An auxiliary card searching module, method and near field communication device

Abstract

The embodiment of the present specification provides an auxiliary card searching module, method and near field communication device. Wherein, 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 used for generating 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 the radio frequency signal sent by the master device; the preset time length is less than the pulse time length of one radio frequency signal sent by the master device; the control unit is used for controlling the modulation unit to switch states according to the trigger signal, so as to promote the master device to enter the polling mode.

Description

Technical Field

[0001] This specification relates to the field of near-field communication technology, and particularly to an auxiliary card finding module. This specification also relates to an auxiliary card finding method and a near-field communication device. Background Technology

[0002] NFC (Near Field Communication) technology, as a near-field communication technology, boasts advantages such as high security and high speed. With the continuous development of NFC technology and its increasing market share, most smartphones are equipped with this technology. LPCD (Low-Power Card Detection) mode, as a power-saving mode for the NFC controller, detects the presence of cards or card-emulated devices by periodically emitting radio frequency signals. When LPCD mode is enabled, the NFC controller only polls upon detecting a card's proximity, thus significantly reducing NFC power consumption and improving the user experience.

[0003] Ideally, when a smartphone in LPCD mode approaches an external device, the change in coil coupling between the smartphone and the external device wakes up the smartphone's NFC controller and sends a polling signal. However, in reality, different smartphones use different NFC controller chips, have different LPCD wake-up strategies, and different antenna positions and shapes. As a result, some phones cannot exit LPCD mode when approaching an external device, leading to communication failure.

[0004] Therefore, how to more quickly promote the exit of smartphones and other devices from LPCD mode is an urgent technical problem to be solved. Summary of the Invention

[0005] In view of this, one or more embodiments of this specification provide an auxiliary card finding module, method, and near-field communication device to solve the problem that existing electronic devices cannot exit LPCD mode.

[0006] According to a first aspect of one or more embodiments of this specification, an auxiliary card finding module is provided, applied to a slave device in near-field communication, the auxiliary card finding 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;

[0007] The pulse detection unit is used to generate a trigger signal within a preset duration based on the response signal of 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 the pulse duration of a radio frequency signal sent by the master device;

[0008] The control unit is used to control the modulation unit to switch states according to the trigger signal, so as 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.

[0009] According to a second aspect of one or more embodiments of this specification, an auxiliary card finding method is provided, applied to a slave device in near-field communication, the slave device having an auxiliary card finding module, the auxiliary card finding 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;

[0010] The method includes:

[0011] The pulse detection unit generates a trigger signal within a preset duration based on the response signal of the slave device's device antenna; the response signal is generated by the slave device's device antenna 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.

[0012] The control unit controls the modulation unit to switch states according to the trigger signal, so as 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.

[0013] According to a third aspect of one or more embodiments of this specification, a near-field communication device is provided, the near-field communication device including the above-described auxiliary card finding module, or the near-field communication device being capable of performing the above-described auxiliary card finding method.

[0014] One embodiment of this specification achieves at least the following beneficial effects: By setting an auxiliary card-finding module in the near-field communication slave device, after the slave device's antenna senses the radio frequency signal emitted by the master device, the pulse detection unit in the auxiliary card-finding module can generate a trigger signal for adjusting the modulation unit of the auxiliary card-finding module within a preset duration of a pulse duration less than the duration of a radio frequency signal emitted by the master device, based on the response signal sensed by the slave device's antenna. The control unit in the auxiliary card-finding module can adjust the state of the modulation unit after acquiring the trigger signal, such as changing the impedance value of the modulation unit or controlling the idling unit to emit an excitation signal. In the near-field communication process, the slave device can be regarded as the load part of the master device. In at least one embodiment of this specification, by changing the impedance value of the modulation unit in the auxiliary card-finding module, the parameter changes generated by the master device under the influence of the slave device can be improved, which can promote the master device to switch from LPCD (Low-Power Card Detection) mode to normal polling mode, so that the master device can successfully conduct near-field communication with the slave device, which is beneficial to improving the success rate and efficiency of near-field communication.

[0015] On the other hand, in at least one embodiment of this specification, the pulse detection unit can generate a trigger signal within a pulse duration shorter than that of a radio frequency signal emitted by the master device after acquiring the response signal of the device antenna of the slave device. In this way, the slave device can affect the master device by switching the state of the modulation unit before the first pulse radio frequency signal (e.g., LPCD signal) emitted by the master device is sensed and before the first pulse radio frequency signal ends. There is no need to wait for the slave device to acquire multiple pulse radio frequency signals before starting the action to promote the master device to exit the LPCD mode. This can promote the master device to exit the LPCD mode and enter the normal polling mode more quickly, and also help improve the success rate and efficiency of near-field communication. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram illustrating an application scenario of an auxiliary card-finding module provided in one embodiment of this specification.

[0018] Figure 2 This is a schematic diagram of the structure of an auxiliary card finding module provided in one embodiment of this specification;

[0019] Figure 3 This is a schematic diagram of the structure of a pulse detection unit provided in one embodiment of this specification;

[0020] Figure 4 A schematic diagram of the circuit principle of a pulse detection unit provided in one embodiment of this specification;

[0021] Figure 5 This is a schematic diagram of the structure of a modulation unit provided in one embodiment of this specification;

[0022] Figure 6 A schematic diagram of a modulation unit provided in one embodiment of this specification;

[0023] Figure 7 This is a flowchart illustrating an auxiliary card-finding method provided in one embodiment of this specification;

[0024] Figure 8 This is a flowchart illustrating an auxiliary card-finding method provided in one embodiment of this specification. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification.

[0026] This specification uses specific terms to describe embodiments thereof. Terms such as "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples, without contradiction.

[0027] The terminology used in one or more embodiments of this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the one or more embodiments of this specification. The singular forms “a,” “an,” “an,” “the,” and “the” as used in one or more embodiments of this 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” as used in one or more embodiments of this specification includes any or all possible combinations of one or more associated listed items.

[0028] The terms “comprising,” “including,” or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, product, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, product, or apparatus. Without further limitation, the presence of additional identical or equivalent elements in the process, method, product, or apparatus that includes said elements is not excluded.

[0029] Although the terms "first," "second," etc., may be used to describe various information in one or more embodiments of this specification, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, "first" may also be referred to as "second," and similarly, "second" may also be referred to as "first," without departing from the scope of one or more embodiments of this specification. Ordinal numbers such as "first," "second," etc., do not necessarily indicate order; often they are used to facilitate the distinction of objects. For example, "first server" and "second server" usually refer to two servers. To distinguish these two servers, they are described as "first server" and "second server." Of course, sometimes these two servers may be the same server.

[0030] Depending on the context, the word "if" as used here can be interpreted as "when," "when," or "in response to determination."

