NFC accessory detection without magnetometer

Abstract

The invention relates to NFC accessory detection without magnetometer. The present description relates to a mobile device comprising a near field communication router and an antenna coupled to the router via at least one impedance matching circuit between at least two impedance values. The first impedance value is selected to communicate with the first type of near field communication device in the presence of the second type of near field communication device, and the second impedance value is selected to communicate with the first type of near field communication device in the absence of the second type of near field communication device. The presence or absence of a near field communication device of the second type is determined based on a polling frame of the antenna transmission.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to French Patent Application No. 2310508, filed on October 2, 2023, entitled “Dispositif NFC”, which is hereby incorporated by reference to the fullest extent permitted by law. Technical Field

[0003] The present disclosure relates generally to the field of near field communications, and more particularly to the association of a mobile device with a plurality of near field communication devices, some of which may be persistently associated with the device. Background Art

[0004] The Near Field Communication (NFC) system uses a radio frequency electromagnetic field generated by a device (the reader) to communicate with another device (the card).

[0005] The same device can now be both a reader and a card, depending on the application.

[0006] Near field communications are generally standardized or follow characteristics set by participants in the field. For example, the "NFC Forum" sets the characteristics that communicating devices follow when exchanging with each other, for example, according to the application or according to the nature of the exchange (payment, access control, authentication, file exchange, etc.).

[0007] To communicate between a device operating in reader mode and a device operating in card emulation mode, the reader generates an electromagnetic field loaded with a card located within range. Communication is performed according to various protocols that provide for modification of the phase and / or amplitude of a modulated carrier wave transmitted by the reader.

[0008] In targeted applications, a device that may be persistently associated (i.e. last longer than the duration of the usual communication) may be an accessory attached to a mobile device, such as a connected cover that displays the time, an electronic wallet, etc. The accessory generally uses the near field communication mode in order to make itself recognized (paired or authenticated) by the mobile phone operating as a reader in card emulation mode, but then communicates functionally with it by means of a link of another nature (e.g. Bluetooth, Wifi, etc.). The fact that the accessory is in card emulation mode can lead to the fact that, when the mobile phone has to establish another communication with a remote reader in card emulation mode, the remote reader sees two "cards" and then refuses the communication. This situation can occur, for example, in the case where a payment terminal detects two communication devices of the card type (the phone and its cover) in its field.

[0009] It is known to provide a system for communicating with an accessory by providing a specific reader or antenna different from the reader or antenna used for communicating in reader / card emulation mode. In these solutions, the accessory must be disabled during the period when the phone in reader / card emulation mode needs to communicate with another device other than the accessory. The detection of the presence of the accessory is then performed with the help of a magnetometer, which indicates the presence of the accessory to the phone microcontroller, thereby enabling the phone microcontroller to select the reader or antenna to be used. As long as the accessory is not needed, the accessory is placed in a mode called "silent", in which it remains invisible to polling frames from remote readers (in particular from readers that expect to communicate when the phone is in card emulation mode). The accessory leaves the "silent" mode by decoding a specific control signal transmitted by an antenna dedicated to it on the phone side. With this solution, the accessory must be dedicated to a certain type of phone to be able to be placed in "silent" mode. Summary of the invention

[0010] Embodiments overcome all or part of the disadvantages of conventional devices with near field communication devices. More particularly, embodiments are directed to preventing the presence of a persistent NFC accessory or device from interfering with the operation of a mobile device equipped with the accessory.

[0011] An embodiment provides a mobile device comprising a near field communication router and an antenna, wherein the antenna is coupled to the router via at least one impedance matching for selecting between at least two impedance values, wherein: when a near field communication device of the second type is present, a first impedance value is selected to communicate with the near field communication device of the first type, and when the near field communication device of the second type is not present, a second impedance value is selected to communicate with the near field communication device of the first type, and the presence or absence of the near field communication device of the second type is determined based on a polling frame transmitted by the antenna.

[0012] Another embodiment provides a near field communication method for a mobile device, the mobile device comprising a near field communication router and an antenna, the antenna being coupled to the router via at least one impedance matching for selecting between at least two impedance values, wherein: when a near field communication device of the second type is present, a first impedance value is selected to communicate with the near field communication device of the first type, and when the near field communication device of the second type is not present, a second impedance value is selected to communicate with the near field communication device of the first type, and the presence or absence of the near field communication device of the second type is determined based on a polling frame transmitted by the antenna.

[0013] According to an embodiment, the device of the second type corresponds to an accessory of the mobile device.

[0014] According to an embodiment, the communication with the device of the first type is performed in a reader or card emulation mode.

[0015] According to an embodiment, the identification of the second type of device is performed with the mobile device in reader mode.

[0016] According to an embodiment, the identification of the device of the second type is performed by a microcontroller of a mobile device different from the router, the microcontroller storing a unique identifier of the device of the second type.

