Auxiliary card searching module and method and near field communication equipment

Abstract

The embodiment of the invention provides an auxiliary card searching module and method and near field communication equipment. Wherein the auxiliary card searching module comprises a pulse detection unit, a control unit and a modulation unit; the control unit is respectively connected with the pulse detection unit and the modulation unit; the pulse detection unit is used for generating a trigger signal within a preset duration based on a response signal of an equipment antenna of the slave equipment; the response signal is generated by the device antenna of the slave device in response to a radio frequency signal sent by the master device; the preset time length is smaller than the pulse time length of a radio frequency signal sent by the main equipment; and the control unit is used for controlling the modulation unit to perform state switching according to the trigger signal so as to promote the main equipment to enter a polling mode.

Description

TECHNICAL FIELD

[0001] One or more embodiments of the present specification relate to the field of near field communication technology, in particular to an auxiliary card searching module. One or more embodiments of the present specification also relate to an auxiliary card searching method and a near field communication device. BACKGROUND

[0002] NFC (Near Field Communication) technology is a kind of near field communication technology, which has the advantages of high security, high speed and high speed. With the continuous development of NFC technology and the increasing market, most smart phones are equipped with this technology. LPCD (Low-Power Card Detection) mode is a power saving mode of NFC controller, which can detect whether there is a card or a card simulation device close by periodically transmitting radio frequency signals. When the LPCD mode is turned on, the NFC controller only polls when a card is detected close by, so it can greatly reduce the power consumption of NFC and improve the user experience.

[0003] In an ideal case, when a smart phone with LPCD mode turned on approaches an external device, the NFC controller of the smart phone can be awakened and send polling signals due to the change of the coil coupling condition of the smart phone and the external device. However, in reality, due to the different NFC controller chips used by different smart phones, the wake-up strategy of the LPCD mode is different, and the antenna position and shape are also different. Some phones cannot exit the LPCD mode after approaching the external device, which leads to communication failure.

[0004] Therefore, how to more quickly promote the smart phone and other devices to exit the LPCD mode is a technical problem to be solved. SUMMARY

[0005] Therefore, one or more embodiments of the present specification provide an auxiliary card searching module and method, and a near field communication device to solve the problem that the existing electronic device cannot exit the LPCD mode.

[0006] According to a first aspect of one or more embodiments of the present specification, an auxiliary card searching module is provided, which is applied to a slave device of near field communication, and the auxiliary card searching module comprises a pulse detection unit, a control unit and a modulation unit; the control unit is connected with the pulse detection unit and the modulation unit respectively; The pulse detection unit is configured to generate a trigger signal within a preset time length based on a response signal of a device antenna of the slave device; the response signal is generated by the device antenna of the slave device in response to a radio frequency signal sent by a master device; and the preset time length is less than the pulse length of one radio frequency signal sent by the master device. The control unit is configured to control the modulation unit to switch states according to the trigger signal, so as to facilitate the master device to enter the polling mode; the modulation unit comprises a first state, a second state and a third state; in the first state, the load impedance of the modulation unit is a first impedance value, in the second state, the load impedance of the modulation unit is a second impedance value, and in the third state, the modulation unit emits an excitation signal.

[0007] According to a second aspect of one or more embodiments of the present specification, there is provided an auxiliary card searching method applied to a slave device of near field communication, the slave device comprising an auxiliary card searching module, the auxiliary card searching module comprising a pulse detection unit, a control unit and a modulation unit; the control unit is connected with the pulse detection unit and the modulation unit respectively; The method comprises: The pulse detection unit generates a trigger signal within a preset time length based on a response signal of a device antenna of the slave device; the response signal is generated by the device antenna of the slave device in response to a radio frequency signal sent by a master device; the preset time length is less than a pulse time length of one radio frequency signal sent by the master device; The control unit controls the modulation unit to switch states according to the trigger signal, so as to facilitate the master device to enter the polling mode; the modulation unit comprises a first state, a second state and a third state; in the first state, the load impedance of the modulation unit is a first impedance value, in the second state, the load impedance of the modulation unit is a second impedance value, and in the third state, the modulation unit emits an excitation signal to the master device.

[0008] According to a third aspect of one or more embodiments of the present specification, there is provided a near field communication device, the near field communication device comprising the auxiliary card searching module described above, or the near field communication device being capable of executing the auxiliary card searching method described above.

[0009] The one embodiment of the specification can achieve at least the following beneficial effects: By setting an auxiliary card searching module in the near field communication slave device, after the device antenna of the slave device senses the radio frequency signal sent by the master device, the pulse detection unit in the auxiliary card searching module can generate a trigger signal for adjusting the modulation unit of the auxiliary card searching module within a preset time period less than the pulse time period of one radio frequency signal sent by the master device based on the response signal sensed by the device antenna of the slave device, and the control unit in the auxiliary card searching module can adjust the state of the modulation unit after obtaining the trigger signal, such as changing the impedance value of the modulation unit or controlling the stale unit to emit an excitation signal. During the near field communication process, for the master device, the slave device can be regarded as a load part of the master device, and in at least one embodiment of the specification, the parameter change of the master device under the influence of the slave device can be improved by changing the impedance value of the modulation unit in the auxiliary card searching module, which can promote the master device to switch from the LPCD (Low-Power Card Detection) mode to the normal polling mode, so that the master device can smoothly perform the near field communication with the slave device, and the success rate and efficiency of the near field communication are improved.

[0010] In another aspect, in at least one embodiment of the specification, the pulse detection unit can generate a trigger signal within a time period less than the pulse time period of one radio frequency signal sent by the master device after obtaining the response signal of the device antenna of the slave device, so that the master device can be affected by switching the state of the modulation unit before the end of the first pulse radio frequency signal sent by the master device (for example, the LPCD signal) is sensed by the slave device, without waiting for the slave device to obtain multiple pulse radio frequency signals to start an action for promoting the master device to exit the LPCD mode, so that the master device can exit the LPCD mode and enter the normal polling mode more quickly, and the success rate and efficiency of the near field communication are improved. BRIEF DESCRIPTION OF DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the specification or the prior art, the drawings needed in the embodiment or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the specification, and those skilled in the art can also obtain other drawings according to these drawings without creating any creative labor.

[0012] Figure 1 An application scenario schematic diagram of an auxiliary card searching module provided by one embodiment of the specification is shown in the following figure: Figure 2 A structure schematic diagram of an auxiliary card searching module provided by one embodiment of the specification is shown in the following figure: Figure 3A structural schematic diagram of a pulse detection unit provided for an embodiment of the present specification; Figure 4 A circuit schematic diagram of a pulse detection unit provided for an embodiment of the present specification; Figure 5 A structural schematic diagram of a modulation unit provided for an embodiment of the present specification; Figure 6 A schematic diagram of a modulation unit provided for an embodiment of the present specification; Figure 7 A flowchart of an auxiliary card searching method provided for an embodiment of the present specification; Figure 8 A flowchart of an auxiliary card searching method provided for an embodiment of the present specification. DETAILED DESCRIPTION

[0013] In order to enable persons skilled in the art to better understand the technical solutions in the present specification, the technical solutions in the embodiments of the present specification will be clearly and completely described below with reference to the drawings in the embodiments of the present specification. Obviously, the described embodiments are only some of the embodiments of the present specification, but not all the embodiments. Based on the embodiments in the present specification, all other embodiments obtained by persons skilled in the art without creative labor should fall within the scope of protection of the present specification.

[0014] The present specification uses specific words to describe the embodiments of the present specification. As "one embodiment", "an embodiment", and / or "some embodiments" means a certain feature, structure or characteristic related to at least one embodiment of the present specification. Therefore, it should be emphasized and noted that the "an embodiment" or "one embodiment" or "one alternative embodiment" mentioned in different positions in the present specification does not necessarily refer to the same embodiment. In addition, the skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of different embodiments or examples without contradiction.

[0015] The terms used in one or more embodiments of the present specification are only for the purpose of describing specific embodiments, and are not intended to limit one or more embodiments of the present specification. The singular forms "a", "an" and "the" used in one or more embodiments of the present specification and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used in one or more embodiments of the present specification includes any or all possible combinations of one or more associated listed items.

[0016] The terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, product, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, product, or apparatus. Without further limitation, it does not preclude the presence of additional identical or equivalent elements in a process, method, product, or apparatus that includes the elements.

