Near field communication method and device

Abstract

The invention relates to a near field communication method and device. The first device operates in a card mode and includes an NFC controller. The second device operates in a reader mode. In an NFC communication method, a first device exits an observer mode when an NFC controller receives content of a captured radio frequency field sequence.

Description

[0001] CLAIM

[0002] This application claims priority to European Patent Application No. 24315361.6 filed on July 26, 2024, and to French Patent Application No. FR 2410563 filed on October 1, 2024, the contents of which are incorporated by reference in their entirety to the maximum extent permitted by law. TECHNICAL FIELD

[0003] The present disclosure relates generally to electronic circuits and devices, and more specifically to electronic circuits and devices configured to implement wireless communications. The present disclosure more particularly relates to near field communications (NFC) and its implementation. BACKGROUND

[0004] It is increasingly common to use wireless communications to transmit data between two or more electronic devices. One type of wireless communication referred to herein is near field communication (NFC), also referred to herein as NFC communication.

[0005] Increasingly, transactions are implemented through wireless communications, for example using near field communication technology. The communication protocols implemented during such wireless communications are continually evolving.

[0006] To implement such NFC communications, a first electronic device can operate in a so-called “card” or “card emulation” mode, while a second electronic device can operate in a so-called “reader” or “terminal” mode. Such electronic devices are for example smart or advanced cellular phones (smartphones).

[0007] It is desirable to be able to at least partially improve certain aspects of the protection of NFC type wireless communications between electronic devices.

[0008] There is a need for improved and faster wireless communications.

[0009] There is a need for improved and faster NFC communications.

[0010] There is a need for electronic devices implementing such communications.

[0011] There is a need for systems comprising at least two electronic devices implementing such communications.

[0012] There is a need to overcome all or part of the drawbacks of known wireless communications.

[0013] There is a need to overcome all or part of the drawbacks of known NFC communications. SUMMARY

[0014] One embodiment provides a method of NFC communication between a first device in a card mode comprising a NFC controller and a second device in a reader mode, wherein said first device exits a listener mode upon reception by said NFC controller of a content of a capture sequence of a radio frequency field.

[0015] One embodiment provides an electronic device configured to operate as a first device in a method of NFC communication between said first device in a card mode comprising a NFC controller and a second device in a reader mode, wherein said first device exits a listener mode upon reception by said NFC controller of a content of a capture sequence of a radio frequency field.

[0016] One embodiment provides an electronic system comprising a first electronic device and a second electronic device, said system being configured to implement a method of NFC communication between said first device in a card mode comprising a NFC controller and said second device in a reader mode, wherein said first device exits a listener mode upon reception by said NFC controller of a content of a capture sequence of a radio frequency field.

[0017] According to an embodiment, said sequence forms part of a polling frame emitted by said second device.

[0018] According to an embodiment, said NFC controller detects the content of said sequence by comparison with one or more reference contents stored in a memory thereof.

[0019] According to an embodiment, said reference contents stored in a memory of the NFC controller are emitted by an application processor of said first device.

[0020] According to one embodiment, said application processor of said first device is configured to trigger said listener mode.

[0021] According to an embodiment, upon reception of said content, the NFC controller is configured to indicate to said application processor a suspension of the listener mode.

[0022] According to one embodiment, said content is at the beginning of a first polling frame.

[0023] According to an embodiment, upon end of the NFC communication, the NFC controller is configured to re-enter the listener mode after a predetermined delay.

[0024] Another embodiment provides a computer program product comprising program code instructions recorded on a medium readable by a computer, these program code instructions comprising: computer readable programming means for implementing the aforementioned method when said program is run on a computer. BRIEF DESCRIPTION OF DRAWINGS

[0025] The foregoing features and advantages, as well as others, will be described in more detail in the disclosure that follows, with reference to the drawings, in which:

[0026] Figure 1 Embodiments of an electronic device configured to implement NFC communication are shown;

[0027] Figure 2 Embodiments of an electronic system configured to implement NFC communication are shown;

[0028] Figure 3 Conventional methods of implementing NFC communication are shown; and

[0029] Figure 4 Implementation modes of NFC communication methods are shown. DETAILED DESCRIPTION

[0030] In the various drawings, like reference numerals refer to like features throughout. In particular, structural and / or functional features common to the various embodiments can have the same reference numerals and can be provided with the same structural, dimensional, and material properties.

