A near-field communication electronic device, a card reader, and a wake-up method thereof

Abstract

This invention discloses a near-field communication electronic device, a card reader, and a wake-up method thereof. In this method, the card reader periodically transmits a probe wave of fixed amplitude; after receiving the probe wave, the analog card modulates it with a pulse wave of varying amplitude and transmits it back to the card reader; the card reader detects the amplitude changes of multiple received signals and calculates the amplitude difference between adjacent signals; if the amplitude difference of multiple consecutive signals conforms to a preset regularity, a wake-up interrupt is triggered and communication is established. This invention significantly improves the card reader's detection sensitivity and anti-interference capability for analog cards by identifying the trend of amplitude changes, making it particularly suitable for wearable devices with limited antenna size.

Description

Technical Field

[0001] This invention relates to a method for waking up a near-field communication electronic device, as well as a corresponding near-field communication electronic device and a corresponding near-field communication card reader, belonging to the field of near-field communication technology. Background Technology

[0002] Electronic devices incorporating contactless near-field communication (NFC) card readers are diverse, ranging from NFC-enabled mobile phones to card readers commonly found in public transportation and subway systems, as well as POS terminals supporting NFC payments. The "cards" used in these devices can be divided into two categories: physical cards, such as common public transport cards and bank cards; and analog cards, which are NFC-enabled wearable devices like smartwatches and fitness trackers that are linked or activated as public transport cards or access cards, simulating a physical card. Physical cards are passive devices, relying on the card reader for contactless power to function; while analog cards have their own power source (such as a built-in battery) and require independent power to power the NFC chip that implements the analog card function.

[0003] To achieve both energy efficiency and real-time card detection, the chip in an NFC reader typically operates in Low Power Card Detection (LPCD) mode. In this mode, the chip periodically emits a brief (approximately 36 microseconds) radio frequency probe wave. This signal, after being emitted by the antenna, is simultaneously fed back to the chip via a receiving loop. Once the amplitude of the probe wave changes, the chip can detect this change and determine whether a card has entered the antenna field. When a physical or analog card approaches the reader's antenna, it causes a change in antenna impedance; the closer the distance, the more significant the impedance change, resulting in a corresponding change in the probe wave amplitude. If this change exceeds a set threshold, the NFC chip determines that a card is approaching, exits LPCD mode, and initiates the communication process. Conversely, if the amplitude remains essentially unchanged or changes too little, the chip will remain in sleep mode after emitting the probe wave.

[0004] However, analog cards face the challenge of low detection reliability in practical applications. This is mainly due to two factors: First, to accommodate miniaturized designs, analog cards typically use a limited size (generally less than 5cm). 2 The analog card's antenna significantly reduces energy capture and radiation efficiency, resulting in weaker ability to receive magnetic field energy from the card reader and weaker ability to transmit signals in the opposite direction. Secondly, as an active device, the analog card generates circuit noise when performing other functions (such as screen illumination and sensor acquisition), raising the noise floor and further deteriorating the signal-to-noise ratio. The combination of these two factors makes the effective signal-to-noise ratio of the analog card much lower than that of the physical card, making it difficult for the card reader to recognize the card stably.

[0005] To address this challenge, existing technologies, such as Chinese invention patent 202311607547.3, propose a solution using an additional wake-up tuning coil. This solution includes a bare coil whose resonant point matches the reader's carrier frequency band. This coil is used to deactivate the reader's low-power card detection mode via coupling when the card device approaches, allowing subsequent communication to be completed by a communication antenna coil integrated with an NFC chip. While this method improves energy capture efficiency by adding a coil structure, it also increases the complexity and cost of the device. Summary of the Invention

[0006] The primary technical problem to be solved by this invention is to provide a method for waking up near-field communication electronic devices.

[0007] Another technical problem to be solved by the present invention is to provide a near-field communication electronic device.

[0008] Another technical problem to be solved by the present invention is to provide a corresponding near-field communication card reader.

