JP2010183423A - Non-contact type communication apparatus, and decoder thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform communication in accordance with a plurality of kinds of communication schemes by enabling a communication scheme to be specified in a "target" of two-way communication of NFC. <P>SOLUTION: A reception signal sampling section 31 inputs a demodulation signal and performs sampling at a predetermined sampling frequency during a predetermined sampling period from a top of the reception frame. A data pattern collating section 32 holds a pattern for each communication scheme beforehand and collates a result of the sampling with each of the patterns. A counter section 33 counts the number of matched bits from a result of the collation. A determination section 34 compares the count value with a threshold to determine a communication scheme. A data value in a leading portion of the demodulation signal is fixedly "0" even in any communication scheme. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a non-contact type communication device and a data decoding method, and more particularly to a non-contact type communication device including a non-contact IC card reader / writer capable of performing communication using a plurality of different communication methods, and a data decoding method.

  In recent years, contactless IC cards have been widely used in fields such as electronic money and electronic tickets. The non-contact IC card system is composed of a reader / writer and a non-contact IC card, and the non-contact IC card activates an internal IC by a magnetic field radiated from the reader / writer. Communication from the reader / writer to the non-contact IC card is realized by modulating the amplitude of the radiated magnetic field, and communication from the non-contact IC card to the reader / writer is performed with respect to the magnetic field radiated by the reader / writer. This is done by switching the load (load modulation) and detecting this by the reader / writer.

  There are a plurality of communication systems such as types A, B, and C shown in FIG. 7 as proximity type communication systems between the IC card and the reader / writer, and specifications such as encoding, modulation system, and transfer rate are different. Even in the same type, specifications such as encoding, modulation method, and transfer rate may differ between “reader / writer → IC card” and “IC card → reader / writer”.

FIGS. 9A to 9E show examples of waveforms at the time of communication in various communication systems for communication between the IC card and the reader / writer.
FIG. 9A shows a waveform at the time of “reader / writer → IC card” communication of the type A communication method.

  In the communication system of type A, at the time of “reader / writer → IC card” communication, the transfer rate is 106 kbps, ASK (Amplitude Shift Keying) modulation is performed with a deformed mirror code, and the magnetic field output in the bit data section is stopped (referred to as a pause pulse). ) Represents 1 and 0 data. The logic (data value) “1” indicates that there is a pause pulse at the center of the bit data, and the logic (data value) “0” indicates that there is a pause pulse at the beginning of the bit data and there is no pause pulse. The start of the communication frame has a start bit of 1 bit (data value 0).

FIG. 9B shows a waveform at the time of “IC card → reader / writer” communication of the type A communication method.
In the type A communication method, during “IC card → reader / writer” communication, the transfer rate is 106 kbps, and the Manchester code is OOK (ON OFF Keying) modulated with a subcarrier 847 kHz, thereby expressing 1,0 data. The case where there is a subcarrier in the first half of bit data is logic “1”, and the case where there is a subcarrier in the second half of bit data is logic “0”. The start of the communication frame has a 1-bit start bit (data value 1).

FIG. 9C shows a waveform at the time of “reader / writer → IC card” communication of the type B communication method.
In the communication method of type B, during “reader / writer → IC card” communication, the transfer rate is 106 kbps, and ASK modulation is performed with an NRZ code to express 1,0 data. A state where the amplitude of the carrier wave is large (unmodulated state) is a logic “1”, and a state where the amplitude of the carrier wave is small is a logic “0”. The start bit of the data portion of the communication frame has 1 bit (data value 0).

FIG. 9D shows a waveform at the time of “IC card → reader / writer” communication of the type B communication method.
In the type B communication system, during “IC card → reader / writer” communication, the transfer rate is 106 kbps, and BPSK (Binary Phase Shift Keying) modulation is performed on the subcarrier 847 kHz with the NRZ code, thereby expressing 1 and 0 data. The initial output phase state of the subcarrier is set to logic “1”, and the subsequent phase shift is set to “0 → 1 → 0 →. The start bit of the data portion of the communication frame has 1 bit (data value 0).

FIG. 9E shows waveforms at the time of “IC card → reader / writer” and “IC card → reader / writer” communication of the type C communication method.
In the type C communication system, the transfer rate is 212 kbps, and ASK modulation is performed with Manchester code to express 1,0 data. The first half of the bit is a state where the amplitude of the carrier wave is small, the second half of the bit is a logic “0” when the amplitude of the carrier wave is large (unmodulated state), and the first half of the bit is the state where the amplitude of the carrier wave is large. Is a logic “1” when the amplitude of the carrier wave is small (even if the polarity is inverted, the polarity can be identified when receiving the unique code in the frame). At the beginning of the communication frame, the preamble is 48 bits (data value 0).

  In order to communicate with a plurality of IC cards of different communication methods, a conventional reader / writer device performs a demodulation process when receiving a response signal from the IC card with an antenna, and measures the time of the pulse width of the obtained demodulated signal. Based on the measurement result, the communication method of the IC card is determined. As a result, the reader / writer can communicate with a plurality of IC cards of different communication methods (see Patent Document 1).

JP 2002-342725 A

  By the way, the communication technology of the conventional non-contact IC card system has been expanded to standardize near field communication (hereinafter referred to as NFC) featuring two-way communication (IEC / ISO18092, etc.). In the conventional IC card system, the reader / writer modulates a carrier wave of a predetermined frequency and transmits command data, and the IC card transmits response data by load-modulating the carrier wave output from the reader / writer. NFC bidirectional communication is a communication method in which a carrier wave is modulated and transmitted and transmitted, and communication is possible between non-contact communication devices such as reader / writer devices.

  The relationship between the conventional “reader / writer” and “IC card” is called “initiator” and “target” in NFC bidirectional communication. The initiator sends a polling command according to a predetermined initialization / communication procedure, By receiving the response from, the target in the communicable RF magnetic field is detected and communication is performed.

