CN113297862A - Card reading device for identifying HID induction card - Google Patents
Card reading device for identifying HID induction card Download PDFInfo
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- CN113297862A CN113297862A CN202110253482.1A CN202110253482A CN113297862A CN 113297862 A CN113297862 A CN 113297862A CN 202110253482 A CN202110253482 A CN 202110253482A CN 113297862 A CN113297862 A CN 113297862A
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- G06K7/10297—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves arrangements for handling protocols designed for non-contact record carriers such as RFIDs NFCs, e.g. ISO/IEC 14443 and 18092
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Abstract
The invention provides a card reading device for identifying an HID (high intensity discharge) induction card, wherein a card reading end of the card reading device is electrically connected with a micro control unit, a totem-pole output circuit, an LC (inductance-capacitance) resonance circuit, a diode detection circuit and a filtering amplification comparison circuit in sequence from front to back; the micro control unit outputs square wave signals, the totem-pole output circuit amplifies the square wave signals, the LC resonance circuit extracts sine wave signals, and sine alternating current is generated to form an electric field to emit carrier signals outwards; the HID induction card receives the carrier signal to generate induction voltage, couples data to be transmitted to the carrier signal to form a modulation signal, and returns the modulation signal to the card reading device; the diode detection circuit picks up the modulation signal and extracts an envelope signal from the modulation signal, the filtering amplification comparison circuit amplifies the envelope signal and compares the envelope signal with a reference level to generate a rectangular signal, and the micro control unit decodes the rectangular signal to acquire identity information corresponding to the HID induction card. The card reading device can identify the HID card.
Description
Technical Field
The invention relates to an inductive card reading device, in particular to a card reading device for identifying an HID inductive card.
Background
An inductive card is called an HID card in the market, the HID card is a 125KHz low-frequency inductive card under the American HID company, and when the HID card leaves a factory, an internal chip of the HID card can be encrypted according to a sequence number set by a region, so that the HID card cannot be identified by card readers of other brands and can only be used by being matched with a special HID card reader.
HID companies account for more than 40% of the international market share, and domestic companies need to consider matching with HID cards when designing inductive card reading systems; if the special HID card reader is directly imported for use, on one hand, the special HID card reader has high cost, so that the cost of domestic products is high, and the market competitiveness of the products is reduced, on the other hand, the special HID card reader is not necessarily suitable for the design of domestic products, so that the design space of the products is difficult to be fully utilized, and the volume of the products is reduced.
It would therefore be of positive interest to provide a card reading device that does not require the identification of an HID card by a dedicated HID reader.
Disclosure of Invention
In view of the above problems, the present invention provides a card reading device for identifying an HID inductive card, which is capable of identifying an HID card.
In order to achieve the purpose, the card reading device adopts the technical scheme that: a card reading device for identifying an HID inductive card is innovative in that: the card reading device comprises a card reading end, wherein a micro control unit, a totem-pole output circuit, an LC resonance circuit, a diode detection circuit and a filtering amplification comparison circuit are electrically connected in the card reading end from front to back in sequence;
the micro control unit outputs a square wave signal to the totem pole output circuit; the totem-pole output circuit amplifies the square wave signals and then transmits the amplified square wave signals to the LC resonance circuit; the LC resonance circuit extracts a sine wave signal in the amplified square wave signal, generates sine alternating current to form an electric field, and transmits a carrier signal to the outside through the electric field; the HID induction card receives the carrier signal in the electric field and generates an induction voltage, and under the action of the induction voltage, the HID induction card couples data to be transmitted to the carrier signal to form a modulation signal and sends the modulation signal back to the LC resonance circuit of the card reading device; the diode detection circuit receives the modulation signal input by the LC resonance circuit and carries out envelope detection on the modulation signal to extract an envelope signal; the filtering amplification comparison circuit amplifies an envelope signal extracted from a modulation signal, compares the amplified envelope signal with a set reference level, defines a signal lower than the reference level as a low level, and defines a signal higher than the reference level as a high level, thereby generating a rectangular signal; and the micro control unit receives and decodes the rectangular signal sent by the filtering, amplifying and comparing circuit, so as to acquire the identity information in the HID induction card.
