CN102930237B - The low frequency card reader arrangement of three kinds of modulation systems can be identified based on EM4095 - Google Patents
The low frequency card reader arrangement of three kinds of modulation systems can be identified based on EM4095 Download PDFInfo
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- CN102930237B CN102930237B CN201210421523.4A CN201210421523A CN102930237B CN 102930237 B CN102930237 B CN 102930237B CN 201210421523 A CN201210421523 A CN 201210421523A CN 102930237 B CN102930237 B CN 102930237B
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Abstract
The present invention relates to a kind of low frequency card reader arrangement that can identify three kinds of modulation systems based on EM4095.Existing reader identification mode is single.The present invention includes single-chip microcomputer main control module, transmission unit and be connected with described single-chip microcomputer main control module and the module for reading and writing based on EM4095 controlled by it, LCD LCD MODULE, key circuit.The described module for reading and writing based on EM4095 can be used for the data message of demodulation ASK, FSK, PSK tri-kinds of modulation systems.The present invention is compatible three kinds of hardware protocols, i.e. FSK modulation mode, PSK modulation system, ASK modulation mode, and radio-frequency card internal information can be identified rapidly, like clockwork, and show on LCD liquid crystal.
Description
Technical field
The invention belongs to radio RF recognition technology field, relate to a kind of low frequency card reader arrangement that can identify three kinds of modulation systems based on EM4095.
Background technology
RFID(Radio Frequency Identification Technology) radio RF recognition technology, be a non-contacting automatic identification technology, it utilizes radiofrequency signal to realize contactless information transmission by Space Coupling and passes through the technology that transmitted information reaches identifying purpose.Radio-frequency card is a kind of contactless read-write card, it is the novel storage card of a kind of difference IC-card or magnetic card in the past, there is information processing rate fast, nothing is worn and torn, memory data output is large, the feature of long service life, is widely used in the numerous areas such as industry, enterprise, business, traffic, transport, control and management.Meanwhile, along with the widespread use of radio-frequency card, identify radio-frequency card equipment---the demand of card reader is also increasing.At present, the application of the card reader in low frequency frequency range field or comparative maturity, but the product developed all can only identify single radio-frequency card.
Low-frequency radio frequency card is divided by the modulation system of signal three types, i.e. FSK mode, PSK mode, ASK mode.Commercially low frequency card reader has purposes very widely at present, as gate control system, anti-theft locking system of automobile engine, handheld reader etc., and has also brought a lot of facilities.But due to the unicity of reader identification, make its universal performance bad, can not identify other types radio-frequency card, some application units even may apply multiple stage card reader, and this greatly reduces work efficiency simultaneously.Therefore, versatility low frequency card reader that is better, that can identify polytype radio-frequency card is developed extremely urgent.
Summary of the invention
The present invention is directed to the defect of above-mentioned technology, propose a kind of low frequency card reader arrangement that can identify three kinds of modulation systems based on EM4095.
In order to solve the problems of the technologies described above, technical scheme of the present invention is as follows:
The low frequency card reader arrangement of three kinds of modulation systems can be identified based on EM4095, comprise single-chip microcomputer main control module, transmission unit and be connected with described single-chip microcomputer main control module and the module for reading and writing based on EM4095 controlled by it, LCD LCD MODULE, key circuit.The described module for reading and writing based on EM4095 can be used for the data message of demodulation ASK, FSK, PSK tri-kinds of modulation systems, specifically its span is limited to the filter capacitor be connected with EM4095 chip 16 pin in the module for reading and writing peripheral circuit of described EM4095, this span is 150pF-330pF, thus realizes the demodulation of ASK, FSK, PSK tri-kinds of modulation systems.
Furtherly, described transmission unit is 125K antenna.
Beneficial effect of the present invention is: by designing a kind of low frequency card reader arrangement that can identify three kinds of modulation systems based on EM4095, can identify polytype radio-frequency card, which greatly enhances the versatility of low frequency card reader in most application.This card reader is compatible three kinds of hardware protocols, i.e. FSK modulation mode, PSK modulation system, ASK modulation mode, and radio-frequency card internal information can be identified rapidly, like clockwork, and show on LCD liquid crystal.A card reader can identify polytype radio-frequency card simultaneously, and this reduces resources costs to undoubtedly a lot of application vendor, also brings a lot of facilities.The whole apparatus structure of card reader is simple, and cost is also lower, is applicable to large-scale production.
Accompanying drawing explanation
Fig. 1 is the structural representation of apparatus of the present invention;
Fig. 2 is the module for reading and writing circuit diagram based on EM4095 in apparatus of the present invention;
When Fig. 3 is apparatus of the present invention identification EM4100 card (namely modulation system is ASK), the digital signal after the modulation signal of gained and demodulation;
When Fig. 4 is apparatus of the present invention identification INDALA card (namely modulation system is PSK), the digital signal after the modulation signal of gained and demodulation;
When Fig. 5 is apparatus of the present invention identification HID card (namely modulation system is FSK), the digital signal after the modulation signal of gained and demodulation.
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention will be further described.