[0031] In this specification, unless explicitly stated otherwise, "receiving and sending data" does not necessarily mean direct receiving and sending; it can also mean indirect receiving and sending. For example, A receiving data sent by B can be understood as A directly receiving the data sent by B, or it can be understood as A indirectly receiving the data sent by B through other entities such as C. Similarly, B sending data to A 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 other entities such as C. Here, C can be one entity, or it can be two or more entities.

[0032] In this specification, unless explicitly stated otherwise, the relationships 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. Similarly, when describing "A is on top of 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.

[0033] The user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in one or more embodiments of this specification are all information and data authorized by the user or fully authorized by all parties. The collection, use and processing of related data shall comply with the relevant laws, regulations and standards of the relevant regions, and corresponding operation entry points shall be provided for users to choose to authorize or refuse.

[0034] The following explains the terms and concepts used in one or more embodiments of this specification.

[0035] NFC (Near Field Communication) is a short-range wireless communication technology with a typical operating distance of less than 10cm, used in scenarios such as mobile payments, access cards, and public transport cards. In NFC, the device that actively transmits signals can be called the master device, such as an NFC card reader or a device in card reader mode, acting as the card reader end of the NFC communication. The device that passively responds to the signals transmitted by the master device can be called the slave device, such as an NFC tag, a device in card emulation mode, or a device with an NFC tag, acting as the tag end of the NFC communication.

[0036] LPCD (Low-Power Card Detection): A power-saving function of an NFC controller that periodically detects the presence of an NFC card at low power; when a card is detected, the main system can be woken up.

[0037] Polling refers to the process by which an NFC active device periodically initiates communication requests to detect the presence of interactive passive devices nearby.

[0038] Figure 1 This is a schematic diagram illustrating an application scenario of an auxiliary card-finding module provided in one embodiment of this specification.

[0039] like Figure 1As shown, the auxiliary card-finding module 206 can be applied to the near-field communication (NFC) slave device 200. The NFC slave device 200 may include an NFC slave antenna 202, an NFC slave control unit 204, and the auxiliary card-finding module 206. The NFC master device 100 may include an NFC master antenna 102 and an NFC master control unit 104. In practical applications, the NFC master control unit 104 in the master device 100 can control the generation of electromagnetic signals and transmit radio frequency signals outward through the NFC master antenna 102. If the slave device 200 is within the radio frequency range of the master device 100, the NFC slave antenna 202 of the slave device 200 can generate electromagnetic coupling with the NFC master antenna 102 of the master device 100. The NFC slave control unit 204 in the slave device 200 can analyze the electromagnetic signals sensed in the NFC slave antenna 202, or it can transmit the information to be transmitted to the master device 100 through the NFC slave antenna 202. For details on the information transmission process between the master device 100 and the slave device 200 via NFC near-field communication, please refer to relevant technologies, which will not be elaborated here.

[0040] To reduce power consumption, the master device 100 can first emit a low-power radio frequency signal in LPCD mode to detect whether there is a nearby near-field communication slave device, such as an NFC card. After sensing the radio frequency signal emitted by the master device 100, the NFC slave antenna 202 in the slave device 200 couples with the NFC master antenna 102 in the master device 100. This causes a change in the signal parameters in the master device 100. If the change in parameters in the master device 100 exceeds a threshold, the master device 100 can determine that there is a nearby slave device 200, exit LPCD mode, and conduct short-range communication with the detected slave device 200 through normal polling.

[0041] To facilitate the rapid exit of the master device 100 from LPCD mode, the auxiliary card search module 206 in the slave device 200 can adjust its operating state based on the signal sensed at the NFC slave device antenna 202. When the master device 100 transmits LPCD radio frequency signals, it can change the load impedance of the master device 100 by altering the impedance value of the auxiliary card search module. Alternatively, the auxiliary card search module can provide an excitation signal, causing the master device 100 to generate a larger signal change under the influence of the slave device 200, thus facilitating a faster exit from LPCD mode. After exiting LPCD mode, the master device 100 can interact with the slave device 200 normally through polling.

[0042] The main device 100 can be a device with near-field communication (NFC) card reader functionality, such as a smartphone, smartwatch, wristband, laptop, tablet, or other portable terminal device; it can also be a smart home device, in-vehicle device, or a POS machine, self-service checkout device, or other payment device. The slave device 200 can be a device with an NFC tag or a device that can simulate an NFC tag. For example, the slave device 200 can be a device used for processing payment transactions, such as a payment device used at a cashier or self-service checkout; or, the slave device 200 can be a device for processing check-in, login, access control, turnstiles, etc., such as a device for checking in at work, school, or events using NFC; a device for member login or application login using NFC; an access control device for residential or office buildings; a card reader for public transportation such as buses and subways; or a device for identity or ticket verification at tourist attractions, events, or concerts.

[0043] In at least one embodiment of this application, an auxiliary card finding module is provided. This application also relates to an auxiliary card finding method and a near-field communication device, which will be described in detail in the following embodiments.

[0044] Figure 2 This is a schematic diagram of an auxiliary card-finding module provided in one embodiment of this specification.

[0045] like Figure 2 As shown, the auxiliary card finding module 206 may include a pulse detection unit 2062, a control unit 2064 and a modulation unit 2066, with the control unit 2064 connected to both the pulse detection unit 2062 and the modulation unit 2066.

[0046] Specifically, the input terminal of the pulse detection unit 2062 can be connected to the NFC slave antenna 202 of the slave device to acquire the response signal generated by the slave device's device antenna in response to the radio frequency signal sent by the master device. The pulse detection unit 2062 can generate a trigger signal based on the response signal of the slave device's device antenna within a preset duration that is shorter than the pulse duration of a radio frequency signal sent by the master device.

[0047] The output of the pulse detection unit 2062 can be connected to the input of the control unit 2064, providing the generated trigger signal to the control unit 2064. The output of the control unit 2064 is connected to the modulation unit 2066. After receiving 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.

[0048] The modulation unit 2066 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.

[0049] The control unit 2064 can control the modulation unit 2066 to switch from a first state to a second state, or from a second state to a first state, or from a first state to a third state, or from a second state to a third state, etc., according to the trigger signal. For example, the pulse period of an LPCD radio frequency 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 duration of less than 25 microseconds. For example, it takes 2 microseconds for the pulse detection unit to go from acquiring the response signal to outputting the trigger signal. Assuming that it takes 3 microseconds for the control unit to control the state of the modulation unit based on the trigger signal, and assuming that the pulse duration of an LPCD radio frequency signal emitted by the master device is 25 microseconds, the state of the modulation unit can be switched before the LPCD radio frequency signal ends, thus affecting the master device in real time.

[0050] The modulation unit 2066 may include circuits or electronic components capable of presenting different impedance values. When the circuits or electronic components presenting a first impedance value are in operation, the modulation unit can be in a first state, acting as a load of the first impedance value to influence the master device. When the circuits or electronic components presenting a second impedance value in the modulation unit 2066 are in operation, the modulation unit can be in a second state, acting as a load of the second impedance value to influence the master device. The first impedance value and the second impedance value are different; 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 senses the radio frequency signal transmitted by the master device, the slave device is equivalent to the load of the master device. In the embodiments of this specification, adjusting the impedance value of the modulation unit is equivalent to adjusting the impedance value of the load of the master device. Therefore, the amount of signal change 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 LPCD mode and enter normal polling mode to interact with the slave device.

