NFC device detection

Abstract

NFC Device Detection This description relates to a method comprising: - activating a detection signal by a field detector (203) of a near-field communication circuit, the near-field communication circuit being placed in a first state in which it is configured to recognize one or more communications transmitted according to a first standard; - triggering a first counter (205_1) of the circuit in response to the activation of the detection signal; and - when the first counter reaches a first threshold value, the near-field communication circuit transitioning to a second state in which it is configured to recognize one or more communications transmitted according to a second standard, the near-field communication circuit being configured to ignore communications transmitted according to the second standard when it is in the first state. Figure for the abstract: Fig. 2

Description

Title of the invention: NFC device detection technical field

[0001] This description relates generally to electronic devices incorporating a near-field communication (NFC) circuit and methods for detecting near-field communication. Prior art

[0002] Electromagnetic transponder communication systems are becoming increasingly common, particularly since the development of near-field communication technologies. These systems typically exploit a radio-frequency electromagnetic field generated by an NFC device (terminal or reader) to detect and then communicate with another NFC device (card) located within range.

[0003] However, there are different standards for field generation by a device in reader mode. In particular, modulation characteristics, coding, and frame start patterns vary according to the standards. A device in card mode is generally configured to detect reader devices using different standards. However, it is common for a device in card mode to miss a request from a reader device. Indeed, since the frame start patterns have different durations depending on the standards followed, a device in card mode may miss a request transmitted by a device transmitting according to one standard because it expects the latter to transmit in a second standard.

[0004] There is a need to improve the detection of NFC devices. Summary of the invention

[0005] One embodiment provides a method comprising: - the activation of a detection signal by a field detector of a near field communication circuit, the near field communication circuit being placed in a first state in which it is configured to recognize one or more communications emitted according to a first standard; - the triggering of a first counter in the circuit in response to the activation of the detection signal; and - when the first counter reaches a first threshold value, the near field communication circuit switches to a second state in which it is configured to recognize one or more communications emitted according to a second standard, the near field communication circuit being configured to ignore communications emitted according to the second standard when it is in the first state.

[0006] According to one embodiment, the first counter is triggered during a first rising edge of the detection signal emitted at the start of the field detector.

[0007] According to one embodiment, the above process further comprises, following the transition of the near-field communication circuit to the second state: - the triggering of a second counter; and - when the second counter reaches a second threshold value, the circuit switches to the first state or to a third state in which the circuit is configured to ignore communications issued according to the second standard.

[0008] According to one embodiment, the second counter is triggered during a first falling edge of the detection signal emitted by the field detector.

[0009] According to one embodiment, the second counter is stopped and reset at each rising edge of the detection signal emitted by the field detector.

[0010] According to one embodiment, the communications emitted according to the first standard are NFC-A type near field communications.

[0011] According to one embodiment, the communications emitted according to the second standard are NFC-B type near field communications.

[0012] According to one embodiment, the near field communication circuit is further configured to, when placed in the first state, detect NFC-F type near field communications.

[0013] According to one embodiment, the near field communication circuit is configured to emulate a plurality of cards.

[0014] One embodiment provides a circuit comprising: - a field detector, the circuit being configured to be placed in a first state upon activation of a detection signal generated by the field detector, the circuit being further configured to, when placed in the first state, detect one or more communications transmitted according to a first standard; and - a first counter configured to be triggered following the activation of the detection signal; the circuit being further configured to be placed in a second state when the first counter reaches a first threshold value, the circuit being configured to, when placed in the second state, detect one or more communications issued according to a second standard, the circuit being configured to ignore communications issued according to the second standard when placed in the first state.

[0015] According to one embodiment, the above circuit is configured to trigger the first counter on a first rising edge of the detection signal emitted at the start of the field detector.

[0016] According to one embodiment, the above circuit is further configured so that, when the first counter, or when a second counter, reaches a second threshold value, it is placed in the first state or in a third state in which the circuit is configured to ignore communications emitted according to the second standard.

[0017] According to one embodiment, the above circuit is further configured to trigger the second counter on a first falling edge of the detection signal emitted by the field detector and to stop and reset the second counter on each rising edge of the signal emitted by the field detector.

[0018] According to one embodiment, communications emitted according to the first standard are NFC-A type near field communications and communications emitted according to the second standard are NFC-B type near field communications.

