Communication method

Abstract

Communication Method This description relates to a method in which, upon receiving a frame indicating a failure (209, 307) of data reception (205, 303) by the second device (100B) via a first near-field communication device (100A) powered by a second near-field communication device (100B), at least one transmission parameter of the first device (100A) is modified (301, 309) prior to another transmission attempt (311) of said data. Figure for the abstract: Fig. 3

Description

Title of the invention: Communication method technical field

[0001] This description relates generally to electronic devices. More particularly, this description relates to electronic devices incorporating a near-field communication (NFC) circuit, more commonly known as NFC devices, and the near-field communication processes implemented by such devices. Previous technique

[0002] When an NFC device communicates in the near field with another NFC device within range, these devices exchange data, for example, in the form of request and response frames transmitted alternately by the NFC devices. Sometimes, data transmitted by one of the NFC devices is not received correctly by the other NFC device, thus disrupting communication between these devices. Summary of the invention

[0003] It would be desirable to improve existing NFC devices and existing near-field communication methods between NFC devices.

[0004] An embodiment overcomes all or part of the drawbacks of known NFC devices and known methods of near-field communication between NFC devices.

[0005] For this purpose, an embodiment provides a method in which, in the event of reception, by a first near field communication device remotely powered by a second near field communication device, of a frame indicating a failure of a data reception by the second device, at least one transmission parameter of the first device is modified prior to another attempt to transmit said data.

[0006] According to one embodiment, said at least one parameter is a duration between the end of transmission of a request by the second device and the start of transmission of a response by the first device.

[0007] According to one embodiment, said at least one parameter is a modulation amplitude, by the first device, of an electromagnetic field radiated by the second device.

[0008] According to one embodiment, the modulation amplitude is decreased if the field has an intensity below a first threshold and increased if the field has an intensity above a second threshold.

[0009] According to one embodiment, the field intensity is estimated by a sensor of current of the first NFC device.

[0010] According to one embodiment, said at least one parameter is a synchronization frequency of a computing unit of the first device.

[0011] According to one embodiment, said at least one parameter includes transition times of the first device between reception, processing and transmission phases.

[0012] According to one embodiment, said at least one parameter is stored in a register of a non-volatile memory of the first device.

[0013] According to one embodiment, the frame indicating the failure of data reception by the second device is a consequence of the transmission, by the first device, of a response frame.

[0014] One embodiment provides a near field communication device configured to implement the process as described. Brief description of the drawings

[0015] 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:

[0016] [Fig.1] represents, schematically and in block form, an example of a near field communication system of the type to which, by way of example, the described embodiments apply;

[0017] [Fig.2] is a chronogram illustrating successive steps of an example of a communication process between NFC devices;

[0018] [Fig.3] is a chronogram illustrating successive steps of a communication process between NFC devices according to an embodiment;

[0019] [Fig. 4] is a flowchart illustrating an example of implementation of the communication process of [Fig. 3]; and

[0020] [Fig.5] represents examples of implementation of the communication process of Figures 3 and 4. Description of the implementation methods

[0021] 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.

[0022] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed. In particular, the generation of radio frequency signals and their interpretation have not been detailed, as the described embodiments are compatible with conventional generation techniques and interpretation of these signals.

[0023] 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.

[0024] 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.

[0025] Unless otherwise specified, the expressions "approximately", "roughly", and "in the order of" mean within 10%, preferably within 5%.

[0026] In this description, "NFC device" means an electronic device incorporating at least one near-field communication circuit.

[0027] Fig. 1 represents schematically and in block form an example of a near field communication system of the type to which, by way of example, described embodiments apply.

[0028] In the example shown, a first NFC 100A device (CARD) communicates, via near-field electromagnetic coupling, with a second NFC 100B device (READER) located within range. In this example, the first NFC 100A device operates more precisely in card mode, while the second NFC 100B device operates in reader mode. By way of example, the NFC 100A device is a microcircuit card, for example a bank card, a personal access card, an identity card, a passport, etc., or, more generally, any type of passive NFC device, that is to say, one without an internal power source.

[0029] In the example illustrated in [Fig. 1], each NFC device 100A, 100B comprises a processing unit 101A, 101B (PU), for example a microcontroller, a microprocessor, a programmable logic circuit, a state machine, etc. The processing units 101A and 101B are configured to implement steps of a communication process, for example by commanding a sequential execution of operations aimed at enabling near-field data exchange between the NFC devices 100A and 100B.

