CN116781112A - Communication method for near field communication device - Google Patents

Abstract

Embodiments of the present disclosure relate to a communication method for a near field communication device. The first near field communication device is remotely powered by the second near field communication device. The first near field communication device receives a frame from the second near field communication device indicating that data was not received by the second near field communication device. In response, at least one transmission parameter of the first near field communication device is modified before another attempt to transmit data.

Description

Communication method for near field communication device

Priority claim

The present application claims priority from french patent application No.2202280 filed 3/16 at 2022, the entire contents of which are incorporated herein by reference to the maximum extent allowed by law.

Technical Field

The present disclosure relates generally to electronic devices. The present disclosure relates more particularly to electronic devices integrating Near Field Communication (NFC) circuitry, more commonly referred to as NFC devices, and near field communication devices implemented by such devices.

Background

When an NFC device communicates in the near field with another NFC device located within range, the devices exchange data in the form of request and response frames that are sent in turn by the NFC device. Sometimes, data transmitted by one of the NFC devices cannot be received correctly by the other NFC device, adversely affecting communication between the devices.

It is desirable to improve existing NFC devices and existing methods of near field communication between NFC devices.

There is a need in the art to overcome all or part of the drawbacks of the known NFC device and the near field communication method between the known NFC devices.

Disclosure of Invention

The embodiment provides a method wherein in case a first near field communication device remotely powered by a second near field communication device receives a frame indicating that data cannot be received by the second device, at least one transmission parameter of the first device is modified before another attempt to transmit said data.

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

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

According to one embodiment, the modulation amplitude is reduced if the field strength is less than a first threshold value and increased if the field strength is greater than a second threshold value.

According to an embodiment, the strength of the field is estimated by a current sensor of the first NFC device.

According to an embodiment, the at least one parameter is a synchronization frequency of the computing unit of the first device.

According to an embodiment, the at least one parameter comprises a transition duration of the first device between the receive phase, the process phase and the transmit phase.

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

According to an embodiment, the frame indicating that no data is received by the second device is after transmission of the response frame by the first device.

One embodiment provides a near field communication device configured to implement the method.

Drawings

The foregoing and other features and advantages will be described in detail in the remainder of the disclosure of the specific embodiments presented by way of illustration and not limitation with reference to the accompanying drawings wherein:

fig. 1 schematically shows in block form an example of a near field communication system to which the embodiments apply;

fig. 2 is a timing chart showing successive steps of an example of a communication method between NFC devices;

fig. 3 is a timing diagram showing successive steps of a communication method between NFC devices according to an embodiment;

FIG. 4 is a logic diagram illustrating an example implementation of the communication method of FIG. 3; and

fig. 5 shows an example of an implementation of the communication method of fig. 3 and 4.

Detailed Description

Like features are denoted by like reference numerals throughout the various figures. In particular, structural and/or functional features common in the various embodiments may have the same reference numerals and may be provided with the same structural, dimensional and material characteristics.

For clarity, only the steps and elements useful for understanding the embodiments described herein are shown and described in detail. In particular, the generation of radio frequency signals and their interpretation are not described in detail, and the described embodiments are compatible with conventional techniques for the generation and interpretation of these signals.

Unless otherwise indicated, when referring to two elements being connected together, this means that there is no direct connection of any intermediate element other than a conductor, and when referring to two elements being connected together, this means that the two elements may be connected or they may be coupled via one or more other elements.

In the following disclosure, unless otherwise indicated, when referring to absolute positional qualifiers, such as the terms "front", "rear", "top", "bottom", "left", "right", etc., or when referring to relative positional qualifiers, such as the terms "upper", "lower", etc., or when referring to orientation qualifiers, such as "horizontal", "vertical", etc., refer to the orientation shown in the figures.

Unless otherwise indicated, the expressions "about", "substantially" and "on the order of … …" mean within 10%, preferably within 5%.

In this specification, "NFC device" means an electronic device integrating at least one near field communication circuit (NFC).