[0031] For the sake of clarity, only those steps and elements that are useful in understanding the embodiments have been shown and described. So long as not otherwise specified, when referring to two elements connected together, this means a direct connection without any intermediate elements other than conductors, and when referring to two elements coupled together, this means that the two elements can be connected or they can be coupled via one or more other elements.

[0032] In the following description, where reference is made to an absolute position qualifier (e.g., "front", "back", "top", "bottom", "left", "right", etc.) or a relative position qualifier (e.g., "top", "bottom", "upper", "lower", etc.) or an orientation qualifier (e.g., "horizontal", "vertical", etc.), reference is made unless otherwise specified to the orientation of the drawings.

[0033] Unless otherwise stated, the order of the expressions "about", "approximately", "substantially" and "of the order of" indicates plus or minus 10%, preferably plus or minus 5%.

[0034] The embodiments described below relate to the implementation of wireless communications, and more specifically to the implementation of faster NFC communications. The present disclosure applies more specifically to portable devices implementing NFC communications. More specifically, the card side is considered, i.e. a device operating in "card" or "card emulation" mode, while another device in the system operates in "reader" mode. Such a device operating in reader mode can be any suitable device, including another phone operating in reader mode. Devices equipped with card emulation mode include smart or advanced cellular phones (smartphones). Furthermore, such phones can operate in reader mode or card mode. In conjunction Figure 1 Such a device is described. In conjunction Figure 2 NFC communications and electronic systems implementing NFC communications are described.

[0035] These embodiments relate to recent developments in NFC communication protocols. In these recent developments, when a portable device is in card mode (hereinafter referred to as device, device in card mode, card or card device), it can enter a listening or observation mode, i.e. in these modes it "observes" its environment in order to detect a reader emitting a radio frequency field, but in which it is not configured to respond to stimuli. However, the use of such an observer mode can slow down NFC communications. In conjunction Figure 2 And Figure 3 The operation of this mode is described in further detail.

[0036] The solution provided here includes detecting a specific command that automatically exits the observer mode. In other words, the present disclosure proposes to exit the observer mode upon detecting a specific content in the processing command received. In conjunction Figure 4 The solution is described in detail.

[0037] The embodiments described below are particularly suitable for any electronic device implementing NFC communications in "card" mode, such as a cellular phone, a smartphone, a connected watch or a portable electronic device of the electronic cigarette type.

[0038] Furthermore, the above embodiments are particularly suitable for any type of industrial market using NFC communications. More specifically, such NFC communications can aim to be used in the automotive industry, for example in the field of electrification of vehicles or in the field of advanced driver assistance systems (ADAS); in the industry, for example in the field of green energy, in the field of electrification of infrastructures, in the field of the Internet of Things (IoT) and in the field of smart homes, where electricity and energy consumption and data exchange are key elements; and in the personal electronics industry, for example in the field of mobile phones and the Internet of Things, and in the field of high-speed interfaces.

[0039] Figure 1 is a block diagram very schematically illustrating the architecture of an example of an electronic device 100 configured to implement a method of NFC communication.

[0040] The electronic device 100 comprises a processor 101 (CPU) configured to perform various processing operations on data stored in memory and / or provided by other circuits of the device 100. According to an embodiment, the processor 101 is configured to implement the NFC communication method. According to a particular embodiment, the processor 101 is configured to implement one or more applications which are themselves configured to implement NFC communication or transactions, in which case the processor 101 can be referred to as an application processor.

[0041] The electronic device 100 also comprises different types of memory 102 (MEM), including for example non-volatile memory, volatile memory and / or read-only memory. Each memory 102 is configured to store different types of data.

[0042] The electronic device 100 also comprises a secure element 103 (SE) configured for example to process sensitive and / or secret data. The secure element 103 can comprise its own processor, its own memory or memories, etc. According to an embodiment, the processor 101 is configured to implement the NFC communication method. According to a particular embodiment, the secure element 103 can comprise a processor configured to implement one or more applications which are themselves configured to implement NFC communication or transactions, in which case the processor of the secure element 103 can be referred to as an application processor.

[0043] The electronic device 100 can also comprise interface circuitry 104 (IN / OUT) configured to emit and / or receive data originating from outside the device 100. The interface circuitry 104 can also be configured to implement data display, for example a display screen.

