NFC device

Abstract

NFC Device This description relates to a mobile device comprising a near-field communication router and an antenna (12), connected to the router via at least one impedance matching circuit between at least two impedance values, wherein: a first impedance value is selected to communicate with a first-type near-field communication device (3) in the presence of a second-type near-field communication device (2), a second impedance value is selected to communicate with a first-type near-field communication device in the absence of a second-type near-field communication device, the presence or absence of a second-type near-field communication device being determined from interrogation frames transmitted by the antenna. Figure for the abstract: Fig. 1

Description

Title of the invention: NFC device technical field

[0001] This description relates generally to the field of near field communications and, more particularly, to the association of a mobile device with several near field communication devices, some of which may be permanently associated with the device. Previous technique

[0002] Near Field Communication (NFC) systems exploit a radio frequency electromagnetic field generated by a device (reader) to communicate with another device (card).

[0003] The same device can be either a reader or a card depending on the application.

[0004] Near field communications are generally standardized or meet characteristics defined by stakeholders in the field. For example, the "NFC Forum" sets characteristics that communication devices must meet in order to exchange information with each other, depending, for example, on the application or the nature of the exchanges (payment, access control, authentication, file exchange, etc.).

[0005] To communicate between a device operating in reader mode and a device operating in card mode, the reader generates an electromagnetic field that is charged by a card within range. Communication takes place according to various protocols that involve modifying the phase and / or amplitude of a modulation carrier emitted by the reader.

[0006] In the applications described, the device that can be permanently associated, that is, for a duration longer than that of a typical call, may be an accessory attached to the mobile device, for example, a smart case that displays the time, an electronic wallet, etc. The accessory generally uses near-field communication (NFC) to be recognized (paired or authenticated), in card mode, by the mobile phone operating as a reader, but then communicates functionally with the latter via a connection of another type, for example, Bluetooth, Wi-Fi, etc. The fact that the accessory is in card mode may cause the mobile phone to see two "cards" when it needs to establish another card-mode connection with a remote reader, and therefore reject the connection.Such a situation is likely to occur, for example, with a payment terminal that detects two card-type communication devices within its field of view (the phone and its case).

[0007] Systems are known that provide a specific reader or antenna, separate from the reader or antenna used for card / reader mode communications, to communicate with the accessory. In these solutions, the accessory must be deactivated when the phone's card / reader mode communication with a device other than the accessory is required. Accessory presence detection is then performed using a magnetometer, which indicates to the phone's microcontroller that the accessory is present, allowing the microcontroller to select the reader or antenna to use. As long as the accessory is not needed, it is placed in a so-called "mute" mode, in which it remains invisible to query frames from a remote reader, particularly a reader wishing to communicate when the phone is in card mode.The accessory exits "mute" mode by decoding a specific command emitted by its dedicated antenna on the phone side. With this solution, the accessory must be designed for a specific type of phone in order to be placed in "mute" mode. Summary of the invention

[0008] One embodiment overcomes all or part of the drawbacks of conventional near-field communication devices. More specifically, one embodiment aims to ensure that the presence of permanent NFC accessories or devices does not disrupt the operation of a mobile device carrying that accessory.

[0009] One embodiment provides a mobile device comprising a near field communication router and an antenna, connected to the router via at least one impedance matching circuit between at least two impedance values, wherein: a first impedance value is selected to communicate with a near field communication device of a first type in the presence of a near field communication device of a second type, a second impedance value is selected to communicate with a near field communication device of the first type in the absence of a near field communication device of the second type, the presence or absence of a near field communication device of the second type being determined from interrogation frames emitted by the antenna.

[0010] Another embodiment provides a method for near-field communication of a mobile device comprising a near-field communication router and an antenna, connected to the router via at least one impedance matching circuit between at least two impedance values, wherein: a first impedance value is selected to communicate with a near-field communication device of a first type in the presence of a near-field communication device of a second type, a second value impedance is selected to communicate with a near field communication device of the first type in the absence of a near field communication device of the second type, the presence or absence of a near field communication device of the second type being determined from interrogation frames emitted by the antenna.

[0011] According to one embodiment, the second type of device corresponds to an accessory of the device.

[0012] According to one embodiment, communication with the first type of device is carried out in reader or card mode.

