Multi-antenna NFC adaptive power-adjusting energy-saving card searching system and card searching method thereof

Abstract

The invention discloses a multi-antenna NFC self-adaptive power-adjusting energy-saving card searching system and a card searching method thereof. The system comprises a terminal controller module, an ADC sampling circuit, a unit enable signal control module, a low-power-consumption trigger event module, an RFID tag group and an HF radio frequency integration module. The method comprises the steps of setting a low-power-consumption trigger event; obtaining an ADC sampling value; entering an LPCD mode; detecting an ADC sampling value based on an LPCD mode, exiting the LPCD mode when an interrupt signal is detected, obtaining an event mark and sending a card searching instruction; and searching the card according to the card searching instruction in combination with the low-power-consumption trigger event, re-entering the LPCD mode according to a card searching result, and clearing the event mark. According to the embodiment of the invention, false triggering events of the chip can be reduced, and NFC multi-label processing and low-power-consumption function experience can be improved. The method can be widely applied to the technical field of radio frequency identification processing.

Description

Technical Field

[0001] The present application relates to the technical field of radio frequency identification processing, and particularly relates to a multi-antenna NFC adaptive power adjustment energy-saving card searching system and a card searching method thereof. Background Art

[0002] With the development of radio frequency identification technology, this technology has been widely applied to scenarios such as access cards, consumer applications, access control, transportation, as well as accessory identification, brand protection, parameter setting, etc. At the same time, in order to reduce power consumption and change the situation where the antenna always radiates an electromagnetic field outward when polling to read card information, the related technology adopts LPCD, that is, a low-power external card detection function / ultra-low-power card detection mode. Its principle is to detect through the in-phase (I) and quadrature (Q) components of the received signal, that is, in the read-write mode, the chip can complete the detection of whether there is a non-contact card approaching externally with a low standby power consumption. The overall process only detects whether the field opening time required for the card to exist is much less than the opening time required for card searching, which can reduce the average power consumption of the reader and meet the low-power requirement.

[0003] However, most NFC read-write systems on the market currently are single-antenna radio frequency systems, which can only communicate with one tag at a time. When multiple tags exist within the reading range of the reader simultaneously, the single-antenna radio frequency system can only identify tag devices one by one in sequence, prolonging the overall identification time and reducing the system processing speed; at the same time, in compensating for the problem of inconsistent antenna impedance matching, due to production process errors or component cost control in the production and manufacturing of antennas, there is a situation where the internal impedance and external impedance are inconsistent. After the initial impedance matching of the antenna, there is an issue of inconsistent card reading effects of the antenna. This inconsistency may lead to unstable performance of the antenna in actual applications, affecting system reliability and user experience; moreover, currently, when the reader uses the LPCD mode to sense the card, it is usually difficult to achieve an ideal effect. Although the reader detects and returns the ADC data result in the LPCD mode, further determines the configured trigger threshold, and realizes the interruption trigger when the card approaches and exits the LPCD mode to perform card searching, in this mode, the amplitude of the magnetic field signal is easily affected by external factors. The factors for magnetic field mis-triggering can include but are not limited to the error accuracy of components, the reduction of the power of the lithium battery for power supply, the approach of metal objects, etc. Even when no card approaches, the reader will automatically exit the LPCD mode, making the reader unable to determine whether there is a card around through the actual change amplitude of the magnetic field signal in the true sense, thereby resulting in the reader being unable to obtain the correct card searching result, significantly reducing the success rate of the reader in sensing the card, and weakening the practical significance of using the LPCD technology.

[0004] In summary, the technical problems existing in the related technology need to be improved. Summary of the Invention

[0005] The main purpose of the embodiments of the present application is to propose a multi-antenna NFC adaptive power adjustment and energy-saving card searching system and its card searching method, which can reduce the events of chip mis-triggering and improve the NFC multi-tag processing and low-power function experience.

[0006] To achieve the above object, on the one hand, an embodiment of the present application proposes a multi-antenna NFC adaptive power adjustment and energy-saving card searching system, the system includes a terminal controller module, an ADC sampling circuit, a unit enable signal control module, a low-power trigger event module, an RFID tag group, and an HF radio frequency integration module. The terminal controller module is respectively connected to the ADC sampling circuit, the HF radio frequency integration module, the unit enable signal control module, and the low-power trigger event module. The ADC sampling circuit is also connected to the HF radio frequency integration module. The HF radio frequency integration module is also respectively connected to the unit enable signal control module and the low-power trigger event module. The RFID tag group is radio-electrically connected to the HF radio frequency integration module, where:

[0007] The terminal controller module is used to control the operation of the ADC sampling circuit, the unit enable signal control module, the low-power trigger event module, and the HF radio frequency integration module;

[0008] The ADC sampling circuit is used to sample and obtain the high-frequency antenna end field strength amplitude data of the HF radio frequency integration module;

[0009] The unit enable signal control module is used to generate a unit enable signal;

[0010] The low-power trigger event module is used to set a low-power trigger event;

[0011] The RFID tag group is used to perform data exchange with the HF radio frequency integration module through radio frequency radio waves;

[0012] The HF radio frequency integration module is used to receive the card searching instruction sent by the terminal controller module and convert it into a radio frequency signal for transmission to the RFID tag group, and then obtain the return data information of the RFID tag group and transmit it to the terminal controller module.