[0044] According to an embodiment, the electronic device comprises NFC circuitry 105 (NFCC). The circuitry 105 comprises a NFC controller configured to exchange data with one or more other electronic devices during implementation of NFC communication. According to an example, the controller comprises components capable of implementing NFC communication. According to an embodiment, the NFC controller is configured to receive commands from a processor configured to implement one or more applications using NFC communication, for example the processor 101 or the secure element 103. The NFC circuitry 105 also comprises circuitry configured to generate a radio frequency electromagnetic field and to capture a radio frequency electromagnetic field. According to an embodiment, the NFC controller comprises a data storage device.

[0045] The electronic device 100 also comprises various circuitry 106 (FCT) configured to perform different functions. For example, the circuitry 106 can comprise measurement circuitry, data conversion circuitry, etc.

[0046] The electronic device 100 also comprises one or more data buses 107 configured to transfer data between its various components.

[0047] According to a particular example, the electronic device 100 is configured to implement a computer program, in particular a computer program capable of implementing a method of wireless communication, for example a computer program capable of implementing a method of wireless communication on the side of a terminal and / or on the side of a card.

[0048] More precisely, the electronic device 100 is configured to implement at least one computer program product comprising program code instructions recorded on a medium usable in a computer, said computer program product comprising a computer readable programming device for implementing a method of wireless communication as a terminal device and / or as a card device when said program is run on a computer.

[0049] Figure 2 An example of a system 200 implementing NFC communication is illustrated very schematically in the form of blocks.

[0050] The system 200 comprises a first device 201 (card) and a second device 202 (terminal). Each device 201, 202 is of the type described above Figure 1 with respect to the device 100 described.

[0051] The device 201 is a card-type device, i.e. an electronic device operating in "card" or "card emulation" mode. The device 201 is hereafter referred to as a card device.

[0052] The device 202 is a reader-type device, i.e. an electronic device operating in "reader" or "terminal" mode. The device 202 is hereafter referred to as a reader device.

[0053] According to one embodiment, the device 201 comprises at least one application processor 2011 (APPROC) and one NFC controller 2012 (NFCC). The application processor 2011 is configured to implement one or more applications capable of using NFC communication, for example to implement transactions (for example banking, transport, access, etc.). As for the NFC controller 2012, it is configured to actually implement NFC communication.

[0054] Even if this is not illustrated in Figure 2 the device 202 comprises at least one NFC controller for implementing NFC communication, and for example a processor.

[0055] NFC communication uses radio frequency (RF) signals emitted by the antenna of the device implementing the communication through an oscillation / resonance circuit. When the reader device 202 emits an electromagnetic field to initiate communication with the card device 201, as long as said field is within range, the card device 201 captures said field. This field is detected by the card device 201.

[0056] Generally speaking, from a communication protocol point of view, a NFC communication starts with the emission by a reader device of one or more poll frames. Once this poll frame is captured by a card device, the card device responds to it and initiates a NFC communication. The NFC communication then takes the form of an exchange of data sequences forming requests and responses. There are various types of poll frames, some of which are defined by the standard, among which are Type A frames, Type B frames or Type F frames. These types of poll frames are defined for example by the bytes of the frame that are emitted. Other bytes of the frame can allow to define the length of an authorization response.

[0057] Moreover, recent developments have led to the creation of a new operating mode of electronic devices configured to implement NFC communications. The operating mode is a listening mode or "watcher" mode during which the electronic device captures data sequences, manages to interpret the various protocols that it captures and configures itself on the protocol for which it detects a command according to the protocols that it can support, so that the reader device can initiate a transaction. When a card device operates in this mode, its NFC controller is configured to receive, capture or watch possible poll frames emitted by a reader device that can have them in its field. Figure 3 The start of a current NFC communication is illustrated in more detail in a communication exchange diagram and in particular how the watcher mode works. Figure 4 The start of an implementation mode of a NFC communication method is illustrated in more detail in a communication exchange diagram and in particular how the watcher mode works.

[0058] Figure 3 Very schematically illustrated is the start of an implementation mode of a NFC communication method within an electronic system of the type described with respect to Figure 2 The start of an implementation mode of a NFC communication method within an electronic system of the type described with respect to

[0059] More particularly, the NFC communication 300 is implemented between a reader device 302 of the type described with respect to Figure 2 a card device 301 of the type described with respect to Figure 2 The card device 301 comprises an application processor 3011 of the type described with respect to Figure 2 a NFC controller 3012 of the type described with respect to Figure 2 a NFC controller 3012 of the type described with respect to Figure 3 The data communication exchanges between the reader device 302, the application processor 3011 and the NFC controller 3012 are illustrated.