[0017] Although the terms first, second, etc. may be used to describe various information in one or more embodiments of this specification, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of one or more embodiments of this specification, the first may also be referred to as the second, and similarly, the second may also be referred to as the first. Ordinal numbers such as first and second do not necessarily indicate order, and are often used to facilitate the distinction between objects. For example, the first server and the second server usually refer to two servers. In order to distinguish the two servers, they are expressed as the first server and the second server. Of course, sometimes the two servers may also be the same server.

[0018] The word "if" as used herein may be interpreted as "when" or "when" or "in response to determining," depending on the context.

[0019] In this specification, unless explicitly stated otherwise, "data reception and transmission" does not necessarily refer to direct reception and transmission; it can be indirect. For example, when A receives data from B, it can be understood as A directly receiving the data from B, or it can be understood as A indirectly receiving the data from B through another entity, such as C. Similarly, when B sends data to A, it can be understood as B sending the data directly to A, or it can be understood as B indirectly sending the data to A through another entity, such as C. Here, C can be a single entity, or two or more entities.

[0020] In this specification, unless explicitly stated otherwise, the associations between structures can be direct or indirect. For example, when describing "A is connected to B," unless it is explicitly stated that A and B are directly connected, it should be understood that A can be directly connected to B or indirectly connected to B. For another example, when describing "A is above B," unless it is explicitly stated that A is directly above B (AB is adjacent and A is above B), it should be understood that A can be directly above B or indirectly above B (AB is separated by other elements and A is above B). And so on.

[0021] The user information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in one or more embodiments of the present specification are all information and data authorized by the user or authorized by all parties, and the collection, use and processing of related data need to comply with relevant laws, regulations and standards in the relevant region, and provide corresponding operation portal for user to choose authorization or refusal.

[0022] The following explains the terms involved in one or more embodiments of the present specification.

[0023] NFC (Near Field Communication): a short-range wireless communication technology with a working distance usually within 10 cm, such as used in mobile payment, access control card and bus card scenarios. In the process of NFC near field communication, the device that actively transmits signals can be called the master device, such as the NFC card reader device, the device in the card reader mode, etc. as the device of the near field communication card reader end; the device that passively responds to the signal transmitted by the master device can be called the slave device, such as the NFC tag, the device in the card simulation mode, the device with the NFC tag, etc. as the device of the near field communication tag end.

[0024] LPCD (Low-Power Card Detection): a power saving function of NFC controller, which can periodically detect whether there is an NFC card close by with lower power; when the card is detected close, it can wake up the main system.

[0025] Polling: refers to the process of the NFC active device periodically initiating a communication request to detect whether there is an interactive passive device nearby.

[0026] Figure 1 An application scenario diagram of an auxiliary card searching module provided by one embodiment of the present specification.

[0027] As Figure 1As shown, the auxiliary card search module 206 can be applied in the NFC slave device 200, which can include the NFC slave device antenna 202, the NFC slave device control unit 204 and the auxiliary card search module 206. The NFC master device 100 can include the NFC master device antenna 102, the NFC master device control unit 104. In actual application, the NFC master device control unit 104 in the master device 100 can control the generation of electromagnetic signals, and transmit the radio frequency signals outwardly through the NFC master device antenna 102. If the slave device 200 is located within the radio frequency range of the master device 100, the NFC slave device antenna 202 in the slave device 200 can generate electromagnetic coupling with the NFC master device antenna 102 in the master device 100, and the NFC slave device control unit 204 in the slave device 200 can analyze the electromagnetic signals perceived in the NFC slave device antenna 202, or can transmit the information to be transmitted to the master device 100 through the NFC slave device antenna 202. The process of information transmission between the master device 100 and the slave device 200 through NFC near field communication can refer to the related art, which will not be described here.

[0028] In order to reduce energy consumption, the master device 100 can first transmit low-power radio frequency signals through the LPCD mode to detect whether there is a near field communication slave device in the vicinity, such as whether there is an NFC card in the vicinity. After the NFC slave device antenna 202 in the slave device 200 perceives the radio frequency signals transmitted by the master device 100, the NFC slave device antenna 202 generates coupling with the NFC master device antenna 102 in the master device 100, so that the signal parameters in the master device 100 change. If the degree of parameter change in the master device 100 is greater than a threshold value, the master device 100 can determine that there is a slave device 200 in the vicinity, and can exit the LPCD mode to perform short-distance communication with the detected slave device 200 through normal polling.

[0029] In order to promote the master device 100 to exit the LPCD mode as soon as possible, the auxiliary card search module 206 in the slave device 200 can adjust the working state of the auxiliary card search module 206 according to the signals perceived by the NFC slave device antenna 202. The device that transmits the LPCD radio frequency signals in the master device 100 can change the load impedance value of the master device 100 by changing the impedance value of the auxiliary card search module, or the auxiliary card search module can provide an excitation signal to make the master device 100 generate a greater signal change under the influence of the slave device 200, so as to promote the master device 100 to exit the LPCD mode more quickly. After the master device 100 exits the LPCD mode, the master device 100 can interact with the slave device 200 in a normal polling manner.

[0030] The master device 100 can be a device with a near field communication card reader function, for example, can be a smart phone, a smart watch, a bracelet, a notebook computer, a tablet computer and the like portable terminal device, or can also be a smart home device, a vehicle-mounted device and the like, or can also be a POS machine, a self-service settlement device and the like payment device. The slave device 200 can be a device with an NFC tag or a device that can be simulated as an NFC tag, for example, the slave device 200 can be a device for processing payment services, such as a payment device used at a cash register or a self-service settlement; or, the slave device 200 can be a device for processing sign-in, login, access control, gate control and the like services, such as a device for signing in by near field communication for work, school or activities; or, a device for member login or application program login by near field communication; or, an access control device used at a resident's residence or office; or, a card reader used at a bus, subway and the like transportation tool; or, a device for identity or ticket verification used at a scenic spot or an activity, a concert and the like.

[0031] In at least one embodiment of the present application, an auxiliary card searching module is provided, and the present application also relates to an auxiliary card searching method and a near field communication device, which are described in detail one by one in the following embodiments.

[0032] Figure 2 A structural schematic diagram of an auxiliary card searching module provided for an embodiment of the present application is shown.

[0033] As shown in Figure 2 The auxiliary card searching module 206 can include a pulse detection unit 2062, a control unit 2064 and a modulation unit 2066, and the control unit 2064 is connected to the pulse detection unit 2062 and the modulation unit 2066 respectively.

[0034] Specifically, the input end of the pulse detection unit 2062 can be connected to the NFC slave device antenna 202 of the slave device, for obtaining a response signal generated by the device antenna of the slave device in response to a radio frequency signal sent by the master device. The pulse detection unit 2062 can generate a trigger signal within a preset time length less than the pulse time length of one radio frequency signal sent by the master device based on the response signal of the device antenna of the slave device.

[0035] The output end of the pulse detection unit 2062 can be connected to the input end of the control unit 2064, and the generated trigger signal can be provided to the control unit 2064. The output end of the control unit 2064 is connected to the modulation unit 2066, and after the control unit 2064 obtains the trigger signal generated by the pulse detection unit 2062, the control unit 2064 can control the modulation unit 2066 to switch states according to the trigger signal.

[0036] The modulation unit 2066 comprises a first state, a second state and a third state. In the first state, the load impedance of the modulation unit is a first impedance value; in the second state, the load impedance of the modulation unit is a second impedance value; and in the third state, the modulation unit emits an excitation signal.

[0037] The control unit 2064 can control the modulation unit 2066 to switch from the first state to the second state, or from the second state to the first state, or from the first state to the third state, or from the second state to the third state, and so on, according to the trigger signal. For example, the pulse period of an LPCD radio signal emitted by the master device is 200 milliseconds, and the pulse duration is 25 microseconds. The pulse detection unit can generate a trigger signal within a time period less than 25 microseconds. For example, the pulse detection unit needs 2 microseconds to output a trigger signal after obtaining a response signal. Assuming that the control unit needs 3 microseconds to control the state of the modulation unit based on the trigger signal, the state of the modulation unit can be switched before the end of an LPCD radio signal, thereby immediately affecting the master device.

