Radio frequency card type identification method

Abstract

According to the radio frequency card type identification method, a radio frequency card type identification circuit comprising an ID card discrimination voltage generation unit, an IC card discrimination voltage generation unit and a microcontroller unit is adopted, and coding signals replied by a near-field low-frequency card and a near-field high-frequency card do not need to be decoded. And the types of the ID and IC radio frequency cards can be distinguished only by directly judging the coupling voltage signal of the near-field low-frequency card or the near-field high-frequency card.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless radio frequency identification, and in particular relates to a radio frequency card type identification method. Background Art

[0002] Contactless passive radio frequency cards are widely used, and the main types are low-frequency cards working at 125kHz and high-frequency cards working at 13.56MHz. Low-frequency cards and high-frequency cards have their own dedicated readers. The card reader module in the dedicated reader is usually composed of a dedicated card reader chip as the core. First, the cost is high, and second, low-frequency cards and high-frequency cards need to be read and identified on the corresponding dedicated readers. In some occasions where there is no need to read the chip content, only the low-frequency card and high-frequency card types need to be distinguished, or only the card needs to be judged whether it can be powered normally, etc., it is inconvenient and inefficient to use a dedicated reader. Summary of the invention

[0003] The purpose of the present invention is to provide a radio frequency card type identification method in view of the defects of the existing technology, using a radio frequency card type identification circuit including an ID card identification voltage generating unit, an IC card identification voltage generating unit and a microcontroller unit, without decoding the coded signals replied by the near-field low-frequency card and the near-field high-frequency card, and only needing to directly judge the coupling voltage signal of the near-field low-frequency card or the near-field high-frequency card to realize radio frequency card type identification.

[0004] The control steps of the microcontroller unit are as follows:

[0005] Step 1, send out a low-frequency cycle signal, after W1ms, start to continuously sample the ID card identification voltage and save it as an ID card identification sequence, the number of continuously sampled data is N1, and the period of continuous sampling is T1; after the continuous sampling is completed, stop sending out the low-frequency cycle signal;

[0006] Step 2, perform N1-2 data comparisons on the ID card identification sequence in sequence; in each data comparison, if the difference between the previous adjacent data of the ID card is greater than the threshold ε1, or the difference between the previous adjacent data of the ID card is greater than the threshold ε1, the ID card difference is valid, otherwise the ID card difference is invalid; the number of valid ID card differences in N1-2 data comparisons is counted as E1;

[0007] Step 3: If the valid number of ID card difference values ​​E1 is greater than the threshold value M1, it is determined that there is an ID card in the near field, otherwise it is determined that there is no ID card in the near field; or, repeat steps 1 to 2, and if the average value of the valid number of ID card difference values ​​E1 repeated multiple times is greater than the threshold value M1, it is determined that there is an ID card, otherwise it is determined that there is no ID card;

[0008] Step 4, control the state control signal to be effective, lasting for W2ms;

[0009] Step 5, the control state control signal sends out a WUPA control command, and then the control state control signal is valid; after the WUPA control command is sent out, the IC card identification voltage is continuously sampled and saved as an IC card identification sequence, the number of continuously sampled data is N2, and the period of continuous sampling is T2; after the continuous sampling is completed, the control state control signal is invalid;

[0010] Step 6, starting from the N3th data position of the IC card identification sequence, the IC card identification sequence is compared N2-N3-2 times in sequence; in each data comparison, if the difference of the adjacent data after the IC card is greater than the threshold ε2, or the difference of the second adjacent data after the IC card is greater than the threshold ε2, or the difference of the third adjacent data after the IC card is greater than the threshold ε2, then the IC card difference is valid, otherwise the IC card difference is invalid; the number of times the IC card difference is valid in the N2-N3-2 data comparisons is counted as E2;

[0011] Step 7, if the effective number of IC card difference values ​​E2 is greater than the threshold value M2, it is judged that there is an IC card in the near field, otherwise it is judged that there is no IC card in the near field; or, repeat steps 4 to 6, and if the average value of the effective number of IC card difference values ​​E2 repeated multiple times is greater than the threshold value M2, it is judged that there is an IC card, otherwise it is judged that there is no IC card.

[0012] In step 2, the difference of adjacent data before the ID card refers to the difference of the current position data in the ID card identification sequence minus the adjacent position data before the current position, and the difference of adjacent data before the ID card refers to the difference of the current position data in the ID card identification sequence minus the second adjacent position data before the current position; in step 6, the difference of adjacent data after the IC card refers to the difference of the current position data in the IC card identification sequence minus the adjacent position data after the current position, the difference of the second adjacent data after the IC card refers to the difference of the current position data in the IC card identification sequence minus the second adjacent position data after the current position, and the difference of adjacent data again after the IC card refers to the difference of the current position data in the IC card identification sequence minus the third adjacent position data after the current position.

[0013] The method for determining the value range of the threshold ε1 is as follows: when there is no ID card in the near field, execute step 1; perform N1-2 data comparisons on the ID card identification sequence in sequence to obtain N1-2 ID card previous adjacent data differences and N1-2 ID card previous adjacent data differences; find M1 maximum values ​​among the N1-2 ID card previous adjacent data differences and the N1-2 ID card previous adjacent data differences, and calculate the average value of the M1 maximum values ​​as A1min; when there is an ID card in the near field, execute step 1; perform N1-2 data comparisons on the ID card identification sequence in sequence to obtain N1-2 ID card previous adjacent data differences and N1-2 ID card previous adjacent data differences; find M1 maximum values ​​among the N1-2 ID card previous adjacent data differences and the N1-2 ID card previous adjacent data differences, and calculate the average value of the M1 maximum values ​​as A1max; the threshold ε1 is greater than A1min and less than A1max, and a typical value is the median value between A1min and A1max. Furthermore, A1min takes the maximum value obtained from multiple tests, and A1max takes the minimum value obtained from multiple tests.

[0014] The method for determining the value range of the threshold ε2 is that, when there is no IC card in the near field, execute steps 4 and 5 to find the maximum value of the data after the N3th data in the IC card identification sequence, which is B1min; when there is an IC card in the near field, execute steps 4 and 5 to find the maximum value of the data after the N3th data in the IC card identification sequence, which is B1max; the threshold ε2 is greater than B1min and less than B1max, and the typical value is the median between B1min and B1max; or, the threshold ε2 is greater than or equal to 2B1min (2 times B1min). Further, B1min takes the maximum value obtained by multiple tests, and B1max takes the minimum value obtained by multiple tests.

