NFC device detection

Abstract

The invention relates to NFC device detection. A device operating in a card emulation mode detects a first near field communication burst emitted by an external device. The first near field communication burst includes a first pulse of duration Tw. The device operating in card analog mode transmits a radio frequency pulse in response to an external device as a result of detecting a first pulse of a first near field communication burst. The duration of the radio frequency pulse is less than or equal to the duration Tw and is transmitted within a period of time less than or equal to 10 [mu] s from the leading edge of the first pulse of the first near field communication burst.

Description

[0001] Priority requirements

[0002] This application claims priority to French patent application No. FR2410388, filed on September 27, 2024, the contents of which are hereby incorporated herein by reference in their entirety to the fullest extent permitted by law. Technical Field

[0003] This disclosure generally relates to electronic devices including near-field communication (NFC) circuitry and near-field communication detection methods. Background Technology

[0004] Communication systems based on electromagnetic transponders are becoming increasingly common, especially since the development of Near Field Communication (NFC) technology. These systems typically use the radio frequency electromagnetic field generated by an NFC device (terminal or reader) to detect another NFC device (card) within range and then communicate with it.

[0005] NFC devices are powered by batteries most of the time. Therefore, their functionality and circuitry typically alternate between periods of use and standby. The standby period specifically allows for reduced power consumption in NFC devices. The NFC device is "wake up" when it detects a tag or other device within range.

[0006] A method is needed to "wake up" the reader device using the card device. Summary of the Invention

[0007] An embodiment provides a method comprising: a device operating in card emulation mode detecting a first near-field communication burst emitted by an external device, the first near-field communication burst including a first pulse having a duration Tw; and the device operating in card emulation mode responding to the external device as a result of detecting the first pulse of the first burst by emitting a radio frequency pulse having a duration less than or equal to the duration Tw for a period of less than or equal to 10 μs from the leading edge of the first pulse.

[0008] According to an embodiment, the method further includes: detecting a second near-field communication burst emitted by an external device before detecting a first burst, the second burst including a first pulse, by a device operating in card emulation mode; measuring the duration of the first pulse of the second burst by the device operating in card emulation mode; determining whether the measured duration of the first pulse belongs to a first reference interval by the device operating in card emulation mode; and when the measured duration belongs to the first reference interval, measuring the period between the first pulse of the second near-field communication burst and the first pulse interval of the first near-field communication burst by the device operating in card emulation mode.

[0009] According to an embodiment, the method further includes: determining whether the measured period belongs to a second reference interval by a device operating in card emulation mode; and when the measured period belongs to the second reference interval, transmitting a radio frequency signal by the device operating in card emulation mode.

[0010] According to an embodiment, the second interval is an interval of 100 to 400 ms, and the first interval is an interval of 40 to 60 μs.

[0011] According to an embodiment, the trailing edge of the radio frequency pulse precedes the trailing edge of the first pulse or is less than 5 μs after the trailing edge of the first pulse.

[0012] According to an embodiment, the external device is in a low-power mode, and the external device exits the low-power mode by transmitting an radio frequency signal from a device operating in card emulation mode.

[0013] According to an embodiment, the external device is a device that transmits only in reader mode.

[0014] According to the embodiment, the near-field communication transmission range of the external device is less than or equal to 10cm.

[0015] According to an embodiment, the radio frequency signal emitted by the device operated by the card in response to the first burst is a signal with a frequency of 13.56 MHz.

[0016] According to an embodiment, the external device is an electronic lock.

[0017] An embodiment provides a near-field communication device operating in card emulation mode, comprising: a field detector configured to detect a first near-field communication burst emitted by an external device, the first near-field communication burst including a first pulse having a duration Tw; and an antenna configured to, in response to the external device as a result of detecting the first pulse of the first near-field communication burst, emit a radio frequency pulse with a duration less than or equal to the duration Tw for a period of less than or equal to 10 μs from the leading edge of the first pulse.

[0018] According to an embodiment, the device further includes a counter configured to: measure the duration of a first pulse of a second near-field communication burst emitted by an external device and detected by a field detector before the first burst is detected; and when the measured duration is within a first reference interval, measure the period between the first pulse of the first near-field communication burst and the first pulse of the second near-field communication burst.

