Near-field wireless communication method using a serial interface microcontroller and near-field wireless communication tag device using the method

Abstract

To provide a method for near field communication with a serial interface microcontroller which does not employ a dedicated integrated circuit to reduce the cost, and a near field communication tag device using the same.SOLUTION: A method includes: providing a serial interface microcontroller; detecting a near field communication carrier wave using a near field communication LC resonant circuit; performing a frequency division to the near field communication carrier wave based on a near field communication protocol, to obtain a near field communication clock signal; filtering the near field communication carrier wave of the near field communication LC resonant circuit to obtain an envelope signal; sequentially receiving a digital sequence of the envelope signal according to triggering of the near field communication clock signal and a serial transmission protocol; and decoding near field communication data from the digital sequence of the envelope signal based on the near field communication protocol.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to near field communication, and more particularly to a method for near field communication (NFC) with serial interface microcontroller and NFC tag device using the same. [Background technology]

[0002] NEAR FIELD COMMUNICATION (NFC) is a communications protocol that allows communication between two electronic devices within a distance of 4cm or even shorter. NFC provides a low-speed connection with simple setup and functionality that can be used to guide users to stronger wireless connections. Summary of the Invention [Problem to be solved by the invention]

[0003] Applications of short-range wireless communication transmission continue to spread, but general microcontrollers (MCUs) do not have hardware dedicated to short-range wireless communication. In addition, short-range wireless communication requires a high bit rate, so applications of short-range wireless communication require dedicated integrated circuits (ICs). These integrated circuits are more expensive than general processing devices.

[0004] Therefore, the present inventors believed that the above-mentioned drawbacks could be improved, and as a result of extensive research, they came to propose the present invention, which effectively improves the above-mentioned problems through rational design.

[0005] The present invention was made in consideration of the above-mentioned problems and was made possible through intensive research by the inventors. It is an object of the present invention to provide a short-range wireless communication method using a serial interface microcontroller that realizes sending and receiving data via short-range wireless communication without using an integrated circuit dedicated to short-range wireless communication, and a short-range wireless communication tag device using said method. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention employs the following means. According to one embodiment of the present invention, a short-range wireless communication tag device is provided. The short-range wireless communication tag device according to the present invention includes a short-range wireless communication LC resonant circuit, a frequency divider circuit, an envelope detector circuit, and a serial interface microcontroller. The short-range wireless communication LC resonant circuit includes a first end and a second end. The frequency divider circuit has an input end and an output end, and the input end of the frequency divider circuit is connected to the first end of the short-range wireless communication LC resonant circuit. The envelope detector circuit has an input end and an output end, and the input end of the envelope detector circuit is connected to the first end of the short-range wireless communication LC resonant circuit. The serial interface microcontroller includes a clock input end and a serial data input end, and the clock input end of the serial interface microcontroller is connected to the output end of the frequency divider circuit, and the serial data input end of the serial interface microcontroller is connected to the output end of the envelope detector circuit. The frequency divider circuit divides the short-range wireless communication clock signal according to the short-range wireless communication carrier of the first end of the short-range wireless communication LC resonant circuit. The envelope detector circuit converts the received signal into an envelope signal according to the received signal. The clock input end of the serial interface microcontroller receives the near field communication clock signal, and the serial data input end of the serial interface microcontroller receives the envelope signal, which is used for decoding the near field communication data from the envelope signal according to the near field communication protocol.

[0007] According to a preferred embodiment of the present invention, the above-mentioned short-range wireless communication tag device further comprises a DC blocking circuit including a first end and a second end, the first end of the DC blocking circuit is connected to the first end of the short-range wireless communication LC resonant circuit, and the second end of the DC blocking circuit is connected to the input end of the frequency divider circuit, and is used to pass the short-range wireless communication carrier wave. In a preferred embodiment, the above-mentioned short-range wireless communication tag device further comprises a bias circuit connected between the DC blocking circuit and the input end of the frequency divider circuit, and is used to operate the short-range wireless communication carrier wave between a power supply voltage and a common voltage.