[0038] The modulation unit 2066 can comprise circuits or electronic elements capable of presenting different impedance values. When the circuits or electronic elements capable of presenting a first impedance value are in a working state, the modulation unit can be in the first state, and can affect the master device as a load with the first impedance value. When the circuits or electronic elements capable of presenting a second impedance value in the modulation unit 2066 are in a working state, the modulation unit can be in the second state, and can affect the master device as a load with the second impedance value. The first impedance value is different from the second impedance value. The first impedance value can be greater than the second impedance value, or the first impedance value can be less than the second impedance value. After the slave device perceives the radio signal emitted by the master device, the slave device is equivalent to the load of the master device. In the embodiments of the present application, adjusting the impedance value of the modulation unit is equivalent to adjusting the impedance value of the load of the master device. Therefore, the signal change amount sensed by the master device under the influence of the slave device will be greater, which is more conducive to promoting the master device to exit the LPCD mode and enter the normal polling mode to interact with the slave device.

[0039] The modulation unit 2066 can also comprise circuits or electronic elements capable of emitting radio signals, which can provide external excitation signals for the master device, and also make the signal change amount sensed by the master device under the influence of the slave device greater, which is also conducive to promoting the master device to exit the LPCD mode.

[0040] The pulse detection unit can obtain a response signal generated by the coil antenna of the slave device in response to the RF signal of the master device (such as an LPCD pulse signal), and can generate a trigger signal based on the response signal within a preset duration that is less than the pulse duration of an RF signal sent by the master device. Then, the control unit can timely adjust the state of the modulation unit according to the trigger signal, so that the slave device can timely adjust the impedance value of the slave device or transmit the excitation signal within the pulse duration of the first RF signal sensed, so that the master device can sense the change in load impedance or the excitation signal provided by the slave device during the transmission of the first RF signal, thereby exiting the LPCD mode more quickly. There is no need to wait for the slave device to receive multiple RF signals sent by the master device, and provide additional influence to the master device after the pulse period of multiple RF signals has passed (for example, after several hundred milliseconds).

[0041] As an implementation method, Figure 3 This is a schematic diagram of the structure of a pulse detection unit provided in one embodiment of this specification. Figure 3 As shown, the pulse detection unit may include a bandpass filter circuit 302 , a signal amplification circuit 304 , an envelope extraction circuit 306 , and a comparison trigger circuit 308 .

[0042] Among them, the input end of the bandpass filter circuit 302 can be connected to the device antenna of the slave device to obtain the response signal perceived by the slave device. The bandpass filter circuit can be used to filter the input signal to obtain a signal of preset specifications. The response signal can obtain a first filtered signal after passing through the bandpass filter circuit 302. In actual application, the input end of the bandpass filter circuit can be connected to the device antenna of the slave device so that the response signal generated by the device antenna of the slave device under the radio frequency signal emitted by the master device can be obtained. Alternatively, the input end of the bandpass filter circuit can be connected to the control unit of the slave device to obtain the response signal generated by the device antenna of the slave device under the radio frequency signal emitted by the master device from the control unit. The specific connection method is not limited here, as long as the bandpass filter circuit can obtain the response signal generated by the device antenna of the slave device under the radio frequency signal emitted by the master device.

[0043] The output of the bandpass filter circuit 302 can be connected to the input of the signal amplifier circuit 304. The signal amplifier circuit can be used to amplify the input signal for subsequent use. The first filtered signal can be amplified by the signal amplifier circuit to obtain an amplified signal.

[0044] The output of the signal amplifying circuit 304 can be connected to the input of the envelope extraction circuit 306. The envelope extraction circuit can be used to extract a signal within a preset range. The amplified signal can be passed through the envelope extraction circuit to obtain an envelope output signal.

[0045] The output of the envelope extraction circuit 306 can be connected to the input of the comparison trigger circuit 308. The comparison trigger circuit can generate a trigger signal, such as a rising edge or a falling edge trigger signal, when the input signal at the input is greater than a threshold value. The envelope output signal can be input to the comparison trigger circuit to obtain the trigger signal.

[0046] The output of the comparison trigger circuit 308 can be connected to the control unit, so that the control unit can control the state switching of the modulation unit according to the trigger signal.

[0047] Here, the radio frequency signal of 13.56 MHz is taken as an example for illustration. The pulse detection circuit can quickly detect the LPCD signal generated by the master device (such as an NFC card reader), and output the detection result (such as a trigger signal) to the control unit of the auxiliary card searching module. The pulse detection circuit is connected to the antenna of the slave device, and the band-pass filter circuit can be a 13.56 MHz band-pass filter, which is used to filter the 13.56 MHz signal and remove the interference signal. The filtered signal is input to the envelope extraction circuit after being amplified by the amplification circuit, and the envelope output signal, which can also be referred to as the signal envelope, is obtained. If the change of the envelope output signal exceeds the reference value set by the comparison trigger circuit, the comparison trigger circuit can output a rising edge signal as the trigger signal, which triggers the external interrupt of the control unit. The control unit can take the trigger signal as an interrupt signal, and switch the state of the modulation unit according to the preset processing logic, such as switching the modulation unit from a high impedance state to a low impedance state, or causing the modulation unit to emit a radio frequency signal, etc.

[0048] In actual application, for different application scenarios, such as different application scenarios using different parameters of radio frequency signals, band-pass filter circuits, amplification circuits, envelope extraction circuits or comparison trigger circuits that match the parameters of the radio frequency signals can be used. Alternatively, the specific parameters or specifications of the electronic devices selected in each circuit can be set according to the actual scene requirements. For example, in a scenario using other frequency bands for near field communication, a band-pass filter circuit for filtering signals of the frequency band used in the scenario can be selected.

[0049] As an implementation manner, Figure 4 A circuit principle schematic diagram of a pulse detection unit is provided for an embodiment of the present specification. As shown in Figure 4 The band-pass filter circuit 302 can include a band-pass filter, the signal amplification circuit 304 can include an envelope signal amplifier, the envelope extraction circuit 306 can include a circuit obtained by connecting devices such as diodes D, capacitors C, resistors R, and the comparison trigger circuit 308 can include a comparator.

[0050] As shown in Figure 4As shown, the envelope extraction circuit 306 may include a diode D, a first capacitor C1, a first resistor R1, a second capacitor C2, and a second resistor R2. The input end of the diode D is connected to the output end of the signal amplification circuit 304; the first capacitor C1 and the first resistor R1 are in parallel. Specifically, one end a of the first capacitor C1 and one end c of the first resistor R1 are respectively connected to the output end of the diode D; the other end b of the first capacitor C1 and the other end d of the first resistor R1 are respectively connected to the ground end. Optionally, the input end of the diode D may be an anode (positive electrode), and the output end may be a cathode (negative electrode).

[0051] The second resistor R2 is connected in series with the second capacitor C2. Specifically, one end e of the second resistor R2 is connected to the output end of the diode D, the other end f of the second resistor R2 is connected to one end g of the second capacitor C2 and the input end of the comparison trigger circuit, and the other end h of the second capacitor C2 is connected to the ground end.

[0052] The diode, first capacitor, second capacitor, first resistor, second resistor, and other components mentioned above may be independent diodes, capacitors, resistors, and other components, or may be a combination of multiple diodes, capacitors, resistors, and other components. The specific number and type of components are not limited here.

[0053] In practical applications, a comparator may include two input terminals and an output terminal, wherein one input terminal inputs a signal to be compared, such as the envelope extraction signal described above, and the other input terminal inputs a reference signal, such as a reference voltage, current, etc. As an embodiment, the input terminal of the comparison trigger circuit described above may be a non-inverting input terminal of the comparator, and the inverting input terminal of the comparator may be connected to the reference signal. Alternatively, the input terminal of the comparison trigger circuit described above may be an inverting input terminal of the comparator, and the non-inverting input terminal of the comparator may be connected to the reference signal.

[0054] like Figure 4 As shown, assuming that the input signal from the device antenna is V in ,V in After passing through the bandpass filter and amplifier, the amplified signal v(t) is obtained. Then the amplified signal v(t) is input into the diode in the envelope extraction circuit for rectification. The rectified signal Contains DC component and complex AC components. DC components Charge the primary envelope extraction circuit composed of resistor R1 and capacitor C1. Assuming that the output impedance of the signal amplifier circuit is R0, the voltage across capacitor C1 reaches 90% of its rated voltage. Time taken It can be expressed as: ; Among them, R0 represents the output impedance of the signal amplifier circuit, C 10 represents the capacitance value of the first capacitor.