  The conventional mode for performing communication between “reader / writer” and “IC card” is called a passive mode, and the mode for performing NFC bidirectional communication is called an active mode. In the case of a device that can handle these two types of communication modes, communication is performed by selecting one of the modes.

  The passive mode is a communication mode for ensuring backward compatibility with an existing non-contact IC card, and a communication start side (reader / writer) generates a magnetic field modulated with information to be transmitted, The side (IC card) is a mode that returns a response by performing load modulation on an unmodulated magnetic field generated by the reader / writer.

  On the other hand, the active mode is a mode in which communication is performed by generating a magnetic field modulated by information transmitted between the initiator and the target (stopping the generation of the magnetic field after information transmission).

As shown in FIG. 10, in NFC bidirectional communication, communication methods such as an encoding method and a modulation degree differ depending on a transfer rate.
FIG. 10A shows a waveform example of a communication method of bidirectional communication 106 kbps.

The communication system of bidirectional communication 106 kbps is ASK-modulated with a modified mirror code, and is equivalent to the above-described system at the time of type A reader / writer transmission.
FIG. 10B shows a waveform example of a communication method of bidirectional communication 212 kbps.

The two-way communication 212 kbps communication method is equivalent to the method used when transmitting type C reader / writer by performing ASK modulation with Manchester code.
FIG. 10 (c) shows a waveform example of a communication method of bidirectional communication 424kbps.

In the communication system of bidirectional communication 424 kbps, ASK modulation is performed with a Manchester code, and the above-described system at the time of type C reader / writer transmission is speeded up.
In the reader / writer device, when a bidirectional communication function is added in addition to the communication with the conventional IC card, particularly in the case of a device that can cope with each of a plurality of types of communication methods, the reception control unit is shown in FIG. In addition to the reception function of various communication methods of “card → reader / writer” shown in FIG. 10, it is necessary to have the reception function of various bidirectional communication of NFC shown in FIG. 10, such as encoding, modulation method, transfer rate, etc. Each specification is different.

  Further, the conventional reader / writer device can wait for a response from the IC card to a command request transmitted by itself by specifying a communication method. Even in NFC bi-directional communication, when operating as an initiator, it is possible to determine the communication method by itself and perform communication.

  However, when becoming a “target” for two-way communication, there is a problem that it is impossible to specify and wait for the communication method because the communication method and transfer rate are unknown when receiving the polling command sent by the initiator. there were. For this reason, it has been difficult to perform communication using a plurality of types of communication methods for NFC bidirectional communication.

  In the prior art described in Patent Document 1, there is a polling transmission unit corresponding to a plurality of communication methods and a reception unit having a decoding function corresponding to a plurality of communication methods, but a communication method corresponding to polling transmitted by itself. It waits for the received signal. Patent Document 1 proposes a control method for measuring a time width of a demodulated input signal by detecting a response signal and determining a modulation method from the measurement result. In this method, the demodulated signal is influenced by noise or the like. If the pulse width is different from that of the regular signal, the modulation method may be erroneously determined.

  An object of the present invention relates to a non-contact type communication device such as a reader / writer device. In particular, not only existing communication with an IC card but also NFC bi-directional communication can be applied to a plurality of types of communication systems, and further noise and the like. To provide a non-contact type communication device, a decoding unit thereof, and the like that can reduce the possibility of misjudgment of a communication method even when the pulse width of a part of a received signal changes from a normal pulse width due to the influence of .

  The non-contact communication device of the present invention performs non-contact data transmission / reception with a non-contact information medium or other non-contact communication device, and supports at least a plurality of types of communication methods using bidirectional communication. A demodulating unit that demodulates a received signal from an antenna unit and outputs demodulated data; and a decoding unit that inputs the demodulated data and decodes the demodulated data. A plurality of decoding means corresponding to each of the plurality of types of communication methods, a selection means for selecting a decoding means for decoding the inputted demodulated data from the plurality of decoding means, and the demodulated data being input. A communication system determination unit that determines a communication system based on the demodulated data and outputs a selection signal corresponding to the determination result to the selection unit, and the communication system determination unit includes the demodulated data. A sampling means for sampling the demodulated data at a predetermined sampling frequency from a head at a predetermined sampling frequency, and a pattern corresponding to each of the plurality of types of communication methods are held in advance, and the sampling data by the sampling means And a matching / counting unit that compares each pattern with each pattern and counts the number of matching data, and compares each count value for each communication method obtained by the matching / counting unit with a preset threshold value And determining means for determining the communication method.

  With the above configuration, even when the non-contact communication device is a “target” for bidirectional communication, when receiving a polling command transmitted by the initiator, the sampling data of the demodulated data of the received signal and the registration are registered in advance. Since the communication method can be determined based on the predetermined pattern for each communication method, a plurality of types of communication methods can be supported for NFC bidirectional communication. Further, in the method having the above-described configuration, it is possible to correctly determine the communication method even when the pulse width of a part of the received signal is changed from the normal pulse width due to the influence of noise or the like.

  In the non-contact communication apparatus having the above configuration, for example, the sampling period is all or part of a period in which the logical value of the demodulated data is fixed in all of the various communication methods. As a result, a predetermined pattern for each communication method can be registered in advance, and the communication method can be determined as described above.

  Alternatively, for example, instead of the communication method determination unit, a plurality of communication method determination units having a smaller number of sampling data than the number of sampling data obtained by the communication method determination unit are provided, and each of the plurality of communication method determination units is different. In the sampling period, the demodulated data is sampled to determine the communication method, and the selection signal is generated based on the plurality of determination results and output to the selection means.

  As the number of sampling data increases, the detection accuracy (accuracy / reliability of the communication method judgment result) improves, but on the other hand, the gate scale increases, causing problems such as high cost and increased current consumption. Thus, the gate scale can be reduced while maintaining the detection accuracy.