[0008] According to a near-field wireless communication tag device according to a preferred embodiment of the present invention, the bias circuit includes a first resistor and a second resistor. The first resistor has a first end and a second end, the first end of the first resistor is connected to a power supply voltage and the second end of the first resistor is connected to the second end of the DC blocking circuit. The second resistor has a first end and a second end, the first end of the second resistor is connected to the second end of the DC blocking circuit and the second end of the second resistor is connected to a common voltage.

[0009] According to a near-field wireless communication tag device according to a preferred embodiment of the present invention, the above-mentioned envelope detection circuit includes a third resistor, a fourth resistor, a first unidirectional conductive element, a second unidirectional conductive element, a first transistor, and a first capacitance. The third resistor has a first end and a second end, and the first end of the third resistor is connected to a power supply voltage. The first unidirectional conductive element has a first end and a second end, and the first end of the first unidirectional conductive element is connected to the second end of the third resistor and the second end of the first unidirectional conductive element is connected to an input end of the envelope detection circuit, and the first unidirectional conductive element restricts a current to flow from the first end of the first unidirectional conductive element to the second end of the first unidirectional conductive element. The first transistor has an emitter terminal, a collector terminal, and a base terminal, the emitter terminal of the first transistor is connected to a common voltage, the collector terminal of the first transistor is connected to a first terminal of the first unidirectional conductive element, and the base terminal of the first transistor is connected to a second terminal of the first unidirectional conductive element. The second unidirectional conductive element has a first terminal and a second terminal, the first terminal of the second unidirectional conductive element is connected to an output terminal of the envelope detection circuit, and the second terminal of the second unidirectional conductive element is connected to the collector terminal of the first transistor, and the second unidirectional conductive element restricts a current to flow from the first terminal of the second unidirectional conductive element to the second terminal of the second unidirectional conductive element. The first capacitance has a first terminal and a second terminal, the first terminal of the first capacitance is connected to the first terminal of the second unidirectional conductive element, and the second terminal of the first capacitance is connected to the common voltage. The fourth resistor has a first end and a second end, the first end of the fourth resistor is connected to the power supply voltage and the second end of the fourth resistor is connected to the first end of the second unidirectional conductive element.

[0010] According to a preferred embodiment of the near-field wireless communication tag device of the present invention, the above-mentioned envelope detection circuit further includes a second capacitance, a fifth resistor, and a sixth resistor. The second capacitance includes a first end and a second end, the first end of the second capacitance is connected to the output end of the envelope detection circuit, and the second end of the second capacitance is connected to the first end of the second unidirectional conductive element. The fifth resistor includes a first end and a second end, the first end of the fifth resistor is connected to a power supply voltage, and the second end of the fifth resistor is connected to the first end of the second capacitance. The sixth resistor includes a first end and a second end, the first end of the sixth resistor is connected to the first end of the second capacitance, and the second end of the sixth resistor is connected to a common voltage.

[0011] According to a preferred embodiment of the present invention, the short-range wireless communication tag device further includes a serial data output terminal, and the short-range wireless communication tag device further includes a switching circuit, which has a first end, a second end, and a control end. The control end of the switching circuit is connected to the serial data output terminal of the serial interface microcontroller, the first end of the switching circuit is connected to the first end of the short-range wireless communication LC resonant circuit, and the second end of the switching circuit is connected to the second end of the short-range wireless communication LC resonant circuit. The clock input terminal of the serial interface microcontroller is used to receive a short-range wireless communication clock signal and control the conduction and disconnection of the first end and the second end of the switching circuit to output short-range wireless communication output data according to a short-range wireless communication protocol.

[0012] According to a near field communication tag device according to a preferred embodiment of the present invention, the above-mentioned near field communication LC resonant circuit includes a near field communication resonant coil and a resonant capacitance. The near field communication resonant coil includes a first end and a second end, the first end of the near field communication resonant coil is connected to the first end of the near field communication LC resonant circuit, and the second end of the near field communication resonant coil is connected to the second end of the near field communication LC resonant circuit. The resonant capacitance has a first end and a second end, the first end of the resonant capacitance is connected to the first end of the near field communication LC resonant circuit, and the second end of the resonant capacitance is connected to the second end of the near field communication LC resonant circuit.