Fig. 1 schematically shows in block form an example of a near field communication system of the type to which the described embodiments are applied.

In the illustrated example, a first NFC device 100A (card) communicates with a second NFC device 100B (reader) located within range by near field electromagnetic coupling. In this example, the first NFC device 100A operates more specifically in a so-called card mode, while the second NFC device 100B operates in a so-called reader mode. By way of example, NFC device 100A is a microcircuit card, such as a bank card, personal access card, identification card, passport, or the like, or more generally, any type of passive NFC device that is deprived of an internal power source.

In the example shown in fig. 1, each NFC device 100a,100b comprises a processing unit 101a,101b (UC), such as a microcontroller, microprocessor, programmable logic circuit, state machine, or the like. The processing units 101A and 101B are configured to implement the steps of the communication method, for example by controlling a sequential execution of operations intended to allow a near field data exchange between the NFC devices 100A and 100B.

In the example shown, each NFC device 100a,100b further comprises a near field communication circuit or oscillating circuit 103a,103b (COM) connected to the processing unit 101a,101b of the device. The circuits 103A and 103B may each include elements for generating and processing signals to be transmitted or received by the NFC device 100A or 100B. For example, each circuit 103a,103b may include one or more elements selected from a signal generator, a digital-to-analog converter of a signal to be transmitted, an analog-to-digital converter of a received signal, a modem circuit (modem), an impedance matching circuit, a radio frequency noise filtering circuit, and the like.

In this example, NFC devices 100a,100b also each include a near field communication antenna 105a,105b (ANT). Antenna 105A of NFC device 100A is configured to capture a radio frequency electromagnetic field (EMF) radiated by antenna 105B of NFC device 100B. When antenna 105A of NFC device 100A captures the EMF field emitted by antenna 105B of NFC device 100B, a coupling is formed between circuits 103A and 103B of these devices. This coupling results in a change in the load formed by the circuitry of NFC device 100A on circuitry 103B for generating the EMF field of NFC device 100B.

In effect, to establish communication between NFC devices 100A and 100B, NFC device 100B detects a phase or amplitude change of the EMF field, and then NFC device 100B initiates a near field communication protocol with NFC device 100A. More precisely, the detection is performed, for example, by detecting, on the NFC device 100B side, whether the amplitude of the voltage across the circuit 103B and/or the phase shift with respect to the signal generated by the circuit 103B is out of the amplitude and/or phase range.

Once NFC device 100B has detected the presence of NFC device 100A in its field, it initiates a procedure (a polling sequence, such as defined in the NFC forum, EMV (european master card visa) or ISO14443 standard specification) for establishing a communication, enabling the transmission of a request by NFC device 100B and the transmission of a response by NFC device 100A.

In the illustrated example, NFC device 100B includes a power supply 107 (PWR). As shown in fig. 1, the source 107 may be a source internal to the NFC device 100B, such as a battery type source. As a variant, NFC device 100B may be powered by an external source, for example of the distribution network or mains type. The source 107 enables powering of one or more elements of the NFC device 100B with electrical energy, e.g., the processing unit 101B and the circuitry 103B of the device 100B as shown in fig. 1. The source 107 also enables the NFC device 100A to be powered via an EMF field radiated by the NFC device 100B. NFC device 100A is powered exclusively in the near field or remotely by NFC device 100B, and power useful for operation of NFC device 100A is drawn entirely from the EMF field.

In the example shown in fig. 1, NFC device 100A further includes a memory 109 (MEM) that includes at least one non-volatile storage area. The memory 109 is connected to the processing unit 101A and, for example, can store program code instructions non-instantaneously, which when executed by the processing unit 101A, enable the NFC device 100A to implement a near field communication method with the NFC device 100B. Memory 109 may also include one or more volatile storage areas, for example, to enable temporary recording of values of variables associated with execution of programs by processing unit 101A.