[0013] In some embodiments, the terminal controller module includes a terminal controller, an ADC conversion module, a communication interface, a control interface, and an event group module. The terminal controller is respectively connected to the ADC conversion module, the communication interface, the control interface, and the event group module. The ADC conversion module is further connected to the ADC sampling circuit. The communication interface is further connected to the HF radio frequency integration module. The control interface is further connected to the unit enable signal control module. The event group module is further connected to the low power consumption trigger event module, where:

[0014] The terminal controller is used to control the operation of the ADC conversion module, the communication interface, the control interface, and the event group module;

[0015] The ADC conversion module is used to convert the analog signal of the high-frequency antenna terminal field strength amplitude data into a digital signal;

[0016] The communication interface is used to control the communication between the terminal controller and the HF radio frequency integration module;

[0017] The control interface is used to send a unit enable signal to control the enable state of the HF radio frequency integration module;

[0018] The event group module is used to set the low power consumption trigger event module and wait to receive data from the low power consumption trigger event module.

[0019] In some embodiments, the ADC sampling circuit includes a first resistor, a second resistor, and a third resistor. The first end of the first resistor is connected to a high-level signal. The second end of the first resistor is respectively connected to the first end of the second resistor, the first end of the third resistor, and the HF radio frequency integration module. The second end of the second resistor is connected to the terminal controller. The second end of the third resistor is grounded.

[0020] In some embodiments, the HF radio frequency integration module includes several HF radio frequency integration units. The several HF radio frequency integration units include an HF radio frequency chip, an EMC filtering circuit, a matching circuit, a receiving circuit, and a high-frequency antenna. The output end of the HF radio frequency chip is respectively connected to the input end of the EMC filtering circuit, the input end of the matching circuit, and the input end of the receiving circuit. The output ends of the EMC filtering circuit, the matching circuit, and the receiving circuit are all connected to the input end of the high-frequency antenna. The output end of the high-frequency antenna is connected to the input end of the ADC sampling circuit, where:

[0021] The HF radio frequency chip is used to perform radio frequency analog power configuration;

[0022] The EMC filtering circuit is used to filter out the derivative harmonics higher than the preset crystal oscillator frequency;

[0023] The matching circuit is used to adjust the operating frequency and input impedance;

[0024] The receiving circuit is used to receive the tag return signal;

[0025] The high-frequency antenna is used to adjust the Q value and bandwidth of the high-frequency antenna.

[0026] In some embodiments, where:

[0027] The EMC filtering circuit includes a first inductor and a first capacitor. The first end of the first inductor is connected to the TX pin of the HF radio frequency chip. The second end of the first inductor is connected to the first end of the first capacitor. The second end of the first capacitor is connected to the matching circuit;

[0028] The matching circuit includes a second capacitor and a third capacitor. The first end of the second capacitor is connected to the EMC filtering circuit. The second end of the second capacitor is connected to the first end of the third capacitor. The second end of the third capacitor is connected to the high-frequency antenna;

[0029] The receiving circuit includes a fourth capacitor, a fifth capacitor, a fourth resistor and a fifth resistor. The first end of the fourth capacitor is connected to the EMC filtering circuit. The second end of the fourth capacitor is connected to the second end of the fourth resistor. The first end of the fourth resistor and the first end of the fifth resistor are connected to the RX pin of the HF radio frequency chip. The second end of the fifth resistor and the first end of the fifth capacitor are connected to the VM ID pin of the HF radio frequency chip. The second end of the fifth capacitor is grounded.

[0030] To achieve the above object, another aspect of the embodiments of the present application proposes a multi-antenna NFC adaptive power adjustment and energy-saving card searching method, and the method includes the following steps:

[0031] Perform communication interface and control interface configuration, create an event group, and set a low-power trigger event;

[0032] Perform radio frequency analog power configuration on the HF radio frequency chip to obtain ADC sampling values;

[0033] Perform LPCD mode initialization configuration and enter the LPCD mode;

[0034] Based on the LPCD mode, detect the ADC sampling values. If an interrupt signal is detected, exit the LPCD mode, obtain an event flag, and issue a card searching instruction;

[0035] Perform card search according to the card search instruction in combination with the low-power trigger event, re-enter the LPCD mode according to the card search result, and clear the event flag.

[0036] In some embodiments, the radio frequency analog power configuration of the HF radio frequency chip and obtaining the ADC sampling value include:

[0037] Perform radio frequency analog power configuration on the HF radio frequency chip, transmit a carrier signal, and obtain the field strength amplitude data at the high-frequency antenna end;

[0038] Convert the analog signal of the field strength amplitude data at the high-frequency antenna end into a digital signal to obtain the ADC sampling value;

[0039] Set the ADC sampling threshold range and judge the ADC sampling value;

[0040] If the ADC sampling value does not meet the ADC sampling threshold range, re-perform radio frequency analog power configuration on the HF radio frequency chip;

[0041] Until the ADC sampling value meets the ADC sampling threshold range, obtain the ADC sampling value.

[0042] In some embodiments, the LPCD mode initialization configuration includes setting an interrupt threshold and defining mixer parameters for the I channel and the Q channel.

[0043] In some embodiments, based on the LPCD mode, detecting the ADC sampling value, exiting the LPCD mode when an interrupt signal is detected, obtaining the event flag and issuing a card search instruction, includes:

[0044] Based on the LPCD mode and set the threshold range of the antenna magnetic field signal amplitude;

[0045] Detect the ADC sampling value. If the amplitude change of the magnetic field signal on the antenna is lower than the threshold range of the antenna magnetic field signal amplitude, exit the LPCD mode, obtain the event flag and issue the card search instruction.