[0013] According to one embodiment, identification of a device of the second type is carried out with the device in reader mode.

[0014] According to one embodiment, the identification of a device of the second type is carried out by a microcontroller of the device, separate from the router, the microcontroller storing a unique identifier of the device of the second type.

[0015] According to one embodiment, if no device of the first or second type is detected during a polling frame, the microcontroller erases any unique identifier of a device of the second type present in memory.

[0016] According to one embodiment, following the identification of a second type NFC device, the thresholds of a detector in standby mode are recalibrated.

[0017] According to one embodiment, if a previously identified NFC device of the second type is no longer detected, the thresholds of a detector in standby mode are recalibrated.

[0018] According to one embodiment, the antenna comprises two loops electrically in series, respectively intended for devices of the first and second type.

[0019] According to one embodiment, the loop for devices of the second type surrounds or is surrounded by a magnet for aligning the respective antennas of the apparatus and the device of the second type.

[0020] According to one embodiment, NFC communications between the device and devices of the second type are of type V. Brief description of the drawings

[0021] 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:

[0022] [Fig.1] represents, in a very schematic way and in block form, a mode of embodiment of a near field communication system according to a first aspect;

[0023] [Fig.2] represents, in a very schematic, partial and block-like way, an embodiment of a near field communication device according to the first aspect;

[0024] [Fig.3] illustrates, in a very schematic way and in block form, a method of implementing the near field communication device of [Fig.2];

[0025] [Fig.3A] illustrates, in more detail, a set of steps in the implementation method of [Fig.3];

[0026] [Fig.4] represents, in a very schematic way and in block form, an embodiment of a near field communication system according to a second aspect;

[0027] [Fig.5] represents, in a very schematic, partial and block-like way, an embodiment of a near field communication device according to the second aspect;

[0028] [Fig. 6] illustrates, in a very schematic and block-like manner, one method of implementing the near-field communication device of [Fig. 5]; and

[0029] [Fig.6A] illustrates, in more detail, a set of steps in the implementation method of [Fig.6]. 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 detailed. In particular, the communication protocols between the different NFC devices have not been detailed, as the described embodiments are compatible with standard communication protocols.

[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 "in the order of" mean within 10%, preferably within 5%.

[0035] Fig. 1 represents, in a very schematic way and in block form, a mode of embodiment of a near field communication system according to a first aspect.

[0036] In the following description, a system consisting of a mobile phone 1 (DEV1) that can be associated with an accessory 2 (DEV2) such as a connected phone case is assumed, but everything described herein applies more generally to any system in which a mobile device can be permanently associated with a near-field communication device. This could be, for example, an electronic wallet or an item that could be recharged by wireless energy transfer, for example, according to the Qi standard. This item could, before starting to charge, request authentication using NFC technology. This item is, for example, a stylus or a connected bracelet (a "fitness band"). Another example is a battery capable of recharging the phone: before recharging the phone by wireless energy transfer, this battery is, for example, authenticated by NFC.

[0037] By permanent association, we mean a device capable of remaining linked to the phone even outside of NFC communication periods, or even outside of cellular network communication periods, and of nevertheless exchanging with the phone via another channel (for example, Bluetooth).

[0038] A communicating phone case includes, for example, a display adapted to communicate with the phone's circuits to duplicate certain information, such as the time, a screensaver, etc. Information exchange is generally carried out via Bluetooth (BT) or Wi-Fi, but near-field communication (NFC) is used for presence detection and / or authentication of the case by the phone.

[0039] In the context of the exchanges between the phone 1 and its accessory 2, the phone operates in reader mode and the accessory in card mode.

[0040] The phone 1 is also capable of communicating with another device 3 (DEV3) within range. In particular, the phone may need to operate in card mode to exchange data with a remote reader, for example a payment terminal or an access control terminal.

[0041] We will subsequently take the example of a payment terminal, but everything described herein applies more generally to any remote device operating as a reader and with which the device 1 carrying an accessory 2 is capable of communicating via NFC. For simplicity, we will refer to NFC devices to designate electronic devices incorporating near-field communication circuits.