[0017] According to an embodiment, if no device of the first or second type is detected during the polling frame, the microcontroller erases any unique identifier of a device of the second type present in the memory.

[0018] According to an embodiment, as a result of the identification of an NFC device of the second type, the thresholds of the detector in standby mode are recalibrated.

[0019] According to an embodiment, if a previously identified NFC device of the second type is no longer detected, the thresholds of the detector in standby mode are recalibrated.

[0020] According to an embodiment, the antenna comprises two loops connected electrically in series, the two loops being intended for devices of the first type and of the second type, respectively.

[0021] According to an embodiment, the loop intended for the device of the second type surrounds or is surrounded by a magnet for aligning the mobile device with a corresponding antenna of the device of the second type.

[0022] According to an embodiment, the NFC communication between the mobile device and the device of the second type is of Type V. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above features and advantages and other features and advantages will be described in detail in the remainder of the disclosure of specific embodiments given by way of illustration and not limitation, with reference to the accompanying drawings, in which:

[0024] Figure 1 An embodiment of a near field communication system according to the first aspect is shown very schematically in block form;

[0025] Figure 2 An embodiment of a near field communication device according to the first aspect is shown very schematically and partly in block form;

[0026] Figure 3 The diagram is shown very schematically in the form of a box. Figure 2 Implementation mode of near field communication device;

[0027] Figure 3A In more detail Figure 3 A collection of steps to implement a pattern;

[0028] Figure 4An embodiment of a near field communication system according to the second aspect is shown very schematically in block form;

[0029] Figure 5 An embodiment of a near field communication device according to the second aspect is shown very schematically and partly in block form;

[0030] Figure 6 The diagram is shown very schematically in the form of a box. Figure 5 Implementation mode of a near field communication device; and

[0031] Fig. 6A In more detail Figure 6 A collection of steps to implement a pattern. DETAILED DESCRIPTION

[0032] Similar features are denoted by similar reference numerals in the various figures. In particular, common structural and / or functional features in various embodiments may have the same reference numerals and may be provided with exactly the same structure, dimensions, and material properties.

[0033] For the sake of clarity, only the steps and elements useful for understanding the described embodiments are illustrated and described in detail. In particular, the communication protocol between different NFC devices is not described in detail, and the described embodiments are compatible with common communication protocols.

[0034] Unless otherwise indicated, when two elements are referred to as being connected together, this means being directly connected without any intermediate elements except conductors, and when two elements are referred to as being coupled together, this means the two elements may be connected or they may be coupled via one or more other elements.

[0035] In the following description, when terms that quantify absolute positions (such as terms "front", "back", "top", "bottom", "left", "right", etc.) or terms that quantify relative positions (such as terms "above", "below", "upper", "lower", etc.) or terms that quantify directions (such as terms "horizontal", "vertical", etc.) are mentioned, unless otherwise specified, they refer to the orientation of the drawing.

[0036] Unless otherwise specified, the expressions “about”, “approximately”, “substantially” and “around” mean plus or minus 10%, preferably plus or minus 5%.

[0037] Figure 1 An embodiment of a near field communication system according to the first aspect is shown very schematically in block form.

[0038] In the rest of the disclosure, a system is considered formed by a mobile phone 1 (DEV1) possibly associated with an accessory 2 (DEV2) of the phone case type connected, but all will be described more generally for any system in which a mobile device can be permanently associated with a near field communication device. It can be, for example, an electronic wallet or an element that can be charged by wireless power transfer, for example according to the Qi standard. This element can request authentication with the help of NFC technology before starting charging. This element is, for example, a connected stylus or a fitness band. Another example is a battery capable of charging a phone: before charging the phone by wireless power transfer, this battery is authenticated, for example, by NFC.

[0039] Persistent association means that even outside of an NFC communication cycle, or even outside of a communication cycle over a cellular network, the device may remain connected to the phone, but may be communicating with the phone via another channel (e.g., Bluetooth).

[0040] The connected phone case comprises, for example, a display adapted to communicate with the phone circuitry to reproduce certain data such as, for example, the time, screen saver, etc. Information exchange is generally performed via a Bluetooth (BT) or Wifi link, but Near Field Communication (NFC) is required for presence detection and / or authentication of the case by the phone.

[0041] In the context of an exchange between a phone 1 and its accessory 2, the phone operates in reader mode, while the accessory operates in card emulation mode.

[0042] The phone 1 may also communicate with another device 3 (DEV3) that brings it within range. In particular, the phone may need to operate in card emulation mode to exchange with a remote reader (eg, a payment terminal or access control terminal).

[0043] Reference will be made below to the example of a payment terminal, but all that will be described more generally applies to any remote device operating in reader mode and with which the device 1 supporting the accessory 2 may communicate in NFC. For simplicity, reference will be made to an NFC device to denote an electronic device incorporating near field communication circuitry.