[0009] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0010] According to a first aspect of the present invention, a method for waking up a near-field communication electronic device is provided, comprising the following steps:

[0011] S1: The card reader periodically emits a probe wave of fixed amplitude;

[0012] S2: The analog card modulates the received probe wave using pulse waves of different amplitudes;

[0013] S3: The analog card transmits the modulated probe wave;

[0014] S4: The card reader receives the modulated probe wave, detects the amplitude of the current modulated probe wave, and calculates the difference Δ between the current amplitude and the amplitude of the previous modulated probe wave.

[0015] S5: Repeat steps S2 to S4 until the preset number of times N is reached, then proceed to the next step, where N is a positive integer greater than or equal to 2;

[0016] S6: Determine whether the N differences satisfy a preset rule. If the amplitude difference between adjacent pulses in the pulse wave is not zero and meets the preset rule, then trigger a wake-up interrupt; otherwise, return to step S1.

[0017] S7: The card reader establishes communication with the emulated card.

[0018] Preferably, when the preset rule is increasing, Δ1, Δ2...ΔN are all positive numbers; when the preset rule is decreasing, Δ1, Δ2...ΔN are all negative numbers.

[0019] Preferably, in step S2, the analog card modulates the probe wave so that the pulse wave and the probe wave produce an amplitude superposition effect in the electromagnetic field.

[0020] Preferably, the carrier is pulse envelope modulated to form an amplitude variation, wherein the pulse envelope is located within the passband of the baseband filter at the front end of the card reader.

[0021] Preferably, the duration of a single pulse in the pulse wave is less than the sampling time of the card reader.

[0022] Preferably, the simulation card uses a 1.5cm... 2 ~2cm 2 The miniature antenna is used for signal transmission and reception.

[0023] Preferably, in step S6, the reader's analog-to-digital converter captures the superimposed waveform at a preset sampling rate; the amplitude characteristics of the superimposed waveform are extracted by an envelope detector, and the peak-to-peak value of the signal is calculated by a digital signal processor; if the amplitude difference of the superimposed waveform obtained by the reader through N consecutive samplings satisfies the preset rule, a wake-up interrupt is triggered.

[0024] According to a second aspect of the present invention, a near-field communication electronic device is provided, which is used as an analog card for near-field communication, including a miniature antenna, an LC resonant circuit, a clock module, and an amplitude shift keying modulator;

[0025] When the coil of the miniature antenna is coupled to radio frequency energy, the LC resonant circuit generates an induced voltage. When the induced voltage is greater than or equal to a preset value, the clock module triggers the amplitude shift keying modulator to use the probe wave as a carrier wave and perform amplitude shift keying modulation on the carrier wave with a square wave of a preset frequency to generate a pulse wave with a non-zero amplitude difference between adjacent pulses and conforming to a preset rule, in order to execute the above-mentioned near-field communication electronic device wake-up method.

[0026] According to a third aspect of the present invention, a near-field communication card reader is provided, including a digital signal processor, an analog-to-digital converter, and an envelope detector;

[0027] The analog-to-digital converter captures the superimposed waveform at a preset sampling rate. The superimposed waveform is formed by superimposing a radio frequency probe wave and a pulse wave. The amplitude characteristics of the superimposed waveform are extracted by the envelope detector, and the peak-to-peak value of the signal is calculated by the digital signal processor. If the amplitude difference of the superimposed waveform obtained by the card reader through N consecutive samplings conforms to a preset rule, a wake-up interrupt is triggered to execute the above-mentioned wake-up method for near-field communication electronic devices.