The relevant content in the above technical solution is explained as follows:
1. in the above scheme, the method for decoding the rectangular signal by the micro control unit includes the following steps:
the method comprises the following steps: in the rectangular signal, regarding high levels corresponding to two adjacent rising edges with a time difference value of less than or equal to 90 μ s as continuous high levels, regarding low levels corresponding to two adjacent rising edges with a time difference value within a range of 400 to 700 μ s as a low level time, regarding low levels corresponding to two adjacent rising edges with a time difference value within a range of 760 to 1000 μ s as two low level times, and regarding low levels corresponding to two adjacent rising edges with a time difference value within a range of 1100 to 1900 μ s as three low level times; defining continuous 5n +/-1 high levels as continuous n '1's, wherein n is a positive integer, defining each low level time as a '0', and defining converted data as data A;
step two: finding 3 consecutive "1" s in data a as starting identifiers;
step three: starting from the first character after the initial identifier, grouping every two adjacent characters in the data A to form character groups '01' and '10', converting the character group '01' into '0', converting the character group '10' into '1', and defining the converted data as data B;
step four: converting every 4-bit binary character in the data B into 1-bit hexadecimal character, and defining the converted data as data C;
step five: and defining the 8 th to 11 th bit characters in the data C as data D, wherein the data D is the identity information of the corresponding HID induction card.
2. In the above scheme, the totem-pole output circuit and the LC resonant circuit jointly form an excitation feedback circuit, which includes a first resistor, a second resistor, a first capacitor, a second capacitor, a third capacitor, a first triode, a second triode, and a first coil; the first end of first resistance is connected little the control unit output square wave signal's output, the base of first triode, second triode is connected to the second end, the collecting electrode of first triode is connected respectively little the control unit's 3V3 power supply port and the first end of first electric capacity, second electric capacity, the second end ground connection of first electric capacity, second electric capacity, the projecting pole of first triode is connected the projecting pole of second triode respectively, the first end of second resistance, the collecting electrode ground connection of second triode, the first end of first coil is connected to the second end of second resistance, the first end of third electric capacity is connected to the second end of first coil, the second end ground connection of third electric capacity.
The first coil is a wound round coil, and the inductance value is 250 uH.
3. In the above scheme, the diode detection circuit and the filtering amplification comparison circuit together form a signal pickup processing circuit, which includes a first diode, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor, a first operational amplifier, and a second operational amplifier; the positive pole of the first diode is connected with the output end for outputting the modulation signal, the negative pole of the first diode is respectively connected with the first end of the ninth resistor, the first end of the sixth capacitor and the first end of the fourth capacitor, the second end of the ninth resistor and the second end of the sixth capacitor are grounded, the second end of the fourth capacitor is respectively connected with the first end of the tenth resistor, the first end of the seventh capacitor and the non-inverting input end of the first operational amplifier, the second end of the tenth resistor and the second end of the seventh capacitor are grounded, the inverting input end of the first operational amplifier is connected with the first end of the sixth resistor, the output end of the first operational amplifier is connected with the first end of the eighth resistor, the first end of the eighth capacitor and the first end of the fifth capacitor, the second end of the eighth resistor and the second end of the eighth capacitor are connected with the first end of the sixth resistor, the second end of the sixth resistor is grounded, and the second end of the fifth capacitor is connected with the first end of the fifth resistor, the second end of the fifth resistor is connected with the first end of the fourth resistor, the first end of the third resistor and the non-inverting input end of the second operational amplifier, the second end of the fourth resistor is grounded, the second end of the third resistor is connected with the output end of the second operational amplifier, the inverting input end of the second operational amplifier is respectively connected with the first end of the seventh resistor, the first end of the eleventh resistor and the first end of the ninth capacitor, the second end of the seventh resistor is connected with the 3V3 power supply port of the micro control unit, the second end of the eleventh resistor and the second end of the ninth capacitor are grounded, the positive power source end of the second operational amplifier is connected with the 3V3 power supply port of the micro control unit, the negative power source end is grounded, and the output end of the second operational amplifier is connected with the rectangular signal input end of the micro control unit.
4. In the above scheme, the card reading device further includes a control end and a communication module, and data intercommunication is realized between the micro control unit of the card reading end and the control end through the communication module. And after the micro control unit acquires the identity information corresponding to the HID induction card, comparing the identity information with local authorization card number information, if the identity information belongs to the authorization card number information, judging that the identity authentication is passed, and if the identity information does not belong to the authorization card number information, judging that the identity authentication is not passed.
The card reading end further comprises an execution module which is electrically connected with the micro control unit.