[0013] According to the near field communication tag device of the preferred embodiment of the present invention, the above-mentioned serial interface microcontroller is used to receive an envelope signal based on a Serial Peripheral Interface Bus (SPI) transmission protocol. In another preferred embodiment, the above-mentioned serial interface microcontroller is used to receive an envelope signal based on an Integrated Interchip Sound (I2S) transmission protocol.

[0014] In order to achieve the above object, the present invention further provides a method for near field communication with a serial interface microcontroller, which includes the steps of providing a serial interface microcontroller, detecting a near field communication carrier wave by a near field communication LC resonant circuit, dividing the near field communication carrier wave according to a near field communication protocol to obtain a near field communication clock signal, performing envelope detection on the near field communication carrier wave of the near field communication LC resonant circuit to obtain an envelope signal, sequentially receiving a digital sequence of the envelope signal according to a serial transmission protocol and a trigger order of the near field communication clock signal, and decoding near field communication data from the digital sequence of the envelope signal according to the near field communication protocol.

[0015] According to a method for short-distance wireless communication using a serial interface microcontroller according to a preferred embodiment of the present invention, the above-mentioned serial transmission protocol is used to receive the envelope signal based on a Serial Peripheral Interface Bus (SPI) transmission protocol. In another preferred embodiment, the above-mentioned serial interface microcontroller is used to receive the envelope signal based on an I2S (Integrated Interchip Sound) transmission protocol.

[0016] According to a preferred embodiment of the present invention, the short-range wireless communication method using a serial interface microcontroller further includes the steps of providing a switching circuit connected between a first end of the short-range wireless communication LC resonant circuit and a second end of the short-range wireless communication LC resonant circuit, and controlling the conduction and disconnection of the first end and the second end of the switching circuit to output short-range wireless communication output data according to a short-range wireless communication protocol. Effect of the Invention

[0017] As described above, the present invention has the following advantages. The spirit of the preferred embodiment of the present invention is to detect the carrier signal from the short-range wireless communication coil, and generate a clock signal corresponding to the short-range wireless communication modulation frequency by dividing the signal, and transmit it to the serial interface microcontroller. The modulated signal is detected by the short-range wireless communication coil, and the binary digital signal sequence of the short-range wireless communication is demodulated by the envelope detection circuit, and is sequentially transmitted to the serial interface microcontroller according to the above-mentioned clock signal. Then, the binary signal of the short-range wireless communication is decoded into short-range wireless communication data by the serial interface microcontroller. In this way, the present invention decodes the short-range wireless communication data without adopting an integrated circuit dedicated to short-range wireless communication, thus saving costs.

[0018] Other objects, configurations and effects of the present invention will become apparent from the following detailed description of the preferred embodiments of the present invention. [Brief description of the drawings]

[0019] [Figure 1] 1 is a block diagram showing a circuit of a short-range wireless communication tag device according to a preferred embodiment of the present invention; [Diagram 2] 1 shows a schematic diagram of three symbols during transmission of the ISO 14443A Downlink transmission link of the present invention. [Diagram 3] 1 is a schematic diagram showing an ISO 14443A short-range wireless communication signal received by a short-range wireless communication tag device according to a preferred embodiment of the present invention. [Figure 4] 1 shows a schematic diagram of three symbols during transmission of an ISO 14443A uplink transmission link (Uplink) according to the present invention. [Diagram 5] 1 is a schematic diagram showing an ISO 14443A short-range wireless communication signal transmitted by a short-range wireless communication tag device according to a preferred embodiment of the present invention. [Figure 6] 1 is a schematic diagram showing a signal being transmitted in the ISO 14443B downlink transmission link (Downlink) of the present invention. [Figure 7] 1 is a schematic diagram showing a signal being transmitted in the ISO 14443B uplink transmission link (Uplink) of the present invention; [Figure 8] 1 is a schematic diagram showing a signal being transmitted in the ISO 15693 downlink transmission link (Downlink) of the present invention. [Figure 9] 1 is a schematic diagram showing an ISO 15693 short-range wireless communication signal received by a short-range wireless communication tag device according to a preferred embodiment of the present invention; [Figure 10] 1 is a schematic diagram showing a signal being transmitted in the ISO 15693 uplink transmission link (Uplink) of the present invention; [Figure 11] 2 is a block diagram showing a more detailed circuit of a short-range wireless communication tag device according to a preferred embodiment of the present invention; [Figure 12] 1 is a circuit diagram showing an envelope detection circuit 103 of a near-field wireless communication tag device according to a preferred embodiment of the present invention. [Figure 13] 4 is a flowchart showing data reception by a short-range wireless communication tag device using a short-range wireless communication method by a serial interface microcontroller according to a preferred embodiment of the present invention. [Figure 14] 4 is a flowchart showing data transmission by a short-range wireless communication tag device using a short-range wireless communication method by a serial interface microcontroller according to a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, the embodiments of the present invention will be described in detail. However, the present invention is not limited to these, and various modifications are possible within the scope of the description. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in the different embodiments.