[0051] The modulation unit 2066 may also include circuits or electronic components capable of transmitting radio frequency signals, which can provide external excitation signals to the master device and increase the amount of signal change sensed by the master device under the influence of the slave device, which is also conducive to promoting the master device to exit LPCD mode.

[0052] The pulse detection unit can acquire the response signal generated by the slave device's coil antenna in response to the master device's radio frequency (RF) signal (e.g., LPCD pulse signal). Based on this response signal, it can generate a trigger signal within a preset duration shorter than the pulse duration of one RF signal emitted by the master device. The control unit can then adjust the modulation unit's state in a timely manner based on this trigger signal. This allows the slave device to adjust its impedance value or transmit an excitation signal within the pulse duration of the first RF signal it senses. This enables the master device to sense the change in load impedance or the excitation signal provided by the slave device during the transmission of the first RF signal, thus allowing for a faster exit from LPCD mode. There is no need to wait for the slave device to receive multiple RF signals emitted by the master device, or for several RF signal pulse cycles (e.g., after several hundred milliseconds), before providing additional influence to the master device.

[0053] As one implementation method, Figure 3 This is a schematic diagram 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.

[0054] The input terminal of the bandpass filter circuit 302 can be connected to the device antenna of the slave device to acquire the response signal sensed by the slave device. The bandpass filter circuit can filter the input signal to obtain a signal of a preset specification. The response signal, after passing through the bandpass filter circuit 302, yields a first filtered signal. In practical applications, the input terminal of the bandpass filter circuit can be connected to the device antenna of the slave device to acquire the response signal generated by the slave device's device antenna under the radio frequency signal emitted by the master device. Alternatively, the input terminal of the bandpass filter circuit can be connected to the control unit of the slave device to acquire the response signal generated by the slave device's device antenna under the radio frequency signal emitted by the master device. The specific connection method is not limited here, as long as the bandpass filter circuit can acquire the response signal generated by the slave device's device antenna under the radio frequency signal emitted by the master device.

[0055] 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 amplify the input signal for subsequent use. The first filtered signal described above can be amplified by the signal amplifier circuit to obtain an amplified signal.

[0056] The output of the signal amplification circuit 304 can be connected to the input of the envelope extraction circuit 306. The envelope extraction circuit can be used to extract signals within a preset range. The amplified signal obtained by the envelope extraction circuit can then produce an envelope output signal.

[0057] The output of the envelope extraction circuit 306 can be connected to the input of the comparison trigger circuit 308. The comparison trigger circuit generates a trigger signal, such as a rising edge or falling edge trigger signal, when the input signal at the input terminal is greater than a threshold. The aforementioned envelope output signal can be used to obtain the trigger signal after passing through the comparison trigger circuit.

[0058] The output of the comparison trigger circuit 308 can be connected to the control unit, so that the control unit can control the modulation unit to switch states according to the trigger signal.

[0059] This explanation uses a 13.56MHz radio frequency signal as an example. The pulse detection circuit can quickly detect the LPCD signal generated by the master device (e.g., an NFC card reader) and output the detection result (such as a trigger signal) to the control unit of the auxiliary card search module. The pulse detection circuit is connected to the antenna of the slave device, and the bandpass filter circuit can be a 13.56MHz bandpass filter to filter the 13.56MHz signal and remove interference signals. After filtering, the signal is amplified by the amplifier circuit and then input to the envelope extraction circuit to obtain the envelope output signal, also known as the signal envelope. If the change in 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 a trigger signal to trigger an external interrupt of the control unit. The control unit can use this trigger signal as an interrupt signal to switch the state of the modulation unit according to the preset processing logic, such as modulating the modulation unit from a high impedance state to a low impedance state, or causing the modulation unit to transmit radio frequency signals, etc.

[0060] In practical applications, depending on the specific application scenario—for example, the parameters of the radio frequency (RF) signals used in different scenarios—bandpass filter circuits, amplifier circuits, envelope extraction circuits, or comparison trigger circuits that match the parameters of the RF signals can be used. Alternatively, the specific parameters or specifications of the electronic components selected in each circuit can be set according to the actual needs of the scenario. For instance, in scenarios using other frequency bands for near-field communication, a bandpass filter circuit for filtering signals in that frequency band can be selected based on the frequency band used in that scenario.

[0061] As one implementation method, Figure 4 This is a schematic diagram of the circuit principle of a pulse detection unit provided in one embodiment of this specification. Figure 4 As shown, the bandpass filter circuit 302 may include a bandpass filter, the signal amplification circuit 304 may include an envelope signal amplifier, the envelope extraction circuit 306 may include a circuit formed by connecting devices such as diodes D, capacitors C, and resistors R, and the comparison trigger circuit 308 may include a comparator.

[0062] like 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 terminal of diode D is connected to the output terminal of signal amplification circuit 304; the first capacitor C1 and the first resistor R1 are connected 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 terminal of 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 ground. Optionally, the input terminal of diode D can be the anode (positive terminal), and the output terminal can be the cathode (negative terminal).

[0063] 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 terminal 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 terminal of the comparison trigger circuit, and the other end h of the second capacitor C2 is connected to the ground terminal.

[0064] The aforementioned diodes, first capacitors, second capacitors, first resistors, and second resistors can be independent components, or they can be combined components consisting of multiple diodes, capacitors, and resistors. The specific number and style of these components are not limited here.

[0065] In practical applications, a comparator may include two input terminals and one output terminal. One input terminal receives the signal to be compared, such as the envelope extraction signal mentioned above, and the other input terminal receives a reference signal, such as a reference voltage or current. As one implementation, the input terminal of the comparison trigger circuit described above can be the non-inverting input terminal of the comparator, and the inverting input terminal of the comparator can be connected to the reference signal. Alternatively, the input terminal of the comparison trigger circuit described above can be the inverting input terminal of the comparator, and the non-inverting input terminal of the comparator can be connected to the reference signal.

[0066] like Figure 4 As shown, assume the input signal from the device's antenna is V. in V in After passing through a bandpass filter and amplifier, the amplified signal v(t) is obtained. Then, the amplified signal v(t) is input to the diode in the envelope extraction circuit for rectification. The rectified signal... Includes DC component And complex AC components. DC components. Charging the primary envelope extraction circuit composed of resistor R1 and capacitor C1, assuming the output impedance of the signal amplification circuit is R0, the voltage across capacitor C1 reaches 90%. Time used It can be represented as: Where R0 represents the output impedance of the signal amplifier circuit, and C 10 This indicates the capacitance value of the first capacitor.