  According to the non-contact type communication device of the present invention, its decoding unit, etc., it relates to a non-contact type communication device such as a reader / writer device, and in particular, a plurality of types of NFC bidirectional communication as well as existing communication with an IC card. It is possible to perform communication using various communication methods, and it is possible to perform communication using various communication methods. Furthermore, even if the pulse width of a part of the received signal is changed from the normal pulse width due to the influence of noise or the like, the possibility of erroneous determination of the communication method is extremely low. Furthermore, the gate scale can be reduced while maintaining the detection accuracy.

It is a figure which shows the example of whole structure of the non-contact-type communication apparatus of this example. It is a figure which shows the structural example (Example 1) of a decoding part. It is a figure which shows the structural example of a reception start position detection part. (A)-(c) is a figure which shows an example of the waveform at the time of communication in the various communication systems of NFC bidirectional communication, and an example of sampling data. It is a figure which shows the structural example (Example 2) of a decoding part. (A) is a diagram showing the relationship between the gate scale and the comparison bit width, and (b) is a diagram showing the gate scale of the second embodiment when compared with the first embodiment. It is a figure which shows the communication system of an IC card and a reader / writer. It is a figure which shows the communication system of NFC bidirectional | two-way communication. (A)-(e) is an example of the waveform at the time of communication in the various communication systems of communication between IC card-reader / writers. (A)-(c) is an example of the waveform at the time of communication in the various communication systems of NFC bidirectional communication.

Embodiments of the present invention will be described below with reference to the drawings.
Hereinafter, Example 1 will be described first.
FIG. 1 is a diagram illustrating an example of the overall configuration of the contactless communication apparatus of this example.

  The illustrated non-contact communication apparatus 10 includes a control unit 11, an RF transmission control unit 12, an RF reception control unit 13, and an antenna unit 19. The control unit 11 includes a decoding unit 11a. The RF transmission control unit 12 includes a modulation unit 14, an amplification unit 15, and a carrier oscillator 16. The RF reception control unit 13 includes a demodulation unit 18 and an A / D conversion unit 17.

  The non-contact type communication device 10 of this example is a non-contact type information medium (a non-contact type IC card, a mobile phone with a non-contact type IC card function, an IC tag, etc.) or another non-contact type communication device 10. Then, non-contact type communication is performed. That is, not only communication with a non-contact type information medium such as an IC card, but also NFC bidirectional communication is performed. The non-contact type communication device 10 is, for example, an IC card reader / writer device or the like, but is not limited to this example. For example, it may be a portable terminal with a non-contact type IC card.

The feature of this method resides in the decoding unit 11a, and other configurations will be briefly described below.
The control unit 11 controls the RF transmission control unit 12 and the RF reception control unit 13 in accordance with an instruction from a host device (not shown), and performs data transmission / reception processing with a non-contact type information medium or another non-contact type communication device 10 Is realized. At the time of RF transmission, parameter information such as a transmission mode and a transfer rate and transmission data are received from the host device, general encoding processing is performed, and data is output to the RF transmission control unit 12. At the time of reception, the reception signal from the antenna unit 19 is filtered by the RF reception control unit 13, receives the demodulated signal that has been binarized, and is decoded into an NRZ code by the decoding unit 11 a to perform frame generation / reception error check, etc. And reception notification to the host device.

  In the RF transmission control unit 12, the carrier oscillator 16 generates a predetermined carrier wave (13.56 MHz) and outputs it to the modulation unit 14. The RF transmission control unit 12 generates the RF magnetic field by the modulation unit 14 modulating the carrier wave with the transmission data from the control unit 11, amplifying it by the amplification unit 15, and sending it to the antenna unit 19. , And send data.

  The RF reception control unit 13 includes a demodulation unit 18 that detects and filters a received signal from the antenna unit 19 and demodulates it, and an A / D conversion unit 17 that binarizes the demodulated signal. The demodulated data (received data) is sent to the decoding unit 11a of the control unit 11.

FIG. 2 is a diagram illustrating a configuration example (configuration example in the first embodiment) of the decoding unit 11 a in the control unit 11.
The decoding unit 11a in the illustrated example receives the demodulated data from the RF reception control unit 13 and the reference clock used by the control unit 11 of the reader / writer device, and generates and outputs data decoded into the NRZ code. .

  The decoding unit 11a includes a reception start position detection unit 21, a level change point detection unit 22, a reception clock extraction unit 23, data selection units 24 and 25, a plurality of decoding units 26 (26a, 26b, and 26c), and the like. Become.

  The feature of the decoding unit 11 a in the control unit 11 is mainly in the reception start position detection unit 21. The reception start position detection unit 21 receives the reception data (demodulation signal) from the A / D conversion unit 17, determines the communication method, and sends the determination result (decoding method selection signal) to the data selection unit 24 and the like. Output. A configuration example of the reception start position detection unit 21 is shown in FIG. 3 and will be described in detail later. Other configurations 22 to 26 will be briefly described below.

  The level change point detector 22 receives the received data (demodulated signal) from the A / D converter 17 and detects the level change point of this demodulated signal (binary data) (level change point detection signal). Is output). The level change point is, for example, a signal falling (1 → 0) or rising (0 → 1) portion. The reception clock extraction unit 23 basically generates a reception clock based on the level change point detection signal from the level change point detection unit 22 and outputs the reception clock to the data selection unit 24. This generates and outputs a reception clock adjusted to a frequency for absorbing a clock frequency deviation from the non-contact information medium. In other words, the frequency of the reception clock is, for example, 212 kHz if the received data communication method is 106 kbps, 424 kHz for 212 kbps, 848 kHz for 424 kbps, etc. It is something to control.

  The configuration itself for generating the reception clock by the level change point detection unit 22 and the reception clock extraction unit 23 is an existing configuration, and although not described in detail, the reception clock extraction unit 23 is, for example, a general digital It is composed of a PLL circuit.

  However, in this example, the reception clock extraction unit 23 can generate a reception clock in a short time by inputting the demodulation method selection signal from the reception start position detection unit 21 and using it. This will be described later.