5. In the scheme, the micro control unit adopts a single chip microcomputer with the model of STM32F 103.
The invention has the beneficial effects that: the card reading device starts from the basic principle of modulation and demodulation, can realize the identification of the HID induction card by combining a hardware circuit structure and a decoding method of a micro control unit for a rectangular signal, has simple structure, low cost and stable performance, solves the problem that a special HID card reader with high price must be purchased for identifying the HID induction card at present, is beneficial to reducing the product cost, fully utilizes the product design space and improves the product competitiveness.
Drawings
FIG. 1 is a flowchart of the operation of an embodiment of the card reader of the present invention;
FIG. 2 is a circuit diagram of an excitation feedback circuit in the embodiment of FIG. 1;
FIG. 3 is a circuit diagram of a signal pickup processing circuit in the embodiment shown in FIG. 1;
FIG. 4 is a waveform diagram of a carrier signal in the embodiment of FIG. 1;
FIG. 5 is a waveform diagram of a modulated signal in the embodiment of FIG. 1;
FIG. 6 is a waveform diagram of a first representation of a rectangular signal in the embodiment of FIG. 1;
FIG. 7 is a waveform diagram of a second representation of a rectangular signal in the embodiment of FIG. 1.
In the above drawings: 1. a card reading end; 11. a micro control unit; 12. a totem-pole output circuit; an LC resonance circuit; 14. a diode detection circuit; 15. a filtering, amplifying and comparing circuit; 16. an execution module; 2. a control end; 3. a communication module; r1, a first resistor; r2, a second resistor; r3. a third resistor; r4. a fourth resistor; r5. a fifth resistor; r6. sixth resistor; r7. a seventh resistor; r8. eighth resistor; r9. ninth resistor; r10, tenth resistance; r 11. eleventh resistor; C1. a first capacitor; C2. a second capacitor; C3. a third capacitor; C4. a fourth capacitor; C5. a fifth capacitor; C6. a sixth capacitor; C7. a seventh capacitance; C8. an eighth capacitor; C9. a ninth capacitor; q1. a first triode; q 2. a second triode; J1. a first coil; D1. a first diode; u1 a. first operational amplifier; u1 b. second operational amplifier.
Detailed Description
The present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the disclosure may be shown and described, and which, when modified and varied by the techniques taught herein, can be made by those skilled in the art without departing from the spirit and scope of the disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms "a", "an", "the" and "the", as used herein, also include the plural forms.
As used herein, the terms "comprising," "including," "having," and the like are open-ended terms that mean including, but not limited to.
As used herein, the term (terms), unless otherwise indicated, shall generally have the ordinary meaning as commonly understood by one of ordinary skill in the art, in this written description and in the claims. Certain words used to describe the disclosure are discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the disclosure.
Example (b): a card reading device for identifying an HID inductive card;
as shown in fig. 1 to 7, the card reading device includes a card reading end 1, a control end 2, and a communication module 3, data communication is realized between the card reading end 1 and the control end 2 through the communication module 3, and a micro control unit 11, a totem pole output circuit 12, an LC resonance circuit 13, a diode detection circuit 14, and a filtering amplification comparison circuit 15 are electrically connected in the card reading end 1 from front to back in sequence.
In another embodiment, the functions of the control terminal 2 can also be integrated in the microcontroller unit 11, so that this embodiment does not require the communication module 3.
In a working state, the micro control unit 11 outputs a 125KHz square wave signal to the totem-pole output circuit 12, the totem-pole output circuit 12 amplifies the square wave signal and then transmits the amplified square wave signal to the LC resonance circuit 13, and the LC resonance circuit 13 extracts a sine wave signal in the amplified square wave signal, generates a sine alternating current to form an electric field, and emits a carrier signal to the outside through the electric field.
The HID induction card (HID is short for American HID Corporation in the present case, and does not have other meanings) receives the carrier signal in the electric field and generates an induction voltage, and under the action of the induction voltage, the HID induction card couples the data to be transmitted to the carrier signal according to the solidified characteristic of the HID induction card to form a modulation signal and sends the modulation signal back to the LC resonance circuit 13 of the card reading device, so that the card reading device can acquire the data to be transmitted by the HID induction card by identifying the modulation signal; the specific working principle of the HID sensor card is known to those skilled in the art and is not the point of the present invention, so that the detailed description thereof is omitted herein.