[0021] FIG. 1 is a block diagram showing a circuit of a short-range wireless communication tag device according to a preferred embodiment of the present invention. As shown in the figure, the short-range wireless communication tag device includes a short-range wireless communication LC resonant circuit 101, a frequency divider circuit 102, an envelope detector circuit 103, a serial interface microcontroller 104, and a switching circuit 105. The short-range wireless communication LC resonant circuit 101 uses, for example, a short-range wireless communication resonant coil and a resonant capacitance, and is connected in parallel. The frequency divider circuit 102 includes an input terminal and an output terminal, and the input terminal of the frequency divider circuit is connected to the first terminal of the short-range wireless communication LC resonant circuit 101. The envelope detector circuit 103 includes an input terminal and an output terminal, and the input terminal of the envelope detector circuit 103 is connected to the first terminal of the short-range wireless communication LC resonant circuit 101. The serial interface microcontroller 104 has a clock input terminal SCK, a serial data input terminal SIN, and a serial data output terminal SOUT, and the clock input terminal SCK of the serial interface microcontroller 104 is connected to the output terminal of the frequency divider circuit 102, and the serial data input terminal SIN of the serial interface microcontroller 104 is connected to the output terminal of the envelope detection circuit 103. The serial data output terminal SOUT of the serial interface microcontroller 104 is connected to the control terminal of the switching circuit 105, and controls the conductive states of the first terminal and the second terminal of the switching circuit 105.

[0022] Near field communication is based on inductive coupling between two antennas, and equipment supporting near field communication uses a carrier frequency of 13.56MHz, and uses the ISO / IEC18000-3 air interface standard in the globally available unlicensed radio frequency ISM band for one-way or two-way communication. Due to differences in specifications, there are mainly two standards for near field communication: ISO 14443 and ISO 15693. A typical near field communication tag device only complies with one of the specifications. Based on the above two types of specifications, the near field communication tag reader outputs a signal to an external near field communication tag device by a polling method, and waits for a response from the external near field communication tag device.

[0023] First, if the short-range wireless communication tag device uses the specifications of ISO 14443A, its data transmission rate is 106Kbps. In the downlink transmission, the short-range wireless communication reader transmits a signal to the short-range wireless communication tag by adopting modified Miller coding, and the modulation method is 100% amplitude shift keying (ASK), and the modified Miller coding and 100% amplitude shift keying mainly include three symbols (see FIG. 2). FIG. 2 shows three symbols during the transmission of the downlink transmission link of the present invention in ISO 14443A. The above-mentioned symbols include sequence X, sequence Y, and sequence Z, and Tb=9.44us; Tx=4.72us; T1=2.36us. The logic low potential (shown as 0 in the figure) is the modulated state, and the logic high potential (shown as 1 in the figure) is the unmodulated state.

[0024] As can be seen from the above diagrams and data, the modified mirror code is encoded with a subcarrier frequency of 423.75KHz, so in this embodiment, the short-range wireless communication carrier frequency of 13.56MHz is divided by 32 to obtain a clock frequency of 423.75KHz.