[0030] In the illustrated example, each NFC device 100A, 100B further comprises a near-field communication (COM) circuit 103A, 103B, or oscillating circuit, connected to the processing unit 101A, 101B of the device. The circuits 103A and 103B may each comprise signal generation and processing elements. transmit, or of received signals, by the NFC 100A or 100B device. As an example, each 103A, 103B circuit may include one or more elements chosen from a signal generator, a digital-to-analog converter of the signals to be transmitted, an analog-to-digital converter of the received signals, a modulation-demodulation circuit (modem), an impedance matching circuit, a radio frequency interference filtering circuit, etc.

[0031] In this example, the NFC devices 100A, 100B further each include a near-field communication antenna 105A, 105B (ANT). The antenna 105A of the NFC device 100A is adapted to receive a radio frequency electromagnetic (EMF) field radiated by the antenna 105B of the NFC device 100B. When the antenna 105A of the NFC device 100A receives the EMF field emitted by the antenna 105B of the NFC device 100B, coupling occurs between the circuits 103A and 103B of these devices. This coupling results in a change in the load exerted by the circuits of the NFC device 100A on the circuit 103B that generates the EMF field of the NFC device 100B.

[0032] In practice, to establish communication between NFC devices 100A and 100B, a variation in phase or amplitude of the EMF field is detected by NFC device 100B, which then initiates a near-field communication protocol with NFC device 100A. More precisely, the detection is carried out, for example, by detecting, on the side of NFC device 100B, whether an amplitude of a voltage across the terminals of circuit 103B and / or a phase shift relative to the signal generated by circuit 103B fall outside the amplitude and / or phase ranges.

[0033] Once the NFC 100B device has detected the presence of the NFC 100A device in its field, it initiates a communication establishment procedure implementing the emission of requests by the NFC 100B device and responses by the NFC 100A device (query sequence as defined in the technical specifications of the NFC Forum, EMV (Europay MasterCard Visa) or ISO 14443 standard).

[0034] In the example shown, the NFC 100B device includes a power supply 107 (PWR). The power supply 107 can, as illustrated in [Fig. 1], be an internal source within the NFC 100B device, for example, a battery. Alternatively, the NFC 100B device can be powered by an external source, for example, a mains power supply. The power supply 107 provides electrical power to one or more elements of the NFC 100B device, for example, the processing unit 101B and the circuit 103B of the device 100B, as illustrated in [Fig. 1]. The power supply 107 also provides electrical power to the NFC 100A device via the EMF field radiated by the NFC 100B device. The NFC 100A device is powered exclusively by the near field, or te powered by the NFC 100B device, the electrical energy useful for the operation of the NFC 100A device being entirely drawn from the EMF field.

[0035] In the example illustrated in [Fig. 1], the NFC 100A device further comprises a memory 109 (MEM) including at least one non-volatile storage area. The memory 109 is connected to the processing unit 101A and allows, for example, the non-transient storage of program code instructions which, when executed by the processing unit 101A, enable the NFC 100A device to implement the near-field communication method with the NFC 100B device. The memory 109 may further include one or more volatile storage areas allowing, for example, the temporary recording of variable values ​​related to the execution of the program by the processing unit 101A.

[0036] Depending on the intended application, each NFC 100A, 100B device may also include various other elements or circuits are symbolized in [Fig. 1] by a functional block 111A, 11 IB (FCT). Although not detailed in [Fig. 1], NFC devices 100A and 100B may further include one or more data, address and / or command buses between the different elements of these devices and one or more input / output interfaces.

[0037] Fig. 2 is a chronogram illustrating, as a function of time t, a sequence of successive steps of an example of a communication process between NFC devices, for example the NFC 100A (CARD) and 100B (READER) devices respectively located on the right and left in Fig. 2.

[0038] During a step 201 (COM START), a near-field communication is established between the reader device 100B and the card device 100A. This corresponds to a case where the device 100A is detected within range of the device 100B, for example when the device 100A is brought close to the NFC device 100B at a distance sufficiently small to cause, on the side of the device 100B, a crossing of the amplitude threshold of the voltage across the terminals of the circuit 103B and / or of the phase shift threshold with respect to the signal generated by the circuit 103B.