[0019] According to one embodiment, the above circuit is configured to emulate a plurality of cards. Brief description of the drawings

[0020] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0021] Fig. 1 represents, in a very schematic way and in block form, an example of a near field communication system;

[0022] [Fig.2] represents, schematically and in block form, an example of the realization of a near field communication device;

[0023] [Fig. 3A] is a chronogram illustrating an example of a frame start pattern, emitted by a reading device;

[0024] [Fig.3B] is a chronogram illustrating another example of a frame start pattern, emitted by a reading device;

[0025] [Fig.4] is a timing diagram illustrating an example in which a detection of a reading device is missed;

[0026] [Fig.5] is a timing diagram illustrating interference in a signal, emitted by a reading device, interfering in a detection process;

[0027] [Fig.6] is a flowchart representing steps in a reading device detection process, according to an embodiment of the present description;

[0028] [Fig. 7A] is a timing diagram illustrating an example of the detection of a reading device, according to an embodiment of the present description; and

[0029] [Fig.7B] is a timing diagram illustrating an example of a detection of a reading device, according to another embodiment of the present description. Description of the implementation methods

[0030] The same elements have been designated by the same reference numerals in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0031] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed. In particular, the generation of radio frequency signals and their interpretation have not been detailed, as the described embodiments and implementation methods are compatible with conventional techniques for generating and interpreting these signals.

[0032] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") together, this means that these two elements can be connected or linked through one or more other elements.

[0033] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0034] Unless otherwise specified, the expressions "approximately", "roughly", and "on the order of" mean to within 10% or 10°, preferably to within 5% or 5°.

[0035] Fig. 1 represents, in a very schematic way and in block form, an example of a 100 near field communication system of the type to which, by way of example, the described embodiments and implementation methods apply.

[0036] The system 100 comprises a first electronic device 102 and a second electronic device 104. The electronic devices 100 and 102 each comprise, for example, one or more Near-Field Communication (NFC) circuits. By way of example, device 102 is configured to operate in so-called card mode, corresponding, for example, to a card emulation mode for one or more cards, while device 104 is configured to operate in so-called reader mode.

[0037] By way of example, the device 102 incorporates a near-field communication circuit 106 comprising at least one electronic element or circuit for generating and detecting a radio frequency signal using an antenna (not shown), for example, modulation or demodulation circuits. By way of example, the device 104 incorporates a near-field communication circuit 108 comprising at least one electronic element or circuit for transmitting and detecting a radio frequency signal using an antenna (not shown), for example modulation or demodulation circuits.

[0038] When communication is established between devices 102 and 104, the radio frequency signal generated by device 104 is detected by device 102 when the latter is within range. Coupling then occurs between two oscillating circuits, in this case, the antenna of device 102 and the antenna of device 104. In the case where device 102 is passive, such as a payment card, the change in charge of device 102 is used, for example, to communicate from card 102 to reader device 104. When device 102 is active, for example, a telephone, a smartwatch, etc., an active charge modulation technique, known to those skilled in the art, is used.In particular, active charge modulation is implemented by device 102 by emitting its own field, synchronized in frequency and phase with the signal emitted by reader 104 and modulated to reproduce a passive charge modulation signal. These charge variation techniques allow, for example, a reduction in the size of the antenna of device 102.

[0039] In practice, to establish communication, device 104 periodically transmits interrogation frames described according to the various near-field communication standards, for example, ISO 14443-A, also known as NFC-A, ISO 14443-B, also known as NFC-B, and FeliCa, also known as NFC-F. When device 102 detects and decodes an interrogation frame transmitted by device 104, it sends a response also described by the communication standards. Device 104 then decodes this response and continues the protocol until the card is selected. An application then takes over, and application frames, known as APDUs (Application Protocol Data Units), are exchanged until the card is deselected, also described in the communication standard. The reader device 104 then cuts off its signal.

[0040] The NFC-A, NFC-B, and NFC-F standards are Reader-Talk-First (RTF) standards. The card reader is then a slave device and only responds to commands from the reader. In particular, a reader is configured, for example, to support several standards and successively transmit query frames, for example, NFC-A, then NFC-B, then NFC-F, and possibly other technologies afterward, such as NFC-V, which corresponds to the ISO 15693 standard. Some readers are configured not to interrupt their signal between each query frame. Other readers are configured to interrupt their signal. between each query frame in order to consume less energy. This operating mode, called "polling", allows the reading device to save energy.