[0055] The AC signal is connected to ground through the small impedance capacitor C1, so the AC component in the output of the signal amplification circuit is small. To further filter the AC signal and prevent the comparator from triggering unstably, a low-pass filter circuit can be built using resistor R2 and capacitor C2. The 90% rise time of the DC signal through the low-pass filter circuit can be represented as: ; wherein R 20 represents the resistance value of the second resistor, and C 20 represents the capacitance value of the second capacitor.

[0056] As an embodiment, the resistance value of the first resistor is equal to the resistance value of the second resistor, or the difference between the resistance value of the first resistor and the resistance value of the second resistor is less than or equal to a first threshold value; the capacitance value of the first capacitor is equal to the capacitance value of the second capacitor, or the difference between the capacitance value of the first capacitor and the capacitance value of the second capacitor is less than or equal to a second threshold value; and the resistance value of the first resistor and the resistance value of the second resistor are greater than the output impedance value of the signal amplification circuit.

[0057] For example, the resistance value of the first resistor in the envelope extraction circuit can be approximately equal to the resistance value of the second resistor, and the resistance value of the first resistor and the resistance value of the second resistor can both be much greater than the output impedance of the signal amplification circuit. The capacitance value of the first capacitor can be approximately equal to the capacitance value of the second capacitor, which can be represented as , so the rise time can be negligible. To ensure sensitivity, the reference voltage of the comparator may be a small value, for example, less than a preset threshold, such as less than 1 volt, for example, 0.8 volts, 0.6 volts, etc., or less than 1.5 volts, 2 volts, etc. For example, the resistance value of the first resistor and the second resistor can be 470 ohms, the capacitance value of the first capacitor and the second capacitor can be 4.7 nF, and the reference voltage of the comparator can be 0.8 V. In actual application, the reference voltage of the comparator may be a fixed value. When the voltage across capacitor C2 is greater than the reference voltage , the comparator can output a rising edge signal to trigger the external interrupt of the control unit of the auxiliary card searching module. The rise time of the signal is about 10 ns (nanoseconds), which is negligible compared to the duration of tens of us (microseconds) of the LPCD signal. Thus, the response time of the above pulse detection circuit can be represented as .

[0058] ​The preset time length in generating the trigger signal based on the response signal of the device antenna of the slave device within a preset time length can also be represented as the above-mentioned pulse detection unit. Optionally, the preset time length τ = -ln(1-0.9)R 20 C 20 , wherein R 20 represents the resistance value of the second resistance, and C 20 represents the capacitance value of the second capacitance.

[0059] In order to quickly change the load of the master device or the influence of the transmission of the excitation signal, and to reserve some time for the control unit to control the modulation unit, the preset time length can be a microsecond level time length; or the preset time length can be less than or equal to one half of the pulse length of a radio frequency signal emitted by the master device.

[0060] For example, in actual application, a terminal such as a smart phone is used as a near field communication card reader device. Different terminals have different lengths or periods of radio frequency signals emitted in the LPCD mode due to brand or system settings. It is found through statistics that the pulse length of a radio frequency signal emitted by most terminals in the LPCD mode is generally 25 us (microseconds) at the minimum, and the pulse period of a radio frequency signal is about 1 ms (milliseconds) to 10 or several tens or several hundreds of ms (milliseconds). For example, the preset time length can be 2 microseconds. In this way, the auxiliary card searching module can affect the master device by adjusting the state of the tuning unit during the emission of a LPCD radio frequency signal by the master device, thereby improving the speed of the master device exiting the LPCD mode.

[0061] The modulation unit in an embodiment of the present specification can be in different states, such as a state of high impedance, a state of low impedance, or a state of transmitting an excitation signal. As an implementation manner, the modulation unit comprises a switching element, a first load impedance circuit, a second load impedance circuit, and a radio frequency signal circuit. The first load impedance circuit, the second load impedance circuit, and the radio frequency signal circuit are respectively connected to the gating terminal of the switching element; the control terminal of the switching element is connected to the control unit; and the control unit controls the state switching of the modulation unit by adjusting the conduction state of the gating terminal.

[0062] The switching element includes multiple gate terminals, and the first load impedance circuit, the second load impedance circuit, and the radio frequency signal circuit are respectively connected to different gate terminals. For example, the first load impedance circuit is connected to the first gate terminal of the switching element, the second load impedance circuit is connected to the second gate terminal of the switching element, and the radio frequency signal circuit is connected to the third gate terminal of the switching element. The control unit can control the state of each gate terminal of the switching element, such as whether each gate terminal is in an on state or an off state. In this way, the control unit can control the on or off state of the first load impedance circuit, the second load impedance circuit, and the radio frequency signal circuit according to the trigger signal output by the pulse detection unit according to the preset processing logic, and control the modulation unit to switch the state.

[0063] Figure 5 This is a schematic diagram of a modulation unit provided in one embodiment of this specification. Here, the switch element is a radio frequency switch element as an example for explanation. Figure 5 As shown, the modulation unit 2066 may include a radio frequency switch element 502, a first load impedance circuit 504, a second load impedance circuit 506, and a radio frequency signal circuit 508. Specifically, the first load impedance circuit 504, the second load impedance circuit 506, and the radio frequency signal circuit 508 are respectively connected to the strobe port of the radio frequency switch element 502. The first load impedance circuit 504, the second load impedance circuit 506, and the radio frequency signal circuit 508 are respectively connected to different strobe ports in the radio frequency switch element 502. For example, the first load impedance circuit 504 is connected to the first strobe port of the radio frequency switch element 502, the second load impedance circuit 506 is connected to the second strobe port of the radio frequency switch element 502, and the radio frequency signal circuit 508 is connected to the third strobe port of the radio frequency switch element 502.

[0064] The common port of the RF switch element 502 is connected to the device antenna of the slave device and is used to obtain the response signal generated by the device antenna of the slave device in response to the RF signal sent by the master device. For example, the response signal input to the pulse detection unit can also be input to the common port of the RF switch element 502.

[0065] The control port of the RF switch element is connected to the control unit 2064. The control unit 2064 can control the modulation unit to switch states by adjusting the gate port in the RF switch element that is connected to the common port of the RF switch element.

[0066] If the common port of the RF switch element is connected to the first selection port connected to the first load impedance circuit, the first load impedance circuit is in a working state, and the impedance value of the modulation unit can be the impedance value of the first load impedance circuit; if the common port of the RF switch element is connected to the second selection port connected to the second load impedance circuit, the second load impedance circuit is in a working state, and the impedance value of the modulation unit can be the impedance value of the second load impedance circuit; if the common port of the RF switch element is connected to the third selection port connected to the RF signal circuit, the RF signal circuit is in a working state, and the modulation unit can emit an excitation signal to the outside.

[0067] In practical applications, the switching element may be an absorptive RF switch, or may be other switching elements, such as a combination of multiple single-pole double-throw (SPDT) switches, a solid-state switch, and the like.

[0068] As an embodiment, at least one of the resistance value, inductance value, and capacitance value in the first load impedance circuit is different from that in the second load impedance circuit, and the load impedance values ​​of the first load impedance circuit and the second load impedance circuit are different. The load impedance value of the first load impedance circuit is a first impedance value, and the second load impedance value is a second impedance value. The first impedance value can be greater than the second impedance value, or the first impedance value can be less than the second impedance value.

[0069] Figure 6 This is a schematic diagram of the principle of a modulation unit provided in one embodiment of this specification. Figure 6 As shown, it is assumed that the device antenna impedance of the slave device is , the impedance value of the first load impedance circuit is greater than the impedance value of the second load impedance circuit, then when the RF switch is connected to the high impedance load (such as the first load impedance circuit), the equivalent impedance of the device antenna from the device It can be expressed as ; When the RF switch is connected to a low impedance load (such as the second load impedance circuit), the equivalent impedance of the device antenna from the device It can be expressed as: .

[0070] In actual applications, the slave device's antenna is electromagnetically coupled to the master device's NFC reader antenna, assuming the mutual inductance is M. If the master device's NFC reader antenna impedance is , then the equivalent impedance after coupling is It can be expressed as: By switching the load through the RF switch, the equivalent impedance of the device antenna of the slave device is changed. , which can be used to calculate the equivalent impedance of the NFC reader antenna of the host device and / or other parameters, thereby affecting the characteristics of the LPCD signal and causing the host device to exit the LPCD mode.