[0039] In a subsequent step 203 (REQ), following step 201, the reader device 100B transmits a request frame to the card device 100A. By sending this request, the NFC device 100B can, for example, request the NFC device 100A to transmit data corresponding to the contents of one or more areas of its memory 109. As an example, the request frame transmitted by the NFC device 100B includes a so-called supervisory block, or S-block. Although not detailed in [Fig. 2], the NFC devices 100A and 100B can perform other standard near-field communication operations between steps 201 and 203.

[0040] During yet another step 205 (RESP), subsequent to step 203, the device Card 100A transmits a response frame to reader device 100B. The response contains, for example, the data from memory 109 of NFC device 100A that NFC device 100B had indicated it wished to retrieve by sending the request frame in step 203. As an example, the response frame transmitted by NFC device 100A includes an information block, or Lblock.

[0041] If the response frame from the card device 100A is correctly received by the reader device 100B, the device 100B then transmits, at yet another step 207 (POS ACK) subsequent to step 205, an acknowledgment frame intended to inform the device 100A that the transmission of the response frame was successful. For example, the frame transmitted by the device 100B at step 207 includes a so-called "Receive ready block" (R-block). The frame at step 207, for instance, more precisely includes an R-block containing a positive acknowledge, more simply designated by the acronym "R(ACK)".

[0042] Depending on the application requirements, near-field communication between NFC devices 100A and 100B can then either continue normally, with another request frame different from that of step 203 being transmitted, for example, by device 100B to obtain other data stored in memory 109, or be interrupted, for example, if all the desired data exchanges have been completed. To avoid cluttering the drawing, the step(s) that may be executed after step 207, which correspond to normal communication, have not been detailed in [Fig. 2].

[0043] Conversely, if the response frame from step 205 is not correctly received by the reader device 100B, for example, if device 100B does not receive all or part of this frame, device 100B then transmits, at yet another step 209 (NEG ACK) subsequent to step 205, an acknowledgment frame intended to inform device 100A that the transmission of the response frame has failed. The failure of this transmission can arise from various causes, or interoperability problems, for example, variability in the form factor of the antennas 105A and 105B, a coupling defect between the reader device 100B and the card device 100A, the use of a reader device 100B that does not conform to the near-field communication standards used by the card device 100A, etc.As an example, the acknowledgment frame emitted by device 100B at step 209 includes an R block containing a negative acknowledge ("R-block containing a negative acknowledge"), more simply designated by the acronym "R(NAK)".

[0044] In the event that the transmission of the response frame during step 205 has failed, the card device 100A then attempts, during yet another step 211 (RESP) pos prior to step 209, to send the response frame back to the reader device 100B. Step 211 is identical to step 205. More specifically, the content and mode of transmission of the response frame by the NFC device 100A are unchanged, in step 211, compared to step 205.

[0045] If the response frame from step 211 is not correctly received by the reader device 100B, device 100B then transmits again, during yet another step 213 (NEG ACK) subsequent to step 211, an acknowledgment frame informing device 100A of the failure to transmit the response frame from step 211. This corresponds, for example, to a situation in which the interoperability problem that affected the transmission of the response frame during step 205 is still present during step 211. Step 213 is, for example, identical or similar to step 209.

[0046] If the second attempt to transmit the response frame during step 211 fails, the card device 100A then attempts again, during yet another step 215 (RESP) subsequent to step 213, to send the response frame a third time to the reader device 100B. Step 215 is identical to steps 205 and 211. More specifically, the content and transmission mode of the response frame by the NFC device 100A are unchanged in step 215 compared to steps 205 and 211.

[0047] Several failed receptions by the reader device 100B of the response frame from the card device 100A, interspersed with several transmissions by the reader device 100B of acknowledgment frames intended to inform the card device 100A of these failures, can thus occur until yet another step 217, subsequent to step 215, at which point communication between the NFC devices 100A and 100B is terminated. For example, the NFC device 100B can terminate near-field communication with the NFC device 100A after successively sending 3 to 5 acknowledgment frames including an R(NAK) block.

[0048] If the interoperability problems are resolved before step 217, communication between NFC devices 100A and 100B can resume normally, and the desired data exchanges can, for example, be fully completed. However, repeated transmissions of the same response frame from device 100A and acknowledgment frames from device 100B result in an undesirable increase in communication time.