[0028] Compared with existing technologies, this invention modulates the detection wave by having the analog card actively send pulse waves with a specific amplitude variation pattern, and then uses a card reader to detect the changing trend of the amplitude difference over multiple consecutive cycles. This significantly improves the detection sensitivity and reliability of analog cards, effectively overcoming the problems of low efficiency of small-sized antennas and signal-to-noise ratio degradation caused by equipment circuit noise. Furthermore, this method is well-compatible with 1.5cm antennas. 2 ~2cm 2 Wearable devices with micro-antennas enable further miniaturization of devices without additional hardware. They also effectively suppress environmental noise interference and reduce the probability of false wake-ups through a multi-sampling judgment mechanism. While achieving an efficient and stable card-swiping experience, they maintain the energy-saving operation of the card reader in low-power card detection (LPCD) mode, which has significant practical value and promotion potential. Attached Figure Description

[0029] Figure 1 A schematic diagram illustrating the principle of the near-field communication electronic device wake-up method provided in the first embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the signal interaction timing between the card reader and the analog card in the first embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the structure of a near-field communication electronic device provided in the second embodiment of the present invention. Detailed Implementation

[0032] The technical content of the present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0033] The technical concept of this invention is as follows: The analog card uses a pulse of a preset frequency (e.g., 2MHz, but not limited to this) to perform amplitude shift keying (ASK) modulation on a square wave to change the load state of the analog card, thereby causing the antenna current to generate a corresponding frequency envelope change. This change is coupled to the reader coil, inducing a corresponding current fluctuation, and then the modulated waveform of the preset frequency is extracted through envelope detection. The comparator or analog-to-digital converter (ADC) inside the reader detects the change in the amplitude of this waveform. If the change conforms to a preset pattern, the reader is controlled to exit the low-power card detection (LPCD) state and enter the wake-up state. Unlike traditional methods that rely solely on the amplitude change of a single probe wave for judgment, this invention overcomes the limitations of single signal detection by analyzing whether the overall trend of amplitude changes between multiple consecutive probe waves meets preset conditions. This effectively avoids missed detections and false detections caused by fixed threshold settings, significantly improving the reader's detection sensitivity and reliability for analog cards.

[0034] First Embodiment

[0035] like Figure 1 and Figure 2 As shown, the first embodiment of the present invention provides a method for waking up a near-field communication electronic device, which includes at least the following steps:

[0036] S1: The card reader periodically emits a probe wave of fixed amplitude.

[0037] Specifically, the card reader's main control chip (MCU) controls the radio frequency transmission circuit to periodically transmit a 13.56MHz radio frequency carrier wave (e.g., every 300ms), with a probe wave duration of Δt 1 (e.g., 50μs) and a power range between 100mW and 1W. This probe wave is used to activate analog cards that enter its sensing range.

[0038] S2: The analog card modulates the received probe wave using pulse waves of different amplitudes.

[0039] In this embodiment, the simulation card uses a 1.5cm diameter. 2 ~2cm 2 The inherent frequency of the LC resonant circuit of the miniature antenna should have an error of no more than 0.1% with the reader's transmission frequency. In practical applications, factors such as a damp wrist environment may introduce a parasitic capacitance of 3-5 pF, absorbing magnetic induction energy; salt in sweat forms an electrolyte, causing radio frequency energy to be converted into heat energy loss; and the metal watchband generates a reverse magnetic field due to eddy current effects, weakening effective magnetic flux coupling. These factors can all lead to a decrease in the analog card coupling performance, causing the reader's received signal to fall below the wake-up threshold.

[0040] To overcome the aforementioned problems, the analog card modulates the received probe wave, causing the pulse wave and the probe wave to superimpose their amplitudes in the electromagnetic field. Specifically, when the miniature antenna coil is coupled with sufficiently strong radio frequency energy, and the induced voltage of the LC resonant circuit reaches or exceeds a preset value (e.g., 1.8V, but not limited to this), the clock module triggers the amplitude shift keying (ASK) modulator. Based on a 13.56MHz carrier, it performs ASK modulation on the carrier using a square wave or pulse train at a preset modulation frequency (e.g., 2MHz, 3MHz, or 5MHz, etc., which are not specifically limited in this invention), thereby generating a pulse wave including sidebands (e.g., 13.56MHz ± 2MHz). It should be noted that the above modulation frequency can be adjusted according to the actual system design, but its frequency must be within the passband of the reader's front-end baseband filter to avoid signal filtering out. In addition, the duration of a single pulse should be less than the reader's sampling time.