[0067] The AC signal is grounded through a low-impedance capacitor C1, therefore... The AC component amplitude is relatively small. To further filter out the AC signal and prevent unstable triggering of the comparator, a low-pass filter circuit can be built using resistor R2 and capacitor C2. The low-pass filter circuit can effectively filter out the AC signal, and for DC signals with a rise time of 90%, it can effectively filter out the AC signal. It can be represented as: Among them, R 20 C represents the resistance value of the second resistor. 20 This indicates the capacitance value of the second capacitor.

[0068] In one implementation, the resistance value of the first resistor is equal to the resistance value of the second resistor, or the difference between the resistance values ​​of the first resistor and 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 values ​​of the first capacitor and the second capacitor is less than or equal to a second threshold; the resistance values ​​of the first resistor and the second resistor are greater than the output impedance value of the signal amplification circuit.

[0069] 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 both the resistance values ​​of the first and second resistors can 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, specifically expressed as follows: This rise time This is negligible. To ensure sensitivity, the comparator's reference voltage... The value can be relatively small, for example, less than a preset threshold, such as less than 1 volt (e.g., 0.8 volts, 0.6 volts, etc.), or less than 1.5 volts, 2 volts, etc. For example, the resistance of the first and second resistors can be 470 ohms, the capacitance of the first and second capacitors can be 4.7 nF, and the comparator's reference voltage can be 0.8V. In practical applications, the comparator's reference voltage... It can be a fixed value. When the voltage across capacitor C2 is greater than the reference voltage... At this time, the comparator can output a rising edge signal to trigger an external interrupt of the control unit of the auxiliary card search module. The rise time of this signal is about 10 ns (nanoseconds), which is negligible compared to the duration of tens of microseconds (µs) of the LPCD signal. Thus, the response time of the above pulse detection circuit can be expressed as follows: .

[0070] This can also refer to the preset duration in the trigger signal generated by the pulse detection unit described above, based on the response signal from the device antenna of the slave device, within a preset duration. Optionally, the preset duration τ = -ln(1-0.9)R 20 C 20 Among them, R 20 C represents the resistance value of the second resistor. 20 This indicates the capacitance value of the second capacitor.

[0071] In order to quickly change the load or transmit excitation signal of the main device, and to allow some time for the control unit to control the modulation unit, the preset duration can optionally be in the microsecond range; or, the preset duration can be less than or equal to half the pulse duration of a radio frequency signal emitted by the main device.

[0072] For example, in practical applications, smartphones and other terminals, acting as near-field communication (NFC) card readers, exhibit slight variations in the length or period of the radio frequency (RF) signals emitted in LPCD mode due to differences in brand or system settings. Statistics show that most terminals currently emit RF signals in LPCD mode with a minimum pulse duration of 25µs (microseconds), and a pulse period ranging from approximately 1ms (milliseconds) to 10, tens, or hundreds of ms (milliseconds). For instance, the preset duration could be 2 microseconds. This allows the auxiliary card-finding module to influence the main device by adjusting the tuning unit's state during the transmission of an LPCD RF signal, thereby increasing the speed at which the main device exits LPCD mode.

[0073] In one embodiment of this specification, the modulation unit may be in different states, such as a high impedance state, a low impedance state, or a state of transmitting an excitation signal. As one implementation, the modulation unit includes 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 selection terminal of the switching element; the control terminal of the switching 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 terminal.

[0074] The switching element includes multiple selectable terminals. A first load impedance circuit, a second load impedance circuit, and an RF signal circuit are each connected to a different selectable terminal. For example, the first load impedance circuit is connected to the first selectable terminal of the switching element, the second load impedance circuit is connected to the second selectable terminal, and the RF signal circuit is connected to the third selectable terminal. The control unit can control the state of each selectable terminal of the switching element, such as whether each selectable terminal is in a conducting or disconnected state. Thus, the control unit can control the conducting or disconnecting states of the first load impedance circuit, the second load impedance circuit, and the RF signal circuit according to a preset processing logic based on the trigger signal output by the pulse detection unit, thereby controlling the modulation unit to switch states.

[0075] Figure 5 This is a schematic diagram of a modulation unit provided in one embodiment of this specification. The description uses an RF switching element as an example. Figure 5 As shown, the modulation unit 2066 may include an RF switching element 502, a first load impedance circuit 504, a second load impedance circuit 506, and an RF signal circuit 508. Specifically, the first load impedance circuit 504, the second load impedance circuit 506, and the RF signal circuit 508 are respectively connected to the selection ports of the RF switching element 502. The first load impedance circuit 504, the second load impedance circuit 506, and the RF signal circuit 508 are respectively connected to different selection ports in the RF switching element 502. For example, the first load impedance circuit 504 is connected to the first selection port of the RF switching element 502, the second load impedance circuit 506 is connected to the second selection port of the RF switching element 502, and the RF signal circuit 508 is connected to the third selection port of the RF switching element 502.

[0076] The common port of the RF switching element 502 is connected to the device antenna of the slave device to acquire the response signal generated by the device antenna of the slave device in response to the RF signal transmitted by the master device. For example, the response signal input to the pulse detection unit mentioned above can also be input to the common port of the RF switching element 502.

[0077] The control port of the radio frequency switching element is connected to the control unit 2064. The control unit 2064 can control the modulation unit to switch states by adjusting the gating port of the radio frequency switching element that is connected to the common port of the radio frequency switching element.

[0078] If the common port of the RF switching element is connected to the first gating port connected to the first load impedance circuit, the first load impedance circuit is in operation, 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 switching element is connected to the second gating port connected to the second load impedance circuit, the second load impedance circuit is in operation, 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 switching element is connected to the third gating port connected to the RF signal circuit, the RF signal circuit is in operation, and the modulation unit can transmit an excitation signal.

[0079] In practical applications, the switching element can be an absorptive RF switch, or it can be other switching elements, such as a combination of multiple single-pole double-throw (SPDT) switches, solid-state switches, etc.

[0080] In one implementation, at least one of the resistance, inductance, and capacitance values ​​in the first load impedance circuit and the second load impedance circuit is different, 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 load impedance value of the second load impedance circuit 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.

[0081] Figure 6 This is a schematic diagram illustrating the principle of a modulation unit provided in one embodiment of this specification. Figure 6 As shown, assume the device antenna impedance is... If 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... (As in the first load impedance circuit), the equivalent impedance of the device antenna is... It can be represented as When the RF switch is connected to a low-impedance load (e.g., in the case of a second load impedance circuit), the equivalent impedance of the device antenna is... It can be represented as: .

[0082] In practical applications, the device antenna of the slave device and the NFC reader antenna of the master device are electromagnetically coupled, assuming a mutual inductance coefficient of M. If the impedance of the master device's NFC reader antenna is... The equivalent impedance after coupling It can be represented as: The equivalent impedance of the device antenna is changed by switching the load through an RF switch. The equivalent impedance of the NFC reader antenna of the main device can be used. And / or other parameters can affect the characteristics of the LPCD signal and cause the master device to exit LPCD mode.