[0015] The value range of N1 is 120 to 220; the value range of T1 is 50μs to 120μs; the value range of W1 is 1ms to 3ms; the value range of threshold M1 is 4 to 12; the value range of N2 is 120 to 220, the value range of N3 is 10 to 20; the value range of T2 is 2μs to 5μs; the value range of W2 is 15ms to 50ms; the value range of threshold M2 is 2 to 10.

[0016] The ID card identification voltage generating unit includes an inductor L11, an NPN transistor V11, a PNP transistor V12, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C14 and a diode D11; the bases of the NPN transistor V11 and the PNP transistor V12 are both connected to one end of the resistor R11, and the other end of the resistor R11 is a low-frequency cycle signal input end; the emitters of the NPN transistor V11 and the PNP transistor V12 are both connected to one end of the inductor L11, and the other end of the inductor L11 is connected to one end of the capacitor C11, and the other end of the inductor L11 is also connected to one end of the resistor R12; the collector of the NPN transistor V11 is connected to The first power supply, the collector of the PNP transistor V12 is connected to the common ground, and the other end of the capacitor C11 is connected to the common ground; the anode of the diode D11 is connected to the other end of R12, and the cathode of the diode D11 is respectively connected to one end of the capacitor C12, the capacitor C13 and the resistor R13; the other ends of the capacitor C13 and the resistor R13 are both connected to the common ground, and the other end of the capacitor C12 is the ID card discrimination signal voltage output end; one end of the resistor R14 and the capacitor C14 are connected to the ID card discrimination signal voltage output end, and the other ends of the resistor R14 and the capacitor C14 are both connected to the common ground; the ID card discrimination voltage generating unit also includes an ID card discrimination signal voltage in-phase amplifier circuit that amplifies the ID card discrimination signal voltage to obtain the ID card discrimination voltage.

[0017] The IC card identification voltage generating unit includes a control gate U21, an inductor coil L21, an NPN transistor V21, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R27, a capacitor C21, a capacitor C22, a capacitor C23, a capacitor C24, a capacitor C25, a capacitor C26, a capacitor C27, a capacitor C28 and a diode D21, a diode D22; the two input terminals of the control gate U21 are respectively a high frequency frequency signal input terminal and a The state control signal input terminal and the output terminal of U21 are connected to one end of the inductor L21, and the other end of the inductor L21 is connected to one end of the capacitor C21 and one end of the capacitor C22 respectively; the other end of the capacitor C22 is connected to the cathode of the diode D21, and the two ends of the capacitor C23 are connected to the cathode of the diode D21 and the common ground respectively; the anode of the diode D21 is connected to one end of the capacitor C25, and the two ends of the resistor R22 and the capacitor C24 are connected to the anode of the diode D21 and the common ground respectively. ; The two ends of the resistor R21 are connected to the anode of the diode D21 and the first power supply respectively; the other end of the capacitor C25 is connected to the base of the NPN transistor V21, the two ends of the resistor R23 are connected to the base of the NPN transistor V21 and the first power supply respectively, and the two ends of the resistor R23 are connected to the base of the NPN transistor V21 and the common ground respectively; the two ends of the resistor R26 and the capacitor C26 are connected to the emitter of the NPN transistor V21 and the common ground respectively, and the two ends of the resistor R25 are connected to The collector of the NPN transistor V21 and the first power supply; the two ends of the capacitor C27 are respectively connected to the collector of the NPN transistor V21 and the anode of the diode D22, the cathode of the diode D22 is the IC card identification signal voltage output terminal, the two ends of the resistor R27 and the capacitor C28 are respectively connected to the cathode of the diode D22 and the common ground; the IC card identification voltage generating unit also includes an IC card identification signal voltage in-phase amplifier circuit for amplifying the IC card identification signal voltage to obtain the IC card identification voltage.

[0018] The microcontroller unit includes a microcontroller, a reset circuit, a crystal oscillator circuit and a first power supply, forming a microcontroller minimum system; the first ADC analog voltage input terminal and the second ADC analog voltage input terminal of the microcontroller respectively input the ID card discrimination voltage and the IC card discrimination voltage, the first PWM signal output terminal outputs a low-frequency cycle signal, the clock output terminal outputs a high-frequency cycle signal, and the first I / O output terminal outputs a state control signal.

[0019] The radio frequency card includes an ID card and an IC card; the ID card is a 125kHz low frequency card; the IC card is a 13.56MHz radio frequency card and is a Type A IC card that complies with the ISO14443A protocol standard.

[0020] The beneficial effects of the present invention are as follows: the types of low-frequency cards and high-frequency cards are distinguished by using the same device (i.e. the same complete circuit), and the contents of the low-frequency cards and high-frequency cards do not need to be read during the distinction; the distinction circuit does not use a special decoding chip, and does not decode the coded content by a microcontroller after demodulating the coded signal, that is, there is no need to decode the coded signals replied by the low-frequency card and the high-frequency card, and only the voltage signal returned by the low-frequency card or the high-frequency card needs to be directly judged, so as to realize the judgment of whether there is a low-frequency card (that can be powered normally) in the near field, and whether there is a high-frequency card (that can be powered normally) in the near field, and realize the distinction of the types of low-frequency cards and high-frequency cards, which is simple, easy and low-cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 An embodiment of a voltage generating unit for distinguishing an ID card;

[0022] Figure 2 An embodiment of an IC card discrimination voltage generating unit;

[0023] Figure 3 is a microcontroller unit embodiment;

[0024] Figure 4 This is a flow chart of the RFID card type identification process;

[0025] Figure 5 This is an example diagram of the sampling data of the ID card identification sequence when there is no ID card in the near field;

[0026] Figure 6 This is an example of the sampling data of the ID card identification sequence when there is an EM4305 ID card in the near field;

[0027] Figure 7 This is an example diagram of the sampling data of the ID card identification sequence when there is a T5557 ID card in the near field;

[0028] Figure 8 This is an example diagram of sampling data of IC card identification sequence when there is no IC card in the near field;

[0029] Fig. 9 This is an example diagram of sampling data of IC card identification sequence when there is an S70 IC card in the near field;

[0030] Fig.10 This is an example diagram of IC card identification sequence sampling data when there is an S50 IC card in the near field. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings. The radio frequency card described in the present invention is a contactless passive radio frequency card, that is, a radio frequency tag (electronic tag), including an ID card and an IC card. Further, the ID card is a 125kHz low-frequency card, for example, a low-frequency card using chips such as EM4100, EM4305, T5577, etc.; the IC card is a 13.56MHz radio frequency card, and is a Type A IC card that complies with the ISO14443A protocol standard.