[0046] In some embodiments, the performing card search according to the card search instruction in combination with the low-power trigger event, re-entering the LPCD mode according to the card search result, and clearing the event flag, includes:

[0047] Perform card search processing according to the card search instruction and set the card search times threshold;

[0048] If the card search times exceed the card search times threshold and no valid card is detected, trigger the low-power trigger event to re-perform the LPCD mode initialization configuration and clear the event flag;

[0049] If a valid card is detected and the card search times meet the card search times threshold, the card search process is completed, the LPCD mode is re-entered, and the event flag is cleared.

[0050] The embodiments of the present application at least include the following beneficial effects: The present application provides a multi-antenna NFC adaptive power adjustment and energy-saving card search system and its card search method. This solution configures the communication interface and control interface, creates an event group, sets low-power trigger events, and adds a limit condition for the card search times. If a valid card is not found after exceeding the preset threshold range, the system will consider this trigger as a false trigger. Further, the RF analog power of the HF RF chip is configured, the ADC sampling value is obtained, and then the LPCD mode initialization configuration is performed to enter the LPCD mode. According to the set normal ADC threshold, the RF analog power configuration is changed to indirectly change the internal resistance of the matching network to make it more adaptable to the external load, so as to achieve a better impedance matching compensation effect. Finally, the card search is performed according to the card search instruction in combination with the low-power trigger event, so that the system can reduce the events of false triggering of the chip and improve the NFC multi-tag processing and low-power function experience. Description of the Drawings

[0051] Figure 1 is a schematic architecture diagram of a multi-antenna NFC adaptive power adjustment and energy-saving card search system provided by an embodiment of the present application;

[0052] Figure 2 is a schematic step flow diagram of a multi-antenna NFC adaptive power adjustment and energy-saving card search method provided by an embodiment of the present application;

[0053] Figure 3 is a schematic architecture diagram of the HF RF integration unit provided by an embodiment of the present application;

[0054] Figure 4 is a schematic architecture diagram of the terminal controller, HF RF chip and peripheral circuit hardware provided by an embodiment of the present application;

[0055] Figure 5 is a schematic diagram of the trigger mode when the LPCD is lower than the detection threshold provided by an embodiment of the present application;

[0056] Figure 6 is a schematic diagram of the adaptive power adjustment and energy-saving card search process provided by an embodiment of the present application. Detailed Embodiments

[0057] In order to make the objectives, technical solutions, and advantages of the present application clearer and more understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the embodiments of the present application. They are only examples of systems and methods that are consistent with some aspects of the embodiments of the present application as detailed in the appended claims.

[0058] It can be understood that the terms "first", "second", etc. used in the present application may be used in this document to describe various concepts, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the words "if", "when" used herein may be interpreted as "when...", "while...", or "in response to determining".

[0059] The terms "at least one", "multiple", "each", "any one", etc. used in the present application, "at least one" includes one, two, or more than two, "multiple" includes two or more than two, "each" refers to each of the corresponding multiple, and "any one" refers to any one of the multiple.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0061] In the related art, there are some deficiencies. Whether it is the defect of a single antenna radio frequency system, the problem of compensating for the inconsistency of antenna impedance matching, or the application challenge of the LPCD low-power mode, these factors have restricted the progress of NFC readers in terms of multi-tag processing ability and energy efficiency improvement.

[0062] In view of this, the embodiments of the present application address the defects of a single-antenna radio frequency system in traditional radio frequency readers and writers, the problem of compensating for inconsistent antenna impedance matching, and the application problem of the LPCD low-power mode. A multi-antenna NFC adaptive power adjustment and energy-saving card search system is provided. Its design aims to change the single-antenna system design to a multi-antenna system design to improve the performance and reliability of the system; adopt an ADC sampling circuit and a software power assist adjustment mechanism to adaptively adjust and compensate for antenna impedance matching to ensure the optimal working state of the antenna under different conditions; at the same time, in the original LPCD mode, use the operating system event group management and synchronization task mechanism to further optimize the card search logic of the reader and writer program and reduce the occurrence of mis-trigger events caused by external factors.

[0063] Referring to Figure 1 , Figure 1 FIG. is a schematic structural diagram of a multi-antenna NFC adaptive power adjustment and energy-saving card search system provided by an embodiment of the present invention. Referring to Figure 1 , the system includes a terminal controller module, an ADC sampling circuit, a unit enable signal control module, a low-power trigger event module, an RFID tag group, and an HF radio frequency integration module. The terminal controller module is respectively connected to the ADC sampling circuit, the HF radio frequency integration module, the unit enable signal control module, and the low-power trigger event module. The ADC sampling circuit is also connected to the HF radio frequency integration module. The HF radio frequency integration module is also respectively connected to the unit enable signal control module and the low-power trigger event module. The RFID tag group is radio-electrically connected to the HF radio frequency integration module, where:

[0064] The terminal controller module is used to control the operation of the ADC sampling circuit, the unit enable signal control module, the low-power trigger event module, and the HF radio frequency integration module;

[0065] Specifically, the terminal controller module includes a terminal controller, an ADC conversion module, a communication interface, a control interface, and an event group module. The terminal controller is respectively connected to the ADC conversion module, the communication interface, the control interface, and the event group module. The ADC conversion module is also connected to the ADC sampling circuit. The communication interface is also connected to the HF radio frequency integration module. The control interface is also connected to the unit enable signal control module. The event group module is also connected to the low-power trigger event module. Among them, the terminal controller is used to control the operation of the ADC conversion module, the communication interface, the control interface, and the event group module; the ADC conversion module is used to convert the analog signal of the high-frequency antenna end field strength amplitude data into a digital signal; the communication interface is used to control the communication between the terminal controller and the HF radio frequency integration module; the control interface is used to send a unit enable signal to control the enable state of the HF radio frequency integration module; the event group module is used to set the low-power trigger event module and wait to receive the data of the low-power trigger event module.