[0083] To more effectively facilitate the master device's exit from LPCD mode, the radio frequency (RF) signal circuit can include a signal source capable of transmitting RF signals compatible with the master device. Specifically, the RF signal circuit can be an active circuit, for example, it may have a transmitting antenna and a power supply, through which it can transmit an excitation signal; or the RF signal circuit can transmit an excitation signal through the slave device's device antenna. Alternatively, the RF signal circuit can be a passive circuit, for example, it may include a coil antenna that cooperates with the slave device's device antenna. This coil antenna can extract energy from the signal sensed by the slave device's device antenna and then convert that energy into an excitation signal for transmission. Specific RF signal circuits can be found in existing related technologies and will not be elaborated upon here.

[0084] In one implementation, when the modulation unit is in at least one of the first, second, or third states, the resonant frequency of the modulation unit, or the resonant frequency of the slave device under the action of the modulation unit, can be a resonant frequency that matches the operating frequency of the master device. This can facilitate the master device's exit from LPCD mode without affecting the information transmission efficiency between the master and slave devices. For example, if the master device's operating frequency is 13.56MHz, the resonant frequency of the modulation unit, or the resonant frequency of the slave device under the action of the modulation unit, can also be 13.56MHz, or the difference between 13.56MHz and the resonant frequency can be less than a preset threshold, and be near 13.56MHz.

[0085] The impedance values ​​of the first and second load impedance circuits 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 in the kiloohm range, such as greater than or equal to 10k ohms; the impedance value of the second load impedance circuit can be in the ohm range, such as greater than or equal to 10k ohms, or the impedance value of the second load impedance circuit can be less than or equal to 20 ohms, 10 ohms, etc., or the impedance value of the second load impedance circuit can be a few ohms. In practical applications, the specific parameter values ​​of each circuit can be set in conjunction with the specific parameters of the master and slave devices; no specific limitations are made here.

[0086] Based on the same idea, this specification also provides an auxiliary card finding method based on the above-mentioned auxiliary card finding module. Figure 7This is a flowchart illustrating an auxiliary card-finding method according to one embodiment of this specification. From a programming perspective, the execution entity of the process can be a program mounted in a slave device, specifically a program in an auxiliary card-finding module. This method can be applied to a slave device in near-field communication, which may include an auxiliary card-finding module. The auxiliary card-finding module may include a pulse detection unit, a control unit, and a modulation unit; the control unit is connected to both the pulse detection unit and the modulation unit. The specific structure of the auxiliary card-finding module can be found in one or more of the foregoing embodiments, and will not be repeated here.

[0087] like Figure 7 As shown, the process may include the following steps.

[0088] Step 702: The pulse detection unit generates a trigger signal within a preset time period based on the response signal of the device antenna of the slave device.

[0089] The response signal may be 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.

[0090] The master device for near-field communication (NFC) acts as a reader device, actively emitting radio frequency (RF) signals to detect the presence of NFC cards nearby. If the master device has an LPCD (Limited-Time Discrete Calibration) operating mode, the RF signal emitted by the master device can be an LPCD-mode signal. Alternatively, the RF signal emitted by the master device can also be a normal polling signal.

[0091] Step 704: 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.

[0092] 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.

[0093] The modulation unit can contain circuits with high impedance values, circuits with low impedance values, and radio frequency signal circuits. The control unit can control the operating state of each circuit in the modulation unit according to the trigger signal, thereby enabling the modulation unit to exhibit different states.

[0094] In one implementation, the control unit controls the modulation unit to switch states according to the trigger signal, which may include: the modulation unit being in the first state before the control unit receives the trigger signal; the control unit switching the modulation unit to the second state and maintaining it for a first duration after receiving the trigger signal; and if the master device has not switched to the polling mode after the modulation unit has been in the second state for the first duration, the control unit controlling the modulation unit to switch to the third state.

[0095] Before the control unit receives the trigger signal, the timeframe can represent the period from when the slave device does not detect the radio frequency signal emitted by the master device, or when there is no master device nearby. Alternatively, it can represent the time period from when the slave device detects the radio frequency signal emitted by the master device to when the pulse detection unit generates the trigger signal and provides it to the control unit. Before the control unit receives the trigger signal, the modulation unit can be in an idle state, an initial state, or a default state. Optionally, in this state, the modulation unit can be in a first state, and the first load impedance circuit can be in a conducting state. If the first load impedance circuit has a high impedance, the modulation unit can be in a high impedance state before the control unit receives the trigger signal.

[0096] After receiving the trigger signal, the control unit can switch the state of the modulation unit from a first state to a second state and maintain this state for a first duration. 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 indicates a switch 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 indicates a switch from low impedance to high impedance. By changing the load impedance, the master device is prompted to exit LPCD mode.

[0097] If the master device has not exited LPCD mode after the modulation unit has been in the second state for a first duration, the control unit can switch the modulation unit to the third state and send an excitation signal to the master device to prompt it to exit LPCD mode. In one embodiment of this specification, the master device is first prompted to exit LPCD mode by adjusting the impedance. If adjusting the impedance fails, the master device is then prompted to exit LPCD mode by transmitting an excitation signal. This avoids the situation where directly transmitting an excitation signal would cause the master device to enter card emulation mode, resulting in communication failure.

[0098] After the modulation unit has been in the second state for a first duration, or during the process of the modulation unit being in the second state, if the master device exits the LPCD mode and sends a polling signal, the control unit can control the modulation unit to return to the initial state, for example, it can control the modulation unit to switch to the first state in order to wait for the next trigger.

[0099] Alternatively, the control unit can also control the modulation unit to transmit an excitation signal within a preset excitation duration. After the preset excitation duration, or when the main device exits LPCD mode during the transmission of the excitation signal by the modulation unit, the control unit can control the modulation unit to return from the third state to the initial state. For example, it can control the modulation unit to switch from the third state to the first state in order to wait for the next trigger.

[0100] To fully utilize load changes to influence the master device and facilitate its exit from LPCD mode, the modulation unit can perform multiple load changes before the auxiliary card search module determines whether to send an RF signal. As one implementation, after the modulation unit is in the second state for a first duration, if the master device has not entered the normal card search mode, the control unit controls the modulation unit to switch to the third state. This can include: after the modulation unit is in the second state for a first duration, the control unit controls the modulation unit to switch to the first state and maintain it; determining whether the master device has entered polling mode; if the master device has not entered 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 has entered polling mode can be executed as soon as the slave device's antenna senses the master device's signal. From a time perspective, this step can be executed in parallel with the steps executed by the auxiliary card search model. The aforementioned determination of whether the master device has entered polling mode can be a check of whether there is result information indicating that the master device has entered polling mode. The actual step of determining whether the master device has entered polling mode does not necessarily begin only after the control unit switches the modulation unit from the second state to the first state.