  The plurality of decoding units 26 (26a, 26b, 26c) are decoding processing units each corresponding to one of a plurality of communication methods. In the illustrated example, the decoding unit 26a is a communication unit A, the decoding unit 26b is a decoding unit corresponding to the communication method B, and the decoding unit 26c is a decoding unit corresponding to the communication method C.

  Here, for example, the communication method A is the communication method shown in FIG. 10A, the communication method B is the communication method shown in FIG. 10B, and the communication method C is the communication shown in FIG. 10C. Suppose that it is a method.

  When the received data (demodulated signal) and the received clock signal are input to the decoding processing units 26a, 26b, and 26c for each communication method, the decoding processing units 26a, 26b, and 26c perform predetermined decoding processing on the received data, respectively. Output decoded data as a code. Note that the processing function itself of the decoding processing unit 26 is a conventional general decoding processing function, and is not particularly described here.

  The data selection unit 24 inputs the reception data (demodulation signal) and the reception clock generated and output by the reception clock extraction unit 23, and outputs the reception data and reception clock to the output of the reception start position detection unit 21. In response to (decoding method selection signal), the signal is output to any one of the plurality of decoding units 26. If the reception start position detection unit 21 determines “communication method A”, the reception data (demodulation signal) and the reception clock are output to the decoding unit 26a.

The data selection unit 25 outputs the output from the decoding unit 26 selected by the data selection unit 24 to, for example, a higher-level device or the like in conjunction with the data selection unit 24.
FIG. 3 shows a configuration example of the reception start position detection unit 21 in the decoding unit 11a.

  The reception start position detection unit 21 in the illustrated example includes a reception signal sampling unit 31, a data pattern matching unit 32 (32a, 32b, 32c) corresponding to each communication method, and a data matching bit number counter unit 33 (33a, 33b, 33c). ), And a reception start position determination unit 34 (34a, 34b, 34c). The reception signal sampling unit 31 has a configuration common to all communication methods, and the other configuration is provided for each communication method.

  Here, the configuration corresponding to the communication method A is the collation unit 32a, the counter unit 33a, and the determination unit 34a. With these configurations, it is determined whether or not the communication method of the received signal is the communication method A. Similarly, the configuration corresponding to the communication method B is the collation unit 32b, the counter unit 33b, and the determination unit 34b. With these configurations, it is determined whether or not the communication method of the received signal is the communication method B. The configuration corresponding to the communication method C is a collation unit 32c, a counter unit 33c, and a determination unit 34c. With these configurations, it is determined whether or not the communication method of the received signal is the communication method C.

  Then, each determination unit 34a, 34b, 34c outputs each illustrated selection signal (method A selection signal, method B selection signal, method C selection signal). These three selection signals correspond to the decoding method selection signal shown in FIG. 2, and are input to the data selection unit 24 and the like. Each selection signal is “1” or “0” (default is “0”). For example, when it is determined that the communication method of the received signal is the communication method A, the method A selection signal is It becomes '1'.

  The reception signal sampling unit 31 samples the reception signal (demodulation signal) at a predetermined sampling frequency (848 kHz in this example) during a predetermined sampling period (9.43 μs from the beginning of the reception frame in this example), and this sampling data ( A predetermined number N (eight data in this example); in other words, Nbit (eight bits in this example) sampling data) is temporarily held, and then output to the data pattern matching unit 32. In this example, the received signal sampling unit 31 needs to have a configuration for holding eight sampling data, that is, a configuration of an 8-bit buffer or the like.

  Here, an example of the sampling data is shown in FIGS. 4A to 4C show examples of sampling data based on FIGS. 10A to 10C, respectively. That is, an example of sampling data for each communication method of the NFC bidirectional communication described with reference to FIGS. As described above, FIG. 4A corresponds to the communication method A, FIG. 4B corresponds to the communication method B, and FIG. 4C corresponds to the communication method C. 4A to 4C, the sampling periods seem to be different in the figure, but in reality, they are the same (all in this example, 9.43 μs from the beginning of the received frame).

  4 (a) to 4 (c), which will be described later in detail, the sampling data differs depending on the communication method as shown in the figure. That is, for each communication method, the head pattern of the received frame in that communication method (pattern data in a predetermined sampling period from the head of the received frame) is determined, and this head pattern is different for each communication method. (Note that this pattern data can also be considered as predetermined (determined for each communication method) sampling data). Therefore, by using this, the sampling method obtained by the received signal sampling unit 31 is collated with the head pattern for each communication method registered in advance to determine the communication method related to the received signal. (It can be determined by the collation unit 32, the counter unit 33, and the determination unit 34).

  As shown in FIGS. 4A to 4C, the sampling data (the same as the head part pattern) is “0” when the received signal (detected / demodulated data shown) is low and “ 1 'and does not mean the logic (data values) “1” and “0” (“transmission data (NRZ)” shown in FIG. 4) described in FIG. This data value is fixed in all communication systems during the sampling period (in this example, it is “0” in all communication systems as described later, but it is not necessary to limit to this example). Therefore, it is possible to register in advance a head pattern determined for each communication method.

Hereinafter, processing operations of the collation unit 32, the counter unit 33, and the determination unit 34 will be described.
Each data pattern matching unit 32a, 32b, 32c corresponds to one of a plurality of communication methods (in this figure, three types of communication methods A, B, and C) as described above, and receives data in that communication method. A function for preliminarily holding the data of the head part pattern of the frame (referred to as a head pattern holding part) is collated with the head part pattern data and the sampling data by the received signal sampling part 31, and this collation result ( A function (referred to as a collation function unit) for outputting data indicating “match / mismatch” (comparison collation data) to the data coincidence bit number counter unit 33.

  Specifically, the collation function unit is, for example, an Ex-OR (exclusive-OR) circuit that inputs the head pattern data and the sampling data. As is well known, the Ex-OR circuit outputs ‘0’ when the two input data match and ‘1’ as the comparison verification data when they do not match.

  Note that the collation result (match / mismatch) means, for example, match / mismatch for each of the eight data in the above example (in the above example, the head pattern data is also 8 bits as shown in FIG. 3). Data). Therefore, the data pattern matching unit 32 outputs eight (8-bit) comparison matching data in the above example.