[0042] According to the first aspect, the mobile phone 1 has a single NFC antenna 12 which has two loops 121 and 123 electrically connected in series. A first loop 121 is dedicated to NFC communications, in card mode or reader mode, with a remote device 3 other than an accessory. A second loop 123 is dedicated to NFC communications with accessory 2. The phone 1 is equipped with other common communication antennas (cellular, WiFi, Bluetooth) and, in particular, a communication antenna 14, outside NFC, for example of the Bluetooth type, used, among other things, for the accessory.

[0043] Two terminals of the antenna are connected to an NFC controller (and where appropriate to other electronic circuits) forming part of the telephone 1 symbolized in [Fig.1] by a block 18 (IC).

[0044] Preferably, a magnet 16 surrounds or is surrounded by the second loop 123. This magnet serves to align this second loop 123 of the antenna 12 with an antenna (not shown) of the accessory 2.

[0045] Figure 2 represents, in a very schematic, partial, and block-like manner, a method of implementation of a 100 near field communication device according to the first aspect.

[0046] More particularly, [Fig.2] represents a device 100 of the mobile phone 1 according to one embodiment, connected to the antenna 12. The antenna 12 is generally associated with one or more capacitive elements not shown (internal and / or external to the device 100) to form an oscillating circuit controlled by the device 100.

[0047] The device 100 comprises various digital and analog electronic circuits depending on its application. For a telephone, its NFC device is based on an NFC router (or controller) controlled by a host circuit or microcontroller 105 (HOST). The NFC controller serves as an interface between the telephone's digital circuits and the radio frequency transmit / receive oscillating circuit. In the example considered, the antenna 12 is adapted to communicate with different devices 2 and 3 depending on the loop used. To do this, the device 100 includes, between the NFC controller 110 and the antenna, two impedance matching circuits 120 and 130 and a selector 140 (SEL) to direct the signals to be transmitted (Tx) or received (Rx) to one or the other of the circuits 120 and 130 depending on the operating mode selected.More specifically, a first impedance matching circuit 120 (MATCHING CIRCUITRY) is dedicated to operation in reader mode with accessory 2, and a second impedance matching circuit 130 (MATCHING CIRCUITRY) is dedicated to operation in reader or card mode with device 3. These circuits 120 and 130 allow the tuning of the oscillating circuit to be adjusted according to the presence or absence of an accessory.

[0048] In the example of [Fig.2]: an output (Tx) of the NFC 110 controller is connected, preferably connected, to a first terminal of the selector 140; an input (Rx) of the NFC 110 controller is connected, preferably connected, to a second terminal of the selector 140; an input / output terminal of selector 140 is connected, preferably connected, to the adaptation circuits 120 and 130; a selector control terminal is connected to the NFC controller; antenna 12 is connected to the two circuits 120 and 130.

[0049] For simplicity, reference is made, at the level of the NFC controller, to a Tx output of the signals to be transmitted and an Rx input of the signals received, but in practice, differential signals are most often used, with a mode-changing converter (balun) not shown being present between the antenna and the selector or the impedance matching circuits.

[0050] Alternatively, the selector 140 is integrated into a single impedance matching circuit provided with components adapted to the two impedance matching configurations.

[0051] The choice of impedance values ​​provided by the matching circuits depends on the characteristics of the antenna loops so that the oscillating circuit remains tuned whether the accessory is present or not. These values ​​are determined, for example, at the time of integration of the circuit into the device 100 as a function of the antenna and the integration, and are preferably fixed.

[0052] According to this embodiment, a general-purpose input / output (GPIO) port of the NFC controller 110 sends a digital control signal (CTRL) to the selector 140. The CTRL signal is preferably a binary signal in which, for example: a high state (or high level) controls the activation, via the selector 140, of the adapter circuit 120 for NFC communication, in reader or card mode with a device 3, in the presence of the accessory 2; and a low state (or low level) controls the activation, via the selector 140, of the other adapter circuit 130 for NFC communication, in reader or card mode with a device 3 or in reader mode with the accessory, in the absence of the accessory 2.

[0053] According to the embodiments described, it is planned to exploit interrogation frames emitted by the device 100 to detect the presence or absence of an accessory in front of the antenna 12. Indeed, the presence of an accessory loads the antenna 12 and requires, for communication with the loop 121 destined for another NFC device, to modify the impedance matching in order to maintain the agreement.