[0044] According to a first aspect, the mobile phone 1 comprises a single antenna NFC 12 comprising two loops 121 and 123 electrically connected in series. The first loop 121 is dedicated to NFC communication with a remote device 3 other than an accessory in card emulation mode or reader mode. The second loop 123 is dedicated to NFC communication with the accessory 2. The phone 1 is equipped with other conventional communication antennas (cellular, WiFi, Bluetooth) and in particular, in addition to NFC, a communication antenna 14, for example of the Bluetooth type, in particular for accessories.

[0045] The two terminals of the antenna are coupled to an NFC controller (and possibly to other electronic circuits) forming part of the phone 1. Figure 1 It is represented by box 18 (IC).

[0046] Preferably, the magnet 16 surrounds or is surrounded by the second loop 123. This magnet is used to align this second loop 123 of the antenna 12 with an antenna (not shown) of the accessory 2.

[0047] Figure 2 An embodiment of a near field communication device 100 according to the first aspect is shown very schematically and partly in block form.

[0048] More specifically, Figure 2 The device 100 of a mobile telephone 1 according to an embodiment is shown coupled to an antenna 12. The antenna 12 is typically associated with one or more not shown capacitive elements (internal and / or external to the device 100) to form an oscillating circuit controlled by the device 100.

[0049] The device 100 includes various digital and analog electronic circuits, depending on its application. For the phone, its NFC device is based on an NFC router (or controller) controlled by a host circuit or microcontroller 105 (host, HOST). The NFC controller serves as an interface between the digital circuit of the phone and the RF transceiver oscillating circuit. In the example considered, the antenna 12 is suitable for communicating with different devices 2 and 3 according to the loop used. To this end, the device 100 includes two impedance matching circuits 120 and 130 and a selector 140 (SEL) between the NFC controller 110 and the antenna to direct the signal Tx to be transmitted or the signal Rx to be received toward one or the other of the circuits 120 and 130 according to the selected operating mode. More specifically, the first impedance matching circuit 120 (matching circuit system, MATCHING CIRCUITRY) is dedicated to the operation in the reader mode with the accessory 2, while the second impedance matching circuit 130 (matching circuit system) is dedicated to the operation in the reader or card emulation mode with the device 3. These circuits 120 and 130 make it possible to adjust the tuning of the oscillating circuit according to the presence or absence of an accessory.

[0050] exist Figure 2 In the example, the output terminal (Tx) of the NFC controller 110 is coupled (preferably connected) to a first terminal of the selector 140, the input terminal (Rx) of the NFC controller 110 is coupled (preferably connected) to a second terminal of the selector 140, the input / output terminals of the selector 140 are coupled (preferably connected) to matching circuits 120 and 130, the selector control terminal is coupled to the NFC controller, and the antenna 12 is coupled to the two circuits 120 and 130.

[0051] For simplicity, for the NFC controller, reference is made to an output terminal Tx for signals to be transmitted and an input terminal Rx for received signals, but in practice, differential signals are most often used, with a not shown balun between the antenna and the selector or impedance matching circuit.

[0052] As a variant, the selector 140 is integrated into a single impedance matching circuit provided with components suitable for both impedance matching configurations.

[0053] The impedance value provided by the matching circuit is selected based on the characteristics of the antenna loop so that the oscillating circuit remains tuned regardless of the presence of the accessory. These values ​​are determined, for example, during integration in the device 100 according to the antenna and the integration situation, and are preferably fixed.

[0054] According to this embodiment, a general purpose input / output port (GPIO) of the NFC controller 110 transmits a digital control signal (CTRL) to the selector 140. The signal CTRL is preferably a binary signal, for example having: a high state (or high level) which controls activation of the matching circuit 120 via the selector 140 for NFC communication with the device 3 in the reader or card emulation mode in the presence of the accessory 2; and a low state (or low level) which controls activation of another matching circuit 130 via the selector 140 for NFC communication with the device 3 in the reader or card emulation mode in the absence of the accessory 2 or NFC communication with the accessory in the reader mode.

[0055] According to the described embodiment, it is provided to use polling frames transmitted by the device 100 to detect the presence or absence of an accessory in front of the antenna 12. In fact, the presence of an accessory increases the load of the antenna 12 and requires a modification of the impedance matching to maintain tuning in order to communicate with the loop 121 addressed to another NFC device.

[0056] In practice, when the reader is "idle" (i.e., no card is in its field), the reader is placed in a low power mode and then periodically generates polling frames to detect a card entering the reader's field. Once a card is detected in the field, the electronic circuitry of the device reader is "woken up" (out of standby mode) and a communication or transaction with the card can be initiated. Polling frames are generally denoted by the acronyms LPCD (Low Power Card Detection) or LPTD (Low Power Tag Detector).

[0057] When a "persistent" accessory is detected, provision is made to store its identifier to account for its presence, including when the phone needs to be exchanged with another device. More particularly, the impedance matching remains in the state determined by circuit 120 as long as the accessory remains present (associated with the phone).