Depending on the target application, each NFC device 100a,100b may also include various other elements or circuits represented in fig. 1 by functional blocks 111a,111b (FCT). Although this is not described in detail in fig. 1, NFC devices 100A and 100B may also each include one or more data, address and/or control buses and one or more input-output interfaces between the different elements of these devices.

Fig. 2 is a timing chart showing a chain of consecutive steps of a communication method between NFC devices (e.g., NFC devices 100A (cards) and 100B (readers) located on the right-hand side and the left-hand side in fig. 2, respectively) according to time t.

During step 201 (communication start), near field communication is established between the reader device 100B and the card device 100A. This corresponds to a situation where the device 100A is detected within the range of the device 100B, e.g. when the device 100A is brought to a sufficiently short distance from the NFC device 100B to cause a crossing of the amplitude threshold of the voltage across the circuit 103B and/or the phase shift threshold with respect to the signal generated by the circuit 103B at one side of the device 100B.

During a further step 203 (REQ), the reader device 100B sends a request frame to the card device 100A after step 201. By sending the request, NFC device 100B may, for example, request NFC device 100A to send data corresponding to the contents of one or more regions of its memory 109. As an example, the request frame transmitted by NFC device 100B includes a block called a supervision block or S block. Although this is not described in detail in fig. 2, the NFC devices 100A and 100B may perform other general near field communication operations between steps 201 and 203.

During a further step 205 (RESP), after step 203, the card device 100A transmits a response frame to the reader device 100B. For example, in response to data containing the memory 109 of the NFC device 100A that the NFC device 100B has, it is obtained by transmitting a request frame to indicate the desire in step 203. As an example, the response frame transmitted by the NFC device 100A includes a so-called information block or I block.

If the reader device 100B receives correctly a response frame originating from the card device 100A, the device 100B sends a so-called acknowledgement frame informing the device 100A that the transmission of the response frame has occurred seamlessly, in a further step 207 (POS ACK) after step 205. As an example, the frame transmitted by the device 100B in step 207 includes a block called a receive ready block or R block. The frame of step 207, for example, more precisely comprises a block R containing a positive acknowledgement, more simply indicated by the acronym "R (ACK)".

Near field communication between NFC devices 100A and 100B may then proceed normally, with the possibility of another request frame than step 203, e.g. being sent by device 100B to obtain further data stored in memory 109, or being interrupted, e.g. if all desired data exchanges can be performed, depending on the needs of the application. In order to avoid overload of the drawing, steps corresponding to normal communication, which may be performed after step 207, are not described in detail in fig. 2.

However, if the reader device 100B does not properly receive the response frame of step 205, e.g., if the device 100B does not receive all or part of the frame, the device 100B then sends an acknowledgement frame at another step 209 (NEGACK) following step 205, intended to inform the device 100A that the transmission of the response frame has failed. The failure of this transmission may be caused by different reasons or interoperability (interoperability) problems, such as a change in the form factor of the antennas 105A and 105B, a coupling defect between the reader device 100B and the card device 100A, a use of the reader device 100B not conforming to the near field communication standard used by the card device 100A, or the like. As an example, the acknowledgement frame sent by device 100B at step 209 includes an R block containing a negative acknowledgement, more simply denoted by the acronym "R (NAK)".

In the case where the second attempt to transmit the response frame fails in step 205, the card device 100A then attempts to transmit the response frame to the reader device 100B a third time again during another step 211 (RESP) after step 209. Step 211 is identical to step 205. More precisely, in step 211, the content and pattern of the nfc device 100A transmission response frame is unchanged with respect to step 205.

If the reader device 100B does not correctly receive the response frame of step 211, the device 100B transmits an acknowledgement frame again during another step 213 (NEGACK) after step 211, informing the device 100A of the transmission failure of the response frame of step 211. This corresponds to the case where there is still an interoperability problem during step 211 that would affect the transmission of the response frame during step 205, for example. Step 213 is, for example, the same as or similar to step 209.