[0054] In practice, a reader, when it is "empty," that is, without a card in its field, is placed in a low-power mode and then periodically generates polling frames in order to detect a card entering the reader's field. Once a card is detected in the field, electronic circuits of the reader device are "waked up" (exit sleep mode) and communication or A transaction with the card can be initiated. The query frames are generally designated by the acronym LPCD (Low Power Card Detection) or LPTD (Low Power Tag Detector).

[0055] When a "permanent" accessory is detected, its identifier is stored to take its presence into account, even when the phone needs to communicate with another device. More specifically, the impedance matching remains in the state set by circuit 120 as long as the accessory remains present (associated with the phone).

[0056] Fig. 3 illustrates, in a very schematic way and in block form, a method of implementing the near field communication device of Fig. 2.

[0057] [Fig.3A] illustrates, in more detail, a set of steps in the implementation method of [Fig.3].

[0058] When in low-power mode, the NFC device 1 periodically activates (blocks 300, "Field Det + Polling" and 310, "Detection?") a field detector to detect the presence of a device in reader mode and emits a radio frequency signal to detect the presence of a device in card mode. Upon detection, the controller 110 sends an identification request to obtain the device identifier (generally a unique identifier - UID).

[0059] In the event of the detection of an electromagnetic field (output "Field" of block 310), this means that the phone 1 is detecting an electromagnetic field and is likely within the range of a reader. The mobile phone 1 then operates in card mode. The phone's circuits are activated so that it can communicate with an NFC reader device 3 (block 320 "Com with R / W"). A data exchange then takes place via NFC between the phone and the reader. Once the exchange is complete (block 330 "R / W removal"), the device returns to standby or low-power mode, and the process resumes at step 300 of field detection and transmission of interrogation frames.

[0060] If no field is detected in step 300, the controller 110 sends an interrogation frame to detect whether an electronic tag (NFC device in card mode) is present. This detection, which is standard practice, exploits variations in amplitude and / or phase of the signal across the oscillating circuit, these parameters being modified in the presence of a card.

[0061] In the presence of a card (output “Tag” of block 310), the identifier obtained in step 300 is compared by the controller 110 to a potential unique identifier previously stored in memory (block 340 “Accessory UIDs known?”).

[0062] If the unique identifier is present in memory (output Y of block 340), this means that the accessory has already been taken into account (for example, that the phone has remained in its case since the previous comparison). Impedance matching is then considered correct, and the system returns to standby mode, if necessary via a calibration phase that will be described later, until the next detection and interrogation frame (step 300).

[0063] If the unique identifier is not present in memory (output N of block 340), the phone's circuits and in particular its main processor 105 (HOST) are woken up and the phone communicates with the NFC device to determine whether it is an accessory 2 or an NFC device 3 (351, "Read Tag" and 352, "Accessory or Legacy?", [Fig.3A]).

[0064] When an NFC 3 device is present (output "Legacy" of block 352), the phone 1 operates in reader mode and the NFC 3 device in card mode. The phone's circuits are activated to communicate with the NFC 3 device (block 354 "Com with Tag"). Data is then exchanged via NFC between the card and the reader (the phone). Once the exchange is complete (block 356 "Tag removal"), the tag is effectively removed from the phone ("Tag removed") and the device returns to standby or low-power mode, and the process resumes at step 300 of field detection and transmission of interrogation frames.

[0065] If step 352 detects that the device within the field emitted by the phone is an accessory 2 (output "Accessory" of block 352), i.e., a device intended to remain permanently associated with the mobile phone, the accessory is identified and its identifier is stored (block 358, "Authent. + Save UID") by the phone's microcontroller 105 (HOST). The stored identifier will be used later (during subsequent query frames) in step 340 to determine whether a device, in card mode, within the field of device 1, is a new device that entered the field during the previous detection loop or corresponds to an accessory that remained within the field.

[0066] Following the memorization of a new accessory (output "Acc. Authentified" of block 105), the device implements a standard calibration process to adjust the amplitude levels to the phone's new environment. For example, one step (block 360, "LPTD Calib") calibrates the detection thresholds in low-power LPTD mode to account for the load represented by the accessory. The polling loops in low-power mode then compensate for the presence of the accessory to correctly detect any other NFC device.