[0066] The ADC sampling circuit is used to sample and obtain the field strength amplitude data of the high-frequency antenna terminal of the HF radio frequency integrated module;

[0067] Specifically, the ADC sampling circuit includes a first resistor, a second resistor, and a third resistor. The first end of the first resistor is connected to a high-level signal, and the second end of the first resistor is respectively connected to the first end of the second resistor, the first end of the third resistor, and the HF radio frequency integrated module. The second end of the second resistor is connected to the terminal controller, and the second end of the third resistor is grounded.

[0068] The unit enable signal control module is used to generate a unit enable signal;

[0069] The low-power trigger event module is used to set a low-power trigger event;

[0070] The RFID tag group is used to exchange data with the HF radio frequency integrated module through radio frequency radio waves;

[0071] The HF radio frequency integrated module is used to receive the card search instruction sent by the terminal controller module, convert it into a radio frequency signal and transmit it to the RFID tag group, and then obtain the return data information of the RFID tag group and transmit it to the terminal controller module.

[0072] Specifically, the HF radio frequency integrated module includes several HF radio frequency integrated units. The several HF radio frequency integrated units include an HF radio frequency chip, an EMC filter circuit, a matching circuit, a receiving circuit, and a high-frequency antenna. The output end of the HF radio frequency chip is respectively connected to the input end of the EMC filter circuit, the input end of the matching circuit, and the input end of the receiving circuit. The output ends of the EMC filter circuit, the matching circuit, and the receiving circuit are all connected to the input end of the high-frequency antenna. The output end of the high-frequency antenna is connected to the input end of the ADC sampling circuit. Among them, the HF radio frequency chip is used to perform radio frequency analog power configuration; the EMC filter circuit is used to filter out the derivative harmonics higher than the preset crystal oscillator frequency; the matching circuit is used to adjust the operating frequency and input impedance; the receiving circuit is used to receive the tag return signal; the high-frequency antenna is used to adjust the Q value and bandwidth of the high-frequency antenna.

[0073] Furthermore, it should be noted that the EMC filter circuit includes a first inductor and a first capacitor. The first end of the first inductor is connected to the TX pin of the HF radio frequency chip, the second end of the first inductor is connected to the first end of the first capacitor, and the second end of the first capacitor is connected to the matching circuit;

[0074] The matching circuit includes a second capacitor and a third capacitor. The first end of the second capacitor is connected to the EMC filter circuit, the second end of the second capacitor is connected to the first end of the third capacitor, and the second end of the third capacitor is connected to the high-frequency antenna;

[0075] The receiving circuit includes a fourth capacitor, a fifth capacitor, a fourth resistor, and a fifth resistor. The first end of the fourth capacitor is connected to the EMC filtering circuit, the second end of the fourth capacitor is connected to the second end of the fourth resistor, the first end of the fourth resistor and the first end of the fifth resistor are connected to the RX pin of the HF RF chip, the second end of the fifth resistor and the first end of the fifth capacitor are connected to the VMID pin of the HF RF chip, and the second end of the fifth capacitor is grounded.

[0076] In this embodiment, as Figure 3 shown in Figure 4 , the HF RF integration unit includes an HF RF chip, an EMC filtering circuit, a matching circuit, a receiving circuit, and a high-frequency antenna. The HF RF chip is used for RF signal transmission, modulation and demodulation, and adjustment processing, etc.; the EMC filtering circuit consists of an inductor L1 and a capacitor C1, and is used to filter out the harmonic derivatives higher than the 13.56 MHz crystal oscillator. The inductor L1 is connected to the TX pin of the HF RF chip; the matching circuit consists of a capacitor C2 and a capacitor C3, and is used to adjust the operating frequency and input impedance. The transmission power of the RF circuit is generally affected by the internal impedance and external impedance of the chip. When the internal impedance and external impedance of the chip are the same, the transmission power is the largest; the amplitude of the received signal of the receiving circuit is determined by the voltage dividing circuit composed of a capacitor C4, a capacitor C5, a resistor R4, and a resistor R5. Among them, the resistor R4 and the resistor R5 play a voltage dividing role, and it is stipulated that the amplitude of the RX pin is between 1.5 V and 3 V, which is convenient for the chip to modulate and demodulate. Among them, the voltage dividing end is connected to the RX pin of the HF RF chip, the other end of the resistor R5 is connected to the VMID pin of the HF RF chip, and at the same time, a capacitor C5 is connected for filtering and grounding; the high-frequency antenna is connected in series with a resistor R6, which is used to adjust the Q value and bandwidth of the antenna. At the same time, one end of the antenna is connected to the ADC sampling circuit. According to the inductive coupling method, the high-frequency antenna is used to transmit the RF signal transmitted by the HF RF chip controlled by the terminal controller, and receive the RF signal reflected by the tag group device.

