CN211236952U - RFID radio frequency tag read-write circuit of non-integrated IC - Google Patents
RFID radio frequency tag read-write circuit of non-integrated IC Download PDFInfo
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- CN211236952U CN211236952U CN202020180072.XU CN202020180072U CN211236952U CN 211236952 U CN211236952 U CN 211236952U CN 202020180072 U CN202020180072 U CN 202020180072U CN 211236952 U CN211236952 U CN 211236952U
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Abstract
The utility model discloses a non-integrated IC's RFID radio frequency identification tag read-write circuit, its characterized in that: the antenna comprises an antenna coil, an antenna matching circuit, a detection circuit, a comparison circuit and a decoding circuit which are connected in sequence. The utility model does not adopt an integrated radio frequency chip, has simple circuit and greatly reduces the production cost; the antenna design requirement of the radio frequency tag read-write circuit is greatly reduced, and the debugging on the card reading distance and the card reading stability is convenient; the RFID tags with different sizes and shapes have strong compatibility and are convenient to debug.
Description
Technical Field
The utility model relates to a RFID radio frequency identification label reading and writing technical field, concretely relates to non-integrated IC's RFID radio frequency identification label reading and writing circuit.
Background
At present, the read-write modules of the RFID radio frequency tags which are popular in the market are all circuits built by integrated IC chips, users can only debug the card reading characteristics of the RFID through adjusting the read-write card antenna of the module, and once the antenna is fixed, the read-write card characteristics are already fixed. For example, the card reading distance and the card reading stability cannot be completely adapted to tags of different sizes and different shapes through fixed antennas, so that one antenna can only be adapted to read and write one tag or a small number of tags. Moreover, the antenna has a very large influence on card reading and the design requirement is also very high. The antenna type is not fixed as a PCB antenna, and can also be externally connected with a coil antenna. The inductance of the antenna is generally 0.5 uH-2 uH. However, such a small inductance is very difficult to test, and especially, the PCB antenna is greatly affected by the circuit, and is difficult to calculate before design and difficult to change after design.
SUMMERY OF THE UTILITY MODEL
Based on prior art's is not enough, the utility model aims at providing a non-integrated IC's RFID radio frequency identification read write circuit overcomes integrated RFID radio frequency identification read write module and can only debug through adjusting the antenna and read the card distance and read the problem of card stability, overcomes the not compatible poor problem of RFID label of equidimension, different shapes, solves the antenna design degree of difficulty height, debugging difficulty and receives the big problem of circuit influence simultaneously.
The technical scheme of the utility model is that:
a RFID radio frequency label read-write circuit of non-integrated IC, its characterized in that: the antenna comprises an antenna coil, an antenna matching circuit, a detection circuit, a comparison circuit and a decoding circuit which are connected in sequence;
the antenna coil is used for transmitting the control signal to the RFID label in a magnetic field coupling mode and returning the modulation signal returned by the RFID label to the antenna matching circuit;
the antenna matching circuit is used for matching the RFID label and the signal intensity thereof and adjusting the read-write stability by adjusting the read-write distance between the read-write module and the RFID label;
the detection circuit is used for detecting the return signal of the RFID label, filtering interference signals, and detecting useful signals and transmitting the useful signals to the comparison circuit;
the comparison circuit is used for comparing and amplifying the useful signals returned by the detection circuit, and converting the analog signals into digital signals which can be identified by the decoding circuit for decoding;
and the decoding circuit is used for controlling the digital signal returned by the comparison circuit, decoding the digital signal according to the RFID tag communication protocol standard ISO14443A and acquiring data information.
Furthermore, the antenna matching circuit comprises a first resistor R41, a first capacitor C42, a second C45, a third capacitor C43, a fourth capacitor C46 and a first inductance coil L5, a first end of the first resistor R41 is connected to the control chip, the control chip sends a card reading command, a second end of the first resistor R41 is respectively connected to a first end of the first capacitor C42 and a first end of the second capacitor C45, a connecting line connecting the second end of the first capacitor C42 and a second end of the second capacitor C45 is respectively connected to a first end of the third capacitor C46, a first end of the fourth capacitor C43 and a first end of the first inductance L5, a second end of the third capacitor C46 and a second end of the fourth capacitor C43 are grounded, a second end of the first inductance L5 is connected to an input end of the detection circuit, a second end of the first inductance L5 is further connected to a first end of the antenna coil, and a second end of the antenna coil is connected to a second resistor R44, the second terminal of the second resistor R44 is connected to ground.