[0067] The mobile phone 1 then returns to standby mode by emitting regular LPTD loops (block 370, "LPTD") as long as no field variation is detected (output N of block 380, "Detection?").

[0068] This 360 calibration is also performed if neither a field nor an electronic tag (output N of block 310) is detected at block 310. This may mean that a previously present and registered accessory is no longer associated with device 1. Its identifier, which was recorded upon detection, is then erased from the device's memory (block 390, "All known UID clear") and a calibration is performed. If necessary, information is sent to the host circuit 105 (HOST) for potential notification to the device user that the accessory is no longer detected.

[0069] After calibration 360, the mobile phone returns to standby mode (block 370) and, when a load variation is detected (output Y of block 380), the phone returns to steps 300 and 310 to determine the nature of the NFC device that caused the disturbance.

[0070] When the phone needs to communicate with a device 3, it is preferable that the accessory 2 does not interfere with the detection of this device 3. For this reason, the accessory 2 must not respond to the phone if the latter is in reader mode, nor to the device 3 operating in reader mode so as to leave the communication to the phone in card mode.

[0071] According to one embodiment, accessory 2 is placed in mute mode, in which it does not respond to NFC polling frames. Accessory 2 is switched to mute mode by a command from phone 1, which sends a specific NFC command interpretable only by accessory 2. When it wishes to communicate with the accessory, phone 1 sends accessory 2 a command to deactivate mute mode. Such a solution requires that the phone and the accessory be compatible with this operation. In particular, the phone and the accessory must have, in their command sets, the commands required for switching the accessory to and from mute mode.

[0072] According to another embodiment, communication between the phone 1 and the accessory 2 is provided to take place in a particular type, namely type V. For example, type V is described in more detail in the ISO / IEC 15693 standard. This takes advantage of the fact that communication between a phone 1 and another device 3 in reader mode generally uses types A or B, particularly for payment and access control applications. Thus, 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.

[0073] Fig. 4 represents, in a very schematic way and in block form, an embodiment of a near field communication system according to a second aspect.

[0074] For the sake of simplicity, only the differences in relation to the embodiment of [Fig.1] will be detailed below, the embodiment of [Fig.4] otherwise taking up the elements of the embodiment of [Fig.1].

[0075] According to the second aspect, the mobile phone 1 comprises two separate NFC antennas 125 and 127. A first antenna 125 is dedicated to NFC communications, in card mode or reader mode, with a remote device 3 other than an accessory 2. A second antenna 127 is dedicated to NFC communications, in reader mode, with the accessory 2. In this embodiment, a magnet 16 surrounds or is surrounded by the second antenna 127.

[0076] Compared to the embodiment of [Fig.1], the difference is therefore the use of two antennas rather than two loops of the same antenna.

[0077] Fig. 5 represents, in a very schematic, partial and block-like manner, an embodiment of a near field communication device according to the second aspect.

[0078] For the sake of simplicity, only the differences in relation to the embodiment of [Fig.2] will be detailed below, the embodiment of [Fig.5] taking up the rest of the elements of the embodiment of [Fig.2].

[0079] The NFC device 1 comprises two antennas 125 and 127 which are connected, preferably connected, to two impedance matching circuits 120' and 130' respectively.

[0080] In this embodiment, the selector 140' (SEL) directs NFC signals to be emitted by the NFC device 1, which includes the circuit 100', to 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 own impedance matching circuit. The selector is connected, in the same way as in [Fig. 2], to the NFC controller 110' (NFC CONTROLLER), which is itself connected to the host circuit 105' (HOST).

[0081] Fig. 6 illustrates, in a very schematic way and in block form, a method of implementing the near field communication device of Fig. 5.

[0082] Figure 6A illustrates, in more detail, a set of steps in the implementation of Figure 6.

[0083] In these figures, "Antl" refers to antenna 125 dedicated to an NFC device 3 and "Ant2" refers to antenna 127 dedicated to an accessory 2.

[0084] When in low power or standby mode, the NFC 1 device periodically activates (block 600, "LPTD") interrogation loops on the two antennas 125 and 127 to detect a load variation (block 602, "Detection?") indicating the arrival or departure of an NFC 2 or 3 device.

[0085] The 600 polling loops repeat as long as no load variation is detected (output N of block 602).