  Each of the data coincidence bit number counter units 33a, 33b, and 33c receives the output of the data pattern collation units 32a, 32b, and 32c (for example, the counter unit 33a inputs the output of the collation unit 32a). Each counts the number of data whose matching results are “match”. Then, the count value is output to the reception start position determination units 34a, 34b, and 34c (for example, the counter unit 33a outputs to the determination unit 34a). In the above Ex-OR example, each data match bit number counter unit 33 receives the output of the corresponding data pattern collation unit 32 (here, eight (8-bit) comparison collation data). Count the number of data (bit). In this example, the data coincidence bit number counter unit 33 can be constituted by an 8-bit adder, for example.

  In the example of the sampling data and the head pattern shown in FIG. 3, the count value is “2” for the communication method A, “8” for the communication method B, and “4” for the communication method C. That is, in the example shown in the figure, the sampling data is “11001100”, but the head pattern (corresponding to the matching unit 32b) corresponding to the communication method B is also “11001100”. Then, the counter value of the counter unit 33b is “8”.

Each reception start position determination unit 34a, 34b, 34c stores a threshold for determination corresponding to the communication method in advance. Here, the determination threshold value corresponding to the communication method A is a threshold value N _A. Therefore, the threshold value N _A is stored in advance in the determination unit 34a. Similarly, threshold value N _B is stored for communication method B (determination unit 34b), and threshold value N _C is stored for communication method C (determination unit 34c). Then, the output (count value for each communication method) of the data matching bit number counter unit 33 is compared with the determination threshold value corresponding to the communication method, and the condition of “count value ≧ determination threshold value” is satisfied. It is determined whether it is satisfied. Then, the selection signal of the determination unit 34 determined to satisfy this condition is output as “1”.

Here, if the above threshold value _{N A,} the threshold _{N B,} all threshold _{N C} a '7'. That is, when 7 or more of the 8 pieces of data match, a selection signal for the communication method is output as “1”. In the above example, only the communication method B satisfies the above condition (since 8 ≧ 7), and only the method B selection signal of the determination unit 34b is output as “1”. That is, it is determined that the communication method of the communication partner this time is the communication method B, and the determination result is output to the selection unit 24 and the like. As a result, the decoding unit 26 decodes the demodulated signal by the above-described operation of the selection unit 24 by the decoding unit 26 (in this example, the system B decoding unit 26b) corresponding to the communication method of the received signal. That is, the reception process corresponding to the communication method of the received signal is possible.

  Of course, the threshold value is not limited to the example of “7”, and may be set arbitrarily. In the above example, the threshold value is set to the same value ('7') in all communication methods. However, the threshold value is not limited to this, and may be another value, for example, '8'. However, there is a possibility that erroneous detection may occur in about 1 bit due to the influence of noise or the like of the received signal. Therefore, in the above example, the threshold is set to “7” (thus, if the influence of noise is further considered, the threshold = “ 6 'etc.).

  Here, it will be described below that the head pattern data is determined in advance for each communication method as described above, and that the head pattern is different depending on the communication method.

  First, as described above, for example, as an example, the communication method A is the communication method shown in FIG. 10A (106 kbps bidirectional communication), and the communication method B is the communication method shown in FIG. The communication method C is assumed to be the communication method (424 kbps bidirectional communication) shown in FIG.

  In this example, as already described with reference to FIG. 10, the data value at the beginning of the communication frame (received signal frame; received frame) is fixed in all of the communication systems A, B, and C. That is, in the case of 106 kbps bidirectional communication in FIG. 10A, the start bit of the communication frame has a start bit of 1 bit (logic (data value) = 0). In each of FIGS. 10B and 10C (212 kbps bidirectional communication, 424 kbps bidirectional communication), the beginning of the communication frame has a preamble of 48 bits (logic (data value) = 0). In the figure, only 4 bits of the preamble are shown, and the remaining 44 bits are omitted.

  In this way, in all communication methods, there is a part where the data is always '0' at the beginning of the communication frame. In this method, a leading part pattern that makes it possible to determine the communication method is used. By determining and registering in advance, the communication method can be determined by collating with the sampling data. This has already been briefly described with reference to FIGS. 4A to 4C, but will be described in more detail with reference to FIGS. 4A to 4C.

  First, as described above, the reception signal sampling unit 31 samples the reception signal (demodulated signal) at a predetermined sampling frequency during a predetermined sampling period. During this sampling period, the logic (data value) is used in all communication methods. It is a fixed period (all or part of it). In the above example, the sampling period is “9.43 μs from the beginning of the received frame”. This 9.43 μs corresponds to a 1-bit length in 106 kbps bidirectional communication, and the start bit in the 106 kbps bidirectional communication. The period of 1 bit length is the sampling period. As shown in FIGS. 4B and 4C, this sampling period (9.43 μs from the beginning of the frame) is the preamble period of the communication systems B and C. The logic (data) is also used in the communication systems B and C. Value) is determined to be '0'.

  As described above, the sampling period (9.43 μs from the beginning of the frame) in this example means a period corresponding to the start bit (1 bit) for 106 kbps bidirectional communication. Similarly, for 212 kbps bidirectional communication, since 1 bit length = 4.72 μs, as shown in FIG. 4B, the above sampling period means a period corresponding to the top 2 bits. Similarly, for 424 kbps bidirectional communication, since 1 bit length = 2.36 μs, as shown in FIG. 5C, the above sampling period means a period corresponding to the top 4 bits. Note that, as already described, the sampling period appears to be different for each communication method in the figure (FIG. 4C is the longest), but in reality all are the same (9.43 μs).

  Here, in FIGS. 4A to 4C, the received signal (demodulated signal) from the A / D converter 17 is, for example, “detected / demodulated data” shown in the figure. As described above, since it is determined that the data value = '0' in all the three communication methods during the sampling period, the received signal during the sampling period is always “detection” shown in the figure. The signal shown in “Demodulated data”.