[0041] By way of example, device 102 is a device capable of emulating one or more cards, such as a mobile phone, a smartwatch, a remote control, a payment card, etc. Device 104 is, for example, a device transmitting in reader mode, such as an access control device, an electronic lock, a payment terminal, etc.

[0042] In practice, the variations in amplitude of the field emitted by a reader device, also called frame start patterns, depend on the NFC standard in which the reader device is configured. Some standards are more widely used than others in certain fields, in certain regions of the world, etc. In some examples, a device in reader mode is configured to emit a first pattern according to a first standard. In some cases, a second pattern according to a second standard is emitted if no device in card mode has responded to the emission of the first pattern.

[0043] The device 102 is in particular configured to emulate several cards in order to be able to detect several types of patterns and consequently to respond to different reading devices, emitting according to different standards.

[0044] Figure 2 schematically represents, in block form, an example of implementation of the near field communication circuit 106 of device 102.

[0045] The near field communication circuit 106 includes, for example, a computing entity 201 (CPU), implemented for example by a processing unit, a microcontroller, a microprocessor, or other processing device configured to execute instructions stored in an instruction memory (not shown in [Fig.2]), although it would also be possible for the computing entity 201 to be implemented by a dedicated circuit, such as a state machine, a programmable logic circuit, etc.

[0046] The circuit 106 further includes, for example, a field detector 203. The field detector 203 of the device 102 is, for example, configured to detect an electromagnetic field radiated by the device 104 when this device is located within range of the device 102. For example, the range of the electromagnetic field radiated by the device 104 is on the order of several centimeters, for example, less than or equal to 50 cm. The field detector 203 is, for example, configured to emit a detection signal to the processing unit 201. For example, the detection signal emitted by the field detector 203 includes a rising edge when the field detector 203 is activated following the detection of a field radiated by the device 104. The signal further includes a falling edge when the field detector 203 is deactivated. When activated, The field detector 203 is configured to detect modulations in the field emitted by the reader device 104.

[0047] The near field communication circuit 106 further includes a first counter 205_l (TSLmi) and a second counter 205_2 (TSLm2) controlled by the computing entity 201.

[0048] The circuit 106 includes, for example, various other elements or circuits depending on the application, for example, a signal generator, analog-to-digital and / or digital-to-analog converters, modulation and / or demodulation circuits, an impedance matching circuit, a filtering circuit, etc. These elements and circuits are symbolized by a single functional block 207 (FCT). The near-field communication circuit 106 further includes, for example, one or more volatile storage areas, one or more non-volatile storage areas, one or more data, address, and control buses between the various internal elements of the circuit 106, as well as one or more input / output interfaces for communication with the outside of the circuit 106.

[0049] The circuit 106 is further coupled to a radio frequency transmitting and receiving antenna 209 (ANT). The antenna 209 is, for example, an element included in the device 102. The antenna 209 is, for example, configured to transmit and receive the electromagnetic field EMF.

[0050] By way of example, the reader device 104 is further configured to operate in so-called "polling" mode. In "polling" mode, the device 104 interrupts its field between one or more query frames to reduce energy consumption. For example, the reader device 104 is configured to interrupt its field between several frames when it supports multiple standards such as NFC-A, NFC-B, NFC-F, or NFC-V. The transmission periods between two interruptions are, for example, between 0.5 and 1 second. The field transmission duration is, for example, on the order of a few milliseconds, for example, 7 ms, when the device 104 supports only one standard. The field transmission duration is, for example, on the order of several tens of milliseconds, for example, between 60 and 80 ms, when the reader device 104 supports all four standards: NFC-A, NFC-B, NFC-F, and NFC-V.

[0051] Figure 3A is a timing diagram 300 illustrating an example of a start-of-frame pattern 302, emitted by a reader device, for example by reader device 104. In particular, the start-of-frame pattern 302 shown corresponds to a pattern emitted by a reader device transmitting according to a standard using 100% modulation. By way of example, pattern 302 corresponds to the start-of-frame pattern specific to the NFC-A standard, also referred to here as Type A communications, and well known to those skilled in the art.