[0058] Figure 3 The diagram is shown very schematically in the form of a box. Figure 2 Implementation mode of near field communication device.

[0059] Figure 3A In more detail Figure 3 A collection of steps to implement a pattern.

[0060] When it is in low power mode, the NFC device 1 periodically activates (boxes 300 "field detection + polling" and 310 "detection?") the field detector to detect the presence of a device in reader mode and transmits a radio frequency signal to detect the presence of a device in card emulation mode. During detection, the controller 110 transmits an identification request to obtain an identifier of the device (generally a unique identifier - UID or Unique Identifier).

[0061] In case an electromagnetic field is detected (output "Field" of block 310), this means that the phone 1 has captured the electromagnetic field and is probably in the field of the reader. The mobile phone 1 then operates in card emulation mode. The phone circuit is awakened so that communication with the reader NFC device 3 can begin (block 320 "Communication with R / W"). Then, a data exchange is performed between the phone and the reader in NFC. Once the exchange is over (block 330 "R / W removed"), the device returns to standby or low power mode and it returns to step 300 of field detection and polling frame transmission.

[0062] When no field is detected at step 300, the controller 110 transmits a polling frame to detect the presence of an electronic tag (NFC device in card emulation mode). This detection itself usually uses amplitude and / or phase changes of a signal across an oscillating circuit, these parameters being modified when a card is present.

[0063] In the event that a card is present (output "Tag" of block 310), the identifier obtained at step 300 is compared by controller 110 to potential unique identifiers previously stored in memory (block 340 "Is Accessory UID Known?").

[0064] When the unique identifier is present in the memory (output "yes" of block 340), this means that the accessory has been taken into account (e.g., the phone has remained in its case since the last comparison). Via the calibration phase to be described below, if relevant, then the impedance matching is considered correct and it returns to standby mode until the next detection and polling frame (step 300).

[0065] When the unique identifier is not present in the memory (output “No” of block 340 ), the circuitry of the phone and in particular its main processor 105 (host) is awakened and the phone communicates with the NFC device to determine whether it is accessory 2 or NFC device 3 ( 351 “Read Tag” and 352 “Accessory or Legacy?”, Figure 3A ).

[0066] In the presence of the NFC device 3 (output "Legacy" of block 352), the phone 1 operates in reader mode and the NFC device 3 operates in card emulation mode. The circuitry of the phone is awakened so that communication with the NFC device 3 can begin (block 354 "Communication with Tag"). Then, a data exchange is performed between the card and the reader (phone) in NFC. Once the exchange is finished (block 356 "Tag removed"), the tag is actually removed from the phone ("Tag removed") and the device returns to standby or low power mode, and it returns to step 300 of field detection and polling frame transmission.

[0067] In the case where it is detected at step 352 that the device present in the field transmitted by the phone is accessory 2 (output "Accessory" of block 352) (i.e. a device intended to remain permanently associated with the mobile phone), the accessory is identified by the phone microcontroller 105 (host) and its identifier is stored (block 358 "Authentication + Save UID"). The storage of the identifier will then be used at step 340 (during subsequent polling frames) to determine whether the device in card emulation mode present in the field of device 1 is a new device that has entered the field since the last detection cycle or corresponds to an accessory that remains in the field.

[0068] As a result of storing the new accessory (output of block 350 "Accessory authenticated"), the device implements the usual calibration process to adjust the level of amplitude to the new environment of the phone. For example, a step (block 360 "LPTD calibration") calibrates the low power mode detection threshold LPTD to take into account the load formed by the accessory. The low power polling loop then compensates for the presence of the accessory to correctly detect any other NFC devices.

[0069] Then, as long as no field change is detected (output "No" of block 380 "Detect?"), the mobile phone 1 returns to standby mode while transmitting a regular LPTD cycle (block 370, "LPTD").

[0070] If the field and the electronic tag are not detected at block 310 (output "No" of block 310), this calibration 360 is also performed. This may mean that the accessory previously present and recorded is no longer relevant to the mobile device 1. Then, its identifier recorded when detected is erased from the mobile device memory (block 390 "all known UIDs cleared"), after which the calibration is performed. If relevant, information is sent to the host circuit 105 (host) to give a potential notification to the user of the mobile device that the accessory is no longer detected.

[0071] At the end of calibration 360, the mobile phone returns to standby mode (block 370), and when a load change is detected ("yes" output of block 380), the phone returns to steps 300 and 310 to determine the nature of the NFC device causing the interference.

[0072] When the phone must communicate with a device 3, the accessory 2 preferably does not interfere with the detection of this device 3. For this reason, the accessory 2 should not respond to the phone if it is in reader mode, nor should it respond to a device 3 operating in reader mode to leave the communication to the phone in card emulation mode.