[0077] The ADC sampling circuit directly samples the ground through a sampling resistor, and is mainly composed of a resistor R1, a resistor R2, and a resistor R3. The input end is connected to the high-frequency antenna end of the HF RF integration unit, and the output end is connected to the ADC conversion module. The AD conversion formula is as follows:

[0078]

[0079] where U DC is the actual input circuit voltage, VCC is the ADC supply voltage, DigVal is the ADC sampling value, ADCR is the ADC sampling accuracy, where the sampling accuracy is related to the ADC bit number, and Gain is the voltage dividing gain.

[0080] Further, it should be noted that the calculation formula for the voltage dividing gain is as follows:

[0081]

[0082] The ADC sampling circuit is connected to the high-frequency antenna terminal of the HF radio frequency integration unit and the ADC conversion module, and is used to transmit the sampled signal of the field strength amplitude of the high-frequency antenna terminal to the ADC conversion module. The ADC conversion module is used to digitally process the analog signal. The terminal controller monitors the working state of the antenna in real time to ensure that its field strength amplitude is within the normal range, so as to adaptively adjust and compensate the antenna impedance matching effect, and further adjust and compensate the antenna field strength with excessive deviation, so as to solve the problem of inconsistent card reading effect of the antenna.

[0083] In summary, the embodiment of the present invention includes a terminal controller, an ADC conversion module, a communication interface, a control interface, an event group, an ADC sampling circuit, unit enable control, a low-power trigger event, an RFID tag group, and N groups of HF radio frequency integration units, where N is a natural number greater than or equal to 2. The terminal controller includes an ADC conversion module, a communication interface, and a control interface, and at the same time adds the mechanism of the event group in the operating system for managing and synchronizing tasks; the ADC conversion module is connected to the ADC sampling circuit and is used to convert the analog signal of the field strength amplitude of the high-frequency antenna terminal into a digital signal; the communication interface is connected to the HF radio frequency integration unit. The communication interface can include but is not limited to UART communication, SPI communication, and I2C communication. The selection of the communication interface is diverse and can be configured according to different application scenarios and performance requirements, so that the terminal controller can efficiently manage the HF radio frequency integration unit and achieve precise control; the control interface is used to control the enable state of the HF radio frequency integration unit by sending a unit enable signal through the terminal controller; the event group is created by the terminal controller system and is used to set the low-power trigger event and wait for receiving the low-power trigger event, so as to realize the control of the terminal controller over a single or multiple groups of HF radio frequency integration units. The terminal controller sends a card search command to the HF radio frequency integration unit through the communication interface, exchanges data with the RFID tag group through radio frequency radio waves, and at the same time transmits the data information returned by the RFID tag group to the terminal controller. The specific data information is monitored by the RFID management host computer or the computer.

[0084] Please refer to Figure 2 , the embodiment of the present application also provides a multi-antenna NFC adaptive power adjustment and energy-saving card search method, which can implement the above multi-antenna NFC adaptive power adjustment and energy-saving card search system. The system includes:

[0085] S100. Configure the communication interface and the control interface, create an event group, and set a low-power trigger event;

[0086] In some specific embodiments, in the specific execution process of the original LPCD mode, the initialization configuration operation is the crucial first step, which ensures that the chip can correctly enter the low-power card detection state according to the preset parameters. This step usually includes setting the interrupt threshold, defining the mixer parameters of the I channel and Q channel, configuring the accuracy and frequency of the pin ADC to collect data, etc. After the initialization is completed, the system enters the LPCD mode. At this time, the power consumption of the chip is reduced to the lowest to achieve the purpose of energy saving. During the process of waiting for the LPCD interrupt, the chip continuously monitors the changes in the surrounding magnetic field. Once an interrupt signal is detected, the system immediately exits the LPCD mode and activates the card search processing program. The card search processing program mainly includes card reset response, anti-collision mechanism, and card selection. The whole process also includes other parts such as waking up the chip to start radio frequency communication and performing encryption and decryption operations. After the card search processing is completed, the system will not immediately re-enter the LPCD mode, but will perform a quick self-check to ensure that all components are in a normal state, and then re-enter the LPCD mode to continue waiting for the next interrupt.

[0087] S200. Perform radio frequency analog power configuration on the HF radio frequency chip to obtain ADC sampling values;

[0088] It should be noted that in some embodiments, step S200 may include: S210. Perform radio frequency analog power configuration on the HF radio frequency chip, transmit a carrier signal, and obtain high-frequency antenna terminal field strength amplitude data; S220. Convert the analog signal of the high-frequency antenna terminal field strength amplitude data into a digital signal to obtain ADC sampling values; S230. Set the ADC sampling threshold range and judge the ADC sampling values; S240. If the ADC sampling values do not meet the ADC sampling threshold range, re-perform radio frequency analog power configuration on the HF radio frequency chip; S250. Until the ADC sampling values meet the ADC sampling threshold range, obtain the ADC sampling values.

[0089] In some specific embodiments, such as Figure 6 shown, the communication interface configuration between the terminal controller and N groups of HF radio frequency integration units. The communication interface may include, but is not limited to, UART communication, SPI communication, and I2C communication; the control interface configuration between the terminal controller and N groups of HF radio frequency integration units is used to control the enable state of the HF radio frequency integration units, create an event group, used to set low-power trigger events and wait for receiving low-power trigger events to achieve the control of the terminal controller over single or multiple groups of HF radio frequency integration units; perform radio frequency analog power configuration on the HF radio frequency chip through the communication interface, transmit a carrier, read the high-frequency antenna terminal field strength amplitude ADC sampling values converted by the ADC conversion module, and change the radio frequency analog power configuration according to the set normal ADC threshold, indirectly change the internal resistance of the matching network to make it more adaptable to the external load, so as to achieve a better impedance matching compensation effect.