[0052] Pattern 302 corresponds to a signal, for example at 13.56 MHz, comprising a pause time Tl preceded by a modulation edge and followed by a demodulation edge. During this pause time, the signal amplitude is reduced to 0 or close to zero, corresponding, for example, to an amplitude equal to or less than 5 percent of the signal amplitude outside the pause time Tl. By way of example, for communication according to the NFC-A standard, the pause time Tl is between 2 [ps] and 3 ps inclusive.

[0053] Figure 3B is a timing diagram 304 illustrating an example of a start-of-frame pattern 306, emitted by a reader device, for example by the reader device 104. In particular, the start-of-frame pattern 306 shown corresponds to a pattern emitted by a reader device transmitting according to a standard using 10% modulation. By way of example, pattern 306 corresponds to the start-of-frame pattern specific to the NFC-B standard or the NFC-F standard, also referred to herein as Type B communications and Type F communications, and well known to those skilled in the art.

[0054] Pattern 306 corresponds to a signal, for example at 13.56 MHz, comprising a pause time T2 preceded by a modulation edge and followed by a demodulation edge. During this pause time, the signal amplitude is reduced by 10%. As an example, for communication according to the NFC-F standard, the pause time T2 is between 2.3 µs and 2.4 ps inclusive for a transfer rate of 212 kilobits per second, and between 1.1 ps and 1.2 ps inclusive for a transfer rate of 424 kilobits per second.

[0055] In the example where pattern 306 corresponds to that emitted during a communication according to the NFC-B standard, the time T2 is between 94 us and 104 ps inclusive.

[0056] The pause time associated with the NFC-B frame start pattern is thus significantly longer than the pause times associated with the NFC-A and NFC-F frame start patterns. If the device in card mode is configured to emulate cards according to different standards, particularly NFC-A and NFC-B, this difference in the order of the pause times can lead to detection errors. Indeed, generally, devices in card mode or emulating card mode are configured to detect communications transmitted according to several standards. For example, when a modulation edge is detected by the device's field strength detector, a processor controls a counter to time the pause between the modulation edge and a demodulation edge. For example, the processor is configured to determine the standard used based on the timed duration.For example, following the detection of a first modulation edge, the field detector, or the processor, is configured to ignore another modulation edge that is directly following it. For example, the field detector is in [mode / state]. Furthermore, the device is configured to detect a modulation edge again if no demodulation edge has occurred within 104 seconds following the first modulation edge. In other words, when a modulation edge is detected, the device in card mode is placed in a start-of-frame pattern detection state in which it is configured to only detect start-of-frame patterns characterized by a modulation edge, a pause, and a demodulation edge. The device in card mode is configured to exit this state when a pattern is detected, or if no pattern is detected, 104 seconds after the modulation edge detection.

[0057] Thus, if the device in card mode detects a first demodulation edge, it waits 104 B5' before determining whether this first edge corresponds to a pattern according to the NFC-B standard. If the first demodulation edge is not followed by another demodulation edge, then the detected modulation edge did not correspond to a pattern according to the NFC-B standard. Since the device in card mode is configured to wait for the demodulation edge, it is possible that patterns according to another standard, for example according to the NFC-A or NFC-F standard, may have been transmitted during these 104 B5' and may not have been detected.

[0058] Figure 4 is a timing diagram illustrating an example in which a detection A reading device is missed. In particular, the timing diagram shown in [Fig. 4] illustrates an example of a 400 signal transmitted by the reading device 104. The 400 signal includes a modulation edge 402 that induces a modulation of the 400 signal amplitude. As an example, the signal amplitude is reduced by 10%. A device in card mode and within range detects this modulation edge and then waits for a demodulation edge to determine the standard being used. Following the detection of the 402 modulation edge, the device in card mode is placed in pattern detection mode.

[0059] However, the modulation edge 402 of the signal 400 does not correspond to a start-of-frame pattern. For example, the modulation edge 402 simply corresponds to an amplitude modulation of the signal. For example, the signal 400 also includes a sequence 404 of start-of-frame patterns. For example, the sequence 404 of patterns includes six start-of-frame patterns 302. The sequence 404 then corresponds, for example, to a request transmitted according to the NFC-A standard. For example, the transmission of the sequence 404 of patterns is transmitted T3 after the modulation edge 402, T3 being strictly less than 104 B5. Since the device in card mode is in pattern detection mode, it ignores the sequence 404 and misses the communication initiated according to the NFC-A standard.