[0049] Conversely, if interoperability problems persist up to step 217, communication between NFC 100A and 100B devices terminates before the desired data exchange can be completed. This results in a failure of near-field communication between the 100A and 100B devices, negatively impacting the user experience of these devices.

[0050] The [Fig.3] is a chronogram illustrating successive steps of a communication process between NFC devices, for example the NFC devices 100A (CARD) and 100B (READER) located respectively on the right and left in [Fig.3], according to one embodiment.

[0051] In general, the embodiment of [Fig.3] provides that in the event of the NFC 100A device, remotely powered by the NFC 100B device, receiving a frame indicating a failure to receive data by the NFC 100B device, at least one transmission parameter of the NFC 100A device is modified prior to another attempt to transmit said data.

[0052] The timing diagram of [Fig. 3] has elements in common with the timing diagram of [Fig. 2]. These common elements will not be described again below. More specifically, the timing diagram of [Fig. 3] includes the steps 201 (COM START), 203 (REQ), 205 (RESP), 209 (NEG ACK), and 217 (COM END) previously described in relation to [Fig. 2]. The timing diagram of [Fig. 3] differs from that of [Fig. 2] in that the timing diagram of [Fig. 3] includes a step 301 (CHG RF SET) for modifying one or more radio frequency communication parameters of the 100A card device. Step 301 is, as illustrated in [Fig.3], subsequent to step 209 of transmission of the frame intended to inform the card device 100A of the failure to receive the data contained in the response frame transmitted by the device 100A during step 205.

[0053] The card device 100A then attempts, in a subsequent step 303 (RESP) after step 209, to send the reply frame back to the reader device 100B. Step 303 differs from step 205 in that, in step 303, at least one radio frequency communication parameter of the NFC device 100A has been modified compared to step 205. This advantageously increases, compared to the method of [Fig. 2], the chances of overcoming the interoperability problem that affected data transmission in step 205 and persists, for example, in step 303. The content of the reply frame transmitted in step 303 by the NFC device 100A is preferably identical to that of the reply frame transmitted in step 205.

[0054] If the response frame from the card device 100A is correctly received by the reader device 100B, the device 100B then transmits, at yet another step 305 (POS ACK) after step 303, an acknowledgment frame to inform the device 100A that the transmission of the response frame was successful. Step 305 of [Fig. 3] is, for example, identical or similar to step 207 of [Fig. 2]. Depending on the application requirements, the near-field communication between the NFC devices 100A and 100B can then either continue normally or be interrupted as previously described in relation to [Fig. 2]. In order to avoid cluttering the drawing, the steps that can be executed subsequent to step 305, which correspond to usual communication, have not been illustrated in [Fig.3].

[0055] On the other hand, if the response frame from step 303 is not correctly received by the reader device 100B, for example if device 100B does not receive all or part of this frame, device 100B then transmits, at yet another step 307 (NEG ACK) subsequent to step 303, an acknowledgment frame intended to inform device 100A that the transmission of the response frame has failed.

[0056] If the second transmission of the reply frame during step 303 fails, one or more radio frequency communication parameters of the 100A card device are modified during yet another step 309 (CHG RF SET), subsequent to step 307. The parameter(s) modified during step 309 may be identical to the radio frequency communication parameters modified during step 301. By way of example, a value or state of this parameter(s) may be changed in step 309 compared to step 301. Alternatively, the parameter(s) modified during step 309 may be different, in whole or in part, from the radio frequency communication parameter(s) modified during step 301.

[0057] In yet another step 311 (RESP), subsequent to step 309, the card device 100A again attempts to send the response frame back to the reader device 100B. Step 311 differs from steps 205 and 303 in that, in step 311, at least one radio frequency communication parameter has been modified compared to steps 205 and 303. This advantageously allows, compared to the method of [Fig. 2], for an even greater increase in the chances of overcoming the interoperability problem that affected data transmission in steps 205 and 303, and which is, for example, still present in step 311.

[0058] Although not illustrated in [Fig. 3], several failures to receive the response frame from the card device 100A by the reader 100B, interspersed with several transmissions of acknowledgment frames by the reader 100B to inform the card device 100A of these failures, can then occur prior to step 217, which follows step 311, at which point the near-field communication between the NFC devices 100A and 100B is terminated. Before each new transmission of the same response frame by the NFC device 100A, one or more radio frequency communication parameters are modified, for example, as described above in relation to steps 301 and 309.