Thereafter, the diode detector circuit 14 picks up the modulated signal from the LC resonant circuit 13, and performs envelope detection on the modulated signal, extracting an envelope signal of which the signal is greater than a zero portion; envelope detection is a vibration signal processing method based on filtering detection, the process of demodulating a low-frequency signal from an amplitude-modulated signal is called envelope detection, namely the envelope detection is amplitude detection, and the common method of envelope detection is to perform low-pass filtering after unidirectional filtering by using a diode. If the diode is not used and the low-pass filtering is directly carried out, the positive envelope line and the negative envelope line can be counteracted, so that a low-frequency signal cannot be detected; by connecting the signal peaks in fig. 5 into a line, an envelope of the waveform appears, where diode detector circuit 14 serves to extract the envelope.
In the scheme, the envelope signal extracted from the modulation signal is amplified by the filtering, amplifying and comparing circuit 15, the amplified envelope signal is compared with a set reference level, a signal lower than the reference level is defined as a low level, a signal higher than the reference level is defined as a high level, and thus a rectangular signal is generated; wherein said reference level refers to an appropriate value artificially set between a lower signal and an upper signal in the envelope signal, and the setting method of the reference level is well known to those skilled in the art.
Then the micro control unit 11 receives the rectangular signal from the filtering, amplifying and comparing circuit 15, and decodes the rectangular signal to obtain the identity information in the HID inductive card; the specific operation method of the micro control unit 11 for "decoding and acquiring information" may be implemented by the following method, or may be implemented by other decoding methods with the same or similar principles.
It should be noted that the rectangular signal includes two expressions, one expression is composed of a high level signal and a low level signal (see fig. 6), and the second expression (see fig. 7) is composed of a wider high level signal (equivalent to the high level signal in the first expression) and a narrower high level signal (equivalent to the low level signal in the first expression), and the two expressions substantially represent the same rectangular signal, which are substantially identical and can be switched according to the mind of the user during operation, so that any expression is within the protection scope of the present invention during operation.
Taking a representation form as an example, the method for decoding the rectangular signal by the mcu 11 includes the following steps:
the method comprises the following steps: in the rectangular signal, regarding high levels corresponding to two adjacent rising edges with a time difference of less than or equal to 90 μ s as continuous high levels (for example, time differences of any two adjacent rising edges in five continuous rising edges are all less than 90 μ s, that is, the high levels corresponding to the two adjacent rising edges are considered as five continuous high levels), regarding low levels corresponding to two adjacent rising edges with a time difference of 400 to 700 μ s as one low level time, regarding low levels corresponding to two adjacent rising edges with a time difference of 760 to 1000 μ s as two low level times, and regarding low levels corresponding to two adjacent rising edges with a time difference of 1100 to 1900 μ s as three low level times; defining continuous 5n +/-1 high levels as continuous n '1's, wherein n is a positive integer, defining each low level time as a '0', and defining converted data as data A; in the step, a rectangular signal is converted into a binary digital signal, the time value of each rising edge is recorded through the micro control unit 11 in actual operation, and the time difference value of each adjacent rising edge is compared and judged to obtain data A, wherein the time difference value of two adjacent rising edges is only in the range due to the data characteristic;
step two: finding 3 consecutive "1" s in data a as starting identifiers;
step three: starting from the first character after the initial identifier, grouping every two adjacent characters in the data A to form character groups '01' and '10', converting the character group '01' into '0', converting the character group '10' into '1', and defining the converted data as data B; for example, data a starts with a start identifier of "1110101010101010110010101010101010101011010100110011001100101010110100101010101011010010110100101010101011010010110. -, and is converted into data B of" 00000001000000000011101010100001100000011001100000011001. -; it should be noted that, due to the nature of the data itself, after grouping adjacent characters in data a, starting with the first character after the start identifier, there are only character groups "01", "10", but not "11", "00";
step four: converting every 4-bit binary character in the data B into a 1-bit hexadecimal character, and defining the converted data as data C, wherein the data C is "01003 aa1819819.. according to the example in step four;
step five: defining the 8 th to 11 th bit characters in the data C as data D, which is "1819" according to the example in step four, where the data D is the identity information of the corresponding HID inductive card.
After the micro control unit 11 obtains the identity information of the corresponding HID sensor card, the identity information is compared with the local authorized card number information, if the identity information belongs to the authorized card number information, the identity authentication is determined to be passed, and if the identity information does not belong to the authorized card number information, the identity authentication is determined not to be passed.