[0032] Figure 1 The present invention is an embodiment of an ID card identification voltage generating unit, comprising an inductor L11, an NPN transistor V11, a PNP transistor V12, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C14 and a diode D11. The bases of the NPN transistor V11 and the PNP transistor V12 are both connected to one end of the resistor R11, and the other end of the resistor R11 is a low-frequency cycle signal input terminal CLK1; the emitters of the NPN transistor V11 and the PNP transistor V12 are both connected to one end of the inductor L11, and the other end of the inductor L11 is connected to one end of the capacitor C11, and the other end of the inductor L11 is also connected to one end of the resistor R12; the collector of the NPN transistor V11 is connected to the first power supply +VDD1, and the collector of the PNP transistor V12 is connected to the common ground G. ND, the other end of capacitor C11 is connected to the common ground GND; the anode of diode D11 is connected to the other end of R12, and the cathode of diode D11 is connected to one end of capacitor C12, capacitor C13 and resistor R13 respectively; the other ends of capacitor C13 and resistor R13 are both connected to the common ground GND, and the other end of capacitor C12 is the ID card identification signal voltage output terminal VO11; one end of resistor R14 and capacitor C14 are connected to the ID card identification signal voltage output terminal VO11, and the other ends of resistor R14 and capacitor C14 are both connected to the common ground GND.

[0033] Figure 1In the embodiment, the NPN transistor V11 and the PNP transistor V12 are 2SC9013 and 2SC 9012 respectively, and may also be 2SC 8050 and 2SC 8550 respectively, or may be 2SC 9014 and 2SC 9015 respectively; the resistance values ​​of the resistor R11, the resistor R12, the resistor R13 and the resistor R14 are 200Ω, 200Ω, 330kΩ and 510kΩ respectively; the capacitances of the capacitor C11, the capacitor C12, the capacitor C13 and the capacitor C14 are 4700pF, 1000pF, 1000pF and 4700pF respectively, the diode D11 is 1N4148, and the inductance of the inductor L11 is 345μH. The resonant frequency of L11 and C11 is 125kHz; since the operating frequency range of the ID radio frequency card is 100kHz to 150kHz, the low-frequency cycle signal CLK1 is generated by the microcontroller using pulse width modulation, and deviations are allowed, that is, it is not necessarily exactly 125kHz. Therefore, the inductor L11 is wound by itself, and its inductance, including the capacitance of the capacitor C11, should be adjusted according to the actual frequency of the low-frequency cycle signal CLK1 to make the resonant frequency as consistent as possible with the actual frequency of the low-frequency cycle signal CLK1. Figure 1 In the circuit, except L11 and C11, the parameters of other circuit components can be adjusted and changed within a certain range.

[0034] Figure 1 In an embodiment of the ID card discrimination voltage generating unit, it also includes an ID card discrimination signal voltage in-phase amplifier circuit for amplifying the ID card discrimination signal voltage VO11 to obtain the ID card discrimination voltage VO12; the ID card discrimination signal voltage in-phase amplifier circuit is composed of a resistor R15, a resistor R16 and an operational amplifier U11; the reference resistance values ​​of the resistor R15 and the resistor R16 are 2kΩ and 300kΩ respectively, and the operational amplifier U11 selects a single-power supply rail-to-rail operational amplifier, for example, a single operational amplifier LMV321, SGM8521, or a single-power supply dual operational amplifier LMV358, SGM8522, or other single-power supply rail-to-rail operational amplifiers.

[0035] Figure 2 This is an embodiment of an IC card identification voltage generating unit, including a control gate U21, an inductor L21, an NPN transistor V21, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R27, a capacitor C21, a capacitor C22, a capacitor C23, a capacitor C24, a capacitor C25, a capacitor C26, a capacitor C27, a capacitor C28 and a diode D21 and a diode D22. Figure 2In the embodiment, the two input terminals of the control gate U21 are respectively the high-frequency frequency signal input terminal CLK2 and the state control signal input terminal TK2, the output terminal of U21 is connected to one end of the inductor L21, and the other end of the inductor L21 is respectively connected to one end of the capacitor C21 and one end of the capacitor C22; the other end of the capacitor C22 is connected to the cathode of the diode D21, and the two ends of the capacitor C23 are respectively connected to the cathode of the diode D21 and the common ground GND; the anode of the diode D21 is connected to one end of the capacitor C25, and the two ends of the resistor R22 and the capacitor C24 are respectively connected to the anode of the diode D21 and the common ground GND; the two ends of the resistor R21 are respectively connected to the anode of the diode D21 and the first power supply +VDD1; the other end of the capacitor C25 is connected to the NP The base of the N transistor V21, the two ends of the resistor R23 are respectively connected to the base of the NPN transistor V21 and the first power supply +VDD1, and the two ends of the resistor R23 are respectively connected to the base of the NPN transistor V21 and the common ground GND; the two ends of the resistor R26 and the capacitor C26 are respectively connected to the emitter of the NPN transistor V21 and the common ground GND, and the two ends of the resistor R25 are respectively connected to the collector of the NPN transistor V21 and the first power supply +VDD1; the two ends of the capacitor C27 are respectively connected to the collector of the NPN transistor V21 and the anode of the diode D22, the cathode of the diode D22 is the IC card identification signal voltage output terminal VO21, and the two ends of the resistor R27 and the capacitor C28 are respectively connected to the cathode of the diode D22 and the common ground GND.