Further, the detector circuit includes a fifth capacitor C47, a third resistor R45, a fourth resistor R42, a sixth capacitor C44, a seventh capacitor C41, and a fifth resistor R43, a first end of the fifth capacitor C47 is connected to the output end of the antenna matching circuit, a first end of the fifth capacitor C47 is further connected to a first end of the third resistor R45 and a first end of the fourth resistor R42, a second end of the fourth resistor R42 is connected to a first end of the sixth capacitor C44 and a first end of the seventh capacitor C41, a second end of the sixth capacitor C44 is connected to a first end of the fifth resistor R43, a second end of the seventh capacitor C41 is connected to a second end of the fifth resistor R43, a second end of the fifth capacitor C47 and a second end of the third resistor R45 are respectively connected to a first end of the fifth resistor R43, and a second end of the fifth resistor R43 is an output end of the detector circuit.
Further, the comparison circuit includes a comparison chip, a first stage comparison signal input terminal of the comparison chip is connected to a second terminal of the fifth resistor R43, a second terminal of the fifth resistor R43 is connected to a first terminal of the sixth resistor R37, a second terminal of the sixth resistor R37 is connected to a first threshold voltage signal input terminal of the comparator circuit corresponding to the first stage comparison signal, a second terminal of the sixth resistor R37 is further connected to a first terminal of the seventh resistor R34 and a first terminal of the eighth resistor R38, respectively, a second terminal of the eighth resistor R38 is grounded, a first voltage is set by the seventh resistor R34 and the eighth resistor R38, a second terminal of the seventh resistor R34 is connected to a power supply terminal of the comparison circuit and a first terminal of the ninth resistor R35 and a first terminal of the tenth resistor R33, a second terminal of the ninth resistor R35 is connected to a first terminal of the eleventh resistor R39 and a second threshold voltage signal input terminal of the comparison chip, the second end of the eleventh resistor R39 is grounded, a second threshold voltage is set by the ninth resistor R35 and the eleventh resistor R39, the second end of the tenth resistor R33 is connected to the first-stage comparison signal output end of the comparator chip and the first end of the twelfth resistor R40, the second end of the twelfth resistor R40 is grounded, the second end of the twelfth resistor R40 is also connected to the second-stage comparison signal input end, and the second-stage comparison signal output end of the control chip is the comparison signal output end of the comparison circuit.
Furthermore, the comparison chip is a comparator chip with the model of LM393, the first-stage comparison signal input terminal is a pin 5, the first threshold voltage signal input terminal is a pin 6, the first comparison signal output terminal is a pin 7, the second-stage comparison signal input terminal is a pin 3, the second threshold voltage signal input terminal is a pin 2, and the comparison signal output terminal is a pin 1.
The utility model has the advantages that: the utility model does not adopt an integrated radio frequency chip, has simple circuit and greatly reduces the production cost; the antenna design requirement of the radio frequency tag read-write circuit is greatly reduced, and the debugging on the card reading distance and the card reading stability is convenient; the RFID tags with different sizes and shapes have strong compatibility and are convenient to debug.
Drawings
FIG. 1 is a schematic circuit diagram of the present embodiment;
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the features of the following embodiments and examples may be combined with each other without conflict.
As shown in fig. 1, an RFID rf tag read/write circuit of a non-integrated IC is characterized in that: the antenna comprises an antenna coil, an antenna matching circuit, a detection circuit, a comparison circuit and a decoding circuit which are connected in sequence;
the antenna coil is used for transmitting a 13.56MHz control signal to the RFID tag in a magnetic field coupling mode and returning a modulation signal returned by the RFID tag to the antenna matching circuit; it should be noted that both the control signal for reading the card and the response signal returned by the RFID tag are transmitted by the magnetic field coupling of the antenna coil.
The antenna coil of the embodiment has a simple structure, is not limited by high requirements of the traditional integrated radio frequency chip on the inductance value, the impedance matching and the antenna shape of the antenna, and can be a PCB antenna or an external coil antenna. The antenna design only needs to consider the size of the wire diameter and the number of turns of the antenna. Such as: the diameter of the PCB antenna is smaller than 40mm of a circular antenna or the length and the width of the PCB antenna are smaller than 35mm of a square antenna, and the number of turns of the antenna is 4. The diameter and the length and the width of the picture are less than 20mm, and 6 circles can be considered to be drawn (the number of circles is more than that of two sides). A round antenna with the length and width larger than 40mm and a square antenna with the length and width larger than 35mm are drawn for 3 circles. The thickness of the wire is 0.2-1 mm, the wire distance is the same as the thickness of the wire, and meanwhile, the large-area copper coating is not carried out in the antenna area. The optimum reading distance is about 0.7 times the antenna diameter.