[0060] Figure 5 is a timing diagram 500 illustrating a signal 500 emitted by a reading device. In particular, the signal 500 includes interference 502 interfering with a detection method. By way of example, the interference 502 induces variations in the amplitude of the signal 500. The amplitude variations caused Interference is, for example, on the order of 5%. However, in some cases, the field detector of a device in card mode within range detects a modulation edge within the interference. The device in card mode then enters detection mode and waits to detect a demodulation edge. In this example, the device in card mode does not detect a modulation edge emitted by the reader device to initiate communication according to, for example, the NFC-A standard.

[0061] Embodiments mitigating the disadvantages due to this discrepancy between the different NFC standards are described below, in relation to Figures 6, 7A and 7B.

[0062] Figure 6 is a flowchart representing steps in a method for detecting a reading device, for example the reading device 104, according to an embodiment of the present description. In particular, the method is implemented by the card-mode device 102.

[0063] Figures 7A and 7B are timing diagrams illustrating two examples of detection of the reader device 104 by the card-mode device 102, according to an embodiment of the present description. In particular, Figures 7A and 7B illustrate examples of embodiments of the method described in relation to [Fig. 6].

[0064] In the examples described in Figures 6, 7A, and 7B, the detection of a field causes a rising edge in the signal emitted by the field detector 203, for example, to the processing unit 201. Similarly, the end of field detection by the field detector 203 causes a falling edge in the signal emitted by the field detector 203. It is, of course, conceivable that the detection of a field by the detector 203 results in a falling edge of the detection signal and that the end of field detection by the detector 203 or the deactivation of the field detector 203 results in a rising edge in the detection signal. A person skilled in the art will be able to adapt the method described in relation to [Fig. 6] to this variant.

[0065] In a step 600 (FIELD ON), the field detector 203 of the device 102 is activated and detects the presence of a field emitted by the device 104. This detection by the field detector 203 causes a first rising edge 700 in the detection signal 702, or 703, emitted by the field detector 203 towards the computing entity 201. According to one embodiment, the device 102 is configured to be placed in a first detection state when the detection signal is activated by the field detector 203. In particular, when placed in the first detection state, the device 102 is configured to ignore requests issued by the reader device 104 according to one or more standards, for example, according to the NFC-B standard. Generally, when placed in the first detection state, the device Device 102 is configured to ignore communications transmitted according to the standard for which the pause time in the start-of-frame pattern is the longest among the standards recognized by Device 102. For example, the choice of a standard to detect or the ignoring of a standard is implemented by the processing unit 201. For example, Processing unit 201 is configured to disable the emulation of the card mode associated with the ignored standard. In another example, Processing unit 201 is configured to retry the detection of a modulation edge if, after a time period strictly shorter than the pause time of the ignored standard, no pattern has been detected. For example, when placed in the first detection state, Device 102 is configured to detect only communications transmitted according to the NFC-A standard.In another example, when placed in the first detection state, device 102 is configured to detect only communications emitted according to NFC-A and NFC-F standards.

[0066] In step 601 (LAUNCH TSLMi), the first counter 205_l is triggered. According to one embodiment, the first counter 205_l is triggered following the rising edge 700 occurring during a first activation of the field detector 203. The triggering of the first counter 205_l, during step 601, causes the device 102 to be placed in the first detection state.

[0067] In a step 602 (TYPE A?), the circuit 106 is configured to determine whether, during a first duration Cl, communication according to a standard recognized by the first detection state is initiated. For example, the first duration is reached when the first counter 205_l reaches a first threshold value. For example, the first duration Cl is equal to 100. In other examples, the first duration is between 50 and 500 inclusive.