[0036] Figure 2 In the embodiment, the NPN transistor V21 is 2SC9013, and 2SC 8050, 2SC 9014, etc. can also be selected; the resistance values ​​of the resistor R21, the resistor R22, the resistor R23, the resistor R24, the resistor R25, the resistor R26, and the resistor R27 are 22kΩ, 22kΩ, 100kΩ, 47kΩ, 7.5kΩ, 1kΩ, and 5.1kΩ respectively; the capacitances of the capacitor C21, the capacitor C22, the capacitor C23, the capacitor C24, the capacitor C25, the capacitor C26, the capacitor C27, and the capacitor C28 are 100pF, 150pF, 150pF, 100pF, 100pF, 10000pF, 100pF, and 100pF respectively; the diode D21 and the diode D22 are both 1N4148, and the inductance of the inductor L21 is 1μH. The high frequency signal CLK2 is generated by a 13.56MHz crystal oscillator; the inductor L21 is self-wound, and its inductance, including the capacitance of the capacitor C21, should be adjusted to make the resonant frequency as consistent as possible with the frequency of the high frequency signal CLK2. Figure 2 In the circuit, except L21 and C21, the parameters of other circuit components can be adjusted and changed within a certain range.

[0037] Figure 2In an embodiment of the IC card identification voltage generating unit, it also includes an IC card identification signal voltage in-phase amplifier circuit for amplifying the IC card identification signal voltage VO21 to obtain the IC card identification voltage VO22; the IC card identification signal voltage in-phase amplifier circuit is composed of a resistor R28, a resistor R29 and an operational amplifier U22; the reference resistance values ​​of the resistor R28 and the resistor R29 are 51kΩ and 300kΩ respectively, and the operational amplifier U22 selects a single-power supply rail-to-rail operational amplifier, for example, a single operational amplifier LMV321, SGM8521 is selected, or a single-power supply dual operational amplifier LMV358, SGM8522 is selected together with the operational amplifier U11, or other single-power supply rail-to-rail operational amplifiers are selected.

[0038] Figure 2 In the embodiment, the control gate U21 is a 2-input AND gate 74HC08, and four 2-input AND gates on the same chip 74HC08 are connected in parallel for use to improve the driving capability; the control gate U21 can also select other 2-input AND gates, or other 2-input NAND gates, such as selecting a 2-input AND gate CD4081, or selecting a 2-input NAND gate 74HC00, CD4011, etc. Similarly, multiple 2-input AND gates on the same chip are connected in parallel for use, or multiple 2-input NAND gates on the same chip are connected in parallel for use to improve the driving capability; when the control gate U21 is a 2-input AND gate or a 2-input NAND gate, the state control signal TK2 is valid when it is at a high level, and the high-frequency frequency signal CLK2 can be applied to the inductor L21 through the control gate U21; the state control signal TK2 is invalid when it is at a low level, and the high-frequency frequency signal CLK2 cannot be applied to the inductor L21 through the control gate U21. The control gate U21 can also select a 2-input OR gate, or a 2-input NOR gate, for example, select a 2-input OR gate 74HC32, CD4071, or a 2-input NOR gate 74HC02, CD4001, etc.; similarly, multiple 2-input OR gates on the same chip are connected in parallel for use, or multiple 2-input NOR gates on the same chip are connected in parallel for use to improve the driving capability; when the control gate U21 is a 2-input OR gate or a 2-input NOR gate, the state control signal TK2 is valid when it is at a low level, and the high-frequency frequency signal CLK2 can be applied to the inductor L21 through the control gate U21; the state control signal TK2 is invalid when it is at a high level, and the high-frequency frequency signal CLK2 cannot be applied to the inductor L21 through the control gate U21.

[0039] Figure 3This is a microcontroller unit embodiment, wherein the microcontroller MCU3, the reset circuit, the crystal oscillator circuit and the first power supply constitute the microcontroller minimum system, the model of the microcontroller MCU3 is STM32F103C8T6, the resistor R30 and the capacitor C30 constitute the reset circuit, the crystal XT31, the capacitor C31 and the capacitor C32 constitute the crystal oscillator circuit, and the first power supply +VDD1 and the common ground GND supply power to the microcontroller MCU3. The ADC analog voltage input terminals ADC_12IN0 and ADC_12IN1 of the microcontroller MCU3 respectively input the ID card discrimination voltage VO12 and the IC card discrimination voltage VO22, the PWM signal output terminal TIM2_CH4 outputs the low-frequency cycle signal CLK1, the clock output terminal MCO outputs the high-frequency cycle signal CLK2, and the I / O level output terminal PB0 outputs the state control signal TK2.

[0040] Figure 3 In the example, the frequency of the crystal XT31 is 13.56 MHz and the first power supply +VDD1 is 3.3 V. Figure 3 The parameters of other components can be selected in the manner of forming a minimum system. For example, the resistance value of the resistor R30 is 10 kΩ, and the capacitances of the capacitors C30, C31, and C32 are 0.1 μF, 22 pF, and 22 pF, respectively. Figure 3 In the embodiment, the clock output terminal MCO is programmed to output a crystal oscillation frequency of 13.56MHz. The microcontroller MCU3 can select other models, and the requirements that need to be met at the same time include: being able to output the system clock frequency (i.e., outputting the oscillation frequency of the crystal oscillator 13.56MHz); having 2 8-bit (or above 8-bit) ADCs that can independently perform 8-bit ADC high-speed continuous sampling, and the ADC conversion time for continuous sampling is not higher than 3μs; having programmed PWM output; having I / O level control output. Low-cost STM32 F103 series microcontrollers, for example, STM32 F103T series and STM32 F103C series microcontrollers all meet the requirements. If the microcontroller does not output an oscillation frequency of 13.56MHz, an independent oscillation circuit can also be used to generate and output a high-frequency cycle signal CLK2 of 13.56MHz.

[0041] Figure 3 In the embodiment, the output control of the ID card confirmation signal LED1 and the IC card confirmation signal LED2 is also included. The ID card confirmation signal LED1 is output from the I / O level output terminal PA11, and the IC card confirmation signal LED2 is output from the I / O level output terminal PA12. Both are valid at low level. When PA11 is low level, the ID card confirmation indicator LED31 is controlled to light up, and when PA11 is low level, the IC card confirmation indicator LED32 is controlled to light up. The resistors R31 and R32 are current limiting resistors, and the resistance values ​​are both 300Ω. Figure 3In the embodiment, the ADC analog voltage input terminals ADC_12IN0 and ADC_12IN1 of MCU3 are respectively the first ADC analog voltage input terminal and the second ADC analog voltage input terminal, the PWM signal output terminal TIM2_CH4 is the first PWM signal output terminal, the I / O level output terminal PB0 is the first I / O output terminal, the I / O level output terminal PA11 is the second I / O output terminal, and the I / O level output terminal PA12 is the third I / O output terminal.