  Therefore, as in the above example, when sampling is performed at 848 kHz, first, regarding 106 kbps bidirectional communication, eight “detection / demodulation data” from the first sampling period of 1 bit shown in FIG. The sampling data is “00111111”.

  Similarly, for 212 kbps bidirectional communication, 8 sampling data is “11001100” from “detection / demodulation data” in the sampling period of 2 bits from the top shown in FIG. 4B.

  Similarly, for the 424 kbps bidirectional communication, the 8 sampling data is “101010100” from the “detection / demodulation data” in the sampling period of 4 bits from the head shown in FIG.

  As described above, by performing sampling at a predetermined sampling frequency in a sampling period for a predetermined time from the beginning of the received frame, sampling data determined for each communication method (and different from each other) can be obtained. . Therefore, for example, each sampling data shown in FIGS. 4A to 4C is held as the head pattern corresponding to each communication method, and compared with the sampling data of the received signal as described above. Thus, the communication method of the received signal can be determined. Of course, the sampling data of the received signal is not necessarily the same as the sampling data shown in FIGS. 4A to 4C due to the influence of noise or the like. It is considered that the number changes, and as described above, the threshold value may be set in consideration of this point.

  As described above, according to this method, even when it becomes a “target” of bidirectional communication, it is possible to determine the communication method when receiving the polling command transmitted by the initiator, With regard to NFC bidirectional communication, it is possible to perform communication using a plurality of types of communication methods. As described above, in both conventional and NFC bidirectional communication, when operating as an initiator, it is possible to determine the communication method by itself and perform communication. Further, regarding the communication between the IC card and the reader / writer, it has been possible to specify and wait for a response from the IC card in response to a command request transmitted by itself.

  Therefore, according to this method, not only the existing communication with the IC card but also the NFC bidirectional communication can be applied to a plurality of types of communication methods. Further, even when the pulse width of a part of the received signal is changed from the normal pulse width due to the influence of noise or the like, as long as about one or two of the eight data changes as in the above example, Normal communication can be performed without erroneously determining the communication method.

  In this example, the number of sampling data is eight in order to simplify the description. However, in practice, it is desirable to use a larger number of sampling data. In other words, the sampling frequency is set to 3.39 MHz, 6.78 MHz, or 13.56 in order to adjust the noise tolerance of the received signal, the tolerance for the received signal distortion (duty shift) in the modulation / demodulation process, and to detect the communication method in a short period of time The detection accuracy and reception performance can be improved by increasing the number of sampling data to 32, 64, 128, etc. by increasing the frequency to MHz (frequency division of the internal reference clock) or the like. Of course, the threshold value of the determination unit 34 is appropriately set to a value corresponding to the number of sampling data instead of the above “7” or the like.

Next, Example 2 will be described below.
The second embodiment described below is particularly effective when the number of sampling data is large.

The overall configuration of the contactless communication apparatus according to the second embodiment is the same as that of the first embodiment. That is, the configuration shown in FIG. Therefore, it is not specifically described here.
FIG. 5 is a diagram illustrating a configuration example (configuration example in the second embodiment) of the decoding unit 11a in the control unit 11 in the configuration of FIG.

  The illustrated decoding unit 11a (40) includes a plurality of reception start position detection units 41 (here, two of 41a and 41b), a level change point detection unit 22, a reception clock extraction unit 23, a data selection unit 24, 25 and a plurality of decoding units 26 (26a, 26b, 26c) and the like.

  Here, in FIG. 5, the same components as those in the configuration of FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. Therefore, the difference from the configuration of FIG. 2 is only that a plurality of reception start position detection units 41a and 41b are provided. In other words, the difference from the first embodiment is that the reception start position detection unit has a plurality of stages.

  Here, the configuration itself of the reception start position detection units 41 a and 41 b may be substantially the same as that of the reception start position detection unit 21. That is, the reception start position detectors 41a and 41b may be substantially the same as the configuration shown in FIG. However, the sampling frequency is different between the reception start position detectors 41a and 41b. Here, as an example, it is assumed that the sampling frequency is 3.39 MHz in the reception start position detection unit 41a and 6.78 MHz in the reception start position detection unit 41b.

  Here, as described above, in order to improve the detection accuracy and reception performance, it is conceivable to increase the sampling frequency, but this increases the number of sampling data and the number of head pattern data (comparison and verification). The data width is increased), and the circuit configuration (gate scale) for holding and comparing the data is also increased. For this reason, when the sampling frequency is increased in the configuration of the first embodiment, the following problems occur.

  In other words, it is possible to improve detection accuracy (accuracy / reliability of communication method determination results) and reception performance by increasing the comparison data width, but the gate size increases in proportion to the data width. As a result, there arises a problem that the current consumption increases and the use of devices such as FPGA / PLD increases the cost due to the gate scale.

  In addition, when it is necessary to detect the communication method within a predetermined period, it is possible to shorten the detection period of the communication method by maintaining the detection accuracy by increasing the sampling frequency, but there is a problem that the current consumption increases. is there.

FIG. 6A shows the relationship between the gate size of the reception start position detector and the comparison verification data width (comparison bit width).
As shown in the figure, when the comparison data width is doubled, for example, the gate scale is doubled (similarly, when it is quadrupled, the gate scale is quadrupled, and when it is eightfold, it is eightfold).

  As a countermeasure against the above problem, in the second embodiment, by suppressing the sampling frequency and the comparison collation data width of each of the plurality of reception start position detection units, by configuring in a plurality of stages, detection accuracy and reception performance are maintained, It is possible to reduce the gate scale and current consumption. This will be described below with a specific example.

  First, in the first embodiment, for example, when the sampling period is 18.86 μs, that is, when the period is 2 bits from the top of the reception frame in the 106 kbps bidirectional communication, the detection accuracy and reception performance are Considering this, if the sampling frequency is 6.78 MHz, this requires a configuration with a comparison verification data width of 128 bits.