In the case where the second attempt to transmit the response frame in step 211 fails, the card device 100A then attempts to transmit the response frame to the reader device 100B a third time again during another step 215 (RESP) after step 213. Step 215 is identical to steps 205 and 211. More precisely, in step 215, the content and pattern of the nfc device 100A transmission response frame is unchanged with respect to steps 205 and 211.

Multiple reception failures of response frames by the reader device 100B to the card device 100A are separated by multiple transmissions by the reader device 100B of negative acknowledgement frames intended to inform the card device 100A of these failures, and thus can follow each other until another step 217 following step 215, during which step 217 the communication between the NFC devices 100A and 100B is stopped. As an example, NFC device 100B may end near field communication with NFC device 100A after 3 to 5 negative acknowledgement frames including a block R (NAK) are consecutively transmitted.

If the interoperability problem is solved before step 217, the communication between the NFC devices 100A and 100B may resume normally and, for example, the desired data exchange is performed in its entirety. However, repeated transmission of the same response frame of device 100A and acknowledgement frame of device 100B results in an undesirable increase in communication time.

However, if there is an interoperability problem before step 217, the communication between NFC devices 100A and 100B ends before the desired data exchange ends. This in turn leads to a failure of the near field communication between the devices 100A and 100B, thereby adversely affecting the user experience of these devices.

Fig. 3 is a timing diagram showing successive steps of a communication method between NFC devices (e.g., NFC devices 100A (cards) and 100B (readers)) located on the right-hand side and the left-hand side, respectively, in fig. 3, according to an embodiment.

In general, the embodiment of fig. 3 provides that, in case the NFC device 100A remotely powered by the NFC device 100B receives a frame indicating that the data reception of the NFC device 100B failed, at least one transmission parameter of the NFC device 100A is modified before another attempt to transmit said data.

The timing diagram of fig. 3 has the same elements as the timing diagram of fig. 2. These common elements will not be described again below. More precisely, the timing diagram of fig. 3 includes steps 201 (communication start), 203 (REQ), 205 (RESP), 209 (neg_ack) and 217 (communication) previously discussed in connection with fig. 2. The timing diagram of fig. 3 differs from the timing diagram of fig. 2 in that the timing diagram of fig. 3 includes a step 301 of modifying one or more radio frequency communication parameters (chgreset) of the card device 100A. As shown in fig. 3, step 301 is after step 209 of transmitting the frame intended to inform the card device 100A that the data contained in the response frame transmitted by the device 100A was not received during step 205.

Then, during another step 303 (RESP) after step 209, the card device 100A attempts to send a response frame back to the reader device 100B. Step 303 differs from step 205 in that during step 303 at least one radio frequency communication parameter of the NFC device 100A has been modified with respect to step 205. This advantageously enables an increased opportunity to overcome interoperability problems that have affected data transmission at step 205 and remain, for example, at step 303, relative to the method of fig. 2. The content of the response frame transmitted by NFC device 100A in step 303 is preferably the same as the content of the response frame transmitted in step 205.

If at this point the reader device 100B correctly receives a response frame originating from the card device 100A, then at a further step 305 (POS ACK) following step 303, the device 100B sends an acknowledgement frame intended to inform the device 100A that the transmission of the response frame has been successful. For example, step 305 of FIG. 3 is the same as or similar to step 207 of FIG. 2. Near field communication between NFC devices 100A and 100B may proceed normally or be interrupted as previously discussed with respect to fig. 2, depending on the needs of the application. In order to avoid overload of the drawing, steps corresponding to normal communication that may be performed after step 305 are not shown in fig. 3.

However, if the response frame of step 303 correctly receives the response frame of step 303, e.g., if device 100B does not receive all or part of the frame, device 100B then sends an acknowledgement frame at another step 307 (NEGACK) after step 303, intended to inform device 100A that the transmission of the response frame has failed.