The card reading end 1 further comprises an execution module 16, wherein the execution module 16 is electrically connected to the micro control unit 11, and performs corresponding operations according to the identity authentication result; the execution module 16 may include a prompt unit such as an LED display lamp and a buzzer, the LED display lamp may display different colors in different states according to the customer requirements, the buzzer may emit different sounds in different states according to the customer requirements, for example, an authorized card may be defined to display a green light, the buzzer sounds one sound, an unauthorized card may display a red light, and the buzzer continuously sounds at a certain fixed frequency to indicate an alarm; the execution module 16 may further include an action unit such as an electromagnet, a motor, a relay, and the like, wherein the electromagnet may be applied to drive the bolt of the door lock to move axially to open and close the smart lock, the motor may be applied to the vehicle blocking rod to rotate to block or release the corresponding vehicle, the relay may be applied to the smart meter to determine whether to energize the user, the relay is energized when the requirement is met, the user can use electricity, and the relay is de-energized when the requirement is not met to cause the circuit to be cut off, so that the user cannot continue to use electricity.
In this embodiment, as shown in fig. 2, the totem pole output circuit 12 and the LC resonant circuit 13 together form an excitation feedback circuit for sending an amplified signal and receiving a feedback signal, and the circuit includes a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a first triode Q1, a second triode Q2, and a first coil J1; the first end of the first resistor R1 is connected to the output end of the micro control unit for outputting the square wave signal, the second end of the first resistor R1 is connected to the bases of the first triode Q1 and the second triode Q2, the collector of the first triode Q1 is connected to the 3V3 power supply port of the micro control unit and the first ends of the first capacitor C1 and the second capacitor C2, the second ends of the first capacitor C1 and the second capacitor C2 are grounded, the emitter of the first triode Q1 is connected to the emitter of the second triode Q2 and the first end of the second resistor R2, the collector of the second triode Q2 is grounded, the second end of the second resistor R2 is connected to the first end of the first coil J1, the second end of the first coil J1 is connected to the first end of the third capacitor C3, and the second end of the third capacitor C3 is grounded.
The totem pole output circuit 12 is composed of a first triode Q1 and a second triode Q2, the drive capability of the I/O signal is amplified, when the input signal is high level, the first triode Q1 is turned on, and the second triode Q2 is turned off; when the input signal is at a low level, the first triode Q1 is turned off, and the second triode Q2 is turned on; the amplification capability is determined by comparing the ratio of the current flowing through the second resistor R2 to the current flowing through the first resistor R1.
The LC resonant circuit 13 is formed by connecting an inductor and a capacitor in series, where the inductor is the first coil J1, the capacitor is the third capacitor C3, and the inductor and the capacitor need to follow the mathematical relationship of formula one:
the formula I is as follows:
in the embodiment, the inductor is formed by winding the self-adhesive enameled wire, the size of the inductor can be determined according to the actual assembly environment, and the size of the inductor is as large as possible under the allowable condition; due to the fact that the design requirement is small and exquisite, under the condition that interference (structural dimension) is not caused, the first coil J1 selects a wound round coil, the specification parameters are that the inner diameter is 15mm, the outer diameter of the coil is 20.5mm, the wire diameter is 0.2mm, and the inductance value is 250 uH; and according to the mathematical relationship of formula one, the capacitance of the third capacitor C3 is 6.48 nF.