  In this hypothetical case, in the second embodiment, the reception start position detection unit has a two-stage configuration (the plurality of reception start position detection units 41a and 41b), and each of the detection units 41a and 41b has a sampling period of 9. 43 μs (1 bit period of 106 kbps) is set. Further, the detection unit 41a at the front stage performs a sampling operation during the first bit period of the period of 2 bits at 106 kbps, and the detection unit 41b at the rear stage performs a sampling operation during the second bit period. Further, the upstream detection unit 41a has a sampling frequency of 3.39 MHz, and the downstream detection unit 41b has a sampling frequency of 6.78 MHz. That is, in both cases, the sampling period is halved, the sampling frequency is reduced (half, 1/4), and the comparison collation data width is smaller than that of the above-described assumption of the first embodiment. This reduces the gate size and power consumption. In particular, even if two gates are combined, the size can be smaller than that in the first embodiment.

  That is, as shown in FIG. 6B, in the period of 2 bits of 106 kbps, the detection unit 41a at the front stage operates using the first half (the first bit) of this period as a sampling period to perform sampling at 32 points, thereby detecting the subsequent stage. The unit 41b operates with the latter half (second bit) of this period as a sampling period and performs sampling at 64 points. In other words, the detection unit 41a at the previous stage needs a configuration for the comparison / collation data width of 32 bits, and the detection unit 41b at the subsequent stage needs a configuration for the comparison / collation data width of 64 bits. On the other hand, in the case of the first embodiment, the above-mentioned period of 2 bits of 106 kbps is operated as a sampling period, and as described above, the configuration for the comparison / collation data width of 128 bits is required.

  Accordingly, from the relationship shown in FIG. 6A, when the gate scale in the first embodiment is “1”, the gate scales of the detection units 41a and 41b are “1/4” and “1/2”, respectively. And both will be '3/4'. Therefore, in the configuration of the second embodiment, the gate scale can be made smaller than that of the first embodiment (thus, the current consumption is also reduced). Moreover, since the two determination results of the detection units 41a and 41b are used, detection accuracy and reception performance can be maintained. As described above, in the second embodiment, it is possible to reduce the gate scale and current consumption (in this example, the gate scale is ¾) while maintaining the detection accuracy and the reception performance.

  In the configuration shown in FIG. 5, first, the detection unit 41a at the preceding stage operates during the period of the first bit, and as a result, each selection signal (the output of the determination unit 34 for each communication method) is sent to the detection unit at the subsequent stage. Next, during the period of the second bit, the subsequent detection unit 41b operates to output the illustrated decoding method selection signal to the data selection unit 24 and the like.

  Here, although not particularly illustrated, the configuration of the detection unit 41b in the subsequent stage is provided with an AND gate corresponding to each communication method, for example, in addition to the configuration illustrated in FIG. The output of the AND gate becomes a decoding method selection signal from the detection unit 41b in the subsequent stage.

  For each communication system, the output of the determination unit 34 of the upstream detection unit 41a and the output of the determination unit 34 of the downstream detection unit 41b are input to each AND gate. For example, taking communication method A as an example, the output of the determination unit 34a of the detection unit 41a and the output of the determination unit 34a of the detection unit 41b are input to the AND gate. The same applies to the other communication systems B and C.

  Here, it is assumed that the output from the determination unit 34 is “1” if “count value ≧ threshold”, and “0” otherwise. Thus, for example, even if the output of the determination units 34a and 34b is '1' in the detection unit 41a in the previous stage, only the output of the determination unit 34a is '1' in the detection unit 41b in the subsequent stage. The AND gate output corresponding to the communication method A is “1”, but the AND gate output corresponding to the communication method B is “0”. Therefore, in this case, the final determination result is “communication method A”. In this way, detection accuracy and reception performance can be maintained.

  The provision of the AND gate is an example, and the present invention is not limited to this example. For example, in the detection unit 41b in the subsequent stage, only the configuration corresponding to the communication method determined by the detection unit 41a in the previous stage (the communication method in which the output of the determination unit 34 is “1”) may be operated. For example, if only the output of the determination unit 34a is '1' in the detection unit 41a in the previous stage (if it is determined as the communication method A), the configuration corresponding to the communication method A in the detection unit 41b in the subsequent stage, That is, only the configuration of the collation unit 32a, the counter unit 33a, and the determination unit 34a operates. The configuration for this is not particularly shown or described, but for example, a switch or the like may be used.

  In the case of 106 kbps communication shown in FIG. 4A, the data value of the first bit is always “0”, but the second bit is not fixed to “0”. Therefore, for example, not only “00111111”, which is a pattern corresponding to the data value “0”, but also “11110011”, which is a pattern corresponding to the data value “1”, is prepared for the pattern corresponding to the communication method A. The configuration of the collation unit 32a, the counter unit 33a, and the determination unit 34a may be provided for each of the two types of patterns. The outputs of the two determination units 34a are input to an OR circuit, and the output of the OR circuit is a method A selection signal. That is, when the sampling pattern matches one of the above two types of patterns (in the above example, seven or more of the eight matches), the method A selection signal is ‘1’.

  The second embodiment is not limited to the configuration of FIG. 5 and the above description. For example, in the above description, the number of sampling data is different between the detection unit 41a and the detection unit 41b (32 points and 64 points). However, of course, the detection unit 41a and the detection unit 41b need to reduce the number of sampling data compared to the detection unit 21 of the first embodiment, thereby reducing the gate scale. Alternatively, in the above example, the detection unit 41a is the first bit and the detection unit 41b is the second sampling period. However, the present invention is not limited to this example. For example, the first and third bits may be used. The sampling may be performed at different sampling periods in each of the plurality of detection units). Further, for example, in the above example, the two detection units are the detection unit 41a and the detection unit 41b. However, the present invention is not limited to this example, and may be three or more.

  In short, as described above, in the second embodiment, a plurality of detection units whose sampling data number is smaller than that of the detection unit 21 in the first embodiment are provided, and the plurality of detection units perform sampling in different sampling periods. A communication system is determined, a final communication system determination result is obtained based on the plurality of determination results, and the determination result is output to the data selection unit 24 or the like as a decoding system selection signal. .