In the event that the second transmission of the response frame fails during step 303, one or more radio frequency communication parameters of the card device 100A are modified during another step 309 (CHG RF SET) following step 307. The parameters modified during step 309 may be the same as the radio frequency parameters modified during step 301. As an example, at step 309, the value or state of the parameter or parameters may be modified relative to step 301. As a variant, the parameters modified during step 309 may be wholly or partly different from the radio frequency parameters modified during step 301.

Then, during another step 311 (RESP) after step 309, the card device 100A attempts to send a response frame back to the reader device 100B. Step 311 differs from steps 205 and 303 in that during step 311 at least one radio frequency communication parameter has been modified for steps 205 and 303. This advantageously enables further increases in opportunities to overcome interoperability problems affecting data transmission at steps 205 and 303, such as still present at step 311, relative to the method of fig. 2.

Although this is not shown in fig. 3, the multiple receptions of the response frames of the card device 100A by the reader device 100B fail, and the multiple transmissions of the acknowledgement frames intended to inform the card device 100A of these failures by the reader device 100B are separated, so that they can follow each other after step 311 before step 217, during which step 217 the near field communication between the NFC devices 100A and 100B is stopped. Before each new transmission of the same response frame by NFC device 100A, one or more radio frequency communication parameters are modified, for example as discussed above with respect to steps 301 and 309.

An advantage of the communication method discussed above with respect to fig. 3 is that it enables an increased opportunity to overcome interoperability problems before the end of the communication between NFC devices 100A and 100B, relative to the method of fig. 2, thereby completing all desired data exchanges between these devices. This results in an improved user experience of NFC devices 100A and 100B.

Fig. 4 is a logic diagram illustrating an example of an implementation of the communication method of fig. 3. The logic diagram of fig. 4 is implemented, for example, by the processing unit 101A of the NFC device 100A.

During an initial step 401 (RATS/ATTRIB), communication between NFC devices 100A and 100B starts, for example, by sending a frame called an answer selection Request (RATS) or a home frame (ATTRIB).

As an example, during a further step 403 (CNT: =0), after step 401, the counter CNT is initialized by assigning a value, e.g. zero, to the counter CNT. In the logic diagram shown in fig. 4, each value of the counter CNT corresponds to a different state or a different value of at least one radio frequency communication parameter of the NFC device 100A. The value of the counter CNT is an integer value and is smaller than or equal to a non-zero maximum value CMAX, for example equal to 2. As an example, each value of the counter CNT corresponds to a configuration or parameterization of the near field communication circuit 103A of the NFC device 100A. Thus, in the case where the maximum value CMAX of the counter CNT is equal to 2, three different configurations of the circuit 103A may be applied, for example, successively in an attempt to solve the problem of affecting the communication between the NFC devices 100A and 100B. The configuration applied when the counter CNT has a zero value corresponds for example to a default or standard configuration, for example a configuration enabling near field communication in most cases using the NFC device 100A.

During another step 405 (receive frame), after step 403, NFC device 100A receives a frame transmitted by NFC device 100B. The frame for example comprises a plurality of Application Protocol Data Units (APDUs). Although this is not described in detail in fig. 4, the transmission of frames by NFC device 100B is, for example, continuous with the transmission of requests by NFC device 100B and then with the attempt by NFC device 100A to transmit data, as discussed with respect to steps 203 and 205 of the method of fig. 3.

During a further step 407 (R (NAK).

In case the frame contains a block R (NAK) (output Y of block 407), e.g. due to interoperability problems between NFC devices 100A and 100B, the counter CNT is incremented (CNT: =cnt+1) during a further step 409, after step 407. During step 409, the value of the counter CNT is increased by one unit.

During a further step 411 (cnt=cmax. At this stage, the value of the counter CNT is equal to 1 (output N of block 411), at least one radio frequency communication parameter of the NFC device 100A being modified during a further step 413 (CHG RF SET) following step 411. For example, step 413 is the same as or similar to step 301 previously described in connection with fig. 3.