[0090] S300. Initialize the LPCD mode configuration and enter the LPCD mode;

[0091] S400. Detect the ADC sampling value based on the LPCD mode. If an interrupt signal is detected, exit the LPCD mode, obtain the event flag, and send a card search command;

[0092] It should be noted that in some embodiments, step S400 may include: S410. Set the amplitude range threshold of the antenna magnetic field signal based on the LPCD mode; S420. Detect the ADC sampling value. If the amplitude change of the magnetic field signal on the antenna is lower than the amplitude range threshold of the antenna magnetic field signal, generate an interrupt signal; S430. According to the interrupt signal, exit the LPCD mode, obtain the event flag, and send a card search command.

[0093] In some specific embodiments, as Figure 5 shown, after initializing the LPCD configuration and entering the LPCD mode, according to the defined amplitude range, the reader periodically sends a specific LPCD pulse. When the reader detects the amplitude change of the magnetic field signal on the antenna and the amplitude is lower than the detection threshold range, the reader defaults that a tag card is approaching. Then, an interrupt is triggered, the LPCD mode is exited, a low-power trigger event is set, the reader enters the normal communication mode with the card, and data interaction is performed to complete the card search process. Although the LPCD mode is to reduce the average power consumption of the reader's continuous polling and meet the low-power requirements, in actual applications, the reader periodically sends a specific LPCD pulse signal, that is, the magnetic field signal amplitude, which is easily affected by external factors. In addition to the reduction of the signal amplitude caused by the approach of the tag card, there are also many magnetic field false trigger factors, which may include but are not limited to the error accuracy of components, the reduction of the power supply lithium battery power, the approach of metal objects, etc. Even if there is no card approaching, the reader will automatically exit the LPCD mode. Therefore, based on the LPCD mode process, in the case of false trigger card search, the software program adds a limit condition for the number of card search times. Specifically, when the chip is falsely triggered by the change of the magnetic field environment and automatically exits the LPCD mode and enters the preparation state, the system obtains a low-power trigger event and starts the card search process. If no valid card is found within a certain number of card searches and exceeds the preset threshold range, the system will consider this trigger as a false trigger. At this time, the chip will update the initialization LPCD configuration, enter the LPCD mode again, and re-obtain the ADC acquisition data to eliminate the false trigger event.

[0094] S500. Perform card search according to the card search command in combination with the low-power trigger event, re-enter the LPCD mode according to the card search result, and clear the event flag;

[0095] It should be noted that in some embodiments, step S500 may include: S510, performing card searching processing according to the card searching instruction and the event flag, and setting the card searching times threshold; S520, if the card searching times exceed the card searching times threshold and the card searching result is that no valid card is detected, triggering a low-power trigger event to re-initialize the LPCD mode, updating the ADC sampling value, re-entering the LPCD mode, and clearing the event flag; S530, if a valid card is detected within the card searching times threshold, completing the card searching processing flow, re-entering the LPCD mode, and clearing the event flag.

[0096] In some specific embodiments, in order to optimize the problem of mis-triggering low-power card searching, on the original basis, the limitation on the card searching times is increased, and this strategy significantly improves the stability and reliability of the system. Specifically, when the system detects an LPCD interruption and exits the LPCD mode to obtain the event group flag, during the card searching operation, if no valid card is detected continuously for multiple times, the system will not continue to search for cards indefinitely, but will trigger the process of updating and initializing the LPCD configuration. During the process of updating and initializing the LPCD configuration, the system will update the ADC value of the magnetic field amplitude again, and this step helps to correct the magnetic field strength deviation caused by environmental changes. After the update is completed, the system enters the LPCD mode again, and at this time the chip can perform more accurate card detection based on the new parameters. If a card is successfully detected within the specified card searching times, the system will continue to perform the card searching processing, and after the processing is completed, clear the event group flag and re-enter the LPCD mode.

[0097] In summary, the present invention has the following advantages compared with the prior art:

[0098] 1) In the multi-antenna solution, N groups of HF RF integrated units are adopted, where N is a natural number greater than or equal to 2. Each HF RF integrated unit has independent working capabilities, which enables the system to perform efficient task allocation according to actual needs. The terminal controller, as the core management unit, establishes a stable connection with the HF RF integrated units through the communication interface, ensuring the reliability and real-time nature of data transmission. The choice of communication interface is diverse and can be configured according to different application scenarios and performance requirements. UART communication is applied in many occasions due to its simple interface and relatively fast transmission speed; SPI communication is suitable for complex data exchanges with its full-duplex communication mode and high throughput; I2C communication is applicable to communication between multiple devices because it supports the multi-master multi-slave mode. The design of these communication interfaces enables the terminal controller to efficiently manage the HF RF integrated units and achieve precise control. Meanwhile, the introduction of the control interface further enhances the system's management capabilities. The terminal controller can precisely control the working state of each group of HF RF integrated units by sending the unit enable signal. This control method not only allows the system to communicate independently with a single tag but also enables collective communication with a group of tags, greatly improving the system's parallel processing capabilities. In addition, this control mechanism of the enable signal can also dynamically adjust the working combination of the antennas according to actual application requirements to optimize the signal coverage and communication efficiency. For example, in a busy retail environment, multiple groups of HF RF integrated units can be enabled simultaneously to achieve simultaneous reading of multiple tags and improve the checkout efficiency; while in a low-traffic scenario, a single group of HF RF integrated units can be enabled individually to save energy and reduce interference.