As shown in Figure 1, the present embodiment adopt low-power consumption, high performance STM32 single-chip microcomputer main control module, 125K antenna and be connected with described main control module and the module for reading and writing based on EM4095 controlled by it, LCD LCD MODULE, key circuit.Specifically, system adopts STM32F103 single-chip microcomputer as main control module, by I/O mouth, controls by the deciphering of EM4095 demodulation original data signal out and display.Described 125K aerial coil is connected with two shown in Fig. 2 shunt capacitance C221, a C222, form resonant tank, and resonance is in 125KHz.When the radio-frequency card of 125KHz is placed on aerial coil, resonant tank produces alternating magnetic field with the telefault in card, thus starts to exchange data.Described EM4095 module for reading and writing demodulation is by the data message of gained after described 125K aerial coil and radio-frequency card exchange data.Described LCD LCD MODULE adopts 84*84 dot matrix LCD, NOKIA5110 Liquid Crystal Module, and it shows the information after reading card number by STM32 Single-chip Controlling.Described key circuit, by STM32 Single-chip Controlling, adopts three buttons to operate LCD, represent respectively upper and lower, determine to return button.
As shown in Figure 2, radio-frequency module is the module for reading and writing based on EM4095.The electric capacity that the module for reading and writing circuit of described EM4095 can realize the sampling of DC filtering, rf filtering, power decoupling and direct current by EM4095 chip and some forms.
In general, the low frequency card reader based on EM4095 can not identify these two kinds of modulation systems of FSK and PSK, in more present application, also can only see its identification to ASK modulation mode.Based on the load signal that FSK, PSK, ASK tri-kinds of modulation systems are all the common 125KHz of modulation, as long as and all just can be realized the feature of perfect restitution by this load signal of filtering, we are studied EM4095, make it successfully achieve demodulation to FSK, PSK, ASK tri-kinds of modulation systems.
EM4095 is one piece of transceiver circuit integrated chip, mainly contains two functions: transmission and reception.In order to realize the identification to three kinds of modulation, we are mainly studied the circuit of receiving unit and the mode of three kinds of modulation.Receiving circuit by maintenance of sampling, go DC component, bandpass filter and comparer to form, this is the process of a signal receiving.In this process, the key distinction of three kinds of modulation signals is exactly when their logical samplings keep and after going DC component, the signal obtained is to the band requirement of bandpass filter.
Rfid system adopts digital modulation mode to transmit information usually, and modulation signal (comprising digital baseband signal and modulated pulse) offset of sinusoidal carrier wave is modulated.ASK is the abbreviation of amplitude shift key modulation, realizes modulation by the amplitude controlling the higher-order of oscillation.Here we illustrate EM4100 card, and it realizes 100% AM depth by adopting Manchester's cde modulation, and the carrier wave recycling different amplitude carrys out transmitting digital information, generally represent different amplitudes with binary zero and " 1 ".When carrier signal is through coding and modulation, data rate is RF/64; FSK is frequency shift keyed abbreviation, realizes modulation by the frequency controlling the higher-order of oscillation.Here we illustrate HID card, and it is modulated subcarrier by the FSK modulating wave of NRZ code, and the carrier wave of recycling different frequency carrys out transmitting digital information, generally represent RF/8 and RF/10 two kinds of frequencies respectively with binary zero and " 1 "; When carrier signal is through coding and modulation, data rate is RF/50; PSK is the abbreviation of phase-shift keying (PSK), realizes modulation by the phase place controlling the higher-order of oscillation.Here we illustrate INDALA card, it is modulated subcarrier by the PSK modulating wave of NRZ code, recycling digital pulse signal controls carrier phase and carrys out transmitting digital information, when carrier signal is through coding and modulation, data rate is RF/32, generally represents phase place 0 and π respectively with binary zero and " 1 ".In sum, the data rate that carrier signal obtains through three kinds of different codings and modulation is different, and in order to enable the signal unsuccessful demodulation of these three kinds of different pieces of information speed, this just needs system to have a rational bandwidth.
Input signal is the voltage that antenna detects, i.e. modulation signal.In order to make signal enough strong, and can obtain the Q value that can ensure communication bandwidth, revise resonant capacitance C221, C217, C219 on antenna resonance loop, modified values is as Fig. 2; Input signal is by after external capacitive voltage divider C217, C219 adjustment, chip is inputted by chip pin DEMOD_IN, through over-sampling keep and after going DC component, enter bandpass filter and carry out filtering, in order to can enable three kinds of modulation signals complete be filtered off waveform, we have modified the external capacitive C225 of influence zone bandpass filter, its effect is the remaining carrier signal of filtering, as Fig. 2, make the value of C225 into 220pF from 6800pF, enable bandpass filter obtain one and can realize simultaneously to the bandwidth of the complete filtering of three kinds of signals.Finally, signal enters asynchronous comparator, then exports restituted signal by pin DEMOD_OUT, same, as long as the value of C225 is between 150pF-330pF, all can realize the demodulation of three kinds of modulation signals.