[0019] An embodiment provides a system including: the aforementioned device operating in card emulation mode; and an external near-field communication device configured to transmit a first near-field communication burst when in a low-power mode.

[0020] According to an embodiment, the external device operates only in reader mode.

[0021] According to an embodiment, the external device is an electronic lock. Attached Figure Description

[0022] The above and other features and advantages will be described in detail in the remaining disclosure by way of specific embodiments given by way of illustration rather than limitation and with reference to the accompanying drawings, wherein:

[0023] Figure 1 An example of a near-field communication system is shown in a very schematic block diagram.

[0024] Figure 2 An example of a near-field communication circuit is schematically shown in the form of a block diagram;

[0025] Figure 3A This is a timing diagram illustrating an example of a method for detecting near-field communication in a reader mode device in standby mode;

[0026] Figure 3B More detailed illustrations Figure 3A A time-series diagram of the detection time for near-field communication;

[0027] Figure 4 The illustration depicts a method for implementing a device-assisted reader mode using a device operating in card emulation mode, according to an embodiment of the present disclosure; and

[0028] Figure 5 This is a flowchart illustrating the steps of an auxiliary method implemented by a device operating in card emulation mode according to an embodiment of the present disclosure. Detailed Implementation

[0029] In the figures, the same features are indicated by the same reference numerals. In particular, common structural and / or functional features in the various embodiments may have the same reference numerals, and may have the same structure, dimensions, and material properties.

[0030] For clarity, only steps and elements that aid in understanding the embodiments are shown and described in detail. In particular, the generation and interpretation of radio frequency signals are not described in detail, and the embodiments and implementations are compatible with conventional techniques for generating and interpreting these signals.

[0031] Unless otherwise indicated, when referring to two elements connected together, it means a direct connection without any intermediate elements other than a conductor, and when referring to two elements coupled together, it means that the two elements can be connected or they can be coupled via one or more other elements.

[0032] In the following description, all references to absolute positional qualifiers, such as “front,” “back,” “up,” “down,” “left,” “right,” etc., or relative positional qualifiers, such as “top,” “bottom,” “upper,” “lower,” etc., or orientation qualifiers, such as “horizontal,” “vertical,” etc., shall refer to the orientation of the accompanying drawings, unless otherwise stated.

[0033] Unless otherwise stated, the expressions “about,” “approximately,” “basically,” and “approximately” indicate plus or minus 10% or 10°, preferably plus or minus 5% or 5°.

[0034] Figure 1 An example of a near-field communication system 100 of the type described in the embodiments and implementations is shown in block diagram form as an example.

[0035] System 100 includes a first electronic device 102 and a second electronic device 104. For example, electronic devices 102 and 104 each include one or more near-field communication (NFC) circuits. As an example, device 102 is configured to operate in a so-called card mode (corresponding to card emulation mode), while device 104 is configured to operate in a so-called reader mode.

[0036] As an example, device 102 includes a near-field communication circuit 106, which includes at least one electronic component or circuit for generating and detecting radio frequency signals by means of an antenna (not shown), such as a modulation or demodulation circuit. As an example, device 104 includes a near-field communication circuit 108, which includes at least one electronic component or circuit for transmitting and detecting radio frequency signals by means of an antenna (not shown), such as a modulation or demodulation circuit. During communication from device 102 to device 104, when device 102 is within range, device 104 captures the radio frequency signal generated by device 102. Device 102 transmits the electromagnetic field (EMF) captured by device 104 within range. Therefore, a coupling is formed between the two oscillating circuits, in this example, the oscillating circuits of the antennas of device 102 and device 104. This coupling causes a change in the load formed on the EMF field generating oscillating circuit of device 102.

[0037] In practice, to establish communication, device 102 detects phase or amplitude changes in the transmission field and then initiates an NFC communication protocol with device 104. When device 102 detects the presence of device 104 in its field, it initiates a communication setup process, in which device 102 sends a request and device 104 sends a response, such as a polling sequence defined in the technical specifications of the NFC Forum standard.