Lastly, a description will be given of the above-described “the reception clock extraction unit 23 can generate a reception clock in a short time”.
First, the configuration itself of the reception clock extracting unit 23 may be a general PLL circuit as described above. Although not particularly illustrated, for example, a phase comparator that inputs the level change point detection signal, A low-pass filter (low-pass filter) that inputs an output, and a voltage-controlled oscillator (VCO) that generates and outputs the reception clock by inputting the output of the low-pass filter. The output of the VCO is fed back to the phase comparator (of course, also output to the external selection unit 24 and the like).

  Here, the voltage controlled oscillator (VCO) generates a reception clock of, for example, a sawtooth wave. The frequency of the reception clock is determined by the inclination of the sawtooth wave. Conventionally, while the reception clock is fed back by the above configuration, the reception clock is gradually controlled so as to have a frequency corresponding to the communication method as described above (the slope of the sawtooth wave is changed).

  In the configuration of this example, as described above, since the reception start position detection unit 21 determines the communication method, the reception clock extraction unit 23 uses this determination result to determine the frequency of the reception clock (slope of the sawtooth wave). decide. That is, the decoding method selection signal output from the reception start position detection unit 21 (for example, the 3-bit signal of the method A selection signal to the method C selection signal shown in FIG. VCO). In the voltage controlled oscillator (VCO), a frequency (slope of the sawtooth wave) is set in advance in association with each of the 3 bits. For example, 212 kHz is set for the method A selection signal, 424 kHz is set for the method B selection signal, and 848 kHz is set for the method C selection signal. Accordingly, for example, if only the method A selection signal is “1”, the voltage controlled oscillator (VCO) controls the slope of the sawtooth so as to generate a reception clock of 212 kHz. The reception clock is adjusted based on the level change point detection signal. Since the frequency (the slope of the sawtooth) is almost determined initially, this adjustment can be done in a short time.

Thus, the reception clock extraction unit 23 of this example can generate a reception clock having a frequency corresponding to the communication method in a short time.
According to the present invention, in a non-contact type communication device including a reader / writer device, various communication methods and communication rates can be discriminated from a received signal. Communication can be performed, and the reception performance can be improved by reducing the gate size and power consumption.

DESCRIPTION OF SYMBOLS 10 Non-contact communication apparatus 11 Control part 11a Decoding part 12 RF transmission control part 13 RF reception control part 14 Modulation part 15 Amplification part 16 Carrier oscillator 17 A / D conversion part 18 Demodulation part 19 Antenna part 21 Reception start position detection part 22 Level change point detection unit 23 Reception clock extraction unit 24, 25 Data selection unit 26 (26a, 26b, 26c) Decoding unit 31 Reception signal sampling unit 32 Data pattern matching unit 33 Data match bit number counter unit 34 Reception start position determination unit 41 (41a, 41b) Reception start position detector

Claims (5)

A non-contact type communication device that performs non-contact data transmission / reception with a non-contact type information medium or another non-contact type communication device, and supports at least a plurality of types of communication methods by bidirectional communication,
A demodulator that demodulates the received signal from the antenna unit and outputs demodulated data; and a decoding unit that inputs the demodulated data and decodes the demodulated data,
The decoding unit
A plurality of decoding means corresponding to each of the plurality of types of communication methods;
A selection means for selecting a decoding means for decoding the inputted demodulated data from the plurality of decoding means;
A communication system determination unit that inputs the demodulated data, determines a communication system based on the demodulated data, and outputs a selection signal according to the determination result to the selection unit;
The communication method determination means includes
Sampling means for sampling the demodulated data at a predetermined sampling frequency during a predetermined sampling period from the beginning of the demodulated data;
A pattern corresponding to each of the plurality of types of communication methods is held in advance, and collation / counting means for comparing the sampling data by the sampling means with the respective patterns to count the number of matching data,
A determination unit for determining a communication method by comparing each count value for each communication method obtained by the matching / counting unit with a preset threshold value;
A non-contact communication apparatus characterized by comprising:   2. The non-contact communication apparatus according to claim 1, wherein the sampling period is all or part of a period in which a logical value of the demodulated data is fixed in all of the various communication methods. In place of the communication method determination means, a plurality of communication method determination means having a smaller number of sampling data than the number of sampling data obtained by the communication method determination means is provided.
Each of the plurality of communication system determination means samples the demodulated data in different sampling periods to determine the communication system, generates the selection signal based on the plurality of determination results, and outputs the selection signal to the selection means The non-contact type communication apparatus according to claim 1 or 2,   The contactless communication apparatus according to claim 3, wherein the total number of sampling data of each of the plurality of communication method determination units is smaller than the number of sampling data of the communication method determination unit according to claim 1. . A non-contact type information medium or other non-contact type having a demodulator that demodulates a received signal from the antenna unit and outputs demodulated data, and a decoding unit that inputs the demodulated data and decodes the demodulated data In the decoding unit in the non-contact type communication device that performs non-contact data transmission / reception with the communication device and supports at least a plurality of types of communication methods by bidirectional communication,
A plurality of decoding means corresponding to each of the plurality of types of communication methods;
A selection means for selecting a decoding means for decoding the inputted demodulated data from the plurality of decoding means;
A communication system determination unit that inputs the demodulated data, determines a communication system based on the demodulated data, and outputs a selection signal according to the determination result to the selection unit;
The communication method determination means includes
Sampling means for sampling the demodulated data at a predetermined sampling frequency during a predetermined sampling period from the beginning of the demodulated data;
A pattern corresponding to each of the plurality of types of communication schemes is held in advance, and a matching / counting unit that counts the number of matching data by comparing the sampling result by the sampling unit with each pattern,
A determination unit for determining a communication method by comparing each count value for each communication method obtained by the verification / counting unit with a preset threshold value;
The decoding part of the non-contact-type communication apparatus characterized by having.