[0060] In the initial state, no communication is initiated between the card device 301 and the reader device 302. Therefore, the card device 301 waits for a request to initiate NFC communication. Thus, the card device 301 can enter observer mode. More specifically, the card device 301 can set its NFC controller to observer mode. To this end, the application processor 3011 triggers the NFC controller 3012 into observer mode by sending a command or request En_Obs_Mode300 to the NFC controller 3012. Upon receiving the command, the NFC controller 3012 enters observer mode and can respond to the application processor 3011, for example, with an acknowledgment Ok_Obs_Mode_EN_300. While in this observer mode, the NFC controller 3012 begins to "observe" possible fields emitted by the reader device 302.

[0061] Once the NFC controller 3012 receives the field transmitted by the reader device 302 and receives the command and request, it transmits the command and request directly to the application processor 3011 without responding to it or analyzing it, for example. When in observer mode, the NFC controller 3012 is not authorized to transmit data.

[0062] exist Figure 3 In the example, reader device 302 transmits multiple polling frames including multiple requests and commands labeled NFC-A-300-CCmd, NFC-A-300-Req1, NFC-B-300-Req2, and NFC-F-300-Cmd. According to one example, if reader device 302 is configured to implement NFC communication using multiple different communication protocols, it can transmit polling frames according to the different protocols it supports. All these requests and commands labeled NFC-A-300-CCmd, NFC-A-300-Req1, NFC-B-300-Req2, and NFC-F-300-Cmd are received by NFC controller 3012 and then transmitted directly to application processor 3011. Then, the application processor 3011 analyzes the contents of these requests and commands, which are labeled NFC-A-300-CCmd, NFC-A-300-Req1, NFC-B-300-Req2, and NFC-F-300-Cmd, and determines whether it wishes to initiate communication with the reader device 302.

[0063] If the application processor 3011 decides to initiate communication with the reader device 302, it sends a command or request to the NFC controller, Dis_Obs_Mode300, causing it to exit observer mode. The NFC controller 3012 receives the command, exits observer mode, and may respond to the application processor 3011, for example, with an acknowledgment, Ok_Obs_Mode_Dis_300. According to variations, the NFC controller 3012 may be removed from observer mode by a processor different from the application processor 3011.

[0064] According to a specific example, the listening mode or observer mode is the operating mode of an NFC controller that exists in an electronic device embedded with an operating system known as "Android".

[0065] Once the NFC controller 3012 is in normal operating mode, that is, in an operating mode that enables NFC communication, it can respond to the terminal device 302 when it receives commands and requests from the terminal device 302.

[0066] exist Figure 3 In the example, reader device 302 transmits a request NFC-A-300-Req, and NFC controller 3012 responds with an NFC-A-300-Rsp response. According to one example, NFC controller 3012 may respond directly, or it may consult application processor 3011 to determine which response to transmit to reader device 302. According to one example, application processor 3011 may select an application to implement NFC communication based on the protocol type used by reader device 302 and / or the content of polling frames transmitted by reader device 302, and have the application generate a response for reader device 302.

[0067] The drawback of NFC communication method 300 is that the use of observer mode wastes NFC communication time, particularly delaying the completion of NFC communication. Combined with... Figure 4 The described implementation is designed to overcome this problem.

[0068] Figure 4 It shows very schematically the information about Figure 2 The description describes the implementation mode of the NFC communication method 400 within an electronic system of type 200.

[0069] More specifically, NFC communication 400 regarding Figure 2 The reader device described is of type 202, and the reader device 402 is about... Figure 2 The described device 201 is implemented between card devices 401. Card device 401 includes... Figure 2The application processor 4011 of the type of processor 2011 described and the NFC controller 4012 described in relation to Figure 2 The NFC controller 4012 of the type of NFC controller 2012 described. Figure 4 The exchange of data between the reader device 402, the application processor 4011 and the NFC controller 4012 is illustrated.

[0070] The embodiments described herein enable the card device 401 to exit the listening mode or the observer mode based on the identification of the content in a sequence emitted by the reader device 402 and recognized by the NFC controller 4012 of the card device 401. Thus, the application processor 4011 does not need to analyze all the protocols.

[0071] Thus, a preparation step or initialization step is first performed. The application processor 4011 emits to the NFC controller 4012 a sequence of data that can be identified as an observer mode stop signal, a command or a request for a list of reference contents. In Figure 4 In the example, the application processor 4011 emits a command Set_Obs_Mode_ExF 400 including the list of reference contents. According to one example, the contents form part of a NFC communication protocol poll frame.