The antenna matching circuit is used for matching the RFID label and the signal intensity thereof and adjusting the read-write stability by adjusting the read-write distance between the read-write module and the RFID label;
the antenna matching circuit comprises a first resistor R41, a first capacitor C42, a second capacitor C45, a third capacitor C43, a fourth capacitor C46 and a first inductance coil L5, wherein a first end of the first resistor R41 is connected with a control chip, the control chip sends a card reading command, a first end of the first resistor R41 of the antenna matching circuit is connected with a crystal oscillator connection port of the control chip, the port directly outputs 13.56MHz carrier pulses, a second end of the first resistor R41 is respectively connected with a first end of a first capacitor C42 and a first end of a second capacitor C45, a connecting wire formed by connecting a second end of the first capacitor C42 and a second end of the second capacitor C45 is respectively connected with a first end of the third capacitor C46, a first end of the fourth capacitor C43 and a first end of the first inductance L5, a second end of the third capacitor C46 and a second end of the fourth capacitor C43 are grounded, and a second end of the first inductance L5 is connected with an input end of the detection circuit, the second end of the first inductor L5 is further connected to the first end of the antenna coil, the second end of the antenna coil is connected to the first end of the second resistor R44, and the second end of the second resistor R44 is grounded. And adjusting the capacitance values and the positions of the RFID tags relative to the antenna coil, and matching the carrier intensity returned by the RFID tag information.
The smaller the second resistor R44, the higher the Q value. The higher the Q value, the farther the card reading distance is, but too high Q value can cause the circuit to have poor anti-interference capability, easily affected by environment to cause circuit frequency deviation, and the card is not read or picked. The lower the Q value, the more stable the reading but the lower the distance. The resistance value is 1-10 ohm. 2 ohm may be taken.
In addition, the C42 and the C45 are matching capacitors, different cards may have different values, and different card manufacturers and different processes of the same RFID radio frequency chip in the card manufacturing process cause different impedance of the card due to different selected card antennas. When the impedance of the card and the antenna circuit is not matched, the card reading distance is short, the card cannot be read, or the card cannot be read or written, so that the matching capacitor needs to try to determine a plurality of cards.
The value ranges of C46 and C43 are 30-120 PF, and the optimal value is 56 pF. The debugging can be performed according to the selected card. According to the circuit, only C42 and C46 or C45 and C43 need to be debugged to adjust the card reading distance and card reading stability and adjust the compatibility of RFID tags with different sizes and shapes.
The adjusting process comprises the following steps:
the first step is as follows: firstly, selecting C42 and C45, and changing C46 into an adjustable capacitor;
the second step is that: placing an RFID label on an antenna, and enabling a control chip to continuously send a card reading instruction according to a communication protocol;
the third step: and measuring the waveforms at the two ends of C46 and C43 by using an oscilloscope, and adjusting the values of C46 and C43 back and forth to maximize the ratio of the useful signal amplitude value to the fundamental wave signal amplitude value of the sensing waveforms at the two ends of C46 and C43.
It should be noted that the useful signal is modulated on the fundamental wave signal, and the useful signal must be analyzed on the basis of the fundamental wave during demodulation, where the fundamental wave signal is the basic signal, and since the signal returned by the RFID tag is a sine wave, we only need negative half waves for decoding, so the useful signal is obtained after filtering out the sine wave interference signal.
The detection circuit is used for detecting the return signal of the RFID label, filtering interference signals, and detecting useful signals and transmitting the useful signals to the comparison circuit;
the embodiment uses a diode for amplitude detection according to the modulation characteristics of the feedback signal of the RFID card, and particularly, the detector circuit comprises a fifth capacitor C47, a third resistor R45, a fourth resistor R42, a sixth capacitor C44, a seventh capacitor C41 and a fifth resistor R43, the first end of the fifth capacitor is connected with the output end of the antenna matching circuit, the first end of the fifth capacitor is further connected with the first end of the third resistor and the first end of the fourth resistor, the second end of the fourth resistor is connected with the first end of the sixth capacitor C44 and the first end of the seventh capacitor C41, the second end of the sixth capacitor C44 is connected with the first end of the fifth resistor R43, the second end of the seventh capacitor C41 is connected with the second end of the fifth resistor R43, the second end of the fifth capacitor C47 and the second end of the third resistor R45 are respectively connected with the first end of the fifth resistor R43, and the second end of the fifth resistor R43 is the output end of the detection circuit.