[0102] Assuming the modulation unit is in state one when processing the initial state, the first load impedance circuit in the modulation unit is in the conducting state. After the slave device senses the RF signal emitted by the master device, the pulse detection unit generates a trigger signal. The control unit can use this trigger signal to switch the second load impedance circuit in the modulation unit to the conducting state, and the first load impedance circuit will no longer be conducting, causing the modulation unit to switch to state two and maintain state two for a first duration, such as 10 microseconds. After that, the control unit switches the modulation unit from state two back to state one and maintains it. During the maintenance of state one, it is determined whether the master device has exited LPCD mode and entered polling mode. If the master device has not entered polling mode, the control unit can switch the modulation unit to state three and use the RF signal circuit to send an excitation signal to the master device to induce the master device to enter polling mode. If the master device has entered polling mode, the control unit can control the modulation unit to switch back to the initial state or maintain state one and wait for the next trigger signal. After the control unit controls the modulation unit to transmit an excitation signal with a preset excitation duration, or if the main device exits LPCD mode during the transmission of the excitation signal by the modulation unit, the control unit can also control the modulation unit to stop sending the excitation signal and restore it from the third state to the initial state. For example, it can control the modulation unit to switch from the third state to the first state in order to wait for the next trigger.

[0103] During the transmission of the excitation signal, it is possible to continuously determine whether the master device has entered polling mode. If the master device has entered polling mode, the transmission of the excitation signal can be terminated, and the modulation unit can switch to the initial state. Alternatively, during the transmission of the excitation signal, it is not necessary to determine whether the master device has entered polling mode. The excitation signal of a specified duration can be transmitted directly, after which the modulation unit switches to the initial state, or the transmission of the excitation signal can be terminated and a preset delay period can be followed by the modulation unit switching to the initial state.

[0104] Optionally, the sum of the first duration and the preset duration can be less than or equal to the pulse duration. This allows for multiple load impedance changes within one pulse duration of the RF signal emitted by the master device, which is more conducive to facilitating the master device to exit LPCD mode as soon as possible.

[0105] In practical applications, to minimize the risk of the main device entering card emulation mode due to actively transmitted excitation signals, one embodiment of this specification can influence multiple pulse cycles of the main device by adjusting the load impedance, thereby facilitating the main device's exit from LPCD mode. As one implementation, before the control unit controls the modulation unit to switch to the third state, it may further include: if the main device has not switched to the normal card search mode, the control unit waits for a subsequent trigger signal; the subsequent trigger signal is the next trigger signal generated after the pulse detection unit generates the trigger signal; if the control unit receives the subsequent trigger signal, the control unit switches the modulation unit from the first state to the second state and maintains it for a second duration; the length of the second duration is greater than the length of the first duration. The control unit controlling the modulation unit to switch to the third state may include: after the modulation unit is in the second state for the second duration, if the main device has not switched to the polling mode, the control unit controls the modulation unit to switch to the third state.

[0106] The trigger signal can represent the first trigger signal generated by the pulse detection unit during a near-field communication process; the subsequent trigger signal represents the second trigger signal generated by the pulse detection unit during the same near-field communication process. Alternatively, the trigger signal and the subsequent trigger signal can be two adjacent trigger signals generated by the pulse detection unit, not necessarily the first or the second. For example, they could be the second and third trigger signals generated by the pulse detection unit, or the third and fourth trigger signals, etc.

[0107] Assuming the modulation unit is initially in state one, after the slave device senses the RF signal emitted by the master device, the pulse detection unit generates a trigger signal. The control unit can then switch the modulation unit from state one to state two based on this trigger signal, maintaining this state for a first duration. Afterward, it checks whether the master device has entered polling mode. If the master device has not switched to polling mode, the modulation unit can remain in state two, waiting for the next trigger signal generated by the pulse detection unit. Once the control unit receives the next trigger signal, it can control the modulation unit to switch from state two back to state one, maintaining this state for a second duration. After the modulation unit has been in state one for two durations, if the master device has not switched to polling mode, the control unit controls the modulation unit to switch to state three.

[0108] Alternatively, assuming the modulation unit is in state one when processing the initial state, after the slave device senses the RF signal emitted by the master device, the pulse detection unit generates a trigger signal. The control unit can switch the modulation unit from state one to state two based on this trigger signal and maintain state two for a first duration. After the first duration, the control unit controls the modulation unit to switch from state two back to state one and maintain it. During the maintenance of state one, it determines whether the master device has entered polling mode. If the master device has not switched to polling mode, the modulation unit can maintain state one and wait for the next trigger signal generated by the pulse detection unit, i.e., the subsequent trigger signal. After the control unit obtains the next trigger signal, it can control the modulation unit to switch from state one to state two and maintain it for a second duration. After the modulation unit is in state two for the second duration, if the master device has not switched to polling mode, the control unit controls the modulation unit to switch to state three.

[0109] The second duration can be longer than the first duration, or the first duration can be longer than the second duration. By using different durations, the main device can avoid fatigue in response, and the main device in LPCD mode can be quickly woken up and made to send polling signals, which effectively improves the user experience.

[0110] Optionally, the sum of the second duration and the preset duration can be less than or equal to the pulse length of a pulse signal emitted by the master device. This allows the master device to sense load changes within a single pulse signal when adjusting load changes based on subsequent trigger signals, thus facilitating the master device's entry into polling mode more quickly.

[0111] Alternatively, the second duration can be longer than the pulse length and different from the first duration, thus providing irregular load changes to encourage the master device to enter polling mode.

[0112] The control unit can also switch the state of the modulation unit multiple times based on subsequent trigger signals, further improving the success rate of the master device exiting LPCD mode. As one implementation, after the modulation unit is in the second state for the second duration, if the master device has not switched to the polling mode, the control unit controls the modulation unit to switch to the third state. This can include: after the modulation unit is in the second state for the second duration, the control unit controls the modulation unit to switch to the first state and maintain it; determining whether the master device has entered the polling mode; if the master device has not entered the polling mode, the control unit controls the modulation unit to switch from the first state to the third state.

[0113] Similar to the process described above where the modulation unit is controlled to switch states based on trigger signals, the step of determining whether the master device has entered polling mode can be executed in parallel with the step of controlling the modulation unit to switch states, performed by the control unit. It doesn't necessarily mean that the process of determining whether the master device has entered polling mode only begins while the modulation unit is in the first state. The aforementioned determination of whether the master device has entered polling mode can refer to whether information indicating that the master device's mode is polling mode has been found; it can be an execution step that obtains the determination result. If the master device has not entered polling mode—for example, if no information indicating that the master device's mode is polling mode has been found, or if the master device's mode is still LPCD mode—the control unit can control the modulation unit to switch to the third state and transmit an excitation signal to the master device. If the master device has entered polling mode, the control unit can control the modulation unit to return to its initial state or maintain the first state, such as the first state where the first load impedance circuit is conducting, or the second state where the second load impedance circuit is conducting, or a state where the first load impedance circuit, the second load impedance circuit, and the RF circuit are all de-conducting. Alternatively, after determining that the master device has entered polling mode, the control unit can delay for a preset time and then control the modulation unit to return to its initial state, waiting for the next near-field communication.