During a further step 415 (send acknowledgement), after step 413, NFC device 100A attempts to send a response frame back to NFC device 100B by applying the parameters modified in step 413.

NFC device 100A then returns to step 405 of receiving the frame transmitted by NFC device 100B. The previously described steps 407, 409, 411, 413 and 415 are repeated as long as the frame received at step 405 contains a negative acknowledgement block R (NAK) and the value of the counter CNT is less than the maximum value CMAX. When the counter CNT reaches its maximum value CMAX (output Y of block 411), the radio frequency communication parameters of the NFC device 100A are no longer modified at step 413, and at step 415, the transmission of the response frame is performed by applying the parameters corresponding to the value CMAX of the counter CNT.

In case the frame received by NFC device 100A during step 405 does not contain a negative acknowledgement block R (NAK) (output N of block 407), the value of counter CNT is reset (cnt=0) in a further step 417, which after step 407 performs the transmission of the response frame by applying a radio frequency communication parameter corresponding to the zero value of counter CNT. In other words, NFC device 100A applies the default configuration of circuit 103A at the beginning of each new near field communication and once interoperability issues can be overcome.

As a variant, the counter CNT may be set to be reset after reaching its maximum value CMAX. For example, in the case of interoperability issues, this amounts to attempting to transmit frames to NFC device 100B by cyclically applying all possible configurations of circuit 103A.

Further, although this is not shown in fig. 4, it may be provided that by applying a configuration corresponding to the maximum value CMAX of the counter CNT, the near field communication between the NFC devices 100A and 100B is interrupted after, for example, one or more attempts to transmit a frame to the NFC device 100B.

Fig. 5 shows an example of an implementation of the communication method of fig. 3 and 4.

Fig. 5 more precisely shows a first example of implementation (example 1, on the left-hand side of fig. 5), in which the NFC device 100A applies the first radio frequency communication configuration 501 (cfg_1) when the value of the counter CNT is equal to 1 (cnt=1). In configuration 501, the value 503 of the Load Modulation Amplitude (LMA) of NFC device 100A is increased relative to a default value applied when counter CNT has a zero value. For example, in the case where the EMF field radiated by the NFC device 100B has a low intensity, the fact of increasing the load modulation amplitude value 503 facilitates communication between the NFC devices 100A and 100B. The strength of the EMF field emitted by NFC device 100B is estimated, for example, by the current sensor of NFC device 100A and compared to a low threshold value, which is crossed to indicate the presence of a low strength field. As an example, in case the counter CNT has a zero value, the increase of the value 503 of the load modulation amplitude between the initial configuration and the configuration 501 is of the order of 5%, for example in the range of 5 to 10 mV.

Further, in the first configuration 501, the further value 505 of the Frame Delay Time (FDT) is reduced with respect to the default value applied when the counter CNT has a zero value. The value 505 corresponds to, for example, a duration between an end of the NFC device 100B transmitting the request and a start of the NFC device 100A transmitting the response. The fact of reducing the value 505 makes it easy to communicate, for example, in case the EMF field radiated by the NFC device 100B has a low intensity. As an example, the decrease in value 505 between the initial configuration and configuration 501 is on the order of-2/fc, where fc represents the oscillation frequency of the carrier wave of the EMF signal radiated by NFC device 100B.

In a first example of implementation, NFC device 100A applies second radio frequency configuration 507 (cfg_2) when the value of counter CNT is equal to 2 (cnt=2). In a second configuration 507, the load modulation amplitude value 503 (LMA) and the frame delay time value 505 (FDT) are reset. In other words, in configuration 507, when counter CNT has a zero value, the same values 503 and 505 as the default configuration are applied.