[0042] Figure 4 The control steps of the microcontroller unit are as follows:

[0043] Step 1, send out the low-frequency cycle signal CLK1, W1ms later, start to continuously sample the ID card identification voltage VO12 and save it as the ID card identification sequence, the number of continuously sampled data is N1, the continuous sampling period is T1; after the continuous sampling is completed, stop sending the low-frequency cycle signal CLK1. The value range of W1 is 1ms to 3ms, and the typical value is 1ms.

[0044] Step 2, perform N1-2 data comparisons on the ID card identification sequence in sequence; in each data comparison, if the difference between the previous adjacent data of the ID card is greater than the threshold ε1, or the difference between the previous adjacent data of the ID card is greater than the threshold ε1, the ID card difference is valid, otherwise the ID card difference is invalid; the number of times the ID card difference is valid in N1-2 data comparisons is counted as E1.

[0045] Step 3, determine whether there is an ID card in the near field; if the valid number of ID card difference values ​​E1 is greater than the threshold value M1, it is determined that there is an ID card in the near field, otherwise it is determined that there is no ID card in the near field. Further, repeat steps 1 to 2, and if the average value of the valid number of ID card difference values ​​E1 repeated multiple times is greater than the threshold value M1, it is determined that there is an ID card, otherwise it is determined that there is no ID card. Further, when it is determined that there is an ID card, the control sends out an effective pulse of the ID card confirmation signal LED1 and lights up LED31; the width of the effective pulse of the ID card confirmation signal LED1 is greater than or equal to 1s and less than or equal to 10s. Judging that there is an ID card in the near field means that the presence of an ID card in the near field can realize spatial (contactless) coupling of radio frequency signals through coupling elements to realize energy transfer, that is, there is an ID card in the near field that can be powered and work normally.

[0046] Step 4: Control the state control signal TK2 to be effective for W2ms; the value range of W2 is 15ms to 50ms, and the typical value is 15ms. The purpose is to provide stable energy to the near-field IC card if there is one.

[0047] Step 5, the control state control signal TK2 sends out a WUPA control command, and then the control state control signal TK2 is valid; after the WUPA control command is sent out, the IC card identification voltage VO22 is continuously sampled and saved as an IC card identification sequence, the number of continuously sampled data is N2, and the continuous sampling period is T2; after the continuous sampling is completed, the control state control signal TK2 is invalid, and the high-frequency frequency signal CLK2 is stopped from being applied to the inductor L21.

[0048] Step 6, starting from the N3th data position of the IC card identification sequence, perform N2-N3-2 data comparisons on the IC card identification sequence in sequence; in each data comparison, if the difference between the adjacent data after the IC card is greater than the threshold ε2, or the difference between the second adjacent data after the IC card is greater than the threshold ε2, or the difference between the third adjacent data after the IC card is greater than the threshold ε2, then the IC card difference is valid, otherwise the IC card difference is invalid; the number of times the IC card difference is valid in the N2-N3-2 data comparisons is counted as E2.

[0049] Step 7, if the effective number of IC card difference values ​​E2 is greater than the threshold value M2, it is judged that there is an IC card in the near field, otherwise it is judged that there is no IC card in the near field. Further, repeat steps 4 to 6, and if the average value of the effective number of IC card difference values ​​E2 repeated multiple times is greater than the threshold value M2, it is judged that there is an IC card, otherwise it is judged that there is no IC card. Further, when it is judged that there is an IC card, the control sends out an effective pulse of the IC card confirmation signal LED2 and lights up LED32; the width of the effective pulse of the IC card confirmation signal LED2 is greater than or equal to 1s and less than or equal to 10s. Judging that there is an IC card in the near field means that the presence of an IC card in the near field can realize spatial (contactless) coupling of radio frequency signals through coupling elements to realize energy transfer, that is, there is an IC card in the near field that can be powered and work normally.

[0050] If you need to continuously identify the RFID card type, repeat steps 1 to 7.

[0051] In step 1, the value range of N1 is 120 to 220, and the typical value is 150; the range of T1 is 50 μs to 120 μs, and the typical value is 100 μs.

[0052] In step 2, the difference of the adjacent data before the ID card refers to the difference between the current position data and the adjacent position data before the current position in the ID card identification sequence. For example, if the current position data is A(i), the difference of the adjacent data before the ID card is A(i)-A(i-1); the difference of the adjacent data before the ID card refers to the difference between the current position data and the second adjacent position data before the current position in the ID card identification sequence, that is, A(i)-A(i-2).

[0053] In step 2, the method for determining the value range of the threshold ε1 is as follows: when there is no ID card in the near field, execute step 1; perform N1-2 data comparisons on the ID card identification sequence in sequence to obtain N1-2 ID card previous adjacent data differences and N1-2 ID card previous adjacent data differences; find M1 maximum values ​​among the N1-2 ID card previous adjacent data differences and the N1-2 ID card previous adjacent data differences, and calculate the average value of the M1 maximum values ​​as A1min; when there is an ID card in the near field, execute step 1; perform N1-2 data comparisons on the ID card identification sequence in sequence to obtain N1-2 ID card previous adjacent data differences and N1-2 ID card previous adjacent data differences; find M1 maximum values ​​among the N1-2 ID card previous adjacent data differences and the N1-2 ID card previous adjacent data differences, and calculate the average value of the M1 maximum values ​​as A1max; the threshold ε1 takes a value between A1min and A1max, and a typical value is the median value between B1min and B1max. Furthermore, A1min takes the maximum value obtained from multiple tests, and A1max takes the minimum value obtained from multiple tests.

[0054] In step 3, the number of repetitions is 2 to 10; the threshold M1 ranges from 4 to 12. If T1 is small, M1 can be large; if T1 is large, M1 can be smaller; for example, when T1 is equal to 100 μs, M1 is recommended to be between 5 and 10.