[0099] 2) In antenna impedance matching compensation, generally, for antennas designed with specific dimensions and after the initial antenna impedance matching, an ADC sampling circuit and a software power-assisted adjustment mechanism are used to adaptively adjust and compensate the antenna impedance matching. Further, the antenna field strength with excessive deviation in effect is adjusted and compensated, solving the problem of inconsistent antenna card reading effects. The ADC sampling circuit collects the field strength amplitude at the antenna end. This process involves converting the 13.56 MHz sine wave signal into a small voltage signal and transmitting the collected analog signal to the ADC conversion module in the terminal controller for digital processing. In this way, the working state of the antenna can be monitored in real time to ensure that its field strength amplitude is within the normal range. During the data acquisition process, if it is found that the value after ADC sampling deviates from the normal range, the deviation may be due to errors in antenna production processes or component cost control (for example, using components with a 5% tolerance), resulting in inconsistent internal and external impedances and affecting the consistency of antenna card reading effects. At this time, the software power-assisted adjustment mechanism is used to appropriately debug the power of the HF radio frequency chip, indirectly changing the internal resistance of the matching network to make it more suitable for the external load, thereby achieving a better impedance matching compensation effect. Such adaptive adjustment not only stabilizes the working efficiency of the antenna but also ensures that the antenna field strength amplitude can be stabilized within a normal value range.

[0100] 3) In the LPCD mode, the HF RF chip sends a short RF pulse and measures the received signal at the RX pin. The received signal is split into the I channel and the Q channel by the mixer. Meanwhile, the field strength within the current field is detected and data is automatically collected by the ADC and recorded into the chip. If the I or Q value reaches a pre-configured threshold, that is, when the changing field strength within the field is lower or higher than the set threshold range, due to the antenna detuning, the chip will be automatically awakened to the ready state, and at the same time, an IRQ interrupt is triggered to notify the MCU. However, in this mode, it is prone to being accidentally triggered to automatically exit and enter the ready state due to changes in the magnetic field environment, and perform the card search process. The magnetic field accidental trigger environment can include, but is not limited to, component error accuracy, reduced battery power of the power supply lithium battery, and the approach of metal objects. The ways to reduce accidental triggers are as follows: First, improve the accuracy of internal components of the chip to reduce errors; second, optimize the power management module to ensure that the lithium battery can still maintain a stable output voltage when the battery power is reduced; third, add a metal object detection function. When a metal object is detected approaching, automatically adjust the working parameters of the chip, that is, the working parameters of the LPCD mode, to reduce the probability of accidental triggers. The present invention also aims at the working parameters of the chip. Based on the LPCD mode process, in the case of accidental card search triggers, a limit condition for the number of card search attempts is added. Specifically, when the chip is accidentally triggered to automatically exit the LPCD mode and enter the ready state due to changes in the magnetic field environment, the system will start the card search process. If no valid card is found within a certain number of card search attempts and exceeds the preset threshold range, the system will consider this trigger as an accidental trigger. At this time, the chip will update the initialization LPCD configuration, enter the LPCD mode again, and re-acquire the ADC collected data to eliminate the accidental trigger event.

[0101] It can be understood that the content in the above method embodiments is applicable to the present system embodiment. The functions specifically implemented by the present system embodiment are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those of the above method embodiments.

[0102] The preferred embodiments of the present application embodiment have been described above with reference to the accompanying drawings, and thus do not limit the scope of rights of the present application embodiment. Any modifications, equivalent replacements, and improvements made by those skilled in the art without departing from the scope and essence of the present application embodiment shall be within the scope of rights of the present application embodiment.

Claims

1. A multi-antenna NFC adaptive power adjustment and energy-saving card searching system, characterized in that The system includes a terminal controller module, an ADC sampling circuit, a unit enable signal control module, a low-power trigger event module, an RFID tag group, and an HF radio frequency integration module. The terminal controller module is respectively connected to the ADC sampling circuit, the HF radio frequency integration module, the unit enable signal control module, and the low-power trigger event module. The ADC sampling circuit is also connected to the HF radio frequency integration module. The HF radio frequency integration module is also respectively connected to the unit enable signal control module and the low-power trigger event module. The RFID tag group is radio-connected to the HF radio frequency integration module. Among them: The terminal controller module is used to control the operation of the ADC sampling circuit, the unit enable signal control module, the low-power trigger event module, and the HF radio frequency integration module; The ADC sampling circuit is used to sample and obtain the high-frequency antenna terminal field strength amplitude data of the HF radio frequency integration module; The unit enable signal control module is used to generate a unit enable signal; The low-power trigger event module is used to set a low-power trigger event; The RFID tag group is used to exchange data with the HF radio frequency integration module through radio frequency radio waves; The HF radio frequency integration module is used to receive the card search instruction sent by the terminal controller module, convert it into a radio frequency signal and transmit it to the RFID tag group, and then obtain the return data information of the RFID tag group and transmit it to the terminal controller module.