[0041] S3: The analog card transmits the modulated probe wave.

[0042] These are standard procedures and will not be elaborated upon here.

[0043] S4: The card reader receives the modulated probe wave, detects the amplitude of the current signal, and calculates the amplitude difference Δ between the current signal and the amplitude of the previously received modulated probe wave.

[0044] S5: Repeat steps S2 to S4 until the preset number of times N (N≥2, for example, 3 times) is reached, and then proceed to step S6.

[0045] S6: Determine whether the obtained N amplitude differences (Δ1, Δ2, ..., ΔN) satisfy the preset rule; if the amplitude difference between adjacent pulses is not zero and meets the rule, trigger the wake-up interrupt; otherwise, return to step S1.

[0046] In this step, the reader's analog-to-digital converter (ADC) captures the superimposed waveform (i.e., the superposition of the RF probe wave and the pulse wave) at a sampling rate of 20 MHz SPS; the amplitude characteristics are extracted by the envelope detector, and the peak-to-peak value of the signal is calculated by the digital signal processor (DSP). If the amplitude difference obtained from N consecutive samples conforms to a preset pattern (e.g., all positive values ​​indicate increasing, and all negative values ​​indicate decreasing), a wake-up interrupt is triggered. It should be noted that the preset pattern can also be other ordered change modes, but actual anti-interference requirements should be considered to balance detection rate and false detection prevention capabilities.

[0047] S7: The card reader establishes communication with the emulated card.

[0048] After the card reader recognizes a valid wake-up signal, its control module switches from low-power card detection mode to data communication mode. First, it sends a REQA command (0x26 frames) to the emulated card; the emulated card replies with an ATQA response (including the UID prefix and capacity code), thus completing the communication establishment.

[0049] In summary, the embodiments of the present invention significantly improve the detection sensitivity and anti-interference capability of the card reader by actively transmitting pulse waves with a specific pattern to modulate the detection wave, and by using the card reader to judge the trend of continuous amplitude changes, effectively supporting the near-field communication needs of miniaturized wearable devices and improving the user experience.

[0050] To verify the effectiveness of the technical solution of this invention, the inventors conducted experiments to test the card detection success rate at different communication distances and recorded the relevant data (see Table 1). The equipment used in the experiment included: 1) a card reader equipped with a low-power card detection (LPCD) mode and supporting the near-field communication electronic device wake-up method provided in the embodiments of this invention; 2) a simulated card that supports the function of actively transmitting pulse waves.

[0051] The experimental setup is as follows:

[0052] First, using traditional detection technology as a control, the active pulse wave transmission function of the emulated card is turned off. The card reader uses a traditional judgment method: the current detection wave amplitude is compared with a preset fixed reference amplitude. If the difference exceeds the set threshold, it is determined that an emulated card has been detected.

[0053] Subsequently, the near-field communication electronic device wake-up method provided in the embodiments of the present invention is applied: the active pulse wave transmission function of the analog card is enabled, and the card reader uses the wake-up method described in the foregoing embodiments for detection.

[0054] During the experiment, the card reader first entered LPCD mode, and then a positioning device fixed the simulated card at different heights relative to the card reader antenna to simulate card swiping scenarios at different communication distances. The test height ranged from 0cm to 6cm, with a total of 7 location points. Each location point was tested 50 times, and the card detection success rate under the two technologies was statistically analyzed and compared.