[0059] An advantage of the communication method described above in relation to [Fig. 3] is that, compared to the method in [Fig. 2], it increases the chances of overcoming an interoperability problem before communication between the NFC 100A and 100B devices is completed, thus enabling the completion of all desired data exchanges between these devices. This results in an improvement in the user experience of NFC 100A and 100B devices.

[0060] Figure 4 is a flowchart illustrating an example of the implementation of the communication process of Figure 3. The flowchart of Figure 4 is, for example, implemented by the processing unit 101A of the NFC 100A device.

[0061] During an initial 401 step (RATS / ATTRIB), communication between NFC devices 100A and 100B begins, for example by transmitting a so-called "Request for Answer To Select" (RATS) frame or an attribution frame (ATTRIB).

[0062] By way of example, in another step 403 (CNT := 0), subsequent to step 401, a CNT counter is initialized by assigning the CNT counter a value, for example, zero. In the logic diagram illustrated in [Fig. 4], each value of the CNT counter corresponds to a different state, or a different value, of at least one radio frequency communication parameter of the NFC 100A device. The values ​​of the CNT counter are integers and less than or equal to a non-zero maximum value CMAX, for example, equal to 2. By way of example, each value of the CNT counter corresponds to a configuration, or parameter setting, of the 103A near-field communication circuit of the NFC 100A device. Thus, in the case where the maximum value CMAX of the CNT counter is equal to 2, three different configurations of the 103A circuit can, for example, be applied successively to try to resolve a problem affecting communication between NFC 100A and 100B devices.The configuration applied when the CNT counter has a zero value corresponds, for example, to a default or standard configuration, for example, a configuration allowing near-field communication to be carried out in a majority of use cases for the NFC 100A device.

[0063] In yet another step 405 (RECEIVE FRAME), subsequent to step 403, a frame transmitted by the NFC 100B device is received by the NFC 100A device. This frame includes, for example, several Application Protocol Data Units (APDUs). Although not detailed in [Fig. 4], the transmission of the frame by the NFC 100B device is, for example, a consequence of the transmission of a request by the NFC 100B device, followed by an attempt to send data by the NFC 100A device, as previously described in relation to steps 203 and 205 of the process in [Fig. 3].

[0064] During yet another step 407 (R(NAK)?), subsequent to step 405, the NFC 100A device checks whether the frame from the NFC 100B device contains a negative acknowledgment block, or R(NAK) block, i.e. whether a communication problem has occurred.

[0065] In a case where the frame contains an R(NAK) block (output Y of block 407), for example due to the presence of an interoperability problem between devices NFC 100A and 1OOB, the CNT counter is incremented during yet another step 409 (CNT := CNT+1), subsequent to step 407. During step 409, the value of the CNT counter is increased by one unit.

[0066] In yet another step 411 (CNT = CMAX?), subsequent to step 409, the NFC 100A device checks whether the value of the CNT counter is equal to the maximum value CMAX, i.e., equal to 2 in this example. Since the value of the CNT counter is equal to 1 at this stage (output N of block 411), at least one radio frequency communication parameter of the NFC 100A device is modified in yet another step 413 (CHG RF SET), subsequent to step 411. Step 413 is, for example, identical or similar to step 301 previously described in relation to [Fig. 3].

[0067] During yet another step 415 (SEND ANSWER), subsequent to step 413, the NFC 100A device attempts to send back a response frame to the NFC 100B device by applying the parameter(s) modified in step 413.

[0068] The NFC 100A device then returns to step 405, which receives a frame transmitted by the NFC 100B device. As long as the frame received in step 405 contains a negative acknowledgment block R(NAK) and the value of the CNT counter is less than the maximum value CMAX, steps 407, 409, 411, 413, and 415 described previously are repeated. When the CNT counter reaches its maximum value CMAX (output Y of block 411), the radio frequency communication parameter(s) of the NFC 100A device are no longer modified in step 413, and the transmission of the reply frame takes place in step 415, applying the parameter(s) corresponding to the CMAX value of the CNT counter.