[0086] In the case of a variation detection (output Y of block 602), a field detector to detect the presence of a device in reader mode is activated, and a radio frequency signal to detect the presence of a device in card mode is emitted by antenna 125 (blocks 610, "Field Det + Polling on Antl" and 612, "Antl Detection?"). Upon detection, controller 110' sends an identification request to obtain the device identifier (generally a unique identifier - UID).

[0087] In the event of the detection of an electromagnetic field (output "Field" of block 612), this means that the phone 1 is detecting an electromagnetic field and is presumably within the range of a reader. The mobile phone 1 then operates in card mode. The phone's circuits are activated so that it can communicate with an NFC reader device 3 (block 620 "Com with R / W"). A data exchange then takes place via NFC between the phone and the reader using antenna 125. Once the exchange is complete (block 622 "R / W removal"), the process returns to step 610, which involves field detection and the transmission of interrogation frames on antenna 125.

[0088] In the absence of a field detected in step 610, the controller 110' transmits an interrogation frame on the antenna 125 in order to detect whether an electronic tag (NFC device in card mode) is present or not.

[0089] In the presence of a card detected by the antenna 125 (output “Tag” of block 612), the controller 110' compares its identifier (generally a unique identifier - UID or Unique Identifier) ​​obtained in step 610 to a potential unique identifier previously stored in memory (block 630 “Accessory UIDs known?”).

[0090] If the unique identifier is present in memory (output Y of block 630), this means that it is an accessory 2 and that it has already been taken into account by antenna 127 (for example, that the phone has remained in its case since the previous comparison). Impedance matching is then considered correct, and the system returns to standby mode, if necessary via a calibration phase that will be described later, until the next detection and interrogation frame (step 610).

[0091] If the unique identifier is not present in memory (output N of block 630), the phone's circuits and in particular its main processor 105' (HOST) are woken up and the phone communicates with the NFC device to determine whether it is an accessory 2 or an NFC device 3 (641, "Read Tag" and 642, "Accessory or Legacy?", [Fig.6A]).

[0092] In the event that one of the antennas detects that the device present in the field emitted by the phone is an NFC 3 device (output “Legacy” of block 642), the The device must use antenna 125. We then check (block 643, "Antl?") whether antenna 125 is being used. If so (output Y of block 643), phone 1 operates in reader mode and NFC device 3 operates in card mode. The phone's circuits are activated to communicate with NFC device 3 (block 644, "Com with Tag"). Data is then exchanged via NFC between the card and the reader (phone). Once the exchange is complete (block 645, "Tag removal"), the tag is removed from the phone ("Tag removed") and host circuit 105' instructs NFC controller 110' to select both antennas (block 646, "NCI param. Antl + Ant2") for subsequent query frames. We repeat the process for example at step 610 to probe for the presence of another NFC device and any addition or removal of an accessory 2 that may have occurred since the last interrogation frame.

[0093] If, at step 642, one of the antennas 125, 127 detects that the device present in the field emitted by the phone is an accessory 2 (output "Accessory" of block 642), that is to say a device intended to remain permanently associated with the mobile phone, the device uses antenna 127. It is then checked (block 647, "Ant2?") whether antenna 127 is being used. If not (output N of block 647), the host circuit 105' communicates to the NFC controller 110' to select antenna 127 (block 648 "NCI param. Ant2").

[0094] The selection of antenna 127 (“Ant2 Sel.”) leads, for example, to the mobile phone 1 emitting interrogation frames by antenna 127 in order to detect whether an electronic tag (NFC device in card mode) is present or not (block 660 “Polling on Ant2”).

[0095] In the presence of a device detected by the antenna 127 (output “Tag” of block 662 “Ant2 Detection?”), the controller 110' compares its identifier to a potential unique identifier previously stored in the memory of the host circuit 105' (block 665 “Accessory UIDs known?”).

[0096] If the unique identifier is present in memory (output Y of block 665), this means that it is an accessory 2 already taken into account (for example, that the phone has remained in its case since the previous comparison). The impedance matching is then considered correct, and the system returns to standby mode (blocks 600 and 602), if necessary via a calibration phase.