[0068] If circuit 106 does not detect any communication according to a standard recognized by the first detection state (branch N) during the first duration Cl, the process continues in step 603 (SLM2). During step 603, circuit 106 is configured to switch to a second detection state. For example, when the first counter 205_l reaches the first threshold value, the arithmetic entity 201 is configured to automatically switch circuit 106 to the second detection state. When placed in the second detection state, circuit 106 is configured to detect at least one standard ignored in the first detection state. For example, when placed in the second detection state, circuit 106 is further configured to ignore one or more states recognized by the first state.For example, in the second detection state, the NFC-B standard is recognized and the NFC-A and NFC-F standards are ignored. In another example, in the second detection state, the NFC-B and NFC-F standards are recognized and the... The NFC-A standard is ignored. In another example, in the second detection state, the NFC-A, NFC-B and NFC-F standards are all recognized.

[0069] In a step 604 (TYPE B?), following an implementation of step 603, the circuit 106 is configured to determine whether communication according to a standard recognized by the second detection state is initiated.

[0070] In cases where, during the execution of steps 602 or 604, communication according to a recognized standard is initiated by device 104 (branch Y at the output of block 602 or at the output of block 604), devices 102 and 104 are, for example, coupled and a transaction is carried out in step 605 (PROCESSING). For example, the transaction corresponds to a data transfer, an authentication, an electronic lock unlocking, etc.

[0071] When the transaction is performed, the field emitted by device 104 and detected by field detector 203 is deactivated in a step 606 (FIELD OFF). This deactivation results, for example, in a falling edge 708 in signal 702 or 703.

[0072] By way of example, step 606 follows step 604 in the case where no communication is detected, for example before the expiry of a reference time, for example on the order of milliseconds or seconds, following the first rising edge 700.

[0073] Deactivating the detection signal triggers a second counter 205_2 in step 607 (LAUNCH TsLM2). In step 607, circuit 106 remains in the second detection state. For example, circuit 106 is configured to remain in the second state during step 607 for a second duration C2. For example, duration C2 expires when the second counter 205_2 reaches a second threshold value. For example, the second threshold value is 500. In another example, the second threshold value is a value between 100 and 1115.

[0074] The circuit 106 of the device 102 is, for example, further configured to activate the second counter 205_2 on each falling edge of the detection signal 702 or 703. The circuit 106 is further configured to, for example, deactivate the second counter 205_2 on each rising edge of the detection signal 702 or 703. Thus, the second counter 205_2 is, for example, triggered during the interrogation cycles of the reader device 104, and in particular during periods of interruption of the field emitted by the reader device 104. By way of example, the circuit 106 is further configured to reset the second counter 205_2 each time it is stopped, in other words, on each rising edge of the signal 702 or 703.

[0075] When the second counter 205_2 reaches the second threshold value, the process terminates in step 608 (END). Circuit 106 is configured, for example, to Perform a new detection, restarting the process from step 600. For example, when the second counter 205_2 reaches the second threshold value, the communication circuit 106 is switched back to the first detection state. In another example, the communication circuit 106 is switched to a different state in which other standards are recognized, and at least one standard recognized by the second state is ignored. For example, the first detection state recognizes only the NFC-A standard, the second detection state recognizes only the NFC-B standard, and the other state recognizes only the NFC-A and NFC-F standards, or only the NFC-F standard.

[0076] Figure 7A illustrates an example of an embodiment in which the reader device 104 does not interrupt its field between the query frames. Figure 7B illustrates an example of an embodiment in which the reader device 104 interrupts its field between the query frames in order to reduce its energy consumption.

[0077] For example, at the first rising edge 700 of the signals 702 and 703 caused by the activation of the field detector 203 and the presence of a field, the first counter 205_l is activated and the circuit 106 is in the first detection state.

[0078] For example, requests 710 are transmitted by the reader device 104, according to one or more standards ignored by the first detection state. Since the circuit 106 of the device in card mode 102 is in the first detection state, it does not respond to these requests 710 issued according to the first standard. For example, the requests 710 correspond to requests issued according to the NFC-B standard.

[0079] In the example illustrated in [Fig. 7B], a succession of falling edges 704 and rising edges 706, shown in [Fig. 7B], is triggered by the reader device 104 when it is in "polling" mode and periodically queries by activating its field and then deactivating it once the polling frames are transmitted. The field detector 203 then detects that the reader device 104 is in "polling" mode. The second counter 205_2 is then triggered during each period of inactivity of the field detector 203. The triggering of the second counter is symbolized in [Fig. 7B] by upward arrows, and the stopping of the second counter at the end of these periods of inactivity is symbolized by downward arrows. As an example, during periods of inactivity, the circuit 106 is automatically placed in the second detection state.The first counter 205_l is configured to continue operating normally, even when the field detector 203 no longer detects a field. In other words, when the first counter 205_l is triggered, a change in the edge of the emitted field is not sufficient to stop it. For example, the first counter 205_l is configured to be stopped only when it reaches the first edge. threshold value, or when detector 203 detects a pattern corresponding to a standard recognized by the first detection state.