[0114] Assuming the modulation unit is initially in state one, after the slave device senses the RF signal emitted by the master device, the pulse detection unit generates a trigger signal. The control unit can then switch the modulation unit from state one to state two based on this trigger signal, maintaining this state for a first duration. Afterward, it determines whether the master device has entered polling mode. If the master device has not switched to polling mode, the modulation unit can remain in state two, waiting for the next trigger signal generated by the pulse detection unit. Upon receiving the next trigger signal, the control unit can switch the modulation unit from state two back to state one, maintaining this state for a second duration. After this second duration, the control unit can switch the modulation unit back to state two and maintain this state. During this period of maintaining state two, if the master device has not switched to polling mode, the control unit can switch the modulation unit to state three. Alternatively, it can maintain state two for a third duration, and if the master device has not switched to polling mode, the control unit can switch the modulation unit to state three.

[0115] Alternatively, assuming the modulation unit is in state one when processing the initial state, after the slave device senses the RF signal emitted by the master device, the pulse detection unit generates a trigger signal. The control unit can switch the modulation unit from state one to state two based on this trigger signal and maintain state two for a first duration. After the first duration, the control unit controls the modulation unit to switch from state two back to state one and maintain it. During the maintenance of state one, it determines whether the master device has entered polling mode. If the master device has not switched to polling mode, the modulation unit can maintain state one and wait for the next trigger signal generated by the pulse detection unit, i.e., the subsequent trigger signal. After the control unit obtains the next trigger signal, it can control the modulation unit to switch from state one to state two and maintain it for a second duration. After the modulation unit is in state two for the second duration, the control unit can control the modulation unit to switch from state two back to state one and maintain it. During the maintenance of state one, if the master device has not switched to polling mode, the control unit controls the modulation unit to switch to state three, or it can maintain state one for a third duration, and if the master device has not switched to polling mode, the control unit controls the modulation unit to switch to state three. If the master device has switched to polling mode, the modulation unit can remain in the first state or be restored to the initial state, waiting for the next trigger.

[0116] Figure 8 This is a flowchart illustrating an auxiliary card-finding method according to one embodiment of this specification. The explanation is based on the example where the impedance of the modulation unit in its first state is higher than that in its second state. Figure 8 As shown, after starting, the parameters of the control unit of the auxiliary card-finding module can be initialized to prepare for subsequent control. Then, the control unit can switch the RF switch of the modulation unit to a high-impedance load, and the modulation unit is in the first state. Afterwards, the control unit waits for a trigger signal provided by the pulse detection unit. This trigger signal can serve as an interrupt signal for the control unit to trigger the execution of a preset process. When the LPCD signal transmitted by the main device is detected by the pulse detection unit, the pulse detection unit generates a rising edge signal and triggers a pulse detection interrupt. The control unit can determine whether a pulse detection interrupt exists. After triggering the interrupt, 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, the modulation unit switches from the first state to the second state, and remains in this state. After a certain time, the circuit switches to high impedance, and the modulation unit switches from the second state to the first state; then it checks whether the NFC reader (master device) is polling. If polling occurs, the auxiliary card search process is complete, and the delay can be initiated. The system is reinitialized after a certain time; otherwise, it waits for the next LPCD pulse. The pulse detection unit generates a subsequent trigger signal based on the next pulse, which serves as the second interrupt signal. After the second trigger interrupt, the control unit can switch the RF switch to low impedance, and the modulation unit switches from the first state to the second state, maintaining this state. After a certain time, the circuit switches to high impedance, and the modulation unit switches from the second state to the first state; then, it checks again whether the NFC reader (master device) is polling. If polling occurs, the auxiliary card finding process is complete, and the process can be delayed. The system will be reinitialized after a certain time; otherwise, a delay will occur. After a certain time, the RF switch is switched to the signal source, the modulation unit switches from the first state to the third state, and transmits. The radio frequency field of time. Delay after active field transmission. The system will be reinitialized after the specified time. This delay time can be in the millisecond range and can be set based on the length of the RF signal pulse period. In practical applications, no delay time can be set, or the duration can be set to 0.

[0117] This explanation uses the example of the modulation unit switching between high and low impedance based on two trigger signals before transmitting the excitation signal. In practical applications, the modulation unit can also transmit the excitation signal again after switching between high and low impedance based on three or more trigger signals if the master device still has not switched to polling state.

[0118] In one embodiment of this specification, an analog circuit is used to quickly detect pulse signals and output the detection result to the control unit of the auxiliary card-finding module via a rising edge signal. Specifically, this circuit performs filtering, amplification, envelope extraction, and comparison triggering on the input signal, enabling rapid detection of pulse signals (such as LPCD pulse signals) within a short time of their appearance, and outputting the detection result in the form of a rising edge.

[0119] In one embodiment of this specification, under the control of the control unit of the auxiliary card finding module, the equivalent impedance of the device antenna of the slave device is quickly adjusted, thereby adjusting the antenna impedance of the NFC card reader (master device) and waking up the card reader (master device).

[0120] In one embodiment of this specification, by employing two unequal-time passive load modulations and one active field transmission, an NFC reader (master device) in LPCD mode can be quickly woken up and prompted to send a polling signal, effectively improving the user experience. Simultaneously, this method also prevents the NFC reader (master device) from entering card emulation mode upon receiving an external radio frequency field, thus avoiding communication failure.

[0121] While one or more embodiments of this specification provide method steps as described in the embodiments or flowcharts, it is understood that the order of steps listed in the embodiments or flowcharts is merely one possible execution order among many steps and does not represent the only possible execution order. The order of some steps may be adjusted according to actual needs, or some steps may be omitted. When the claims involve method steps, changes in the order of such steps, or parallel execution between steps, are also within the scope of protection of the claims.

[0122] The various technical features in the above embodiments can be combined arbitrarily, as long as there is no conflict or contradiction between the combinations of features. However, due to space limitations, they have not been described one by one. Therefore, the arbitrary combination of various technical features in the above embodiments is also within the scope of this specification.

[0123] Based on the same idea, one embodiment of this specification also provides a near-field communication device, which may include the above-described auxiliary card finding module, or the near-field communication device may be able to execute the above-described auxiliary card finding method.

[0124] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for the near-field communication device embodiments, since they are basically similar to the module or method embodiments, the description is relatively simple, and relevant parts can be referred to the descriptions of the module or method embodiments. The near-field communication devices, modules, and methods provided in the embodiments of this specification correspond to each other; therefore, the near-field communication devices also have similar beneficial technical effects to the corresponding modules or methods. Since the beneficial technical effects of the modules or methods have been described in detail above, the beneficial technical effects of the corresponding devices will not be repeated here.