[0097] If the unique identifier is not present in memory (output N of block 665), the phone's circuits and in particular its main processor 105' (HOST) are woken up and the phone communicates with the NFC device, as in the case described previously with the antenna 127, to determine whether there is an accessory 2 or an NFC device 3 (blocks 641 and 642, [Fig.6A]).

[0098] If the tag in the field of antenna 127 is an NFC 3 device (output "Legacy" of block 642), the host circuit 105' communicates to the NFC controller 110' to select antenna 125, after verifying (block 643, "Antl?") that antenna 127 is activated (output N of block 643). Selecting antenna 125 (block 649, "NCI param. Antl") causes the mobile phone to discontinue communication with the NFC 3 device and return to step 610 to perform a detection with antenna 125 ("Antl Sel").

[0099] If the label in the field of antenna 127 is an accessory 2 (output "Accessory" of block 642), after verifying (block 647, "Ant2?") that antenna 127 is indeed being used (output Y of block 647), the accessory is identified and its identifier is stored (block 650, "Authent. + Save UID") by the host microcontroller 105' of the telephone. The stored identifier will be used later (during subsequent query frames) in steps 630 and 665 to determine whether a device in card mode present in the field of device 1 is a new device that entered the field from the previous detection loop or corresponds to an accessory that remained in the field.

[0100] Once memorization has been performed, the host circuit 105' communicates to the NFC controller 110' to select the two antennas (block 651 "NCI param. Antl + Ant2") for subsequent interrogation frames.

[0101] Following this memorization of a new accessory (“Acc. Authentified”), the device 100' implements a usual calibration process (steps 670 corresponding to step 360) in order to adjust the amplitude levels to the new environment of the phone.

[0102] The mobile phone 1 then returns to standby mode by emitting regular LPTD loops (block 600) as long as no field variation is detected.

[0103] If, during the detection step 612 by antenna 125, no field or digital label is detected (output N of block 612), polling frames are transmitted only by antenna 127 (block 660). If no accessory is detected from the field emitted by antenna 127 (output N of block 662), this means that no accessory is near device 1. Any identifier that had been recorded is then cleared from the device's memory (block 680, "All known UID clear"). If applicable, information is sent to the host circuit 105' (HOST) for potential notification to the device user that the accessory is no longer detected.

[0104] The thresholds taken into account by the LPTD polling loops are recalibrated (block 670) to take into account the absence of an accessory and the device returns to standby mode with periodic polling frames (blocks 600 and 602).

[0105] In the embodiment shown in Figures 4 to 6A, the impedance matching circuit 120' of the antenna 125 can, as in the first aspect, be adjustable between Two values ​​are used depending on whether an accessory is present or not. Alternatively, the corresponding adaptation is performed during the calibration phases. A similar approach can be implemented on the 130' circuit side, although this is less useful since communication with this antenna is only necessary when an accessory is present.

[0106] As with the embodiments described in relation to the first aspect (Figures 1 to 3A), in the embodiments described above in relation to the second aspect (Figures 4 to 6A), it is provided that the accessory can be placed in mute mode or that its NFC communications are of type V.

[0107] One advantage of the described embodiments is that they avoid the use of a magnetometer.

[0108] Another advantage of the described embodiments using type V for NFC accessory-phone communications is that they are compatible with any accessory without requiring a special set of commands.

[0109] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will be apparent to those skilled in the art. In particular, each antenna loop may contain one or more turns. Furthermore, although not explicitly stated, the antennas in the applications covered by this description are formed of planar windings.

[0110] Finally, the practical implementation of the described embodiments and variants is within the reach of a person skilled in the art, based on the functional specifications given above. In particular, with regard to the sizing of the antennas or antenna loops.

[0111] Other examples of embodiments of this description are explained later.

[0112] Example 1: a mobile device comprising a near-field communication router (110') and two antennas (125, 127) connected 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 devices (3), a second antenna (127) is dedicated to a second operating mode with a second type of NFC device (2), the selection of one or the other antenna being carried out following a detection carried out during interrogation frames (600) emitted by one or the other of the antennas.

[0113] Example 2: a near-field communication method for a mobile device comprising a near-field communication router (110') and two antennas (125, 127) connected 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), the selection of one or the other antenna being carried out following a detection carried out during interrogation frames (600) emitted by one or the other of the antennas

[0114] Example 3: apparatus according to example 1, or method according to example 2, in which the second type of device corresponds to an accessory (2) of the apparatus (1).