As shown in Figure 3, apparatus of the present invention (i.e. a kind of low frequency card reader arrangement that can identify three kinds of modulation systems based on EM4095) are the modulation /demodulation of the radio-frequency card of ASK to modulation system.EM4100 card is modulation system is one of radio-frequency card of ASK, for EM4100 card, carries out modulation /demodulation, as Fig. 3 to it.Described EM4100 card, its data rate is RF/64, and adopt Manchester coding method, data length is 64.Decode procedure adopts the input capture function of STM32 timer internal to detect the output signal of EM4095.Half bit pulse length is 32*8=256us 125KHz.Need to capture 128 half bit data.In logic these 128 " subluxation " data are used as a buffer circle, judge that 128 data are that odd term or even item are effective.This ordered sequence is exactly 64 original bit data, then this 64 bit data is decoded as a buffer circle in logic.The implication of 64 bit data provides in the databook of card, and verification correctly then can draw card number.
As shown in Figure 4, apparatus of the present invention (i.e. a kind of low frequency card reader arrangement that can identify three kinds of modulation systems based on EM4095) are the modulation /demodulation of the radio-frequency card of PSK to modulation system.INDALA card is modulation system is one of radio-frequency card of PSK, for INDALA card, carries out modulation /demodulation, as Fig. 4 to it.Described INDALA card, its raw data has 64 and 224 two kinds.The relation of card number and raw data do not known by this card yet.Data rate is RF/32.Method is detection two secondary data, if the same thinks and meets form.
As shown in Figure 5, apparatus of the present invention (i.e. a kind of low frequency card reader arrangement that can identify three kinds of modulation systems based on EM4095) are the modulation /demodulation of the radio-frequency card of FSK to modulation system.HID card is modulation system is one of radio-frequency card of FSK, for HID card, carries out modulation /demodulation, as Fig. 5 to it.Described HID card, its data rate is RF/50.0 and 1 uses RF/8 and RF/10 two kinds of frequency representations respectively.If there is the frequency representation logical zero of 6.25 RF/8 continuously, if there is the frequency representation logical one of 5 RF/10 continuously.When carrier frequency is 125K, the frequency of these two kinds of signals is respectively 15.625K and 12.5K.
The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, without departing from the inventive concept of the premise; can also make some improvements and modifications, these improvements and modifications also should be considered within the scope of protection of the present invention.
Claims (2)
1. the low frequency card reader arrangement of three kinds of modulation systems can be identified based on EM4095, comprise single-chip microcomputer main control module, transmission unit and being connected with described single-chip microcomputer main control module and the module for reading and writing based on EM4095 controlled by it, LCD LCD MODULE and key circuit, it is characterized in that: the described module for reading and writing based on EM4095 can be used for demodulation ASK, FSK, the data message of PSK tri-kinds of modulation systems, specifically its capacitance is limited to the filter capacitor be connected with EM4095 chip 16 pin in the module for reading and writing peripheral circuit of described EM4095, the span of this capacitance is 150pF-330pF, thus realize ASK, FSK, the demodulation of PSK tri-kinds of modulation systems.
2. the low frequency card reader arrangement that can identify three kinds of modulation systems based on EM4095 according to claim 1, is characterized in that: described transmission unit is 125K antenna.
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| CN201210421523.4A CN102930237B (en) | 2012-10-29 | 2012-10-29 | The low frequency card reader arrangement of three kinds of modulation systems can be identified based on EM4095 |
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| CN201210421523.4A CN102930237B (en) | 2012-10-29 | 2012-10-29 | The low frequency card reader arrangement of three kinds of modulation systems can be identified based on EM4095 |
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| CN102930237A CN102930237A (en) | 2013-02-13 |
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| CN101561889A (en) * | 2008-04-18 | 2009-10-21 | 上海坤锐电子科技有限公司 | SIM card chip with radio frequency identification function |
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| WO2002052485A1 (en) * | 2000-12-22 | 2002-07-04 | Gallagher Group Limited | Improved identification reader |
| CN1488118A (en) * | 2000-12-22 | 2004-04-07 | 加拉格尔集团有限公司 | Improved identification reader |
| CN201156257Y (en) * | 2008-02-20 | 2008-11-26 | 福建师范大学 | Data reading circuit for low frequency radio frequency IC card suitable for low voltage and corresponding apparatus |
| CN101561889A (en) * | 2008-04-18 | 2009-10-21 | 上海坤锐电子科技有限公司 | SIM card chip with radio frequency identification function |
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| 基于FPGA的ASK、PSK、FSK信号的设计与实现;贾达等;《兰州石化职业技术学院学报》;20070630;第7卷(第2期);第20-22页 * |
| 基于RF前端芯片EM4095的RFID阅读器设计;曾庆远等;《2008年中国西部青年通信学术》;20081201;第515-521页 * |
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Effective date of registration: 20201202 Address after: No. 200, Majiazhai Road, Nanqiao Town, Fengxian District, Shanghai, 201401 Patentee after: SHANGHAI INTER-ROCK HARDWARE Co.,Ltd. Address before: Hangzhou City, Zhejiang province 310018 Xiasha Higher Education Park No. 2 street Patentee before: HANGZHOU DIANZI University |
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Granted publication date: 20150812 Termination date: 20211029 |