[0071] To more effectively cause the host device to exit the LPCD mode, the radio frequency signal circuit can include a signal source capable of emitting a radio frequency signal matched to the host device. Specifically, the radio frequency signal circuit can be an active circuit, for example, the radio frequency signal circuit can have a transmitting antenna and a power source, through which an excitation signal can be transmitted outwardly; or the radio frequency signal circuit can transmit the excitation signal through the device antenna of the slave device. For another example, the radio frequency signal circuit can be a passive circuit, for example, the radio frequency signal circuit can include a coil antenna matched to the device antenna of the slave device, which can obtain energy from the signal perceived by the device antenna of the slave device, and then convert the energy into an excitation signal to be transmitted outwardly through the coil antenna. The specific radio frequency signal circuit can refer to the introduction of the related art, which will not be described here.

[0072] As an implementation, when the modulation unit is in at least one of the first state, the second state or the third state, the resonance frequency of the modulation unit or the resonance frequency of the slave device under the action of the modulation unit can be a resonance frequency matched to the operating frequency of the host device. In this way, the host device can be caused to exit the LPCD mode while the information transmission efficiency of the host device and the slave device can not be affected. For example, the operating frequency of the host device is 13.56 MHz, and the resonance frequency of the modulation unit or the resonance frequency of the slave device under the action of the modulation unit can also be 13.56 MHz, or the difference from 13.56 MHz is less than a preset threshold, near 13.56 MHz.

[0073] The impedance values of the first load impedance circuit and the second load impedance circuit can be set according to actual needs, for example, if the impedance value of the first load impedance circuit is higher than that of the second load impedance circuit, the impedance value of the first load impedance circuit can be kilo-ohm, for example, greater than or equal to 10 kΩ; the impedance value of the second load impedance circuit can be ohm, for example, greater than or equal to 10 kΩ, or the impedance value of the second load impedance circuit can be less than or equal to 20 Ω, 10 Ω, etc., or the impedance value of the second load impedance circuit can be several ohms. In actual application, the specific parameter values of each circuit can be set in combination with the specific parameters of the host device and the slave device, which are not specifically limited here.

[0074] Based on the same idea, the present specification also provides an auxiliary card searching method based on the auxiliary card searching module. Figure 7A flowchart of an auxiliary card searching method provided by one embodiment of the present application is shown. From the perspective of a program, the execution subject of the flowchart can be a program in a slave device, specifically, a program in an auxiliary card searching module. The method can be applied to a near field communication slave device, which can have an auxiliary card searching module. The auxiliary card searching module can include a pulse detection unit, a control unit, and a modulation unit. The control unit is connected to the pulse detection unit and the modulation unit respectively. The specific structure of the auxiliary card searching module can be found in one or more of the preceding embodiments, which will not be described here.

[0075] As shown in Figure 7 , the flowchart can include the following steps.

[0076] Step 702: The pulse detection unit generates a trigger signal within a preset time period based on a response signal of a device antenna of the slave device.

[0077] The response signal can be generated by the device antenna of the slave device in response to a radio frequency signal sent by a master device. The preset time period is less than the pulse duration of one radio frequency signal sent by the master device.

[0078] The master device of near field communication can actively send a radio frequency signal as a card reader device of near field communication to detect whether there is an NFC card nearby. If the master device has an LPCD working mode, the radio frequency signal sent by the master device can be an LPCD mode signal. Alternatively, the radio frequency signal sent by the master device can also be a normal polling signal.

[0079] Step 704: The control unit controls the modulation unit to switch states according to the trigger signal, so as to promote the master device to enter a polling mode.

[0080] The modulation unit includes a first state, a second state, and a third state. In the first state, the load impedance of the modulation unit is a first impedance value. In the second state, the load impedance of the modulation unit is a second impedance value. In the third state, the modulation unit transmits an excitation signal to the master device.

[0081] The modulation unit can have a high impedance value circuit, a low impedance value circuit, and a radio frequency signal circuit. The control unit can control the working state of each circuit in the modulation unit according to the trigger signal, so that the modulation unit can present different states.

[0082] As an implementation, the control unit controls the modulation unit to switch states according to the trigger signal, which can include: before the control unit acquires the trigger signal, the modulation unit is in the first state; after the control unit acquires the trigger signal, the control unit switches the modulation unit to the second state and keeps it for a first time length; after the modulation unit is in the second state for the first time length, if the master device has not switched to the polling mode, the control unit controls the modulation unit to switch to the third state.

[0083] Before the control unit acquires the trigger signal, it can mean that the slave device does not perceive the radio frequency signal emitted by the master device, that there is no master device near the slave device, or that it can mean the time phase performed from when the slave device perceives the radio frequency signal emitted by the master device to the process of the pulse detection unit generating a trigger signal and providing it to the control unit. Before the control unit acquires the trigger signal, the modulation unit can be in an idle state or an initial state or a default state. Optionally, in this state, the modulation unit can be in the first state, and the first load impedance circuit can be in the on state; if the first load impedance circuit has a high impedance, before the control unit acquires the trigger signal, the modulation unit can be in a high-impedance state.

[0084] After the control unit acquires the trigger signal, it can switch the state of the modulation unit, which can be switched from the first state to the second state and kept for a first time length. If the impedance value of the first load impedance circuit is higher than that of the second load impedance circuit, the modulation unit switching from the first state to the second state can mean that the modulation unit switches from high impedance to low impedance. If the impedance value of the first load impedance circuit is lower than that of the second load impedance circuit, the modulation unit switching from the first state to the second state can mean that the modulation unit switches from low impedance to high impedance. By changing the load impedance, the master device can be prompted to exit the LPCD mode.

[0085] After the modulation unit is in the second state for a first time length, if the master device has not exited the LPCD mode, the control unit can switch the modulation unit to the third state and send an excitation signal to the master device to prompt the master device to exit the LPCD mode. In one embodiment of the present specification, the master device is first prompted to exit the LPCD mode by adjusting the impedance, and when the method of adjusting the impedance is unsuccessful, the master device is then prompted to exit the LPCD mode by emitting an excitation signal. This can avoid the situation where the master device enters the card simulation mode and causes communication failure when the excitation signal is directly emitted.

[0086] After the modulation unit is in the second state for the first time length, or in the process of the modulation unit being in the second state, if the host device exits the LPCD mode and sends the polling signal, the control unit can control the modulation unit to restore to the initial state, for example, can control the modulation unit to switch to the first state, so as to wait for the next trigger.

[0087] Alternatively, the control unit can also control the modulation unit to emit the excitation signal within the preset excitation time length, after the preset excitation time length, or in the process of the modulation unit emitting the excitation signal, if the host device exits the LPCD mode, the control unit can control the modulation unit to restore to the initial state from the third state, for example, can control the modulation unit to switch to the first state from the third state, so as to wait for the next trigger.

[0088] In order to fully utilize the load change to affect the host device and promote the host device to exit the LPCD mode, the auxiliary card searching module can also perform multiple load changes before determining whether to send the radio frequency signal. As an embodiment, after the modulation unit is in the second state for the first time length, if the host device does not enter the normal card searching mode, the control unit controls the modulation unit to switch to the third state, which can include: after the modulation unit is in the second state for the first time length, the control unit controls the modulation unit to switch to the first state and keep; determining whether the host device enters the polling mode; if the host device does not enter the polling mode, the control unit controls the modulation unit to switch to the third state from the first state.

[0089] Among them, the determination step of determining whether the host device enters the polling mode can be executed after the device antenna of the slave device senses the signal of the host device, from the time point, the determination step can be executed in parallel with the steps executed by the auxiliary card searching module. The above-mentioned determination whether the host device enters the polling mode can be to determine whether there is result information indicating that the host device enters the polling mode, and the actual determination step of determining whether the host device enters the polling mode does not necessarily start to execute after the control unit controls the modulation unit to switch to the first state from the second state.