The D12 detection diode takes negative half-wave waveform, C47 carries out filtering and direct current clamping, R42 and C44 are low-pass filtering, and C41 and R43 carry out high-pass filtering and direct current blocking.
The comparison circuit is used for comparing and amplifying the useful signals returned by the detection circuit, and converting the analog signals into digital signals which can be identified by the decoding circuit for decoding;
the comparison circuit comprises a comparison chip, a first-stage comparison signal input end of the comparison chip is connected with a second end of a fifth resistor R43, a second end of a fifth resistor R43 is connected with a first end of a sixth resistor R37, a second end of a sixth resistor R37 is connected with a first threshold voltage signal input end of the comparator circuit corresponding to a first-stage comparison signal, a second end of the sixth resistor R37 is further respectively connected with a first end of a seventh resistor R34 and a first end of an eighth resistor R38, a second end of the eighth resistor R38 is grounded, a first threshold voltage is set by the seventh resistor R34 and the eighth resistor R38, a second end of the seventh resistor R34 is respectively connected with a power supply end of the comparison circuit, a first end of a ninth resistor R35 and a first end of a tenth resistor R33, a second end of a ninth resistor R35 is respectively connected with a first end of an eleventh resistor R39 and a second threshold voltage signal input end of the comparison chip, and a second end of an eleventh resistor R39 is grounded, the ninth resistor R35 and the eleventh resistor R39 set a second threshold voltage, the second end of the tenth resistor R33 is connected to the first-stage comparison signal output end of the comparator chip and the first end of the twelfth resistor R40 respectively, the second end of the twelfth resistor R40 is grounded, the second end of the twelfth resistor R40 is also connected to the second-stage comparison signal input end, and the second-stage comparison signal output end of the control chip is the comparison signal output end of the comparison circuit. The comparison chip adopts a comparator chip with the model of LM393, the first comparison signal input end is a pin 5, the first threshold voltage signal input end is a pin 6, the first comparison signal output end is a pin 7, the second comparison signal input end is a pin 2, the second threshold voltage signal input end is a pin 3, and the comparison signal output end is a pin 1. The circuits R34 and R38 determine a first threshold voltage of a first-stage comparison circuit, R35 and R39 determine a second threshold voltage of a second-stage comparison circuit, a high-frequency analog input signal is compared with a threshold set by IN 2-from an IN2+ input, a comparison result is output to IN1+ from OUT2, and an IN1+ input is compared with the threshold set by IN 1-so as to carry OUT two-stage comparison, and a square wave signal with upper and lower limits is obtained and is output to a decoding circuit for decoding by OUT 1.
And the decoding circuit is used for controlling the digital signal returned by the comparison circuit, decoding the digital signal according to the RFID tag communication protocol standard ISO14443A and acquiring data information. The decoding circuit of the embodiment is composed of an 8-bit or 32-bit MCU, and mainly decodes the digital signal according to the RFID tag communication protocol standard ISO14443A to acquire data information.
The above embodiments are only intended to represent the concentrated embodiments of the present invention, and the description thereof is more specific and detailed, but it is not to be understood as the limitation of the scope of the present invention, and it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the concept of the present invention, and all of them belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (5)
1. A RFID radio frequency label read-write circuit of non-integrated IC, its characterized in that: the antenna comprises an antenna coil, an antenna matching circuit, a detection circuit, a comparison circuit and a decoding circuit which are connected in sequence;
the antenna coil is used for transmitting the control signal to the RFID label in a magnetic field coupling mode and returning the modulation signal returned by the RFID label to the antenna matching circuit;
the antenna matching circuit is used for matching the RFID label and the signal intensity thereof and adjusting the read-write stability by adjusting the read-write distance between the read-write module and the RFID label;
the detection circuit is used for detecting the return signal of the RFID label, filtering interference signals, and detecting useful signals and transmitting the useful signals to the comparison circuit;
the comparison circuit is used for comparing and amplifying the useful signals returned by the detection circuit, and converting the analog signals into digital signals which can be identified by the decoding circuit for decoding;
and the decoding circuit is used for controlling the digital signal returned by the comparison circuit, decoding the digital signal according to the RFID tag communication protocol standard ISO14443A and acquiring data information.