[0038] As an example, device 102 is a device capable of operating in both card emulation and reader modes, such as a telephone or remote control. Device 104 is, for example, a device that cannot emulate a card. In the example, device 104 is an electronic lock, access control device, etc. As an example, device 104 is configured to unlock doors, such as car doors, house doors, or locker doors. As an example, device 104 is integrated into a structure, such as a door handle or lock, and is powered by, for example, a battery. As an example, devices 102 and 104 form a contactless transaction system, such as a transportation card verification system or a contactless payment system.

[0039] Devices 102 and 104 are configured to switch to a so-called “low-power” mode or standby mode when not communicating, in order to reduce power consumption. This is especially true for battery-powered NFC devices. In low-power mode, an NFC device configured in reader mode performs a so-called “low-power card detection” (LPCD) mode, also known as a “low-power tag detection” (LPTD) mode, in which it cyclically detects another device in its field (range) in order to exit standby mode for communication. An example of a low-power mode is described in U.S. Patent Application Publication No. 2023 / 0189149 (incorporated herein by reference). As an example, devices 102 and 104 are both cellular phones that include NFC circuitry configured to switch to low-power mode.

[0040] For example, U.S. Patent Application Publication No. 2023 / 0223989 (incorporated herein by reference) describes an example of detection in a low-power mode. In this example, detection in low-power mode is similar to detection performed when the device is not in a low-power mode. However, in normal mode, carrier (field) transmission is continuous and periodically includes polling frames; while in standby mode, field transmission occurs in periodic bursts without polling frames to reduce power consumption. The duration of the burst is significantly shorter than the duration of a polling request in normal mode, for example, at least ten times shorter, preferably at least one hundred times shorter.

[0041] Figure 2 An example of an embodiment of the near-field communication circuit 106 of device 102 is illustrated schematically in the form of a block diagram.

[0042] The near-field communication circuit 106 includes, for example, a computing unit 201 (CPU), such as a state machine, microcontroller, microprocessor, programmable logic circuit, etc. In this example, circuit 106 also includes a field detector 203 (field detection). For example, the field detector 203 of device 102 is configured to detect the electromagnetic field radiated by device 104 when device 104 is within range of device 102. As an example, the range of the electromagnetic field radiated by device 104 is approximately a few centimeters, for example, less than or equal to 50 cm.

[0043] The near-field communication circuit 106 also includes a counter 205 (timer) controlled by the computing entity 201.

[0044] Circuit 102 includes, for example, various other components or circuits depending on the application, such as signal generators, analog-to-digital converters and / or digital-to-analog converters, modulation and / or demodulation circuits, impedance matching circuits, filter circuits, etc. These components and circuits are represented by a single functional block 207 (FCT). Near-field communication circuit 106 also includes, for example, one or more volatile memory regions, one or more non-volatile memory regions, one or more data, address, and control buses between the various components within circuit 106, and one or more input / output interfaces for communicating with the outside of circuit 106.

[0045] Device 102 includes an antenna 209 (antenna) coupled to circuit 106 for transmitting and receiving radio frequency (RF) signals. Antenna 209 is configured, for example, to transmit an electromagnetic field (EMF). According to an embodiment, circuit 106 includes a fast-response feature, enabling it to rapidly transmit an RF signal, for example, within 2 to 10 microseconds (inclusive) after detecting the leading edge of an RF pulse originating from an external device (e.g., device 104). In one example, this feature is implemented in hardware by a state machine. In another example, this feature is implemented by computational entity 201 executing software instructions. In yet another example, this feature is integrated into field detector 203. As an example, in low-power mode, field detector 203 consumes power between 0.1 μA and 15 μA (inclusive), and its detection sensitivity is between 50 mVpp and 15 Vpp. In this example, the fast-response feature is achieved by detecting the amplitude and frequency of the event signal. The detection duration is thus approximately one hundred microseconds. In another example, only the amplitude of the event signal is detected, and in this case, the detection duration is approximately a few microseconds, for example, between 2 and 10 μs.

[0046] Figure 3A This is a timing diagram illustrating an example of a method by which a device in reader and standby mode (e.g., device 104) detects a device operating in card emulation mode (i.e., where an NFC-enabled device (such as a smartphone (e.g.) acts as a contactless card, as known to those skilled in the art)) (e.g., device 102). Figure 3B It is a timing diagram that shows the detection time in more detail.