Further, in the second configuration 507 of the first implementation example, the synchronization frequency 509 (CLK) or the clock frequency of the computing unit 101A of the NFC device 100A is reduced relative to a default value applied when the counter CNT has a zero value. The fact of reducing the frequency 509 enables, for example, to reduce electromagnetic interference that may be generated by one or more elements of the NFC device 100A. This simplifies the communication between NFC devices 100A and 100B. As an example, the reduction in frequency 509 between the initial configuration and the configuration 507 is approximately-20%.

Further, in configuration 507, one or more durations 511 (TRANS) of transitions between data frame reception, processing, and transmission phases of NFC device 100A during communication with NFC device 100B are modified. For example, the duration or durations are increased in configuration 507 relative to the initial configuration. This enables a more gradual transition between the receive, process and transmit phases.

Fig. 5 also shows a second example of implementation (example 2, on the right-hand side of fig. 5), wherein when the value of the counter CNT is equal to 1 (cnt=1), the NFC device 100A applies the first radio frequency communication configuration 501 (cfg_1), as previously described with respect to the first example of implementation.

In a second example of implementation, NFC device 100A applies third radio frequency configuration 513 (cfg_3) when the value of counter CNT is equal to 2 (cnt=2). In the third configuration 513, when the counter CNT has a zero value, the value 503 (LMA) of the load modulation amplitude is reduced relative to the default value. For example, in the case where the EMF field radiated by the NFC device 100B has a high intensity, the fact of reducing the load modulation amplitude value 503 facilitates communication between the NFC devices 100A and 100B. The strength of the EMF field emitted by NFC device 100B is estimated, for example, by the current sensor of NFC device 100A and compared to a low threshold value, which is crossed to indicate the presence of a high strength field. As an example, the decrease in load modulation amplitude value 503 between the initial configuration and configuration 513, corresponding to the case where the counter CNT has a zero value, is on the order of-5%, for example in the range of-5 to-10 mV.

Further, in the third configuration 513, the frame delay time value 505 (FDT) is increased with respect to a default value applied when the counter CNT has a zero value. The fact of adding value 505 makes it easy to communicate, for example, in the presence of a high intensity EMF field radiated by NFC device 100B. As an example, the increase in value 505 between the initial configuration and the configuration 513 is on the order of 2/fc.

An example of a radio frequency communication configuration has been described above in connection with fig. 5. These examples are not limiting. In particular, other radio frequency communication parameters may be modified. The selection and parameterization of the states or values of these parameters is performed, for example, according to the intended use case of the NFC device 100A.

In general, the methods discussed above with respect to fig. 4 and 5 advantageously enable NFC device 100A to benefit from at least one alternative radio frequency communication configuration that can address interoperability issues between NFC devices during near field communication, in addition to the default radio frequency communication configuration.

An advantage of the NFC device 100A implementing the method is that it is able to avoid near field communication errors or failures, in particular for NFC devices not implementing the method.

Various embodiments and modifications have been described. Those skilled in the art will appreciate 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, the example of a radio frequency communication configuration discussed in connection with fig. 5 is not limiting. More generally, any number of radio frequency communication configurations may be provided depending on the target application, each configuration implying a modification of one or more radio frequency communication parameters.

Finally, based on the functional indications given above, the practical implementation of the described embodiments and variants is within the reach of a person skilled in the art. In particular, the state or value of the radio frequency communication parameter corresponding to each configuration may be stored, for example, in the memory 109 of the NFC device 100A, for example in a different memory register accessible via a pointer. These states or values may be defined in the factory by the manufacturer of NFC device 100A. As a variant, these states or values are parameterized by the user of NFC device 100A.

Claims (20)

1. A method, comprising:

establishing a near field communication connection between a first near field communication device and a second near field communication device;

wherein the first near field communication device is remotely powered by the second near field communication device;

transmitting, by the first near field communication device, a transmit frame comprising data over the established near field communication connection;

receiving, by the first near field communication device, an acknowledgement frame indicating that the second near field communication device failed to receive the data within the transmit frame sent by the first near field communication device;

modifying, by the first near field communication device, at least one near field communication transmission parameter in response to the acknowledgement frame; and

the transmit frame comprising data is then retransmitted by the first near field communication device over the established near field communication connection.