[0115] Example 4: device according to example 1 or 3, or method according to example 2 or 3, wherein communication with the first type of device (3) is carried out in reader or card mode with the first antenna (125).

[0116] Example 5: apparatus according to any one of Examples 1, 3 and 4, or method according to any one of Examples 2 to 4, wherein identification of a device of the second type is carried out with the apparatus in reader mode communicating with the second antenna (127).

[0117] Example 6: apparatus or method according to example 5, in which an identification (650) of a device of the second type (2) is carried out by a microcontroller (105') of the apparatus, distinct from the router (110'), the microcontroller then stores a unique identifier (650) of the device of the second type.

[0118] Example 7: apparatus or method according to Example 6, wherein if no device is detected by either of the two antennas during a polling frame, the microcontroller erases any unique identifier (680) of a device of the second type present in memory.

[0119] Example 8: apparatus or method according to any one of examples 5 to 7, in which, following an identification (650) of a second type NFC device by the second antenna (127), thresholds of a low power detector are recalibrated (670).

[0120] Example 9: apparatus according to any one of examples 1, 3 to 8, or method according to any one of examples 2 to 8, wherein, if a previously identified NFC device of the second type (650) is no longer detected by either of the two antennas during a interrogation frame, thresholds of a low-power detector are recalibrated (670).

[0121] Example 10: apparatus according to any one of Examples 1, 3 to 9, or method according to any one of Examples 2 to 9, wherein if a device of the second type whose identifier has not been stored by the microcontroller is identified (650) by the first antenna (125), the antennas are switched (648) so that detection takes place on the second antenna (127).

[0122] Example 11: apparatus or method according to example 10, in which the antenna (127) for devices of the second type surrounds or is surrounded by a magnet (16) for aligning the respective antennas of the apparatus and device of the second type.

[0123] Example 12: apparatus according to any one of examples 1, 3 to 11, or method according to any one of examples 2 to 11, wherein the devices of the second type are of type V.

Claims

Demands

1. A mobile device comprising a near-field communication router (110) and an antenna (12), connected to the router via at least one impedance matching circuit between at least two impedance values ​​(120 and 130), wherein: a first impedance value is selected to communicate with a near-field communication device of a first type (3) in the presence of a near-field communication device of a second type (2), a second impedance value is selected to communicate with a near-field communication device of the first type in the absence of a near-field communication device of the second type,the presence or absence of a second-type near-field communication device being determined from interrogation frames (370) emitted by the antenna and from a communication or transaction between the mobile device and the second-type near-field communication device.

2. Apparatus according to claim 1, wherein the second type of device corresponds to an accessory (2) of the apparatus (1).

3. Device according to claim 1 or 2, wherein communication with the first type of device (3) is carried out in reader or card mode.

4. Device according to any one of claims 1 to 3, wherein identification of a device of the second type is carried out with the device in reader mode.

5. Device according to claim 4, wherein the identification of a device of the second type (2) is carried out by a microcontroller (105) of the device, separate from the router (110), the microcontroller storing (358) a unique identifier of the device of the second type.

6. Device according to claim 5, wherein if no device of the first or second type is detected during a polling frame (310), the microcontroller erases (390) any unique identifier of a device of the second type present in memory.

7. Device according to any one of claims 4 to 6, wherein, following identification of a second type NFC device, thresholds of a standby detector are recalibrated (360).

8. Device according to any one of claims 1 to 7, wherein, if a previously identified NFC device of the second type is no longer detected (output N of block 310), thresholds of a detector in standby mode are recalibrated (360).

9. Apparatus according to any one of claims 1 to 8, wherein the antenna (12) comprises two electrically in series loops (121 and 123), respectively intended for devices of the first (3) and second type (2).

10. Apparatus according to claim 9, wherein the loop (123) for the devices of the second type (2) surrounds or is surrounded by a magnet (16) for aligning the respective antennas of the apparatus and the device of the second type.

11. Device according to any one of claims 1 to 10, wherein the NFC communications between the device and devices of the second type (2) are of type V.

12. Near field communication method employing a mobile device according to any one of claims 1 to 11.

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