[0047] When attempting to detect the presence of device 102 within range, device 104 is in a state of... Figure 3ADuring standby mode corresponding to time period 303, device 104 periodically transmits field bursts. For example, each field burst includes a pulse 301 corresponding to an unmodulated carrier. The period of pulse 301 corresponding to the interval between two pulses 301 depends on the device, but is typically tens or hundreds of milliseconds. For example, in low-power mode, the frequency of pulse 301 is approximately a few hertz, such as approximately 3 or 4 Hz.

[0048] The duration of pulse 301 is, for example, about tens or hundreds of microseconds, such as between 20 and 100 μs (inclusive), and between 40 and 60 μs (inclusive), such as about 50 μs.

[0049] As an example, device 104 temporarily and periodically exits low-power mode to emit burst 301. However, in general, a state machine is preferably used to emit bursts in low-power mode. This avoids waking up the microcontroller (e.g., computing unit 201) of device 104, thus enabling standby mode to be maintained.

[0050] If the amplitude and / or phase measured by device 104 exceeds a detection threshold, then device 104 exits low-power mode and initiates detection phase 305, including, for example, transmitting a pulse 307 with a shorter period compared to the period of pulse 301, and used to confirm near-field detection. Detection by device 102 is possible because the charging effect of device 102 on the antenna of device 104 affects the amplitude and phase of burst 301. Then, a near-field communication establishment process 309 is performed, implementing a transmission request and response between devices 102 and 104, such as a polling sequence as defined in the technical specifications of the NFC Forum standard.

[0051] However, when the antenna coupled to the reader device 104 has a relatively short range (e.g., less than 10 cm), the device 104 has difficulty detecting the device 102.

[0052] The low-power mode-assisted method enables device 102 to extend the detection range of device 104. Device 102 is then configured to transmit an radio frequency signal, for example, at 13.56 MHz, while device 104 transmits in low-power mode to modify the electrical characteristics of device 104, thereby facilitating device 104's detection of device 102's presence. However, to comply with NFC Forum standards, device 104 should cease transmitting bursts in the presence of external radio frequency signals.

[0053] Figure 4 The illustration shows a method of an auxiliary device 104 implemented by device 102 according to an embodiment of the present disclosure.

[0054] In the example shown, reader device 104 is in a low-power mode and transmits a detection burst including pulse 301.

[0055] The duration of the two pulses 301 interval Ts ms of the two consecutive detection bursts, wherein Ts is, for example, in the range of 10 to 500 ms (inclusive), and in the range of 100 to 400 ms (inclusive).

[0056] The duration of each pulse 301 emission is Tw μs, where Tw is, for example, in the range of 20 to 100 μs (inclusive), in the range of 40 to 60 μs (inclusive), such as approximately 50 μs.

[0057] Device 102 is configured to detect continuous bursts. Specifically, device 102 is configured to transmit an radio frequency signal 400, for example, at 13.56 MHz, upon detecting one or more bursts. According to an embodiment, device 104 implements its Fast Response (EFD) feature. As an example, this feature is activated when device 102 is also in a low-power mode.

[0058] Figure 4 Figure 402 is an enlarged view of the pulse 301 emitted by device 102. As an example, device 102 is configured to, in response to the detection of pulse 301, emit an RF signal 400 with a duration less than or equal to Tw ms. Signal 400 is a pulse emitted before the end of a pulse emitted by device 104, and its leading edge 404 is within an interval equal to or less than 10 μs from the leading edge 406 of the detected pulse 301. As an example, in response to the emission of the detected pulse 301, pulse 400 is emitted between 2 and 10 μs from the leading edge 406 of the detected pulse 301.

[0059] exist Figure 4 In one example, the trailing edge 408 of pulse 400 follows the trailing edge 410 of pulse 301. However, the duration of pulse 400 is chosen, for example, to limit the overshoot to 5 μs after the trailing edge 410. In other examples, the trailing edge 408 precedes the trailing edge 410. In particular, pulse 400 affects the electrical amplitude and / or phase characteristics of pulse 301. Figure 4 In the figure, the effect on the amplitude of pulse 301 is represented by the symbol Δ.

