forcing said signal at a low level by means of a tactile key to activate the acoustic operating mode. 9. Method according to claim 8, characterized in that it consists in using the reset contact (RST) and the earth contact (GND) of the standard interface with contacts (11) as a touch key. 10. Method according to any one of claims 3 to 9, characterized in that it consists, when the card is placed in an environment outside of the contact reader and equipped with an interface of radio frequency type (13), in selecting said interface as a priority when the card is placed in an electromagnetic field determined, and then to validate the corresponding operating mode following a voluntary action by the user of the card. 11. Method according to claim 10, characterized in that the voluntary action of the user consists in activating a tactile key (T) which is constituted by the contact of the reset signal (RST) of the standardized interface to contacts (11). 12. Chip card for implementing the method as defined by any one of the preceding claims, said card comprising a set (E) of electronic microcircuits and at least one standardized communication interface with contacts (11) used in a contact card reader environment according to a mode of synchronous or asynchronous operation, characterized in that it also comprises a selection logic L for selecting the operating mode of the card and the associated interface from the respective levels of the voltage supply signal (VCC) and of the signal reset (RST) to which two contacts of the standard interface with contacts are dedicated. 13. Chip card according to claim 12, characterized in that it also comprises an acoustic type interface (12), a "pull up" circuit (12) for forcing the reset signal (RST) to a high level, and a touch key (T) consisting of the contact of the standard interface with contacts which is dedicated to the reset signal (RST) to validate the acoustic operating mode. 14. Smart card according to claim 12 or 13, characterized in that it also comprises an interface of radio frequency type (13).