[0090] Assuming the first state is the initial state when the modulation unit processes the initial state, the first load impedance circuit in the modulation unit is in the on state. After the device perceives the radio frequency signal sent by the host device, the pulse detection unit generates a trigger signal, and the control unit can switch the second load impedance circuit in the modulation unit to the on state according to the trigger signal, so that the first load impedance circuit is no longer in the on state, so that the modulation unit switches to the second state and remains in the second state for a first time period, for example, 10 microseconds, and then the control unit switches the modulation unit from the second state to the first state and remains in the first state. During the process of remaining in the first state, it is determined whether the host device exits the LPCD mode and enters the polling mode. If the host device does not enter the polling mode, the control unit can switch the modulation unit to a third state and send an excitation signal to the host device using the radio frequency signal circuit to promote the host device to enter the polling mode. If the host device has entered the polling mode, the control unit can control the modulation unit to switch to the initial state or remain in the first state and wait for the next trigger signal. After the control unit controls the modulation unit to transmit the excitation signal for a preset excitation time period, or during the process of transmitting the excitation signal, the host device exits the LPCD mode, the control unit can also control the modulation unit to stop sending the excitation signal and restore to the initial state from the third state, for example, the control unit can control the modulation unit to switch from the third state to the first state, so as to wait for the next trigger.

[0091] During the process of transmitting the excitation signal, it can also be continuously determined whether the host device enters the polling mode. If the host device enters the polling mode, the transmission of the excitation signal can be terminated, and the modulation unit can switch to the initial state. Alternatively, during the process of transmitting the excitation signal, it can no longer be determined whether the host device enters the polling mode, and the excitation signal can be directly transmitted for a specified time period, and then the modulation unit switches to the initial state, or after the transmission of the excitation signal is terminated and a preset delay time period elapses, the modulation unit switches to the initial state.

[0092] Optionally, the sum of the first time period and the preset time period can be less than or equal to the pulse time period, so that the load impedance can be changed multiple times within one pulse time period of the radio frequency signal sent by the host device, which is more conducive to promoting the host device to exit the LPCD mode as soon as possible.

[0093] In actual application, in order to avoid the active excitation signal from making the host device enter the card simulation mode as far as possible, in an embodiment of the present specification, the load impedance can be adjusted to affect the multiple pulse periods of the host device, and the load impedance is adjusted to promote the host device to exit the LPCD mode as far as possible. As an implementation, before the control unit controls the modulation unit to switch to the third state, the control unit can further include: if the host device does not switch to the normal card search mode, the control unit waits for a subsequent trigger signal; the subsequent trigger signal is a next trigger signal generated by the pulse detection unit after the trigger signal is generated; if the control unit acquires the subsequent trigger signal, the control unit switches the modulation unit from the first state to the second state and maintains for a second time length; the length of the second time length is greater than the length of the first time length. The control unit controls the modulation unit to switch to the third state can include: if the host device does not switch to the polling mode after the modulation unit is in the second state for the second time length, the control unit controls the modulation unit to switch to the third state.

[0094] The trigger signal can represent a first trigger signal generated by the pulse detection unit in a process of a near field communication; and the subsequent trigger signal represents a second trigger signal generated by the pulse detection unit in the process of the near field communication. Alternatively, the trigger signal and the subsequent trigger signal are two adjacent trigger signals generated by the pulse detection unit, which are not necessarily the first or the second, for example, can be the second and the third trigger signals generated by the pulse detection unit, or the third and the fourth trigger signals, and the like.

[0095] Suppose that the modulation unit processes the initial state as the first state, after the slave device perceives the radio frequency signal emitted by the host device, the pulse detection unit generates a trigger signal, and the control unit can switch the modulation unit from the first state to the second state according to the trigger signal, and maintain the second state for a first time length. Then, it is judged whether the host device enters the polling mode, if the host device does not switch to the polling mode, the modulation unit can maintain the second state, and wait for a next trigger signal, i.e. a subsequent trigger signal, generated by the pulse detection unit; after the control unit acquires the next trigger signal, the control unit can control the modulation unit to switch from the second state to the first state and maintain for a second time length. If the host device does not switch to the polling mode after the modulation unit is in the first state for the second time length, the control unit controls the modulation unit to switch to the third state.

[0096] Alternatively, assuming that the modulation unit is in the first state when processing the initial state, after the slave device senses the radio frequency signal sent by the master device, the pulse detection unit generates a trigger signal, and the control unit can switch the modulation unit from the first state to the second state according to the trigger signal, and keep the second state for a first time length. After the first time length, the control unit controls the modulation unit to switch from the second state to the first state and keep it. During the process of keeping the first state, it is determined whether the master device enters the polling mode. If the master device does not switch to the polling mode, the modulation unit can keep the first state and wait for the next trigger signal, i.e. the subsequent trigger signal, generated by the pulse detection unit. The control unit can control the modulation unit to switch from the first state to the second state after obtaining the next trigger signal, and keep it for a second time length. After the modulation unit is in the second state for the second time length, if the master device does not switch to the polling mode, the control unit controls the modulation unit to switch to the third state.

[0097] The second time length can be greater than the first time length, or the first time length can be greater than the second time length. In this way, by using different time lengths, the master device can be quickly awakened from the LPCD mode and sent a polling signal to improve the user experience.

[0098] Alternatively, the second time length can be greater than the pulse length, and different from the first time length. In this way, by providing irregular load changes, the master device can also be promoted to enter the polling mode.

[0099] Alternatively, the second time length can be greater than the pulse length, and different from the first time length. In this way, by providing irregular load changes, the master device can also be promoted to enter the polling mode.

[0100] The control unit can also switch the state of the modulation unit multiple times based on the subsequent trigger signal to further improve the success rate of the master device exiting the LPCD mode. As an implementation, after the modulation unit is in the second state for the second time length, if the master device does not switch to the polling mode, the control unit controls the modulation unit to switch to the third state, which can include: after the modulation unit is in the second state for the second time length, the control unit controls the modulation unit to switch to the first state and keep it; it is determined whether the master device enters the polling mode; if the master device does not enter the polling mode, the control unit controls the modulation unit to switch from the first state to the third state.

[0101] The step of determining whether the master device enters the polling mode can be executed in parallel with the step of controlling the modulation unit executed by the control unit, and does not necessarily start to execute the flow of determining whether the master device enters the polling mode during the process of keeping the modulation unit in the first state. The step of determining whether the master device enters the polling mode can represent whether information indicating that the mode of the master device is the polling mode is queried, and can be an execution step of obtaining a determination result. If the master device does not enter the polling mode, for example, information indicating that the mode of the master device is the polling mode is not queried, or the mode of the master device is still the LPCD mode, the control unit can control the modulation unit to switch to the third state to transmit the excitation signal to the master device. If the master device has entered the polling mode, the control unit can control the modulation unit to return to the initial state or can keep the first state, for example, the first state in which the first load impedance circuit is turned on, or the second state in which the second load impedance circuit is turned on, or the state in which the first load impedance circuit, the second load impedance circuit, and the radio frequency circuit are all turned off. Alternatively, the control unit controls the modulation unit to return to the initial state after delaying for a preset time length after determining that the master device enters the polling mode, and waits for the next near field communication.

[0102] It is assumed that the first state is the initial state of the modulation unit. After the slave device senses the radio frequency signal transmitted by the master device, the pulse detection unit generates a trigger signal. The control unit can switch the modulation unit from the first state to the second state according to the trigger signal, and keep the second state for a first time length. Then, the control unit determines whether the master device enters the polling mode. If the master device does not switch to the polling mode, the modulation unit can keep the second state and wait for the next trigger signal generated by the pulse detection unit, i.e., a subsequent trigger signal. After the control unit obtains the next trigger signal, the control unit can control the modulation unit to switch from the second state to the first state and keep the second state for a second time length. After the second time length, the control unit can control the modulation unit to switch from the first state to the second state and keep the second state. During the process of keeping the second state, if the master device does not switch to the polling mode, the control unit controls the modulation unit to switch to the third state, or can keep the second state for a third time length. If the master device does not switch to the polling mode after the third time length, the control unit controls the modulation unit to switch to the third state.