[0072] This is referred to as the content of the sequence of data, command or request, the data or set of data included in the sequence of data, command or request.

[0073] According to a first embodiment, the list of reference contents can be a list of complete data, i.e. bit or byte strings, complete data and / or complete sets of data. According to one example, each content can have a defined length and be placed anywhere in the sequence of data or data frame. According to one example, each content can have an undefined length and be placed anywhere in the sequence of data or data frame.

[0074] According to a specific example, the command Set_Obs_Mode_ExF 400 can include for example different information segments in which: the list of reference contents, each reference content being characterized by a type, a length and a value; a delay value for the resumption of the observer mode; and a value of a plurality of sequences of data following the reference contents.

[0075] According to a second embodiment, the list of reference contents can be a list of data masks. A mask can be one data, for example a prefix of one data, or a set of data.

[0076] The preparation step can be performed at any time during the lifetime of the NFC controller 4012 and more specifically, the list can be updated by adding or removing contents at any time during the lifetime of the NFC controller 4012.

[0077] In the state preceding the NFC communication, the card device 401 thus waits for a request to implement an NFC communication. Thus, the card device 401 can enter an observer mode. More specifically, the card device 401 can set its NFC controller in observer mode. To this end, the application processor 4011 initiates the observer mode of the NFC controller 4012 by transmitting a command or a request En_Obs_Mode 400 to it. The NFC controller 4012 receives said command, enters the observer mode and can respond to the application processor 4011, for example, with an acknowledgement Ok_Obs_Mode_EN 400. When the NFC controller 4012 is in such an observer mode, the NFC controller 4012 is configured to observe a possible field transmitted by the reader device 302 without responding.

[0078] The reader device 402 generates a radio frequency field to attempt to start a communication with the card device. The NFC controller 4012 captures said field. According to an example, the NFC controller 4012 can indicate to the application processor 4011 that it is capturing the field by transmitting a notification RF_Field_NTF 400_ON to the application processor 4011.

[0079] The reader device 402 transmits one or more polling frames corresponding to one or more different communication protocols while waiting for a response. In Figure 4 According to a particular example, the reader device 402 transmits at least one polling frame having a communication protocol compatible with the card device 401. More specifically, the reader device 402 starts by transmitting at least one data sequence NFC-A-400-CCmd whose content forms part of a list stored in the NFC controller 4012.

[0080] Upon reception of the data sequence NFC-A-400-CCmd, the NFC controller 4012 detects the content and automatically suspends the observer mode. According to an example, the NFC controller 4012 can indicate to the application processor 4011 that it has suspended the observer mode by transmitting a notification Obs_Mode_Susp 400.

[0081] According to a particular example, the command Obs_Mode_Susp 400 can comprise, for example, various information, among which: a value indicating the type of the command Obs_Mode_Susp 400; a value indicating the length of the command Obs_Mode_Susp 400; and a value indicating the received content that has triggered the transmission of the command Obs_Mode_Susp 400.

[0082] Once the NFC controller 3012 has suspended the observer mode and is in the normal operation mode, i.e. it can implement the operating mode of NFC communication, it can respond to the terminal device 302 upon receiving a command and a request from the terminal device 302. According to an example, the reader device 402 transmits the command or request NFC-A-400-Cmdl or NFC-A-400-Cmd2 to which the NFC controller responds with the response NFC-A-400-Rspl or NFC-A-400-Rsp2. The NFC controller 4012 can also indicate to the application processor 4011 that it is in NFC communication with the reader device 402, e.g. by transmitting the notification RF_Field_ACT 400. According to an example, the NFC controller 4012 can also transmit a response wait request to the reader device when it needs to poll the application processor 4011 before responding to the reader device 402.

[0083] The rest of the NFC communication can take place, e.g. with the application processor 4011 involved. The latter can e.g. select an application and let said application implement the NFC communication with the NFC controller 4012.

[0084] Once the NFC communication has been completed and ended, the reader device 402 stops its radio frequency field. According to an example, the NFC controller 4012 can indicate to the application processor 4011 that it is no longer capturing the field by transmitting the notification RF_Field_NTF 400 OFF to the application processor 4011. According to an example, the NFC controller can further re-enter or return to the observer mode. According to an example, the NFC controller can indicate this to the application processor 4011 by transmitting the notification Res_Obs_Mode 400 to the application processor 4011.

[0085] According to a particular example, the command Obs_Mode_Susp 400 can e.g. comprise an empty data field.