[0080] When the first counter reaches the first threshold value, the circuit 106 is automatically switched to the second detection state. In the example illustrated in [Fig. 7B], the first counter 205_l reaches the first threshold value during a period of inactivity of the field detector 203. In this example, the circuit 106 has already switched to the second detection state.

[0081] Device 104, for example, sends a new request 712 according to the first standard, for example, according to the same standard as requests 710. Circuit 106, being in the second state, responds to this request, for example, by initiating a response step towards device 104. In one example, a transaction, or communication, 714 takes place between devices 102 and 104. In another example, the transaction, or communication, fails. Once the communication, or transaction, is completed, whether successfully or not, the field detector 203 is deactivated, which results in the falling edge 708 in the signal emitted by detector 203. The second counter 205_2 is then triggered. When the second counter 205_2 reaches the second threshold value, circuit 106 is, for example, automatically switched back to the first detection state.The second counter 205_2 allows for monitoring the standards detected during periods of field interruption when the reader device 104 is in "polling" mode, as illustrated in [Fig. 7B]. One or more standards are, for example, ignored or not detected during the active time of the first counter 205_1. The device 102 is then configured to detect these standards if no communication has been detected during the first duration Cl, counted by the first counter 205_1. The circuit 106 then enters the second detection state, and upon the expiration of the first duration Cl, or upon a field interruption in communication with the reader device 104, the second counter 205_2 is activated. When the second counter 205_2 reaches its limit, for example by reaching the second threshold value, the standards recognized in the second detection state are, for example, ignored again.

[0082] The first counter 205_l is, for example, started, or activated, by the first field detection corresponding to the rising edge 700. The device 102 is then configured to be placed, for example, in the first detection state, in which it ignores at least one communication standard. If no communication is detected during the activity duration Cl of the first counter 205_l, the device 102 switches to the second detection state, and detection of the standard(s) previously ignored becomes possible. However, leaving the device 102 in the second detection state for too long a period This could be problematic in certain cases. Indeed, device 102 might miss communications again, depending, for example, on the NFC-A or NFC-F standard. However, it is not possible, for instance, to return to the first detection state immediately after the first field extinction detection corresponding to the falling edge 708. In fact, if a communication error occurs, the reader device 104 can interrupt its field for a few milliseconds to reset the communication. The duration C2 is then such that device 102 remains, for example, in the second detection state. In another example, if the user prematurely removes device 102, or if they keep it at a distance, a field interruption occurs. This interruption corresponds, for example, to the falling edge 708. However, the transaction is not completed and will resume when the user brings device 102 closer.Device 102 is therefore configured, for example, to remain in the second detection state when a transaction is interrupted. In another example, some card readers are configured to detect the removal of a card reader. To do this, these readers revert to query mode, and in some cases to polling mode. In this case, device 102 is, for example, configured to remain in the second detection state in order to respond to these queries.

[0083] An advantage of the described embodiments is that they allow the detection of a particular technology for a duration C1 counted by the first counter 205_1, and then the reactivation of the detection of this technology after a duration C2 counted by the second counter 205_2, in the case where no technology has been detected during the duration C1

[0084] One advantage of the described embodiments is that they allow the detection of an NFC-A request to be targeted first, and then to be switched to the detection of an NFC-B request. This is advantageous since the NFC-B and NFC-A standards are generally used for the same type of transaction. NFC-A detection occurs, for example, during a relatively short period of time, for example, on the order of 100, which corresponds to the pause time in the NFC-B pattern. If no NFC-A request is detected, then the circuit focuses on detecting NFC-B requests. The time spent waiting for an NFC-A request is then negligible compared to the time required for NFC-B detection.

[0085] Another advantage of the described embodiments is that the implementation of the process is entirely hardware-based and managed by the detection circuit 106. Compared to a software implementation, for example managed by the device 102 via a digital tool, the described embodiments have the advantage of being faster.