2. The system according to claim 1, characterized in that, The terminal controller module includes a terminal controller, an ADC conversion module, a communication interface, a control interface, and an event group module. The terminal controller is respectively connected to the ADC conversion module, the communication interface, the control interface, and the event group module. The ADC conversion module is also connected to the ADC sampling circuit. The communication interface is also connected to the HF radio frequency integration module. The control interface is also connected to the unit enable signal control module. The event group module is also connected to the low-power trigger event module. Among them: The terminal controller is used to control the operation of the ADC conversion module, the communication interface, the control interface, and the event group module; The ADC conversion module is used to convert the analog signal of the high-frequency antenna terminal field strength amplitude data into a digital signal; The communication interface is used to control the communication between the terminal controller and the HF radio frequency integration module; The control interface is used to send a unit enable signal to control the enable state of the HF radio frequency integration module; The event group module is used to set the low-power trigger event module and wait to receive the data of the low-power trigger event module.

3. The system according to claim 1, characterized in that, The ADC sampling circuit includes a first resistor, a second resistor, and a third resistor. The first end of the first resistor is connected to a high-level signal. The second end of the first resistor is respectively connected to the first end of the second resistor, the first end of the third resistor, and the HF radio frequency integration module. The second end of the second resistor is connected to the terminal controller. The second end of the third resistor is grounded.

4. The system according to claim 1, wherein The HF radio frequency integrated module includes several HF radio frequency integrated units. The several HF radio frequency integrated units include an HF radio frequency chip, an EMC filtering circuit, a matching circuit, a receiving circuit, and a high-frequency antenna. The output end of the HF radio frequency chip is respectively connected to the input end of the EMC filtering circuit, the input end of the matching circuit, and the input end of the receiving circuit. The output ends of the EMC filtering circuit, the matching circuit, and the receiving circuit are all connected to the input end of the high-frequency antenna. The output end of the high-frequency antenna is connected to the input end of the ADC sampling circuit, where: The HF radio frequency chip is used for radio frequency analog power configuration; The EMC filtering circuit is used to filter out the derivative harmonics higher than the preset crystal oscillator frequency; The matching circuit is used to adjust the operating frequency and input impedance; The receiving circuit is used to receive the tag return signal; The high-frequency antenna is used to adjust the Q value and bandwidth of the high-frequency antenna.

5. The system according to claim 4, wherein Where: The EMC filtering circuit includes a first inductor and a first capacitor. The first end of the first inductor is connected to the TX pin of the HF radio frequency chip. The second end of the first inductor is connected to the first end of the first capacitor. The second end of the first capacitor is connected to the matching circuit; The matching circuit includes a second capacitor and a third capacitor. The first end of the second capacitor is connected to the EMC filtering circuit. The second end of the second capacitor is connected to the first end of the third capacitor. The second end of the third capacitor is connected to the high-frequency antenna; The receiving circuit includes a fourth capacitor, a fifth capacitor, a fourth resistor, and a fifth resistor. The first end of the fourth capacitor is connected to the EMC filtering circuit. The second end of the fourth capacitor is connected to the second end of the fourth resistor. The first end of the fourth resistor and the first end of the fifth resistor are connected to the RX pin of the HF radio frequency chip. The second end of the fifth resistor and the first end of the fifth capacitor are connected to the VMID pin of the HF radio frequency chip. The second end of the fifth capacitor is grounded.

6. A multi-antenna NFC self-adaptive power adjustment and energy-saving card searching method, characterized in that, The method includes the following steps: Configure the communication interface and control interface, create an event group, and set the low-power trigger event; Perform radio frequency analog power configuration on the HF radio frequency chip and obtain the ADC sampling value; Perform LPCD mode initialization configuration and enter the LPCD mode; Based on the LPCD mode, detect the ADC sampling value. If an interrupt signal is detected, exit the LPCD mode, obtain the event flag, and send a card search command; Perform card search according to the card search command and in combination with the low-power trigger event. Re-enter the LPCD mode according to the card search result and clear the event flag.

7. The method according to claim 6, wherein The performing radio frequency analog power configuration on the HF radio frequency chip and obtaining the ADC sampling value includes: Perform radio frequency analog power configuration on the HF radio frequency chip, transmit a carrier signal, and obtain the high-frequency antenna end field strength amplitude data; Convert the analog signal of the high-frequency antenna end field strength amplitude data into a digital signal to obtain the ADC sampling value; Set the ADC sampling threshold range and judge the ADC sampling value; If the ADC sampling value does not meet the ADC sampling threshold range, reconfigure the RF analog power of the HF RF chip; Until the ADC sampling value meets the ADC sampling threshold range, obtain the ADC sampling value.

8. The method according to claim 6, wherein The LPCD mode initialization configuration includes setting the interrupt threshold and defining the mixer parameters of the I channel and Q channel.

9. The method according to claim 6, characterized in that, Based on the LPCD mode, detect the ADC sampling value. When an interrupt signal is detected, exit the LPCD mode, obtain the event flag and issue a card search command, including: Based on the LPCD mode and set the threshold range of the antenna magnetic field signal amplitude; Detect the ADC sampling value. If the detected amplitude change of the magnetic field signal on the antenna is lower than the threshold range of the antenna magnetic field signal amplitude, exit the LPCD mode, obtain the event flag and issue the card search command.

10. The method according to claim 6, characterized in that Perform card search according to the card search command in combination with the low-power trigger event, re-enter the LPCD mode according to the card search result, and clear the event flag, including: Perform card search processing according to the card search command and set the card search times threshold; If the number of card searches exceeds the card search times threshold and no valid card is detected, trigger the low-power trigger event to re-initialize the LPCD mode configuration and clear the event flag; If a valid card is detected and the number of card searches meets the card search times threshold, complete the card search processing flow, re-enter the LPCD mode, and clear the event flag.

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