[0073] According to an embodiment, it is then provided that the accessory 2 is placed in a "silent" mode in which it does not respond to NFC polling frames. The accessory 2 is switched to silent mode under the control of the phone 1, which transmits in NFC a specific command that only the accessory 2 can interpret. When the phone 1 wishes to communicate with the accessory, it sends a command to deactivate the silent mode to the accessory 2. This solution requires that the phone and the accessory are compatible with this operation. In particular, the phone and the accessory have in their command sets the commands required to switch into and out of the silent mode of the accessory.

[0074] According to another embodiment, it is provided that the communication between the phone 1 and the accessory 2 is performed in a specific type, namely type V. Type V is described in further detail in the ISO / IEC 15693 standard, for example. The advantage then lies in the fact that the communication between the phone 1 and another device 3 in reader mode generally uses type A or B, in particular for payment and access control applications. Therefore, since the accessory does not respond to type A or type B requests but only to type V requests, these applications are not affected by its presence. Types A, B and V are defined by the NFC Forum.

[0075] Figure 4 An embodiment of a near field communication system according to the second aspect is shown very schematically in block form.

[0076] For simplicity, only the Figure 1 The difference between the embodiments, Figure 4 The rest of the embodiment includes Figure 1 Elements of an embodiment.

[0077] According to a second aspect, the mobile phone 1 comprises two different NFC antennas 125 and 127. The first antenna 125 is dedicated to NFC communication with a remote device 3 other than the accessory 2 in card emulation mode or reader mode. The second antenna 127 is dedicated to NFC communication with the accessory 2 in reader mode. In this embodiment, the magnet 16 surrounds the second antenna 127 or is surrounded by the second antenna 127.

[0078] Therefore, with Figure 1 The difference compared to the embodiment is that two antennas are used instead of two loops of the same antenna.

[0079] Figure 5 An embodiment of a near field communication device according to the second aspect is shown very schematically and partly in block form.

[0080] For simplicity, only the Figure 2 The difference between the embodiments, Figure 5 The rest of the embodiment includes Figure 2 Elements of an embodiment.

[0081] The NFC device 1 includes two antennas 125 and 127, which are coupled (preferably connected) to two impedance matching circuits (matching circuitry) 120' and 130', respectively.

[0082] In this embodiment, a selector 140' (SEL) enables the NFC signal to be transmitted by the NFC device 1 comprising the circuit 100' to be directed towards one or the other of the antennas 125 and 127, depending on the remote device 2 or 3 with which the mobile phone 1 wishes to communicate. The selector 140' is an antenna selector, each antenna being associated with its impedance matching circuit. Figure 2 In the same manner as in NFC, the selector is coupled to an NFC controller 110' (NFC controller), which itself is coupled to a host circuit 105' (host).

[0083] Figure 6 The diagram is shown very schematically in the form of a box. Figure 5 Implementation mode of near field communication device.

[0084] Fig. 6A In more detail Figure 6 A collection of steps to implement a pattern.

[0085] In these figures, “Ant1” refers to the antenna 125 dedicated to the NFC device 3 , while “Ant2” refers to the antenna 127 dedicated to the accessory 2 .

[0086] While in low power or standby mode, NFC device 1 periodically activates (block 600, "LPTD") a polling loop on both antennas 125 and 127 to detect load changes reflecting the arrival or departure of NFC device 2 or 3 (block 602, "Detect?").

[0087] As long as no load change is detected ("No" output of block 602), the polling loop 600 is repeated.

[0088] In case of change detection (output "yes" of block 602), the field detector for detecting the presence of a device in reader mode is activated and a radio frequency signal for detecting the presence of a device in card emulation mode is transmitted by antenna 125 (blocks 610 "Field detection + polling on Ant1" and 612 "Ant1 detection?"). During detection, controller 110' transmits an identification request to obtain an identifier of the device (generally a unique identifier - UID).

[0089] In the case where an electromagnetic field is detected (output "field" of block 612), this means that the phone 1 has captured the electromagnetic field and is probably in the field of the reader. The mobile phone 1 then operates in card emulation mode. The phone circuit is awakened so that communication with the reader NFC device 3 can begin (block 620 "communication with R / W"). Then, a data exchange is performed between the phone and the reader in NFC by means of the antenna 125. Once the exchange is finished (block 622 "R / W removed"), it returns to step 610 of field detection and transmission of the polling frame to the antenna 125.

[0090] In the absence of a detected field at step 610 , the controller 110 ′ transmits a polling frame on the antenna 125 to detect the presence of an electronic tag (NFC device in card emulation mode).

[0091] When the presence of a card is detected by antenna 125 (output "Tag" of block 612), controller 110' compares its identifier (typically a unique identifier - UID) obtained at step 610 with previously stored potential unique identifiers (block 630 "Is accessory UID known?").