[0055] Table 1. Experimental Statistics on Card Detection Success Rate

[0056] Distance (cm) Success rate of traditional techniques Success rate of this invention 0 100.0％ 100.0％ 1 100.0％ 100.0％ 2 96.0％ 100.0％ 3 68.0％ 100.0％ 4 22.0％ 92.0％ 5 0.0％ 64.0％ 6 0.0％ 18.0％

[0057] The experimental results above demonstrate that the near-field communication electronic device wake-up method provided in this embodiment of the invention significantly improves performance compared to traditional detection techniques. As shown in Table 1, at longer distances or under weaker signal conditions (e.g., 4–6 cm), the card detection success rate of traditional methods drops sharply, or even fails completely; while the wake-up method provided by this invention maintains a high wake-up success rate, for example, reaching 92% at 4 cm and retaining 64% recognition capability at 5 cm. This proves that the present invention, through its judgment mechanism of detecting the trend of continuous amplitude changes, effectively enhances the card reader's detection sensitivity and communication distance for analog cards, significantly improving the card-swiping experience and system reliability of wearable devices in complex usage environments.

[0058] Second Embodiment

[0059] Based on the aforementioned near-field communication device wake-up method, the second embodiment of the present invention provides a near-field communication electronic device. This device, used as an analog card for near-field communication, includes a miniature antenna, an LC resonant circuit, a clock module, and an amplitude shift keying modulator. When the coil of the miniature antenna is coupled to radio frequency energy, the LC resonant circuit generates an induced voltage. If this induced voltage is greater than or equal to a preset threshold (e.g., 1.8V), the clock module triggers the amplitude shift keying modulator to perform amplitude shift keying modulation on the carrier wave, using a square wave of a preset frequency, with a probe wave emitted by the card reader as the carrier wave. This generates a pulse wave with a non-zero amplitude difference between adjacent pulses that conforms to a preset rule, thereby executing the aforementioned near-field communication electronic device wake-up method.

[0060] Third Embodiment

[0061] Based on the aforementioned near-field communication device wake-up method, the third embodiment of the present invention further provides a near-field communication card reader, including a digital signal processor, an analog-to-digital converter, and an envelope detector. The analog-to-digital converter captures a superimposed waveform at a preset sampling rate (e.g., 20 MHz SPS, but not limited to this), which is formed by the superposition of a radio frequency probe wave and a pulse wave. The envelope detector extracts the amplitude characteristics of the superimposed waveform, and the digital signal processor calculates the peak-to-peak value of the signal. If the amplitude difference of the superimposed waveform obtained by the card reader through N consecutive samplings satisfies a preset rule, a wake-up interrupt is triggered, thereby executing the aforementioned near-field communication electronic device wake-up method.

[0062] In another exemplary embodiment, the present invention also provides a computer-readable storage medium including program instructions that, when executed by a processor, implement the steps of the near-field communication device wake-up method in any of the above embodiments. For example, the computer-readable storage medium may be the memory including the program instructions described above, which can be executed by the system's processor to complete the near-field communication device wake-up method described above and achieve the same technical effects as the method described above.

[0063] It should be noted that the above embodiments are merely illustrative examples, and the technical solutions of each embodiment can be combined, and the order of each step can be changed, all of which are within the protection scope of this invention.

[0064] Compared with existing technologies, this invention modulates the detection wave by having the analog card actively send pulse waves with a specific amplitude variation pattern, and then uses a card reader to detect the changing trend of the amplitude difference over multiple consecutive cycles. This significantly improves the detection sensitivity and reliability of analog cards, effectively overcoming the problems of low efficiency of small-sized antennas and signal-to-noise ratio degradation caused by equipment circuit noise. Furthermore, this method is well-compatible with 1.5cm antennas. 2 ~2cm 2 Wearable devices with miniature antennas enable further miniaturization of devices without additional hardware. They also effectively suppress environmental noise interference and reduce the probability of false wake-ups through a multi-sampling judgment mechanism. While achieving an efficient and stable card-swiping experience, they maintain the energy-saving operation of the card reader in LPCD mode, demonstrating significant practicality and promotional value.

[0065] The near-field communication electronic device, card reader, and wake-up method provided by this invention have been described in detail above. Any obvious modifications made by those skilled in the art without departing from the essence of this invention will constitute an infringement of the patent rights of this invention and will incur corresponding legal liability.