[0055] In step 5, the value range of N2 is 120 to 220, and the typical value is 150; the range of T2 is 2 μs to 5 μs, and the typical value is 3 μs.

[0056] In step 6, the value range of N3 is 10 to 20, and the typical value is 15; the difference of adjacent data after the IC card refers to the difference of the current position data in the IC card identification sequence minus the adjacent position data after the current position, for example, the current position data is B(i), then the adjacent data difference is B(i+1)-B(i+1); the difference of the second adjacent data after the IC card refers to the difference of the current position data in the IC card identification sequence minus the second adjacent position data after the current position, that is, B(i)-B(i+2); the difference of the third adjacent data after the IC card refers to the difference of the current position data in the IC card identification sequence minus the third adjacent position data after the current position, that is, B(i)-B(i+3).

[0057] In step 6, the method for determining the value range of the threshold ε2 is that, when there is no IC card in the near field, execute steps 4 and 5 to find the maximum value of the data after the N3th data in the IC card identification sequence, which is B1min; when there is an IC card in the near field, execute steps 4 and 5 to find the maximum value of the data after the N3th data in the IC card identification sequence, which is B1max; the threshold ε2 takes values ​​between B1min and B1max, and the typical value is the median value between B1min and B1max; or, the threshold ε2 is greater than or equal to 2B1min (2 times B1min). Further, B1min takes the maximum value obtained by multiple tests, and B1max takes the minimum value obtained by multiple tests.

[0058] In step 7, the number of repetitions is 2 to 10; the value range of threshold M2 is 2 to 10, if T2 is small, M2 can be large; if T2 is large, M2 can be smaller; for example, when T2 is equal to 3μs, M2 is recommended to be between 3-5.

[0059] In step 5, the control state control signal TK2 issues a WUPA control command (0x52 control command), the purpose of which is to wake up the IC card in the IDLE (idle) or HALT (sleeping) state. When there is an IC card in the near field and it is awakened, it will reply with an ATQA response code. The WUPA instruction is issued using a 13.56MHz radio frequency carrier, and a synchronous and improved Miller coding method is adopted, and the signal is transmitted through a 100% ASK (amplitude shift keying) method; how to use a specific signal coding method to control the state control signal TK2 to issue a WUPA control command is a conventional technical means mastered by those skilled in the art. The control state control signal TK2 issues a WUPA control command, and it can also be replaced by the control state control signal TK2 issuing a REQA control command (0x26), the purpose of which is to wake up the IC card in the IDLE (idle) state. When there is an IC card in the near field and it is awakened by the REQA command, it will also reply with an ATQA response code.

[0060] Figure 5 This is an example diagram of the sampling data of the ID card identification sequence when there is no ID card in the near field (multiple superpositions); Figure 6 This is an example diagram of the sampling data of the ID card identification sequence when there is an EM4305 ID card in the near field (multiple superpositions); Figure 7This is an example diagram of the sampling data of the ID card identification sequence when there is a T5557 ID card in the near field (multiple superpositions). The horizontal axis is 0 to 200, representing the sampling points (including virtual sampling points), and the sampling period T1 is 100μs; the vertical axis is the sampling value. At sampling point 50, a low-frequency cycle signal CLK1 is issued; at sampling point 60 (W1 equals 1ms), continuous sampling of the ID card identification voltage VO12 begins, ending at sampling point 200, and N1 equals 141. Sampling points 0 to 59 are all virtual sampling points, and the obtained sampling data is not the ID card identification sequence data in step 1. That is to say, when implementing the radio frequency card type identification method and executing the step 1 process, sampling points 0 to 59 do not need to be sampled; Figure 5 , Figure 6 , Figure 7 The sampling points 0 to 59 are also sampled in order to facilitate the understanding of the overall picture of the ID card identification voltage VO12 in the process of implementing the radio frequency card type identification method. N1 is equal to 141, and the ID card identification sequence data is A(1) to A(141) in sequence; the ID card identification sequence is compared N1-2 times, that is, 139 times; the first comparison of the difference between the adjacent data before the ID card is A(3)-A(2), and the 139th comparison is A(141)-A(140); the first comparison of the difference between the adjacent data before the ID card is A(3)-A(1), and the 139th comparison is A(141)-A(139).

[0061] from Figure 5 , Figure 6 , Figure 7 It can be seen that after the low-frequency cycle signal CLK1 is emitted and amplified and applied to the inductor L11, the ID card identification voltage VO12 quickly rises to the maximum value VO12max, and then begins to decline. The decline begins earlier than the minimum W1 moment (the moment when W1 is equal to 1ms is the sampling point 60 moment); W1 takes a value of 1 to 3ms, corresponding to the sampling point 60 to 80 moments. Figure 5 When there is no ID card in the near field, VO12 basically maintains a monotonic decline process. After the sampling point 105, the VO12 sampling value fluctuates around 0. When the ID card enters the sensing area (the coupling area generated by the low-frequency frequency signal CLK1 applied to the inductor L11), it will automatically repeat the Manchester encoding signal of its own ID number, forming a coupling voltage signal to cause VO12 to fluctuate. After sampling VO12, the coupling voltage signal fluctuation is reflected in Figure 6 After sampling point 80 (to sampling point 150), Figure 7 After sampling point 70 (between sampling point 150). Figure 5 , Figure 6 , Figure 7In the embodiment, the ID card identification sequence sampling data is 8-bit binary data. For 12-bit and 10-bit ADCs, the embodiment only retains the upper 8 bits, which is equivalent to using the 12-bit and 10-bit ADCs as 8-bit ADCs, reducing the accuracy and facilitating the improvement of the ADC conversion speed. Figure 1 The circuit adjusts the amplification factor of the ID card identification signal voltage in-phase amplifier circuit (changes the resistance value of resistors R15 and R16) so that the sampling value corresponding to VO12max (the retained high 8-bit value) is between 245 and 255. The value range of the threshold ε1 is greater than 1 and less than 13, and the middle value is 7.