In this embodiment, as shown in fig. 3, the diode detector circuit 14 and the filtering amplification comparator circuit 15 together form a signal pickup processing circuit, which is used for picking up a modulated signal and processing the modulated signal, and includes a first diode D1, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, a first operational amplifier U1A, and a second operational amplifier U1B; the anode of the first diode D1 is connected to the output end for outputting the modulation signal, the cathodes of the first diode D1 are connected to the first end of the ninth resistor R9, the first end of the sixth capacitor C6, the first end of the fourth capacitor C4, the second end of the ninth resistor R9 and the second end of the sixth capacitor C6 are grounded, the second end of the fourth capacitor C4 is connected to the first end of the tenth resistor R10, the first end of the seventh capacitor C7 and the non-inverting input end of the first operational amplifier U1A, the second end of the tenth resistor R10 and the second end of the seventh capacitor C7 are grounded, the inverting input end of the first operational amplifier U1A is connected to the first end of the sixth resistor R6, the output end of the first operational amplifier U1 84 is connected to the first end of the eighth resistor R8, the first end of the eighth capacitor C8, the first end of the fifth capacitor C5, the second end of the eighth resistor R8 and the second end of the eighth capacitor C5 are connected to the first end of the sixth resistor R6, the second end of the first resistor R57324 and the second end of the sixth resistor R5857323, a second end of the fifth capacitor C5 is connected to a first end of the fifth resistor R5, a second end of the fifth resistor R5 is connected to a first end of the fourth resistor R4, a first end of the third resistor R3 and a non-inverting input terminal of the second operational amplifier U1B, a second end of the fourth resistor R4 is grounded, a second end of the third resistor R3 is connected to an output terminal of the second operational amplifier U1B, inverting input terminals of the second operational amplifier U1B are respectively connected to a first end of the seventh resistor R7, a first end of an eleventh resistor R11, a first end of a ninth capacitor C9, a second end of a seventh resistor R7 is connected with a 3V3 power supply port of the micro-control unit, a second end of the eleventh resistor R11 and a second end of the ninth capacitor C9 are grounded, a positive power supply end of a second operational amplifier U1B is connected with a 3V3 power supply port of the micro-control unit, a negative power supply end is grounded, and an output end of the second operational amplifier U1B is connected with a rectangular signal input end of the micro-control unit.
The output end of the modulation signal, that is, the second end of the first coil J1, that is, the diode detector circuit 14 obtains the modulation signal from the LC resonant circuit 13.
In order to acquire a weak signal loaded on a carrier signal by the HID induction card, a diode detection mode is adopted for signal pickup, when a modulation signal is greater than the voltage of a rear-end sixth capacitor C6, a first diode D1 is conducted, and as the resistance ratio of a conducted charging loop is small, the time constant of charging is small, namely the charging is rapid, and the charging waveform changes along with the change of the modulation signal; when the modulation signal is less than the voltage of the rear-end sixth capacitor C6, the first diode D1 is turned off, and the voltage of the sixth capacitor C6 is discharged through the subsequent load; because the resistance is large, the discharge time constant is large, and therefore, the discharge is slow; the envelope of the modulated signal can be detected by the diode detector circuit 14.
In addition, the control terminal 2 is a device with a GUI interface, display and interaction functions, such as a PC or a controllable LCD display interface.
The communication module 3 may adopt a wireless communication mode such as UHF/ZigBee/Lora/WiFi/BLE/NB-IoT/mobile network, etc., or a wired communication mode such as on-off amount of wires/RS 232/RS485/USB, etc., as long as the mode of realizing communication between two independent modules is within the scope of the communication module 3; in addition, the communication module 3 described in this case also includes portions for communication on the card reading terminal 1 and the control terminal 2.
The micro control unit 11 is a chip having a central processing unit and equipped with certain peripherals (such as a memory and a counter), in this embodiment, a single chip microcomputer of the model STM32F103 is adopted, and other single chip microcomputers such as STM8 series can also be adopted, so long as the single chip microcomputers capable of configuring an I/O port to generate a signal of a certain frequency and processing an external interrupt signal all belong to the scope of the micro control unit 11; in the embodiment, a STM32F103 timer is configured to set a 125KHz square wave signal required by I/O output.
In order to reduce power consumption, the interval time of square wave signal outage (the interval time can be 100mS, 200mS and 500 mS) can be properly relaxed under the condition of considering the card swiping experience of a client; the output signal of STM32F103 is coupled to the input of the totem pole via a first resistor R1. The input end of the first resistor R1 can verify whether the I/O port output signal meets the requirement; if the emission current is increased, a primary amplifying circuit can be added or higher voltage driving can be adopted; because the card swiping distance of the design can reach 20mm, the card swiping distance of a customer is basically close to the card reader, and therefore the I/O output signal is not amplified in the scheme in consideration of the cost and the customer requirements.
In addition, the control end 2 can set the authority level and the attribute of the induction card according to the needs of the user, for example, the card for opening the authority can be set as a permanent opening authority or a partial time period opening authority or an authority for opening limited times according to the needs.