[0086] According to a variant, the NFC controller 4012 can wait for a predefined delay after receiving the NFC sequence and resume the observer mode if it does not receive a further sequence from the reader device 402. According to an example, said predefined delay can be zero.

[0087] Figure 4 The embodiments provided by the application have the advantage that they enable to avoid waiting for the analysis of the polling frame by the application processor to start the NFC communication, thus saving time for the completion of the NFC communication.

[0088] Another advantage of these embodiments is the backward compatibility with existing devices, the provision of their internal procedures being updatable. Indeed, the reader side does not need to be changed.

[0089] Various embodiments and variants have been described. The person skilled in the art will understand that certain features of these various embodiments and variants can be combined and that other variants will occur to the person skilled in the art.

[0090] Among the possible variants, mention can be made of the possibility of responding to so-called "proprietary" frames to exit the observer mode; and hardware or hardware and software implementation (then requiring structural modifications) on the side of the card device.

[0091] Furthermore, although the "Android" device is taken as an example, the described solution is applicable and can be transposed to any other system in which similar problems exist.

[0092] Finally, the actual implementation of the described embodiments and variants is within the capabilities of the person skilled in the art, based on the functional indications given above.

Claims

1. An NFC communication method, the method being performed between a first device configured to operate in card mode and a second device configured to operate in reader mode, the first device including an NFC controller, the method comprising: The NFC controller receives a sequence of radio frequency field captures. Identify the contents of the captured sequence; And in response to identifying the content, the first device exits observer mode.

2. The method of claim 1, wherein the capture sequence forms part of a polling frame emitted by the second device.

3. The method of claim 1, wherein identifying the content of the captured sequence includes the NFC controller comparing the content with one or more reference contents stored in a memory.

4. The method of claim 3, further comprising transmitting the reference content by the application processor of the first device to store it in the memory of the NFC controller.

5. The method of claim 4, wherein the application processor of the first device is configured to trigger the observer mode.

6. The method according to claim 4, further comprising: Upon receiving the content, the NFC controller instructs the application processor to pause the observer mode.

7. The method of claim 1, wherein the content is at the beginning of the first polling frame.

8. The method according to claim 1, further comprising: When NFC communication ends, the NFC controller is caused to re-enter the observer mode after a predetermined delay.

9. An electronic device configured to operate as a first device in an NFC communication method between a first device in card mode and a second device in reader mode, the first device including an NFC controller, and wherein the first device is configured to receive a capture sequence of a radio frequency field through the NFC controller, identify the contents of the capture sequence; and exit observer mode in response to identifying the contents.

10. The device of claim 9, wherein the capture sequence forms part of a polling frame emitted by the second device.

11. The device of claim 9, wherein the NFC controller is configured to identify the content of the captured sequence by comparing the content of the captured sequence with one or more reference contents stored in a memory.

12. The device of claim 11, wherein the reference content stored in the memory of the NFC controller is received from the application processor of the first device.

13. The device of claim 12, wherein the application processor of the first device is configured to trigger the observer mode.

14. The device of claim 11, wherein upon receiving the content, the NFC controller is configured to instruct the application processor to pause the observer mode.

15. The device of claim 9, wherein the content is at the beginning of the first polling frame.

16. The device of claim 9, wherein the NFC controller is configured to re-enter the observer mode after a predetermined delay upon termination of NFC communication.

17. An electronic system comprising: First equipment; as well as Second equipment; The first device and the second device are configured to enable NFC communication using the first device operating in card mode and the second device operating in reader mode. The first device includes an NFC controller configured to receive a capture sequence of radio frequency fields; and The first device is configured to identify the contents of the captured sequence; And in response to the identified content, exit observer mode.

18. The system of claim 17, wherein the sequence forms part of a polling frame transmitted by the second device.

19. The system of claim 17, wherein the NFC controller identifies the content of the sequence by comparing it with one or more reference contents stored in a memory.

20. The system of claim 19, wherein the reference content is sent by the application processor of the first device to the reference content stored in the memory of the NFC controller.

21. The system of claim 20, wherein the application processor of the first device is configured to trigger the observer mode.

22. The system of claim 19, wherein the NFC controller is configured to instruct the application processor to pause the observer mode upon receiving the content.

23. The system of claim 17, wherein the content is at the beginning of the first polling frame.

24. The system of claim 17, wherein the NFC controller is configured to re-enter the observer mode after a predetermined delay upon the termination of NFC communication.

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