[0060] The pulse 400 emitted by device 102 enables device 104 to exit low-power mode in order to enter, for example, polling mode (polling).

[0061] Figure 5 This is a flowchart illustrating the steps of a method for an auxiliary device 104 implemented by device 102 according to an embodiment of the present disclosure.

[0062] At step 500 (Start EFD), for example, device 102 in low power mode activates the fast response feature.

[0063] At step 501 (first burst?), after activating the fast response feature, device 102 is configured to detect, via field detector 203, the first burst, specifically the first pulse 301, emitted by an external reader device (such as device 104 in low power mode, for example).

[0064] When device 102 does not detect a burst (the branch "No" at the output of box 501), the method continues to the new detection step 501.

[0065] When device 102 detects an external field (the branch "Yes" at the output of block 501), the method continues to step 502 (measurement burst). Device 102 is then configured to measure the length of pulse 301 emitted by device 104. As an example, the pulse length measurement is performed by counter 205.

[0066] After the pulse is measured, the method continues to step 503 (Tw?), where device 102 is configured to determine whether the obtained measurement falls within a reference interval that includes the expected duration of pulse 301. As an example, for a duration Tw of 50 μs, the reference intervals are 40 and 60 μs. When the measured duration of the pulse is outside the reference interval (the branch "No" at the output of box 503), the method returns to step 501.

[0067] When the measured duration of the pulse falls within the reference interval (the "Yes" branch at the output of block 503), the method proceeds to step 504 (timer). During the implementation of step 504, device 102 is configured to trigger counter 205. As an example, counter 205 is triggered immediately after the end of the first burst of pulses.

[0068] As an example, at step 505 (New Burst?), it is determined whether detector 203 detected a new burst before counter 205 reaches a threshold time period T. As an example, time T is greater than the expected period Ts between pulses 301, and is, for example, approximately 500 ms. If no other burst is detected when the threshold time expires (the branch "No" at the output of box 505), then the method returns to the new implementation at step 502.

[0069] If field detector 203 detects a new burst before the threshold time period expires (the branch "Yes" at the output of block 505), the method proceeds to step 506 (Period?). During the implementation of step 506, the time period between the two bursts measured by counter 205 (corresponding to the period of the field emitted by device 104) is compared to a reference period interval including the period Ts. As an example, for a period Ts of 50 ms, the reference period interval is within an interval of 100 to 400 ms. If the measured period is outside the reference period interval, the method returns to the new implementation of step 502. If the measured period actually falls within the reference period interval, the method proceeds to step 507 (Auxiliary).

[0070] During step 507, device 102 is configured to rapidly transmit an radio frequency (RF) signal, i.e., transmit the RF signal before the end of the transmission of the second burst pulse. This RF signal transmission is achieved, for example, via a fast response feature. As an example, the RF signal transmitted by device 102 is transmitted within a time period of less than or equal to 10 μs after the external device begins transmitting a new burst pulse. As an example, the RF signal is transmitted 5 μs after the leading edge of the new burst pulse is detected. The transmission duration of the RF signal transmitted by device 102 is, for example, less than or equal to the transmission duration Tw of the burst pulse transmitted by device 104.

[0071] Device 102 responds to the transmitted radio frequency signal, for example, a 13.56 MHz signal. As an example, the transmitted radio frequency signal enables modification of the electrical characteristics of external device 104. After implementing step 507, the method continues to a new implementation of step 504, where counter 205 is activated.

[0072] As an example, this method takes effect once card emulation mode is activated in the device. For example, card emulation mode is activated when a card or digital key is added to the device's wallet, or when the device's user activates the device's near-field communication.

[0073] The advantage of these embodiments is that they enable devices operating in card emulation mode to be detected by external devices that can only transmit in reader mode.

[0074] Another advantage of the embodiments is that they enable devices operating in card emulation mode to be detected by reader devices at short distances (e.g., less than about ten centimeters).

[0075] Another advantage of these embodiments is that they enable assistance for devices in low-power reader mode while conforming to NFC Forum standards.