[0086] Another advantage of the described embodiments is that they allow device 102 not to miss a transaction, which would be particularly damaging in cases where the transaction between the two devices is a banking transaction, an access control verification, or a transport card validation.

[0087] Various embodiments and variations have been described. A person skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art. In particular, with regard to standards recognized or not in the first and second states, although the NFC-A, NFC-B, and NFC-F standards have been primarily described in the description, a person skilled in the art will be able to adapt to recognize and / or disregard other standards.

[0088] Finally, the practical implementation of the described embodiments and variants is within the grasp of a person skilled in the art, based on the functional specifications given above, particularly with regard to the implementation of the first and second counters 205_l and 205_2. Indeed, it is possible that the first and second counters 205_l and 205_2 are two distinct counters of the device 102, or more specifically of the communication circuit 106. It is also conceivable that the first and second counters 205_l and 205_2 are a single counter. In this case, the calculation entity 201 is, for example, configured to apply one or the other of the first and second threshold times to the counter.

Claims

Demands

1. Method comprising: - activating a detection signal by a field detector (203) of a near field communication circuit (106), the near field communication circuit being placed in a first state in which it is configured to recognize one or more communications transmitted according to a first standard; - triggering a first counter (205_l) of the circuit (106) in response to the activation of the detection signal; and - when the first counter reaches a first threshold value, the transition of the near field communication circuit (106) into a second state in which it is configured to recognize one or more communications transmitted according to a second standard, the near field communication circuit (106) being configured to ignore communications transmitted according to the second standard when it is in the first state.

2. Method according to claim 1, wherein the first counter (205_l) is triggered on a first rising edge (700) of the detection signal emitted at the start of the field detector (203).

3. A method according to claim 1 or 2, further comprising, following the transition of the near field communication circuit (106) into the second state: - the triggering of a second counter (205_2); and - when the second counter reaches a second threshold value, the transition of the circuit into the first state or into a third state in which the circuit is configured to ignore communications transmitted according to the second standard.

4. Method according to claim 3, wherein the second counter (205_2) is triggered on a first falling edge (704, 708) of the detection signal emitted by the field detector (203).

5. Method according to claim 3 or 4, wherein the second counter (205_2) is stopped and reset at each rising edge (700, 706) of the detection signal emitted by the field detector (203).

6. A method according to any one of claims 1 to 5, wherein the communications emitted according to the first standard are NFC-A type near-field communications.

7. A method according to any one of claims 1 to 6, wherein the communications emitted according to the second standard are NFC-B type near-field communications.

8. A method according to any one of claims 1 to 7, wherein the near field communication circuit (106) is further configured to, when placed in the first state, detect NFC-F type near field communications.

9. A method according to any one of claims 1 to 8, wherein the near-field communication circuit (106) is configured to emulate a plurality of cards.

10. Circuit (106) comprising: - a field detector (203), the circuit being configured to be placed in a first state upon activation of a detection signal generated by the field detector, the circuit being further configured to, when placed in the first state, detect one or more communications transmitted according to a first standard; and - a first counter (205_l) configured to be triggered following activation of the detection signal; the circuit being further configured to be placed in a second state when the first counter reaches a first threshold value, the circuit being configured to, when placed in the second state, detect one or more communications transmitted according to a second standard, the circuit being configured to ignore communications transmitted according to the second standard when placed in the first state.

11. Circuit (106) according to claim 10, configured to trigger the first counter (205_l) on a first rising edge (700) of the detection signal emitted at the start of the field detector (203).

12. Circuit (106) according to claim 10 or 11, further configured so that when the first counter, or when a second counter, reaches a second threshold value, it is placed in the first state or in a third state in which the circuit is configured to ignore communications issued according to the second standard.

13. Circuit (106) according to claim 12, further configured to trigger the second counter (205_2) on a first falling edge (704, 708) of the detection signal emitted by the field detector (203) and to stop and reset the second counter at each rising edge (700, 706) of the signal emitted by the field detector.

14. Circuit (106) according to any one of claims 10 to 13, wherein communications emitted according to the first standard are NFC-A type near field communications and communications emitted according to the second standard are NFC-B type near field communications.

15. Circuit (106) according to any one of claims 10 to 14, configured to emulate a plurality of cards.

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