[0025] The logic 1 of the modified mirror code according to this embodiment corresponds to the sequence X described above, and its digital sequence is 1101. The logic 0 corresponds to the sequence Y described above, and its digital sequence is 1111. When there are two or more consecutive logic 0s, the second and subsequent logic 0s adopt the sequence Z described above, and their digital sequence is 0111. Since the end of communication code combines one logic 0 with one of the above-mentioned sequences Y, when the bit immediately before the end of communication code is logic 1 (digital sequence is 1101), the end of communication code is two Ys (11111111). When the bit immediately before the end of communication code is logic 0 (digital sequence is 0111), the end of communication code is one Z and one Y (01111111). No information is at least two sequences Y. Also, start of communication is the sequence Z.

[0026] In this embodiment, the serial interface microcontroller 104 employs a serial peripheral interface transmission protocol (SPI) to transmit and receive data. The frequency divider circuit 102 detects a 13.56MHz carrier wave, divides the carrier wave frequency by 32 to obtain a 423.75KHz clock, and then provides a serial peripheral interface clock signal SPI CLK to the serial interface microcontroller 104. Note that the start of communication is sequence Z, and the first bit is a logical constant voltage, which is used to trigger the operation of the serial peripheral interface in this embodiment.

[0027] For example, the communication start of the near field communication reader is shown in the signal of Fig. 3, which is a schematic diagram of the ISO 14443A near field communication signal received by the near field communication tag device according to the preferred embodiment of the present invention. Referring to Fig. 3, upon receiving the carrier wave, the frequency divider circuit 102 divides the near field communication clock signal according to the near field communication carrier wave of the first end of the near field communication LC resonant circuit, and transmits it to the clock input terminal SCK of the serial interface microcontroller 104. After receiving the transmitted sequence Z, the serial peripheral interface is triggered, and the serial data input terminal SIN of the serial interface microcontroller 104 sequentially receives the envelope of the signal of Fig. 3 from the output terminal of the envelope detection circuit 103, and temporarily stores the received signal in the memory of the serial interface microcontroller 104 by a direct memory access (DMA) method.

[0028] In this embodiment, the received sequence is SOF (Start Of Frame) Z, Z, Z, Z, Z, Z, X, X, Y, X, Y, Z…………Y, Y (End Of Frame, EOF), and the corresponding data received by the serial peripheral interface is: 0111, 0111, 0111, 0111, 0111, 0111, 1101, 1101, 1111, 0111, 1111, 0111…………, 1111, 1111.

[0029] Then, the serial interface microcontroller 104 decodes the received raw data into 000001101000000001101.....0100 based on the modified mirror code described above. In this way, the data transmitted by the near field communication reader to the near field communication tag device is decoded.

[0030] For the uplink transmission link (Uplink), that is, for the part where the short-range wireless communication tag device transmits data to the short-range wireless communication reader, Manchester code is adopted, and the modulation method is On-Off Keying (OOK), which mainly includes three symbols (see FIG. 4). FIG. 4 shows the three symbols during the transmission of the uplink transmission link (Uplink) in the ISO 14443A of the present invention. The above-mentioned symbols include sequence D, sequence E, and sequence F, where the first 50% of sequence D is modulated, the second 50% of sequence E is modulated, and sequence F is unmodulated (pure carrier wave).

[0031] A logic 1 corresponds to the above sequence D, a logic 0 corresponds to the above sequence E, an end of communication corresponds to the above sequence F, and a start of communication corresponds to the above sequence D. The frequency of the above modulated subcarrier is 1.696 MHz, and when performing an uplink transmission link, the divider circuit 102 divides the 13.56 MHz carrier transmitted from the short-range wireless communication reader by 8 to obtain a 1.696 MHz clock.