Claims

1. A method for waking up a near-field communication electronic device, characterized in that... Includes the following steps: S1: The card reader periodically emits a probe wave of fixed amplitude; S2: The analog card modulates the received probe wave using pulse waves of different amplitudes; S3: The analog card transmits the modulated probe wave; S4: The card reader receives the modulated probe wave, detects the amplitude of the current modulated probe wave, and calculates the difference Δ between the current amplitude and the amplitude of the previous modulated probe wave. S5: Repeat steps S2 to S4 until the preset number of times N is reached, then proceed to the next step, where N is a positive integer greater than or equal to 2; S6: Determine whether the N differences satisfy the preset rule. If the amplitude difference between adjacent pulses in the pulse wave is not zero and meets the preset rule, then trigger the wake-up interrupt. Otherwise, return to step S1; S7: The card reader establishes communication with the emulated card.

2. The wake-up method for near-field communication electronic devices as described in claim 1, characterized in that: When the preset rule is increasing, Δ1, Δ2, ..., ΔN are all positive numbers; when the preset rule is decreasing, Δ1, Δ2, ..., ΔN are all negative numbers. Δ1, Δ2, ..., ΔN represent the 1st, 2nd, ..., Nth amplitude differences, respectively.

3. The wake-up method for near-field communication electronic devices as described in claim 1, characterized in that: In step S2, the analog card modulates the probe wave, causing the pulse wave and the probe wave to have an amplitude superposition effect in the electromagnetic field.

4. The wake-up method for near-field communication electronic devices as described in claim 1, characterized in that: The carrier is pulse envelope modulated to form an amplitude variation, wherein the pulse envelope is located within the passband of the baseband filter at the front end of the card reader.

5. The wake-up method for near-field communication electronic devices as described in claim 1, characterized in that: The duration of a single pulse in the pulse wave is less than the sampling time of the card reader.

6. The wake-up method for near-field communication electronic devices as described in claim 1, characterized in that: The simulation card uses a 1.5cm... 2 ~2cm 2 The miniature antenna is used for signal transmission and reception.

7. The wake-up method for near-field communication electronic devices as described in claim 1, characterized in that: In step S6, the reader's analog-to-digital converter captures the superimposed waveform at a preset sampling rate; the amplitude characteristics of the superimposed waveform are extracted by an envelope detector, and the peak-to-peak value of the signal is calculated by a digital signal processor; if the amplitude difference of the superimposed waveform obtained by the reader through N consecutive samplings meets the preset rule, a wake-up interrupt is triggered.

8. A near-field communication electronic device, used as an analog card for near-field communication, characterized in that, Includes miniature antennas, LC resonant circuits, clock modules, and amplitude shift keying modulators; When the coil of the micro antenna is coupled to radio frequency energy, the LC resonant circuit generates an induced voltage. When the induced voltage is greater than or equal to a preset value, the clock module triggers the amplitude shift keying modulator to use the probe wave as a carrier wave and perform amplitude shift keying modulation on the carrier wave with a square wave of a preset frequency to generate a pulse wave with a non-zero amplitude difference between adjacent pulses and conforming to a preset rule, so as to execute the near-field communication electronic device wake-up method according to any one of claims 1 to 7.

9. A near-field communication card reader, characterized in that... This includes digital signal processors, analog-to-digital converters, and envelope detectors; The analog-to-digital converter captures the superimposed waveform at a preset sampling rate. The superimposed waveform is formed by superimposing a radio frequency probe wave and a pulse wave. The amplitude characteristics of the superimposed wave are extracted by the envelope detector, and the peak-to-peak value of the signal is calculated by the digital signal processor. If the amplitude difference of the superimposed waveform obtained by the card reader through N consecutive samplings conforms to a preset rule, a wake-up interrupt is triggered to execute the wake-up method for near-field communication electronic devices according to any one of claims 1 to 7.

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