[0062] Figure 8 This is an example diagram of IC card identification sequence sampling data when there is no IC card in the near field (multiple superpositions); Fig. 9 This is an example diagram of IC card identification sequence sampling data when there is a Mifare1S70 IC card in the near field (multiple superpositions); Fig.10 This is an example of the IC card identification sequence sampling data when there is a Mifare1S50 IC card in the near field (multiple superpositions). The horizontal axis is 0 to 200, representing the sampling points (including virtual sampling points), and the sampling period T2 is 3μs; the vertical axis is the sampling value. At sampling point 20, the WUPA control command begins to be issued; at sampling point 30, the IC card identification voltage VO22 is continuously sampled, ending at sampling point 200, and N2 is equal to 151. Sampling points 0 to 49 are all virtual sampling points, and no data sampling is performed.

[0063] Figure 8 In the figure, the first high pulse, that is, the high pulse between sampling points 50 and 60, is caused by the influence of the tail of the WUPA command, and because there is no IC card (no load) in the near field, the IC card discrimination voltage VO22 rushes very high; after sampling point 60, there is interference data not exceeding 10. Fig. 9 , Fig.10 In the example, the first pulse, that is, the pulse between sampling points 50 and 60, is also generated by the influence of the tail of the WUPA command, and because there is an IC card (load) in the near field, the IC card discrimination voltage VO22 is much lower than when there is no card. Fig. 9 , Fig.10 In the near-field IC card, after receiving the WUPA command, it uses the subcarrier load modulation Manchester coding to reply the ATQA response. The modulation causes the coupling voltage signal, that is, the IC card discrimination voltage VO22 to fluctuate. After sampling VO22, the coupling voltage signal fluctuation is reflected in Fig. 9 , Fig.10 After sampling point 60 (between sampling point 90).

[0064] Figure 8 , Fig. 9 , Fig.10In the embodiment, the IC card identification sequence sampling data is 8-bit binary data. For 12-bit and 10-bit ADCs, only the upper 8 bits are retained, which is equivalent to using the 12-bit and 10-bit ADCs as 8-bit ADCs, reducing the accuracy and facilitating the improvement of the ADC conversion speed. Figure 2 The circuit can change the maximum value of the IC card discrimination voltage VO22 by changing the amplification factor of the IC card discrimination signal voltage in-phase amplifier circuit (changing the resistance values ​​of resistors R28 and R29), thereby changing the maximum sampling value of the interference signal when there is no card in the near field ( Figure 8 After the sampling point 60), the effective sampling value of the ATQA response signal when there is a card in the near field ( Fig. 9 , Fig.10 Sampling point between 60 and 90). Figure 8 , Fig. 9 , Fig.10 In the embodiment, N3 is 12, and the threshold ε2 is 37. N2 is 151, and the IC card identification sequence data is B(1) to B(151) in sequence; starting from the 12th data position of the IC card identification sequence, the IC card identification sequence is sequentially compared N2-N3-2 times, that is, 137 times; the first comparison of the difference between the adjacent data after the IC card is B(12)-B(13), and the 137th comparison is B(148)-B(149); the first comparison of the difference between the adjacent data after the IC card is B(12)-B(14), and the 137th comparison is B(148)-B(150); the first comparison of the difference between the adjacent data after the IC card is B(12)-B(15), and the 137th comparison is B(148)-B(151).

Claims

1. A method for identifying the type of radio frequency card, characterized in that: The radio frequency card type identification circuit including an ID card identification voltage generating unit, an IC card identification voltage generating unit and a microcontroller unit is used. It is not necessary to decode the coded signals replied by the near-field low-frequency card and the near-field high-frequency card. The coupling voltage signal of the near-field low-frequency card or the near-field high-frequency card is directly judged to realize the radio frequency card type identification. The control steps of the microcontroller unit are as follows: Step 1, send out a low-frequency cycle signal, after W1ms, start to continuously sample the ID card identification voltage and save it as an ID card identification sequence, the number of continuously sampled data is N1, and the period of continuous sampling is T1; after the continuous sampling is completed, stop sending out the low-frequency cycle signal; Step 2, perform N1-2 data comparisons on the ID card identification sequence in sequence; in each data comparison, if the difference between the previous adjacent data of the ID card is greater than the threshold ε1, or the difference between the previous adjacent data of the ID card is greater than the threshold ε1, the ID card difference is valid, otherwise the ID card difference is invalid; the number of valid ID card differences in N1-2 data comparisons is counted as E1; Step 3: If the valid number of ID card difference values ​​E1 is greater than the threshold value M1, it is determined that there is an ID card in the near field, otherwise it is determined that there is no ID card in the near field; or, repeat steps 1 to 2, and if the average value of the valid number of ID card difference values ​​E1 repeated multiple times is greater than the threshold value M1, it is determined that there is an ID card, otherwise it is determined that there is no ID card; Step 4, control the state control signal to be effective, lasting for W2ms; Step 5, the control state control signal sends out a WUPA control command, and then the control state control signal is valid; after the WUPA control command is sent out, the IC card identification voltage is continuously sampled and saved as an IC card identification sequence, the number of continuously sampled data is N2, and the period of continuous sampling is T2; after the continuous sampling is completed, the control state control signal is invalid; Step 6, starting from the N3th data position of the IC card identification sequence, the IC card identification sequence is compared N2-N3-2 times in sequence; in each data comparison, if the difference of the adjacent data after the IC card is greater than the threshold ε2, or the difference of the second adjacent data after the IC card is greater than the threshold ε2, or the difference of the third adjacent data after the IC card is greater than the threshold ε2, then the IC card difference is valid, otherwise the IC card difference is invalid; the number of times the IC card difference is valid in the N2-N3-2 data comparisons is counted as E2; Step 7, if the effective number of IC card difference values ​​E2 is greater than the threshold value M2, it is judged that there is an IC card in the near field, otherwise it is judged that there is no IC card in the near field; or, repeat steps 4 to 6, and if the average value of the effective number of IC card difference values ​​E2 repeated multiple times is greater than the threshold value M2, it is judged that there is an IC card, otherwise it is judged that there is no IC card.

2. A radio frequency card type identification method as claimed in claim 1, characterized in that: In step 2, the difference of adjacent data before the ID card refers to the difference of the current position data in the ID card identification sequence minus the adjacent position data before the current position, and the difference of adjacent data before the ID card refers to the difference of the current position data in the ID card identification sequence minus the second adjacent position data before the current position; in step 6, the difference of adjacent data after the IC card refers to the difference of the current position data in the IC card identification sequence minus the adjacent position data after the current position, the difference of the second adjacent data after the IC card refers to the difference of the current position data in the IC card identification sequence minus the second adjacent position data after the current position, and the difference of adjacent data again after the IC card refers to the difference of the current position data in the IC card identification sequence minus the third adjacent position data after the current position.