[0069] In the event that the frame received by the NFC 100A device during step 405 does not contain a negative acknowledgment R(NAK) block (output N of block 407), the value of the CNT counter is reset at yet another step 417 (CNT := 0) subsequent to step 407, and the transmission of the reply frame takes place, at step 415, by applying the radio frequency communication parameter(s) corresponding to a zero value of the CNT counter. In other words, the NFC 100A device applies the default configuration of circuit 103A at the beginning of each new near-field communication and as soon as an interoperability problem has been overcome.

[0070] As an alternative, the CNT counter can be reset after reaching its maximum value CMAX. This would amount, for example, in the event of an interoperability problem, to attempting to transmit a frame to the NFC 100B device by cyclically applying all possible configurations of the 103A circuit.

[0071] Furthermore, although not illustrated in [Fig. 4], near-field communication between NFC 100A and 100B devices can be interrupted after, for example, one or more attempts to transmit a frame to NFC 100B by applying the configuration corresponding to the maximum value CMAX of the CNT counter.

[0072] Fig. 5 represents examples of implementation of the communication process of Figures 3 and 4.

[0073] Figure 5 more precisely illustrates a first implementation example (EXAMPLE 1, on the left in Figure 5) in which, when the CNT counter value is equal to 1 (CNT = 1), the NFC 100A device applies a first radio frequency communication configuration 501 (CFG_1). In configuration 501, a field modulation value 503 (LMA) ("Load Modulation Amplitude" - LMA) applied by the NFC 100A device is increased relative to a default value, which is applied when the CNT counter has a value of zero. Increasing the field modulation value 503 makes it possible, for example, to facilitate communication between the NFC 100A and 100B devices in a case where the EMF field radiated by the NFC 100B device has a low intensity.The intensity of the EMF field emitted by the NFC 100B device is, for example, estimated by a current sensor of the NFC 100A device and compared to a low threshold, the crossing of which indicates the presence of a low-intensity field. As an example, the increase in the field modulation value 503 between the initial configuration, in the case where the CNT counter has a value of zero, and configuration 501 is on the order of 5%, for example, between 5 and 10 mV.

[0074] Furthermore, in the first configuration 501, another Frame Delay Time (FDT) value, 505, is reduced from a default value applied when the CNT counter is zero. The value 505 corresponds, for example, to the time between the end of a request transmission by the NFC 100B device and the start of a response transmission by the NFC 100A device. Reducing the value 505 facilitates communication, for example, in cases where the EMF field radiated by the NFC 100B device is weak. As an example, the reduction in the value 505 between the initial configuration and configuration 501 is on the order of -2 / fc, where fc represents the oscillation frequency of a carrier wave of the EMF signal radiated by the NFC 100B device.

[0075] In the first implementation example, when the CNT counter value is equal to two (CNT = 2), the NFC 100A device applies a second radio frequency communication configuration 507 (CFG_2). In this second 507 configuration, the field modulation value 503 (LMA) and the frame delay time value 505 (FDT) are reset. In other words, in configuration 507, the same 503 and 505 values ​​are applied as in the default configuration when the CNT counter has a value of zero.

[0076] Furthermore, in the second configuration 507 of the first implementation example, The 509 (CLK) synchronization frequency, or clock frequency, of the 101A processing unit of the NFC 100A device is reduced from a default value applied when the CNT counter has a zero value. Reducing the 509 frequency helps, for example, to mitigate electromagnetic interference that might be generated by one or more components of the NFC 100A device. This facilitates communication between NFC 100A and 100B devices. As an example, the reduction in the 509 frequency between the initial configuration and the 507 configuration is approximately -20%.

[0077] Furthermore, in configuration 507, one or more transition durations 511 (TRANS) of the NFC 100A device between the reception, processing, and transmission phases of data frames during communication with the NFC 100B device are modified. For example, this duration or these durations are increased in configuration 507 compared to the initial configuration. This allows for smoother transitions between the reception, processing, and transmission phases.

[0078] Fig. 5 further represents a second implementation example (EXAMPLE 2, right in Fig. 5) in which, when the value of the CNT counter is equal to 1 (CNT = 1), the NFC 100A device applies the first 501 (CFG_1) radio frequency communication configuration as described previously in relation to the first implementation example.