2. The non-integrated IC RFID radio frequency tag read-write circuit of claim 1, wherein: the antenna matching circuit comprises a first resistor R41, a first capacitor C42, a second capacitor C45, a third capacitor C43, a fourth capacitor C46 and a first inductance coil L5, the first end of the first resistor R41 is connected with a control chip, the control chip sends a card reading instruction, the second end of the first resistor R41 is connected to the first end of the first capacitor C42 and the first end of the second capacitor C45, the second end of the first capacitor C42 and the second end of the second capacitor C45 are connected to a connecting line, and then connected to the first end of the third capacitor C46, the first end of the fourth capacitor C43 and the first end of the first inductor L5, the second end of the third capacitor C46 and the second end of the fourth capacitor C43 are grounded, the second end of the first inductor L5 is connected to the input end of the detector circuit, the second end of the first inductor L5 is further connected to the first end of the antenna coil, the second end of the antenna coil is connected to the first end of the second resistor R44, and the second end of the second resistor R44 is grounded.
3. The non-integrated IC RFID radio frequency tag read-write circuit of claim 1, wherein: the detector circuit comprises a fifth capacitor C47, a third resistor R45, a fourth resistor R42, a sixth capacitor C44, a seventh capacitor C41 and a fifth resistor R43, wherein the first end of the fifth capacitor C47 is connected with the output end of the antenna matching circuit, the first end of the fifth capacitor C47 is further connected with the first end of the third resistor R45 and the first end of the fourth resistor R42, the second end of the fourth resistor R42 is connected with the first end of the sixth capacitor C44 and the first end of the seventh capacitor C41, the second end of the sixth capacitor C44 is connected with the first end of the fifth resistor R43, the second end of the seventh capacitor C41 is connected with the second end of the fifth resistor R43, the second end of the fifth capacitor C47 and the second end of the third resistor R45 are respectively connected with the first end of the fifth resistor R43, and the second end of the fifth resistor R43 is the output end of the detector circuit.
4. The non-integrated IC RFID radio frequency tag read-write circuit of claim 3, wherein: the comparison circuit comprises a comparison chip, a first-stage comparison signal input end of the comparison chip is connected with a second end of a fifth resistor R43, a second end of a fifth resistor R43 is connected with a first end of a sixth resistor R37, a second end of a sixth resistor R37 is connected with a first threshold voltage signal input end of the comparator circuit corresponding to a first-stage comparison signal, a second end of the sixth resistor R37 is further respectively connected with a first end of a seventh resistor R34 and a first end of an eighth resistor R38, a second end of the eighth resistor R38 is grounded, a first threshold voltage is set by the seventh resistor R34 and the eighth resistor R38, a second end of the seventh resistor R34 is respectively connected with a power supply end of the comparison circuit, a first end of a ninth resistor R35 and a first end of a tenth resistor R33, a second end of a ninth resistor R35 is respectively connected with a first end of an eleventh resistor R39 and a second threshold voltage signal input end of the comparison chip, and a second end of an eleventh resistor R39 is grounded, the ninth resistor R35 and the eleventh resistor R39 set a second threshold voltage, the second end of the tenth resistor R33 is connected to the first-stage comparison signal output end of the comparator chip and the first end of the twelfth resistor R40 respectively, the second end of the twelfth resistor R40 is grounded, the second end of the twelfth resistor R40 is also connected to the second-stage comparison signal input end, and the second-stage comparison signal output end of the control chip is the comparison signal output end of the comparison circuit.
5. The non-integrated IC RFID radio frequency tag read-write circuit of claim 4, wherein: the comparison chip adopts a comparator chip with the model of LM393, the first-stage comparison signal input end is a pin 5, the first threshold voltage signal input end is a pin 6, the first comparison signal output end is a pin 7, the second-stage comparison signal input end is a pin 3, the second threshold voltage signal input end is a pin 2, and the comparison signal output end is a pin 1.
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| CN202020180072.XU CN211236952U (en) | 2020-02-18 | 2020-02-18 | RFID radio frequency tag read-write circuit of non-integrated IC |
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| CN202020180072.XU CN211236952U (en) | 2020-02-18 | 2020-02-18 | RFID radio frequency tag read-write circuit of non-integrated IC |
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