[0076] Various embodiments and variations have been described. Those skilled in the art will recognize that certain features of these various embodiments and variations can be combined, and other variations will occur to those skilled in the art.

[0077] Finally, based on the functional indications given above, those skilled in the art can practically implement the embodiments and variations described above. In particular, this relates to hardware or software implementations of the fast response feature. Furthermore, the embodiments can be applied, for example, to situations where both devices are cellular phones and their near-field communication circuitry is configured to switch to a low-power mode. Implementations of the embodiments enable an increase in the detection distance between the two phones when they communicate with each other via NFC.

Claims

1. A method comprising: The device, operating in card emulation mode, detects a first near-field communication burst emitted by an external device, the first near-field communication burst comprising a first pulse having a first duration; as well as The device operating in card emulation mode responds to the external device as a result of detecting the first pulse of the first near-field communication burst, and transmits a radio frequency pulse with a second duration of less than or equal to the first duration within a time period of less than or equal to 10 μs from the leading edge of the first pulse of the first near-field communication burst.

2. The method of claim 1, further comprising, before detecting the first pulse of the first near-field communication burst: The device, operating in card emulation mode, detects a second near-field communication burst emitted by an external device, the second near-field communication burst including the first pulse; The third duration of the first pulse of the second near-field communication burst is measured by a device operating in card analog mode; The device, operating in card analog mode, determines whether the measured third duration belongs to the first reference interval; as well as When the measured third duration falls within the first reference interval, the period between the first pulse of the second near-field communication burst and the first pulse of the first near-field communication burst is measured by the device operating in the card analog mode.

3. The method according to claim 2, further comprising: The device, operating in card analog mode, determines whether the measured period belongs to the second reference interval; as well as When the measured period falls within the second reference interval, the device operating in analog mode transmits an radio frequency signal.

4. The method according to claim 3, wherein the second interval is an interval of 100 to 400 ms, and the first interval is an interval of 40 to 60 μs.

5. The method of claim 2, wherein the trailing edge of the radio frequency pulse precedes the trailing edge of the first pulse.

6. The method of claim 2, wherein the trailing edge of the radio frequency pulse follows the trailing edge of the first pulse by less than 5 μs.

7. The method of claim 1, wherein the external device is in a low-power mode, and wherein the external device exits the low-power mode by transmitting an radio frequency signal from a device operating in card emulation mode.

8. The method of claim 1, wherein the external device is a device that transmits only in reader mode.

9. The method according to claim 1, wherein the near-field communication transmission range of the external device is less than or equal to 10 cm.

10. The method of claim 1, wherein the radio frequency signal transmitted by the device operating in card emulation mode in response to the first burst is a signal having a frequency of 13.56 MHz.

11. The method of claim 1, wherein the external device is an electronic lock.

12. A near-field communication device operating in card emulation mode, comprising: A near-field detector is configured to detect a first near-field communication burst emitted by an external device, the first near-field communication burst comprising a first pulse having a first duration; as well as The antenna is configured to respond to an external device in response to the detection of a first pulse of a first near-field communication burst, and to transmit a radio frequency pulse of a second duration of less than or equal to a first duration for a period of less than or equal to 10 μs from the leading edge of the first pulse of the first near-field communication burst.

13. The device of claim 12, further comprising a counter configured to: The third duration of the first pulse of the second near-field communication burst, transmitted by an external device and detected by a field detector before the first near-field communication burst is detected, is measured; and When the measured third duration is within the first reference interval, the period between the first pulse of the second near-field communication burst and the first pulse of the first near-field communication burst is measured.

14. The device according to claim 13, further configured to: Determine whether the measurement period falls within the second reference interval; and When the measurement period falls within the second reference interval, an radio frequency signal is transmitted.

15. A system comprising: The near-field communication device operating in card emulation mode according to claim 12; as well as An external near-field communication device is configured to transmit a first near-field communication burst when in a low-power mode.

16. The system of claim 15, wherein the transmission of a radio frequency signal by a near-field communication device operating in card emulation mode causes an external near-field communication device to exit low-power mode.

17. The system of claim 15, wherein the external device operates only in reader mode.

18. The system of claim 17, wherein the external device is an electronic lock.

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