3. A radio frequency card type identification method as described in any one of claims 1 to 2, characterized in that: The method for determining the value range of the threshold ε1 is as follows: when there is no ID card in the near field, execute step 1; perform N1-2 data comparisons on the ID card identification sequence in sequence to obtain N1-2 ID card previous adjacent data differences and N1-2 ID card previous adjacent data differences; search for M1 maximum values ​​among the N1-2 ID card previous adjacent data differences and the N1-2 ID card previous adjacent data differences, and calculate the average value of the M1 maximum values ​​as A1min; when there is an ID card in the near field, execute step 1; perform N1-2 data comparisons on the ID card identification sequence in sequence to obtain N1-2 ID card previous adjacent data differences and N1-2 ID card previous adjacent data differences; search for M1 maximum values ​​among the N1-2 ID card previous adjacent data differences and the N1-2 ID card previous adjacent data differences, and calculate the average value of the M1 maximum values ​​as A1max; the threshold ε1 is greater than A1min and less than A1max. The method for determining the value range of the threshold ε2 is: when there is no IC card in the near field, execute steps 4 and 5 to find the maximum value of the data after the N3th data in the IC card identification sequence, which is B1min; when there is an IC card in the near field, execute steps 4 and 5 to find the maximum value of the data after the N3th data in the IC card identification sequence, which is B1max; the threshold ε2 is greater than B1min and less than B1max.

4. A radio frequency card type identification method as claimed in claim 3, characterized in that: The value range of N1 is 120 to 220; the value range of T1 is 50μs to 120μs; the value range of W1 is 1ms to 3ms; the value range of threshold M1 is 4 to 12; the value range of N2 is 120 to 220, the value range of N3 is 10 to 20; the value range of T2 is 2μs to 5μs; the value range of W2 is 15ms to 50ms; the value range of threshold M2 is 2 to 10.

5. A radio frequency card type identification method as claimed in any one of claims 1 to 4, characterized in that: The ID card identification voltage generating unit includes an inductor L11, an NPN transistor V11, a PNP transistor V12, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C11, a capacitor C12, a capacitor C13, a capacitor C14 and a diode D11; the bases of the NPN transistor V11 and the PNP transistor V12 are both connected to one end of the resistor R11, and the other end of the resistor R11 is a low-frequency cycle signal input end; the emitters of the NPN transistor V11 and the PNP transistor V12 are both connected to one end of the inductor L11, and the other end of the inductor L11 is connected to one end of the capacitor C11, and the other end of the inductor L11 is also connected to one end of the resistor R12; the collector of the NPN transistor V11 is connected to A first power supply, a collector of a PNP transistor V12 is connected to a common ground, and the other end of a capacitor C11 is connected to a common ground; an anode of a diode D11 is connected to the other end of R12, and a cathode of a diode D11 is connected to one end of a capacitor C12, a capacitor C13, and a resistor R13, respectively; the other ends of the capacitor C13 and the resistor R13 are both connected to a common ground, and the other end of the capacitor C12 is an ID card discrimination signal voltage output end; one end of a resistor R14 and a capacitor C14 are connected to an ID card discrimination signal voltage output end, and the other ends of the resistor R14 and the capacitor C14 are both connected to a common ground; the ID card discrimination voltage generating unit also includes an ID card discrimination signal voltage in-phase amplifier circuit for amplifying the ID card discrimination signal voltage to obtain the ID card discrimination voltage; The IC card identification voltage generating unit includes a control gate U21, an inductor coil L21, an NPN transistor V21, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R27, a capacitor C21, a capacitor C22, a capacitor C23, a capacitor C24, a capacitor C25, a capacitor C26, a capacitor C27, a capacitor C28 and a diode D21, a diode D22; the two input terminals of the control gate U21 are respectively a high frequency frequency signal input terminal and a The state control signal input terminal and the output terminal of U21 are connected to one end of the inductor L21, and the other end of the inductor L21 is connected to one end of the capacitor C21 and one end of the capacitor C22 respectively; the other end of the capacitor C22 is connected to the cathode of the diode D21, and the two ends of the capacitor C23 are connected to the cathode of the diode D21 and the common ground respectively; the anode of the diode D21 is connected to one end of the capacitor C25, and the two ends of the resistor R22 and the capacitor C24 are connected to the anode of the diode D21 and the common ground respectively. ; The two ends of the resistor R21 are connected to the anode of the diode D21 and the first power supply respectively; the other end of the capacitor C25 is connected to the base of the NPN transistor V21, the two ends of the resistor R23 are connected to the base of the NPN transistor V21 and the first power supply respectively, and the two ends of the resistor R23 are connected to the base of the NPN transistor V21 and the common ground respectively; the two ends of the resistor R26 and the capacitor C26 are connected to the emitter of the NPN transistor V21 and the common ground respectively, and the two ends of the resistor R25 are connected to The collector of the NPN transistor V21 and the first power supply; the two ends of the capacitor C27 are respectively connected to the collector of the NPN transistor V21 and the anode of the diode D22, the cathode of the diode D22 is the IC card identification signal voltage output terminal, the two ends of the resistor R27 and the capacitor C28 are respectively connected to the cathode of the diode D22 and the common ground; the IC card identification voltage generating unit also includes an IC card identification signal voltage in-phase amplifier circuit for amplifying the IC card identification signal voltage to obtain the IC card identification voltage.

6. A radio frequency card type identification method as claimed in claim 5, characterized in that: The microcontroller unit includes a microcontroller, a reset circuit, a crystal oscillator circuit and a first power supply, forming a microcontroller minimum system; the first ADC analog voltage input terminal and the second ADC analog voltage input terminal of the microcontroller respectively input the ID card discrimination voltage and the IC card discrimination voltage, the first PWM signal output terminal outputs a low-frequency cycle signal, the clock output terminal outputs a high-frequency cycle signal, and the first I / O output terminal outputs a state control signal.

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