[0092] If the unique identifier is present in the memory ("yes" output of block 630), then this means that it is accessory 2 and has been taken into account by antenna 127 (e.g. the phone has remained in its case since the last comparison). The impedance matching is then considered correct and, if relevant, returns to standby mode via the calibration phase to be described below until the next detection and polling frame (step 610).

[0093] If the unique identifier is not present in the memory (output “No” of block 630 ), the circuitry of the phone and in particular its main processor 105 ′ (host) is awakened and the phone communicates with the NFC device to determine whether it is accessory 2 or NFC device 3 ( 641 “Read Tag” and 642 “Accessory or Legacy?”, Fig. 6A ).

[0094] In the case where one of the antennas detects that the device present in the field emitted by the phone is an NFC device 3 (output "legacy" of block 642), the device must use antenna 125. It is then verified (block 643 "Ant1?") whether antenna 125 is active. If so (output "yes" of block 643), the phone 1 operates in reader mode and the NFC device 3 operates in card emulation mode. The phone circuit is awakened so that communication with the NFC device 3 can begin (block 644 "communication with tag"). Then, a data exchange is performed between the card and the reader (phone) in NFC. Once the exchange is over (block 645 "tag removed"), the tag is actually removed from the phone ("tag removed") and the host circuit 105' communicates with the NFC controller 110' to select the two antennas (block 646 "NCI parameters Ant1+Ant2") for subsequent polling frames. For example, the method resumes at step 610 to detect the presence of another NFC device and any addition or removal of accessory 2 that may have occurred since the last polling frame.

[0095] If at step 642 one of the antennas 125, 127 detects that the device present in the field transmitted by the phone is accessory 2 (output "Accessory" of block 642), i.e., a device intended to maintain a permanent association with the mobile phone, the device uses antenna 127. It is then checked (block 647 "Ant2?") whether antenna 127 is active. If not (output "No" of block 647), the host circuit 105' communicates with the NFC controller 110' to select antenna 127 (block 648 "NCIparam.Ant2").

[0096] For example, the selection of antenna 127 ("Ant2 selection") causes the mobile phone 1 to transmit a polling frame by means of antenna 127 to detect the presence of an electronic tag (NFC device in card emulation mode) (block 660 "Poll on Ant2").

[0097] When antenna 127 detects the presence of a device (output "Tag" of block 662 "Ant2 detected?"), controller 110' compares its identifier to previously stored potential unique identifiers of host circuitry 105' (block 665 "Accessory UID known?").

[0098] If the unique identifier is present in the memory (output "yes" of block 665), then this means that it is accessory 2 that has been considered (e.g. the phone has remained in its case since the last comparison). The impedance matching is then considered to be correct and, if relevant, then switching back to standby mode is done via the calibration phase (blocks 600 and 602).

[0099] If the unique identifier is not present in the memory (output “No” of block 665), the circuitry of the phone and in particular its host processor 105′ (HOST) is awakened and the phone communicates with the NFC device, as previously described with respect to antenna 127, to determine whether it is in the presence of accessory 2 or in the presence of NFC device 3 (blocks 641 and 642, Fig. 6A ).

[0100] In the case that the tag in the field of antenna 127 is NFC device 3 (output "legacy" of block 642), host circuit 105' communicates with NFC controller 110' to select antenna 125 after verifying (block 643 "Ant1?") that antenna 127 is activated (output "No" of block 643). The selection of antenna 125 (block 649 "NCI param.Ant1") causes the mobile phone not to perform communication with NFC device 3 and return to step 610 to perform detection using antenna 125 ("Ant1 selected").

[0101] In the case where the tag in the field of antenna 127 is accessory 2 (output "Accessory" of block 642), after verifying (block 647 "Ant2?") that antenna 127 is being used effectively (output "Yes" of block 647), the accessory is identified by the host microcontroller 105' of the phone and its identifier is stored (block 650, "Authentication+Save UID"). The storage of the identifier will subsequently be used at steps 630 and 665 (during subsequent polling frames) to determine whether the device in card emulation mode present in the field of device 1 is a new device that has entered the field since the last detection cycle or corresponds to an accessory that has remained in the field.

[0102] Once the storage is performed, the host circuit 105' communicates with the NFC controller 110' to select two antennas (block 651 "NCI param.Ant1+Ant2") for subsequent polling frames.

[0103] At the end of storing the new accessory ("Accessory Authenticated"), device 100' implements the usual calibration process (step 670, corresponding to step 360) to adjust the amplitude level to the new environment of the phone.

[0104] The mobile phone 1 then returns to standby mode while transmitting a constant LPTD cycle (block 600) as long as no field changes are detected.

[0105] If neither the field nor the digital tag is detected during the step 612 of detection by the antenna 125 (output "No" of block 612), then only the polling frame is transmitted via the antenna 127 (block 660). If no accessory is detected from the field transmitted by the antenna 127 (output "No" of block 662), then this means that no accessory is close to the mobile device 1. Then, any identifier recorded is erased from the memory of the mobile device (block 680, "all known UIDs cleared"). If relevant, information is sent to the host circuit 105' (host) to provide a potential notification to the user of the mobile device that the accessory is no longer detected.