[0079] In the second implementation example, when the CNT counter value is equal to two (CNT = 2), the NFC 100A device applies a third radio frequency communication configuration 513 (CFG_3). In this third configuration 513, the field modulation value 503 (LMA) is reduced compared to the default value applied when the CNT counter has a value of zero. Reducing the field modulation value 503 makes it possible, for example, to facilitate communication between the NFC 100A and 100B devices in a case where the EMF field radiated by the NFC 100B device has a high intensity. The intensity of the EMF field emitted by the NFC 100B device, estimated by the current sensor of the NFC 100A device, is, for example, compared to a high threshold, the crossing of which indicates the presence of a high-intensity field.As an example, the decrease in the field modulation value 503 between an initial configuration, corresponding to the case where the CNT counter has a zero value, and the configuration 513 is on the order of -5%, for example between -5 and -10 mV.

[0080] Furthermore, in the third configuration 513, the frame delay time value 505 (FDT) is increased compared to the default value applied when the CNT counter has a zero value. Increasing the value 505 makes it possible, for example, to facilitate communication in the presence of a high-intensity EMF field radiated by the NFC 100B device. For example, increasing the value 505 between the initial configuration and the 513 configuration is on the order of 2 / fc.

[0081] Examples of radio frequency communication configurations have been described above in relation to [Fig. 5]. These examples are not limiting. In particular, other radio frequency communication parameters could be modified. The selection and setting of the states or values ​​of these parameters is, for example, carried out according to the intended use cases of the NFC 100A device.

[0082] In general, the method described above in relation to Figures 4 and 5 advantageously allows the NFC 100A device to benefit, in addition to a default radio frequency communication configuration, from at least one alternative radio frequency communication configuration allowing to resolve interoperability problems between NFC devices during near field communication.

[0083] One advantage of the NFC 100A device implementing this process is that it helps to avoid errors or failures in near-field communication, especially compared to an NFC device that does not implement this process.

[0084] 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, the examples of radio frequency communication configurations shown in relation to [Fig. 5] are not limiting. More generally, any number of radio frequency communication configurations can be envisaged depending on the intended application, each configuration involving the modification of one or more radio frequency communication parameters.

[0085] 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, the states or values ​​of the radio frequency communication parameters corresponding to each configuration can, for example, be stored in the memory 109 of the NFC 100A device, for example in different memory registers accessible via a pointer. These states or values ​​can be defined at the factory by the manufacturer of the NFC 100A device. Alternatively, these states or values ​​are configured by a user of the NFC 100A device.

Claims

Demands

1. A method in which, upon receipt by a first near-field communication device (100A) remotely powered by a second near-field communication device (100B), of a frame indicating a failure (209, 307; 407) of a data reception (205, 303) by the second device (100B), at least one transmission parameter of the first device (100A) is modified (301, 309; 413) prior to another attempt to transmit (311; 415) said data, in which said frame is received by the first device (100A) after establishment (201; 401) of a near-field communication between the first and second devices (100A, 100B).

2. Method according to claim 1, wherein said at least one parameter is a duration (FDT) between an end of transmission of a request (203) by the second device (100B) and a start of transmission of a response (205) by the first device (100A).

3. Method according to claim 1 or 2, wherein said at least one parameter is a modulation amplitude (LMA), by the first device (100A), of an electromagnetic field (EMF) radiated by the second device (100B).

4. A method according to claim 3, wherein the modulation amplitude (LMA) is decreased if the field (EMF) has an intensity below a first threshold and increased if the field has an intensity above a second threshold.

5. Method according to claim 4, wherein the field intensity (EMF) is estimated by a current sensor of the first NFC device (100A).

6. A method according to any one of claims 1 to 5, wherein said at least one parameter is a synchronization frequency (CLK) of a computing unit (101A) of the first device (100A).

7. A method according to any one of claims 1 to 6, wherein said at least one parameter comprises transition times (TRANS) of the first device (100A) between reception, processing and transmission phases.

8. A method according to any one of claims 1 to 7, wherein said at least one parameter is stored in a register of a non-volatile memory (109) of the first device (100A).

9. A method according to any one of claims 1 to 8, wherein the frame indicating failure (209, 307 ; 407) of the reception of data (205, 303) by the second device (100B) is subsequent to an emission, by the first device (100B), of a response frame.

10. Near field communication device (100A) configured to implement the method according to any one of claims 1 to 9.

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