[0125] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0126] In the 1990s, improvements to a technology could be clearly distinguished as either hardware improvements (e.g., improvements to the circuit structure of diodes, transistors, switches, etc.) or software improvements (improvements to methodology). However, with technological advancements, many methodological improvements today can be considered direct improvements to hardware circuit structures. Designers almost always obtain the corresponding hardware circuit structure by programming the improved methodology into the hardware circuit. Therefore, it cannot be said that a methodological improvement cannot be implemented using hardware physical modules. For example, a Programmable Logic Device (PLD) (such as a Field Programmable Gate Array (FPGA)) is such an integrated circuit whose logic function is determined by the user programming the device. Designers can program a digital system themselves to "integrate" it onto a PLD, without needing chip manufacturers to design and manufacture dedicated integrated circuit chips. Furthermore, nowadays, instead of manually manufacturing integrated circuit chips, this programming is mostly implemented using "logic compiler" software. Similar to the software compiler used in program development, the original code before compilation must also be written in a specific programming language, called a Hardware Description Language (HDL). There are many HDLs, 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, and RHDL (Ruby Hardware Description Language). Currently, the most commonly used are VHDL (Very-High-Speed ​​Integrated Circuit Hardware Description Language) and Verilog. Those skilled in the art should also understand that by simply performing some logic programming on the method flow using one of these hardware description languages ​​and programming it into an integrated circuit, the hardware circuit implementing the logical method flow can be easily obtained.

[0127] The controller can be implemented in any suitable manner. For example, it can take the form of a microprocessor or processor and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro)processor, logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers. Examples of controllers include, but are not limited to, the following microcontrollers: ARC 625D, Atmel AT91SAM, Microchip PIC18F26K20, and Silicon Labs C8051F320. A memory controller can also be implemented as part of the control logic of the memory. Those skilled in the art will also recognize that, in addition to implementing the controller in purely computer-readable program code form, the same functionality can be achieved by logically programming the method steps to make the controller take the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, such a controller can be considered a hardware component, and the means included therein for implementing various functions can also be considered as structures within the hardware component. Alternatively, the means for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0128] The systems, devices, modules, or units described in 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, a computer can be, for example, a personal computer, laptop computer, cellular phone, camera phone, smartphone, personal digital assistant, media player, navigation device, email device, game console, tablet computer, wearable device, or any combination of these devices.

[0129] For ease of description, the above devices are described separately by function as various units. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware.

[0130] Those skilled in the art will understand that one or more embodiments of this specification can be provided as a method, system, or computer program product. Therefore, the invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0131] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0132] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0133] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0134] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0135] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0136] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (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, CD-ROM, digital character versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0137] This application can be described in the general context of computer-executable instructions, such as program modules, that are executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. This application can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0138] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. An auxiliary card searching 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 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 a 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 is configured to control the modulation unit to switch states according to the trigger signal, so as to promote the master device to enter a polling mode; the modulation unit comprises a first state, a second state and a third state; in the first state, a 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 outward.

2. The auxiliary card searching module according to claim 1, wherein the pulse detection unit comprises a band-pass filter circuit, a signal amplification circuit, an envelope extraction circuit and a comparison trigger circuit; an input end of the band-pass filter circuit is connected with a device antenna of the slave device, and is configured to acquire the response signal; the response signal is a first filtered signal obtained by the band-pass filter circuit; an output end of the band-pass filter circuit is connected with an input end of the signal amplification circuit; the first filtered signal is an amplified signal obtained by the signal amplification circuit; an output end of the signal amplification circuit is connected with an input end of the envelope extraction circuit; the amplified signal is an envelope output signal obtained by the envelope extraction circuit; an output end of the envelope extraction circuit is connected with an input end of the comparison trigger circuit; the envelope output signal is the trigger signal obtained by the comparison trigger circuit.

3. The auxiliary card searching 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; an input end of the diode is connected with an output end of the signal amplification circuit; the first capacitor and the first resistor are parallel, one end of the first capacitor and one end of the first resistor are connected with an output end of the diode respectively; the other end of the first capacitor and the other end of the first resistor are connected with a ground end respectively; the second resistor and the second capacitor are connected in series, one end of the second resistor is connected with an output end of the diode, the other end of the second resistor is connected with one end of the second capacitor and an input end of the comparison trigger circuit, and the other end of the second capacitor is connected with a ground end.

4. The auxiliary card searching module according to claim 3, wherein the preset time length is a microsecond level time length; or the preset time length is less than or equal to one half of a pulse time length of one radio frequency signal sent by the master device.

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

6. The auxiliary card searching module according to any one of claims 1 to 5, wherein 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 connected to the gating terminal of the switching element, respectively. The control terminal of the switching element is connected to the control unit; and the control unit controls the modulation unit to switch states by adjusting the conduction state of the gating terminal.

7. The auxiliary card searching module according to claim 6, wherein the switching element comprises a radio frequency switching element.

8. The auxiliary card searching module according to claim 6, wherein the load impedance of the first load impedance circuit is different from the load impedance of the second load impedance circuit; the load impedance of the first load impedance circuit is a first impedance value, the load impedance of the second load impedance circuit is a second impedance value, and 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 comprises a signal source capable of emitting a radio frequency signal matched with the master device.

9. An auxiliary card searching method applied to a slave device of near field communication, the slave device having 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 to the pulse detection unit and the modulation unit, respectively. The method comprises: The pulse detection unit generates a trigger signal within a preset time period based on the response signal of 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; and the preset time period is less than the pulse duration of one radio frequency signal emitted by the master device. The control unit controls the modulation unit to switch states according to the trigger signal to facilitate the master device to enter the polling mode; the modulation unit comprises a first state, a second state, and a third state; the load impedance of the modulation unit in the first state is a first impedance value, the load impedance of the modulation unit in the second state is a second impedance value, and the modulation unit emits an excitation signal to the master device in the third state.

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 is switched to the second state and maintained for a first time period; After the first 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.

11. The method of claim 10, wherein, after the first time duration in the second state, if the host device does not enter the polling mode, the control unit controls the modulation unit to switch to the third state, comprising: the modulation unit being in the second state for the first time duration, the control unit controls the modulation unit to switch to the first state and remain in the first state; the sum of the first time duration and the preset time duration is less than or equal to the pulse duration; 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 from the first state to the third state.

12. The method of claim 10, wherein, before the control unit controls the modulation unit to switch to the third state, further comprising: if the host device does not switch to the polling 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 remains in the second state for a second time duration; the length of the second time duration is greater than the length of the first time duration; the control unit controls the modulation unit to switch to the third state, comprising: the modulation unit being in the second state for the second time duration, if the host device does not switch to the polling mode, the control unit controls the modulation unit to switch to the third state.

13. The method of claim 12, wherein, after the modulation unit is in the second state for the second time duration, if the host device does not switch to the polling mode, the control unit controls the modulation unit to switch to the third state, comprising: the modulation unit being in the second state for the second time duration, the control unit controls the modulation unit to switch to the first state and remain in the first state; 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 from the first state to the third state.

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

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