In summary, the card reader starts from the basic principle of modulation and demodulation, can realize the identification of the HID sensor card and perform corresponding operations by combining the hardware circuit structure and the decoding method of the micro control unit 11 for the rectangular signal, and can determine whether to open/cancel the authority for the corresponding sensor card according to the command of the control terminal 2, and has the advantages of simple structure, low cost and stable performance, solving the problem that a special HID card reader with high price must be purchased for identifying the HID sensor card at present, being beneficial to reducing the product cost, fully utilizing the product design space and improving the product competitiveness.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (9)
1. A card reading device for identifying an HID inductive card, characterized in that:
the card reading device comprises a card reading end (1), wherein a micro control unit (11), a totem-pole output circuit (12), an LC resonance circuit (13), a diode detection circuit (14) and a filtering amplification comparison circuit (15) are electrically connected in the card reading end (1) from front to back in sequence;
the micro control unit (11) outputs a square wave signal to the totem-pole output circuit (12);
the totem-pole output circuit (12) amplifies the square wave signals and then transmits the amplified square wave signals to the LC resonance circuit (13);
the LC resonance circuit (13) extracts a sine wave signal in the amplified square wave signal, generates sine alternating current to form an electric field, and transmits a carrier signal to the outside through the electric field;
the HID induction card receives the carrier signal in the electric field and generates an induction voltage, and under the action of the induction voltage, the HID induction card couples data to be transmitted to the carrier signal to form a modulation signal and sends the modulation signal back to an LC resonance circuit (13) of the card reading device;
the diode detection circuit (14) receives the modulation signal input by the LC resonance circuit (13), and carries out envelope detection on the modulation signal to extract an envelope signal;
the filtering amplification comparison circuit (15) amplifies an envelope signal extracted from a modulation signal, compares the amplified envelope signal with a set reference level, defines a signal lower than the reference level as a low level, and defines a signal higher than the reference level as a high level, thereby generating a rectangular signal;
and the micro control unit (11) receives and decodes the rectangular signal sent by the filtering, amplifying and comparing circuit (15), so as to acquire the identity information in the HID induction card.
2. The card reading device for identifying the HID inductive card according to claim 1, wherein: the decoding method of the rectangular signal by the micro control unit (11) comprises the following steps:
the method comprises the following steps: in the rectangular signal, regarding high levels corresponding to two adjacent rising edges with a time difference value of less than or equal to 90 μ s as continuous high levels, regarding low levels corresponding to two adjacent rising edges with a time difference value within a range of 400 to 700 μ s as a low level time, regarding low levels corresponding to two adjacent rising edges with a time difference value within a range of 760 to 1000 μ s as two low level times, and regarding low levels corresponding to two adjacent rising edges with a time difference value within a range of 1100 to 1900 μ s as three low level times; defining continuous 5n +/-1 high levels as continuous n '1's, wherein n is a positive integer, defining each low level time as a '0', and defining converted data as data A;
step two: finding 3 consecutive "1" s in data a as starting identifiers;
step three: starting from the first character after the initial identifier, grouping every two adjacent characters in the data A to form character groups '01' and '10', converting the character group '01' into '0', converting the character group '10' into '1', and defining the converted data as data B;
step four: converting every 4-bit binary character in the data B into 1-bit hexadecimal character, and defining the converted data as data C;
step five: and defining the 8 th to 11 th bit characters in the data C as data D, wherein the data D is the identity information of the corresponding HID induction card.
3. The card reading device for identifying the HID inductive card according to claim 1, wherein: the totem pole output circuit (12) and the LC resonance circuit (13) jointly form an excitation feedback circuit, which comprises a first resistor (R1), a second resistor (R2), a first capacitor (C1), a second capacitor (C2), a third capacitor (C3), a first triode (Q1), a second triode (Q2) and a first coil (J1); the first end of the first resistor (R1) is connected with the output end of the micro control unit (11) for outputting the square wave signal, the second end of the first resistor (R1) is connected with the bases of a first triode (Q1) and a second triode (Q2), the collector of the first triode (Q1) is respectively connected with the 3V3 power supply port of the micro control unit (11), the first end of a first capacitor (C1) and the first end of a second capacitor (C2), and a first capacitor (C1), the second end of the second capacitor (C2) is grounded, the emitter of the first triode (Q1) is respectively connected with the emitter of the second triode (Q2) and the first end of the second resistor (R2), the collector of the second triode (Q2) is grounded, the second end of the second resistor (R2) is connected with the first end of the first coil (J1), the second end of the first coil (J1) is connected with the first end of the third capacitor (C3), and the second end of the third capacitor (C3) is grounded.
4. A card reading device for identifying HID inductive cards according to claim 3, wherein: the first coil (J1) is a wound round coil, and the inductance value is 250 uH.