2. The method of claim 1, wherein the at least one parameter modified by the first near field communication device is a duration between an end of transmission of a request by the second near field communication device and a beginning of transmission of a response by the first near field communication device.

3. The method of claim 1, wherein the at least one parameter modified by the first near field communication device is a modulation amplitude of an electromagnetic field radiated by the second near field communication device by the first near field communication device.

4. A method according to claim 3, wherein modifying comprises decreasing the modulation amplitude when the electromagnetic field has an intensity less than a first threshold value, and increasing the modulation amplitude when the electromagnetic field has an intensity greater than a second threshold value.

5. The method of claim 4, further comprising estimating the strength of the electromagnetic field using a current sensor of the first near field communication device.

6. The method of claim 1, wherein the at least one parameter modified by the first near field communication device is a synchronization frequency of a computing unit of the first near field communication device.

7. The method of claim 1, wherein the at least one parameter modified by the first near field communication device comprises a transition duration of the first near field communication device between a receive phase, a process phase, and a transmit phase.

8. The method of claim 1, further comprising storing the at least one parameter in a register of a non-volatile memory of the first near field communication device.

9. The method of claim 1, wherein the acknowledgement frame is received by the first near field communication device after the transmission frame is sent by the first near field communication device.

10. The method of claim 9, wherein the transmitting a frame comprises: after receiving the data request frame sent by the second near field communication device, a response frame sent by the first near field communication device.

11. A first near field communication device, comprising:

an antenna;

near field communication circuitry coupled to the antenna and configured to establish a near field communication connection with a second near field communication device in dependence on a selected one of a plurality of near field communication transmission parameters;

wherein the first near field communication device is remotely powered by the second near field communication device;

wherein the near field communication circuit is configured to:

transmitting a transmission frame comprising data over the established near field communication connection using a first near field communication transmission parameter;

receiving an acknowledgement frame indicating that the second near field communication device failed to receive the data within the transmit frame;

in response to the acknowledgement frame, modifying to use a second near field communication transmission parameter; and

the transmit frame comprising data is then retransmitted over the established near field communication connection.

12. The first near field communication device of claim 10, wherein the first near field communication transmission parameter and the second near field communication transmission parameter specify different durations between an end of transmission of a request by the second near field communication device and a start of transmission of a response by the first near field communication device.

13. The first near field communication device of claim 10, wherein the first near field communication transmission parameter and the second near field communication transmission parameter specify different modulation magnitudes of an electromagnetic field radiated by the second near field communication device by the first near field communication device.

14. The first near field communication device of claim 13, wherein the second near field communication transmission parameter specifies a reduced modulation amplitude than the first near field communication transmission parameter when the electromagnetic field has an intensity less than a first threshold, and wherein the second near field communication transmission parameter specifies an increased modulation amplitude than the first near field communication transmission parameter when the electromagnetic field has an intensity greater than a second threshold.

15. The first near field communication device of claim 14, further comprising a current sensor configured to estimate the intensity of the electromagnetic field.

16. The first near field communication device of claim 10, wherein the first near field communication transmission parameter and the second near field communication transmission parameter specify different synchronization frequencies of a computing unit of the first near field communication device.

17. The first near field communication device of claim 10, wherein the first near field communication transmit parameter and second near field communication transmit parameter specify different transition durations of the first near field communication device between a receive phase, a process phase, and a transmit phase.

18. The first near field communication device of claim 10, further comprising a non-volatile memory configured to store the plurality of near field communication transmission parameters.

19. The first near field communication device of claim 10, wherein the acknowledgement frame is received by the first near field communication device after the transmission frame is sent by the first near field communication device.

20. The first near field communication device of claim 19, wherein the transmit frame comprises: after receiving the data request frame sent by the second near field communication device, a response frame sent by the first near field communication device.