[0106] The thresholds considered by the polling cycle LPTD are recalibrated (block 670) to account for the absence of the accessory, and the mobile device switches back to standby mode (blocks 600 and 602) via periodic polling frames.

[0107] exist Figures 4 to 6A In an embodiment of the present invention, the impedance matching circuit 120' of the antenna 125 can be adjustable between two values, depending on whether an accessory is present, as in the first aspect. As a variant, the corresponding matching is performed during a calibration phase. This can also be provided on the side of the circuit 130', but this is less useful because it means that an accessory is present when communication with this antenna is required.

[0108] As for the embodiment described in relation to the first aspect ( Figures 1 to 3A ), in the above-mentioned embodiment related to the second aspect ( Figures 4 to 6A ), offering the possibility to put the accessory in silent mode or to put its NFC communication in Type V.

[0109] An advantage of the described embodiments is that they avoid the use of a magnetometer.

[0110] Another advantage of the described embodiments using Type V for NFC accessory to phone communications is that they are compatible with any accessory without requiring a specific command set.

[0111] Various embodiments and variations have been described. It will be appreciated by those skilled in the art that certain features of these various embodiments and variations may be combined, and that other variations will occur to those skilled in the art. In particular, each antenna loop may contain one or more turns. In addition, although not specified, the antennas for applications to which the present disclosure is directed are formed by planar windings.

[0112] Finally, based on the functional indications given above, the practical implementation of the described embodiments and variants is within the capabilities of a person skilled in the art, in particular with regard to the dimensioning of the antenna or antenna loop.

[0113] Other examples of embodiments of the present disclosure are discussed below.

[0114] Example 1: A mobile device comprising a near field communication router (110') and two antennas (125, 127) coupled to the router via a selector (140'), wherein a first antenna (125) is dedicated to a first operating mode with a first type of NFC device (3), a second antenna (127) is dedicated to a second operating mode with a second type of NFC device (2), and selection of one antenna or the other is performed as a result of detection performed during a polling frame (600) transmitted by one antenna or the other antenna.

[0115] Example 2: A near field communication method for a mobile device, the mobile device comprising a near field communication router (110') and two antennas (125, 127) coupled to the router via a selector (140'), wherein the first antenna (125) is dedicated to a first operation mode with a first type of NFC device (3), the second antenna (127) is dedicated to a second operation mode with a second type of NFC device (2), and the selection of one antenna or the other antenna is performed as a result of a detection performed during a polling frame (600) transmitted by one antenna or the other antenna.

[0116] Example 3: A mobile device according to example 1, or a method according to example 2, wherein the second type of device corresponds to an accessory (2) of the mobile device (1).

[0117] Example 4: A mobile device according to example 1 or 3, or a method according to example 2 or 3, wherein the communication with the first type of device (3) is performed using the first antenna (125) in a reader or card emulation mode.

[0118] Example 5: A mobile device according to any one of Examples 1, 3 and 4, or a method according to any one of Examples 2 to 4, wherein the identification of the second type of device is performed by the mobile device communicating with the second antenna (127) in reader mode.

[0119] Example 6: A mobile device or method according to Example 5, wherein identification (650) of a second type of device (2) is performed by a microcontroller (105') of the mobile device, the microcontroller (105') being different from the router (110'), and the microcontroller then stores a unique identifier (650) of the second type of device.

[0120] Example 7: A mobile device or method according to Example 6, wherein when no device is detected by either antenna during the polling frame, the microcontroller erases any unique identifier of the second type of device present in the memory (680).

[0121] Example 8: The mobile device or method of any of Examples 5 to 7, wherein as a result of the second antenna (127) identifying (650) the second type of NFC device, a threshold of the low power detector is recalibrated (670).

[0122] Example 9: A mobile device according to any of Examples 1, 3 to 8, or a method according to any of Examples 2 to 8, wherein the threshold of the low power detector is recalibrated (670) when a previously identified second type of NFC device (650) is no longer detected by either antenna during a polling frame.

[0123] Example 10: A mobile device according to any one of Examples 1, 3 to 9, or a method according to any one of Examples 2 to 9, wherein when a second type of device having an identifier that has not yet been stored by the microcontroller is identified (650) by the first antenna (125), the antenna is switched (648) so that detection is performed on the second antenna (127).

[0124] Example 11: A mobile device or method according to Example 10, wherein an antenna (127) intended for a second type of device surrounds or is surrounded by a magnet (16), and the magnet (16) is used to align the mobile device with a corresponding antenna of the second type of device.

[0125] Example 12: A mobile device according to any one of Examples 1, 3 to 11, or a method according to any one of Examples 2 to 11, wherein the second type of device is of type V.