5. The card reading device for identifying the HID inductive card according to claim 1, wherein: the diode detection circuit (14) and the filtering amplification comparison circuit (15) jointly form a signal pickup processing circuit, which comprises a first diode (D1), a third resistor (R3), a fourth resistor (R4), a fifth resistor (R5), a sixth resistor (R6), a seventh resistor (R7), an eighth resistor (R8), a ninth resistor (R9), a tenth resistor (R10), an eleventh resistor (R11), a fourth capacitor (C4), a fifth capacitor (C5), a sixth capacitor (C6), a seventh capacitor (C7), an eighth capacitor (C8), a ninth capacitor (C9), a first operational amplifier (U1A) and a second operational amplifier (U1B); the anode of the first diode (D1) is connected with the output end which outputs the modulation signal, the cathode of the first diode is respectively connected with the first end of the ninth resistor (R9), the first end of the sixth capacitor (C6) and the first end of the fourth capacitor (C4), the second end of the ninth resistor (R9) and the second end of the sixth capacitor (C6) are grounded, the second end of the fourth capacitor (C4) is respectively connected with the first end of the tenth resistor (R10), the first end of the seventh capacitor (C7) and the non-inverting input end of the first operational amplifier (U1A), the second end of the tenth resistor (R10) and the second end of the seventh capacitor (C7) are grounded, the inverting input end of the first operational amplifier (U1A) is connected with the first end of the sixth resistor (R6), the output end of the first operational amplifier (U1A) is connected with the first end of the eighth resistor (R8), the first end of the eighth capacitor (C8) and the first end of the fifth capacitor (C5), a second end of an eighth resistor (R8) and a second end of an eighth capacitor (C8) are connected with a first end of a sixth resistor (R6), a second end of the sixth resistor (R6) is grounded, a second end of a fifth capacitor (C5) is connected with a first end of a fifth resistor (R5), a second end of a fifth resistor (R5) is connected with a first end of a fourth resistor (R4), a first end of a third resistor (R3) and a non-inverting input end of a second operational amplifier (U1B), a second end of a fourth resistor (R4) is grounded, a second end of a third resistor (R3) is connected with an output end of a second operational amplifier (U1B), inverting input ends of the second operational amplifier (U1B) are respectively connected with a first end of a seventh resistor (R7), a first end of an eleventh resistor (R11), a first end of a ninth capacitor (C9), and a second end of a seventh resistor (R7) is connected with a power supply unit (V3) of the micro-control unit, the second end of the eleventh resistor (R11) and the second end of the ninth capacitor (C9) are grounded, the positive power supply end of the second operational amplifier (U1B) is connected with the 3V3 power supply port of the micro control unit (11), the negative power supply end is grounded, and the output end of the second operational amplifier (U1B) is connected with the rectangular signal input end of the micro control unit (11).
6. The card reading device for identifying the HID inductive card according to claim 1, wherein: the card reading device further comprises a control end (2) and a communication module (3), and data intercommunication is realized between the micro control unit (11) of the card reading end (1) and the control end (2) through the communication module (3).
7. The card reading device for identifying the HID sensor card as recited in claim 6, wherein: after the micro control unit (11) acquires the identity information of the corresponding HID induction card, the identity information is compared with local authorization card number information, if the identity information belongs to the authorization card number information, the identity authentication is judged to be passed, and if the identity information does not belong to the authorization card number information, the identity authentication is judged not to be passed.
8. The card reading device for identifying the HID inductive card according to claim 7, wherein: the card reading end (1) further comprises an execution module (16), and the execution module (16) is electrically connected with the micro control unit (11).
9. The card reading device for identifying the HID inductive card according to claim 1, wherein: the micro control unit (11) adopts a single chip microcomputer with the model of STM32F 103.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110253482.1A CN113297862B (en) | 2021-03-09 | 2021-03-09 | Card reading device for identifying HID induction card |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106682553A (en) * | 2016-12-21 | 2017-05-17 | 福建升腾资讯有限公司 | Strip-card software decoding method |
| CN206877335U (en) * | 2017-03-25 | 2018-01-12 | 河源市江东新区全程精工制品有限公司 | A kind of circuit structure of magnetic card Card Reader |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106682553A (en) * | 2016-12-21 | 2017-05-17 | 福建升腾资讯有限公司 | Strip-card software decoding method |
| CN206877335U (en) * | 2017-03-25 | 2018-01-12 | 河源市江东新区全程精工制品有限公司 | A kind of circuit structure of magnetic card Card Reader |
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