[0103] Alternatively, assuming that the modulation unit is in the first state during processing in the initial state, after the slave device senses the RF signal transmitted by the master device, the pulse detection unit generates a trigger signal. The control unit can switch the modulation unit from the first state to the second state based on the trigger signal and maintain the second state for a first duration. After the first duration, the control unit controls the modulation unit to switch from the second state to the first state and maintain it. While maintaining the first state, the control unit determines whether the master device has entered the polling mode. If the master device has not switched to the polling mode, the modulation unit can remain in the first state and await the next trigger signal generated by the pulse detection unit, i.e., the subsequent trigger signal. After receiving the next trigger signal, the control unit can control the modulation unit to switch from the first state to the second state and maintain it for a second duration. After the modulation unit has been in the second state for a second duration, the control unit can control the modulation unit to switch from the second state to the first state and maintain it. While maintaining the first state, if the master device has not switched to the polling mode, the control unit can control the modulation unit to switch to the third state. Alternatively, after maintaining the first state for a third duration, if the master device has not switched to the polling mode, the control unit can control the modulation unit to switch to the third state. If the master device has switched to the polling mode, the modulation unit may remain in the first state, or may be restored to the initial state, waiting for the next trigger.

[0104] Figure 8 This is a flow chart of an auxiliary card search method provided by one embodiment of this specification. Here, the impedance of the modulation unit in the first state is higher than the impedance in the second state as an example. Figure 8 As shown, after the start, the parameters of the control unit of the auxiliary card search module can be initialized to prepare for subsequent control. The control unit can then switch the RF switch of the modulation unit to a high impedance load, and the modulation unit is in the first state; thereafter, the control unit waits for the trigger signal provided by the pulse detection unit, which can be used as an interrupt signal of the control unit to trigger the control unit to execute a preset process. When the LPCD signal emitted by the main device is detected by the pulse detection unit, the pulse detection unit will generate a rising edge signal and trigger a pulse detection interrupt, and the control unit can determine whether there is a pulse detection interrupt. After the interrupt is triggered, the control unit can also determine whether it is the first interrupt. If it is the first interrupt, the RF switch can be switched to low impedance, and the modulation unit can be switched from the first state to the second state and maintained. After a certain time, it switches to high impedance and the modulation unit switches from the second state to the first state; then it determines whether the NFC card reader (master device) is polling. If it is polling, the auxiliary card search process has been completed and can be delayed. reinitializes the system after a certain time; otherwise, waits for the next LPCD pulse, and the pulse detection unit generates a subsequent trigger signal according to the next pulse as a second interrupt signal. After the second trigger interrupt, the control unit can switch the radio frequency switch to a low impedance, the modulation unit is switched from the first state to the second state, and remains a high impedance after a certain time, the modulation unit is switched from the second state to the first state; then, it is determined again whether the NFC card reader (master device) is polling. If polling, the auxiliary card search process is completed, and the control unit can delay a certain time before reinitializing the system; otherwise, delays a certain time, switches the radio frequency switch to a signal source, and the modulation unit is switched from the first state to the third state and transmits a radio frequency field for a certain time. After the active field emission is completed, the control unit delays a certain time before reinitializing the system. The above delay time can be a millisecond level time, which can be set according to the length of the pulse period of the radio frequency signal. In actual application, the delay time can also not be set, or the time length is 0.

[0105] Here, the switching between the high impedance and the low impedance according to the two trigger signals before the modulation unit transmits the excitation signal is taken as an example for description. In actual application, after the switching between the high impedance and the low impedance according to three or more trigger signals, if the master device is still not switched to the polling state, the modulation unit transmits the excitation signal again.

[0106] In an embodiment of the present specification, the detection of the pulse signal is quickly completed through an analog circuit, and the detection result is output to the control unit of the auxiliary card search module through a rising edge signal. Specifically, the circuit can quickly detect the pulse signal (such as a pulse signal with a frequency of 13.56 MHz) within a short time when the pulse signal (such as an LPCD pulse signal) appears through filtering and amplifying the input signal, envelope extraction, and comparison triggering, and output the detection result in the form of a rising edge.

[0107] In an embodiment of the present specification, under the control of the control unit of the auxiliary card search module, the equivalent impedance of the device antenna of the slave device is quickly adjusted, and then the impedance of the antenna of the NFC card reader (master device) is adjusted, and the wake-up of the card reader (master device) is realized.

[0108] In an embodiment of the present specification, through twice passive load modulation with different times and once active field emission, the NFC card reader (master device) in the LPCD mode can be quickly woken up and made to send a polling signal, effectively improving the user experience. At the same time, this method can also avoid the NFC card reader (master device) entering the card simulation mode after receiving an external radio frequency field, thereby causing communication failure.

[0109] Although the one or more embodiments of the present specification provide the method steps as described in the embodiments or flowcharts, it can be understood that the order of steps listed in the embodiments or flowcharts is only one of the many execution orders of the steps, and does not represent the only execution order. The order of some steps can be adjusted according to actual needs, or some steps can be omitted. When the claims refer to the method steps, the adjustment of the order of the steps or the parallelism between the steps is also within the protection scope of the claims.

[0110] The various technical features in the above embodiments can be combined in any manner, as long as there is no conflict or contradiction between the features. However, due to the limited space, they are not described one by one, and therefore any combination of the various technical features in the above embodiments is also within the disclosure of the present specification.

[0111] Based on the same idea, the present specification also provides a near field communication device, which can include the auxiliary card searching module described above, or the near field communication device can execute the auxiliary card searching method described above.

[0112] Each of the embodiments in the present specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment mainly describes the differences from other embodiments. In particular, for the near field communication device embodiment, since it is basically similar to the module or method embodiment, the description is relatively simple, and the relevant parts can be referred to the part of the module or method embodiment. The near field communication device provided by the embodiments of the present specification corresponds to the module and method, and therefore the near field communication device also has similar beneficial technical effects as the corresponding module or method. Since the beneficial technical effects of the module or method have been described in detail above, the beneficial technical effects of the corresponding device will not be described here.

[0113] The above describes specific embodiments of the present specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be executed in a different order than the order in which they are recited in the embodiments and still achieve the desired results. In addition, the processes depicted in the figures do not necessarily require the particular order or sequential order shown or to achieve the desired results. In some embodiments, multi-task processing and parallel processing are possible or can be advantageous.

[0114] In the 1990s, it was possible to distinguish whether an improvement in a technology was a hardware improvement (e.g., an improvement in the circuit structure of a diode, transistor, switch, etc.) or a software improvement (an improvement in a method flow). However, as technology has advanced, many improvements in method flows today can be considered as direct improvements in hardware circuit structures. Designers almost always obtain a corresponding hardware circuit structure by programming an improved method flow into a hardware circuit. Therefore, it cannot be said that an improvement in a method flow cannot be implemented using a hardware entity module. For example, a programmable logic device (PLD) (e.g., a field programmable gate array (FPGA)) is an integrated circuit whose logic function is determined by user programming of the device. A designer programs a digital system "integrated" on a PLD by himself / herself, without having to ask a chip manufacturer to design and manufacture a special integrated circuit chip. Furthermore, instead of manually manufacturing an integrated circuit chip, this programming is now mostly implemented using "logic compiler" software, which is similar to a software compiler used when developing a program, and the original code before compilation is also written in a specific programming language, which is called a hardware description language (HDL), and there are many types of HDL, such as ABEL (Advanced Boolean Expression Language), AHDL (Altera Hardware Description Language), Confluence, CUPL (Cornell University Programming Language), HDCal, JHDL (Java Hardware Description Language), Lava, Lola, MyHDL, PALASM, RHDL (Ruby Hardware Description Language), etc., and the most commonly used are VHDL (Very-High-Speed Integrated Circuit Hardware Description Language) and Verilog. Those skilled in the art should also be aware that it is only necessary to logically program a method flow using the above-mentioned hardware description languages and program it into an integrated circuit to easily obtain a hardware circuit that implements the logical method flow.

[0115] The controller can be implemented in any suitable way, for example, the controller can take the form of a microprocessor or processor and a computer readable medium storing computer readable program code, such as software or firmware, executable by the (micro)processor, logic gates, switches, an application specific integrated circuit (ASIC), a programmable logic controller and an embedded microcontroller, examples of which include but are not limited to the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20 and Silicone Labs C8051F320, the memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art will also know that, in addition to implementing the controller in pure computer readable program code, it is also possible to implement the controller in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers and embedded microcontrollers, etc. to perform the same functions by logically programming the method steps. Such a controller can therefore be considered as a hardware component, and the means included therein for performing various functions can also be considered as structures within the hardware component. Alternatively, the means for performing various functions can even be considered as both a software module implementing the method and a structure within the hardware component.