Claims

1. A mobile device, comprising: antenna; at least one impedance matching circuit coupled to the antenna; as well as A near field communication (NFC) router is coupled to the at least one impedance matching circuit and is configured to: determining the presence or absence of a second type of NFC device based on the polling frame transmitted by the antenna; controlling the at least one impedance matching circuit to select a first impedance value to communicate with the first type of NFC device in the presence of a second type of NFC device; as well as The at least one impedance matching circuit is controlled to select a second impedance value to communicate with the first type of NFC device in the absence of the second type of NFC device. 2 . The mobile device of claim 1 , wherein the second type of NFC device corresponds to an accessory of the mobile device. 3 . The mobile device of claim 1 , wherein the mobile device is configured to communicate with a first type of NFC device when in a reader or card emulation mode. 4 . The mobile device of claim 1 , wherein the mobile device is configured to determine identification of the second type of NFC device when in the reader mode.

5. The mobile device of claim 4, wherein the mobile device comprises a memory and a microcontroller, the microcontroller being configured to determine identification of a second type of NFC device, wherein the microcontroller is different from the NFC router, and wherein the microcontroller is configured to store a unique identifier of the second type of NFC device in the memory.

6. The mobile device according to claim 5, wherein: In response to not detecting a first type or a second type of NFC device during the polling frame, the microcontroller is configured to erase any unique identifier of the second type of NFC device present in the memory.

7. The mobile device according to claim 4, wherein: In response to the identification of the second type of NFC device, the mobile device is configured to recalibrate a threshold of the detector in the standby mode.

8. The mobile device according to claim 1, wherein: In response to no longer detecting the previously identified NFC device of the second type, the mobile device is configured to recalibrate a threshold of the detector in the standby mode.

9. The mobile device of claim 1, wherein the antenna comprises two loops electrically connected in series, intended for a first type of NFC device and a second type of NFC device, respectively.

10. The mobile device of claim 9, wherein the loop intended for the second type of NFC device surrounds or is surrounded by a magnet configured to align an antenna of the mobile device with a second antenna of the second type of NFC device.

11. The mobile device of claim 1, wherein the NFC communication between the mobile device and the second type of NFC device is Type V.

12. A system comprising: The mobile device according to claim 1; A near field communication device of a first type; as well as A second type of near field communication device.

13. A near field communication (NFC) method for a mobile device, the mobile device comprising a near field communication (NFC) router, an antenna, and at least one impedance matching circuit coupling the NFC router and the antenna, the method comprising: determining the presence or absence of a second type of NFC device based on the polling frame transmitted by the antenna; In the presence of a NFC device of the second type, selecting a first impedance value to communicate with the NFC device of the first type; as well as In the absence of an NFC device of the second type, a second impedance value is selected to communicate with the NFC device of the first type. The method of claim 13 , wherein the second type of NFC device corresponds to an accessory for the mobile device.

15. The method of claim 13, further comprising communicating with the first type of NFC device using the mobile device in a reader or card emulation mode.

16. The method of claim 13, further comprising identifying a second type of NFC device using the mobile device in reader mode.

17. The method according to claim 16, further comprising: A microcontroller of the mobile device, different from the NFC router, performs identification of the second type of NFC device; as well as A unique identifier of the second type of NFC device is stored by the microcontroller.

18. The method of claim 17, further comprising, in response to not detecting a first type or a second type of NFC device during the polling frame, erasing, by the microcontroller, any unique identifier of the second type of NFC device present in a memory of the mobile device.

19. The method of claim 18, further comprising, in response to identifying the second type of NFC device, recalibrating a threshold of the detector in the standby mode.

20. The method of claim 13, further comprising, in response to no longer detecting a previously identified NFC device of the second type, recalibrating a threshold of a detector in the standby mode.

21. The method of claim 13, wherein the antenna comprises two loops electrically connected in series, intended for a first type of NFC device and a second type of NFC device, respectively.

22. The method of claim 21, wherein the loop intended for the second type of NFC device surrounds or is surrounded by a magnet, and the method further comprises aligning the mobile device with a corresponding antenna of the second type of NFC device via the magnet.

23. The method of claim 13, wherein the NFC communication between the mobile device and the second type of NFC device is Type V.

24. A system comprising: Mobile devices, including: antenna; at least one impedance matching circuit coupled to the antenna; and A near field communication (NFC) router is coupled to the at least one impedance matching circuit and is configured to: determining the presence or absence of a second type of NFC device based on the polling frame transmitted by the antenna; controlling the at least one impedance matching circuit to select a first impedance value to communicate with the first type of NFC device in the presence of a second type of NFC device; and controlling the at least one impedance matching circuit to select a second impedance value to communicate with the first type of NFC device in the absence of the second type of NFC device; A near field communication device of a first type; and A second type of near field communication device.

25. The system of claim 24, wherein the second type of NFC device is an accessory for a mobile device.

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