[0116] The systems, apparatuses, modules or units illustrated by the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer can be a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0117] For the sake of description, the above apparatuses are described in various units with functions respectively. Of course, the functions of the units can be implemented in one or more software and / or hardware in the implementation of the present application.

[0118] Those skilled in the art will understand that one or more embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer usable program code.

[0119] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks in the flowcharts and / or combination thereof. Figure 1 one or more flowcharts and / or blocks in the flowcharts and / or combination thereof.

[0120] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks in the flowcharts and / or combination thereof. Figure 1 one or more flowcharts and / or blocks in the flowcharts and / or combination thereof.

[0121] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flowcharts and / or blocks in the flowcharts and / or combination thereof. Figure 1 one or more flowcharts and / or blocks in the flowcharts and / or combination thereof.

[0122] In one typical configuration, the computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0123] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) and / or cache memory, non-volatile memory, such as read-only memory (ROM), EPROM, and / or flash memory. The memory is an example of computer-readable media.

[0124] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can be implemented using any method or technology for information storage. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change RAM (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media such as modulated data signals and carrier waves.

[0125] The present application may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The present application may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communications network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0126] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. An auxiliary card search module, applied to a slave device of near field communication, comprising a pulse detection unit, a control unit, and a modulation unit; the control unit is connected to the pulse detection unit and the modulation unit respectively; The pulse detection unit is configured to generate a trigger signal within a preset time period based on a response signal from a device antenna of the slave device; The response signal is generated by the device antenna of the slave device in response to the radio frequency signal sent by the master device; the preset duration is less than the pulse duration of a radio frequency signal sent by the master device; The control unit is configured to control the modulation unit to switch states according to the trigger signal, so as to facilitate the master device to enter a polling mode; The modulation unit includes a first state, a second state and a third state; in the first state, the load impedance of the modulation unit is a first impedance value, in the second state, the load impedance of the modulation unit is a second impedance value, and in the third state, the modulation unit emits an excitation signal externally.

2. The auxiliary card search module according to claim 1, wherein the pulse detection unit comprises a bandpass filter circuit, a signal amplification circuit, an envelope extraction circuit, and a comparison trigger circuit; An input end of the bandpass filter circuit is connected to the device antenna of the slave device for obtaining the response signal; the response signal is passed through the bandpass filter circuit to obtain a first filtered signal; The output end of the bandpass filter circuit is connected to the input end of the signal amplification circuit; the first filtered signal is passed through the signal amplification circuit to obtain an amplified signal; The output end of the signal amplifying circuit is connected to the input end of the envelope extraction circuit; the amplified signal passes through the envelope extraction circuit to obtain an envelope output signal; The output end of the envelope extraction circuit is connected to the input end of the comparison trigger circuit; the envelope output signal passes through the comparison trigger circuit to obtain the trigger signal.

3. The auxiliary card search module according to claim 2, wherein the envelope extraction circuit comprises a diode, a first capacitor, a first resistor, a second capacitor, and a second resistor; The input end of the diode is connected to the output end of the signal amplifying circuit; The first capacitor and the first resistor are connected in parallel, one end of the first capacitor and one end of the first resistor are connected to the output end of the diode respectively; the other end of the first capacitor and the other end of the first resistor are connected to the ground end respectively; The second resistor is connected in series with the second capacitor, one end of the second resistor is connected to the output end of the diode, the other end of the second resistor is connected to one end of the second capacitor and the input end of the comparison trigger circuit, and the other end of the second capacitor is connected to the ground end.

4. The auxiliary card-searching module according to claim 3, wherein the preset duration is in microseconds; or the preset duration is less than or equal to half of a pulse duration of a radio frequency signal emitted by the main device.

5. The auxiliary card search module according to claim 3, wherein the preset time length τ = -ln (1-0.9) R 20 C 20 ,in, R 20 represents the resistance value of the second resistor, C 20 represents the capacitance value of the second capacitor; And / or, the resistance value of the first resistor is equal to the resistance value of the second resistor, or the difference between the resistance value of the first resistor and the resistance value of the second resistor is less than or equal to a first threshold; The capacitance value of the first capacitor is equal to the capacitance value of the second capacitor, or the difference between the capacitance value of the first capacitor and the capacitance value of the second capacitor is less than or equal to a second threshold; the resistance value of the first resistor and the resistance value of the second resistor are greater than the output impedance value of the signal amplification circuit.

6. The auxiliary card-finding module according to any one of claims 1 to 5, wherein the modulation unit comprises a switch element, a first load impedance circuit, a second load impedance circuit, and a radio frequency signal circuit; The first load impedance circuit, the second load impedance circuit and the radio frequency signal circuit are respectively connected to the gate end of the switch element; The control end of the switch element is connected to the control unit; the control unit controls the modulation unit to switch states by adjusting the conduction state of the selection end. The auxiliary card-finding module according to claim 6 , wherein the switch element comprises a radio frequency switch element.

8. The auxiliary card-finding module according to claim 6, wherein the first load impedance circuit and the second load impedance circuit have different load impedance values, the load impedance value of the first load impedance circuit is a first impedance value, the second load impedance value is a second impedance value, the first impedance value is greater than the second impedance value, or the first impedance value is less than the second impedance value; The radio frequency signal circuit includes a signal source capable of transmitting a radio frequency signal matching the main device.

9. An auxiliary card search method, applied to a slave device for near field communication, wherein the slave device has an auxiliary card search module, the auxiliary card search module including a pulse detection unit, a control unit, and a modulation unit; The control unit is connected to the pulse detection unit and the modulation unit respectively; The method comprises: The pulse detection unit generates a trigger signal within a preset duration based on a response signal from the device antenna of the slave device; the response signal is generated by the device antenna of the slave device in response to the radio frequency signal sent by the master device; the preset duration is less than a pulse duration of a radio frequency signal sent by the master device; The control unit controls the modulation unit to switch states according to the trigger signal to promote the master device to enter the polling mode; the modulation unit includes a first state, a second state and a third state; in the first state, the load impedance of the modulation unit is a first impedance value, in the second state, the load impedance of the modulation unit is a second impedance value, and in the third state, the modulation unit transmits an excitation signal to the master device.

10. The method according to claim 9, wherein the control unit controls the modulation unit to switch states according to the trigger signal, comprising: Before the control unit obtains the trigger signal, the modulation unit is in the first state; After the control unit obtains the trigger signal, the modulation unit switches to the second state and maintains the state for the first duration; After the modulation unit is in the second state for the first period of time, if the master device does not switch to the polling mode, the control unit controls the modulation unit to switch to the third state.

11. The method according to claim 10, wherein after the modulation unit is in the second state for a first period of time, if the host device does not enter the normal card search mode, the control unit controls the modulation unit to switch to the third state, comprising: After the modulation unit is in the second state for a first time period, the control unit controls the modulation unit to switch to the first state and maintain the state; The sum of the first duration and the preset duration is less than or equal to the pulse duration; Determining whether the master device enters a polling mode; If the master device does not enter the polling mode, the control unit controls the modulation unit to switch from the first state to the third state.

12. The method according to claim 10, before the control unit controls the modulation unit to switch to the third state, further comprising: If the master device has not switched to the normal card search mode, the control unit waits for a subsequent trigger signal; The subsequent trigger signal is a next trigger signal generated after the pulse detection unit generates the trigger signal; If the control unit obtains the subsequent trigger signal, the control unit switches the modulation unit from the first state to the second state and maintains the state for a second time period; the second time period is longer than the first time period; The control unit controls the modulation unit to switch to the third state, including: After the modulation unit is in the second state for the second time period, if the master device does not switch to the polling mode, the control unit controls the modulation unit to switch to the third state.

13. The method according to claim 12, wherein after the modulation unit is in the second state for the second time period, if the master device has not switched to the polling mode, the control unit controls the modulation unit to switch to the third state, comprising: After the modulation unit is in the second state for the second time period, the control unit controls the modulation unit to switch to the first state and maintain the state; Determining whether the master device enters a polling mode; If the master device does not enter the polling mode, the control unit controls the modulation unit to switch from the first state to the third state.

14. A near field communication device, comprising the auxiliary card searching module according to any one of claims 1 to 8, or capable of executing the auxiliary card searching method according to any one of claims 9 to 13.

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