[0032] For ease of understanding, Fig. 5 is a schematic diagram showing an ISO 14443A short-range wireless communication signal transmitted by a short-range wireless communication tag device according to a preferred embodiment of the present invention. As shown in the figure, in this embodiment, the data to be transmitted is assumed to be 1011010.... Therefore, the corresponding sequences are D (Start Of Frame, SOF), D, E, D, D, E, D, E.... These sequences are converted to 0101010100000000, 0101010100000000, 0000000001010101, 0101010100000000, 0101010100000000, 0000000001010101, 101010100000000, 0000000001010101... and stored in memory. The serial interface microcontroller 104 uses the 1.696MHz clock as the serial peripheral interface clock signal SPI CLK, and sequentially retrieves data from the memory by a direct memory access (DMA) method and outputs the data to the serial data output terminal SOUT of the serial interface microcontroller 104, thereby controlling the conduction and cut-off of the switching circuit 105. In this way, the above-mentioned data 1011010... is transmitted to the near field communication reader.

[0033] Next, if the short-range wireless communication tag device is an ISO 14443B short-range wireless communication tag device, its data transmission rate may be 106 / 212 / 424 / 848 Kbps. During transmission of the downlink transmission link (Downlink), that is, when the short-range wireless communication reader transmits to the short-range wireless communication tag, a non-return-to-zero line code (NRZ) is adopted, and the modulation method is 10% Amplitude Shift Keying (ASK), and this non-return-to-zero line code is a modulated signal when it is logic 0, and a low potential with an amplitude of 10% when it is logic 1 (see FIG. 6). FIG. 6 is a schematic diagram showing a signal during transmission of the ISO 14443B downlink transmission link (Downlink) of the present invention. After detecting the envelope by the envelope detection circuit 103, the data is received using a serial peripheral interface to correspond to 106KHz (or higher frequency) simply by comparing with a threshold value.

[0034] Similarly, for the uplink transmission link (Uplink) part, the modulation adopts non-return-to-zero line code (NRZ) and binary phase shift keying (BPSK). The clock corresponding to the serial peripheral interface is 1.696MHz (see FIG. 7). FIG. 7 is a schematic diagram showing the signals during the transmission of the uplink transmission link (Uplink) of the ISO 14443B of the present invention. As shown in the figure, during the transmission of the uplink transmission link, a logical 1 is encoded as 0101010101010101, and a logical 0 is encoded as 1010101010101010. The phase difference between the encoded signals of logical 1 and logical 0 is 180 degrees. Therefore, when the near field communication tag device transmits data to the near field communication reader, the serial interface microcontroller 104 uses the 1.696MHz clock as the serial peripheral interface clock signal SPI CLK, sequentially retrieves the encoded data from the memory by a direct memory access (DMA) method, and outputs it to the serial data output terminal SOUT of the serial interface microcontroller 104, sequentially controls the conduction and disconnection of the switching circuit 105, and transmits the data to the near field communication reader.

[0035] Similarly, if the short-range wireless communication tag device is an ISO 15693 short-range wireless communication tag device, during the transmission of the downlink transmission link (Downlink), that is, when the short-range wireless communication reader transmits to the short-range wireless communication tag, a pulse-position modulation (PPM) with a subcarrier of 106KHz is adopted, and 100% amplitude shift keying (ASK) or 10% to 30% amplitude shift keying of a 13.56MHz carrier is combined. The main symbols are as shown in FIG. 8, which is a schematic diagram showing a signal during transmission of the ISO 15693 downlink transmission link (Downlink) of the present invention. As shown in the figure, the symbol code of the start of frame (SOF) is 01111011, and the corresponding clock of 106KHz is a total of 8 bits. The symbol code of the end of frame (EOF) is 11011111. The symbol codes for symbols 00, 01, 10, and 11 are 10111111, 11101111, 11111011, and 11111110, respectively.

[0036] Similarly, in this embodiment, the logic 0 of the first bit of a Start Of Frame (SOF) symbol is used as a trigger for the serial peripheral interface to start a receive operation.

[0037] For example, the short-range wireless communication reader starts transmitting 0xE1 (see the signal in FIG. 9), and FIG. 9 is a schematic diagram showing an ISO 15693 short-range wireless communication signal received by the short-range wireless communication tag device according to a preferred embodiment of the present invention. As shown in FIG. 9, 0xE1 is 11100001 in binary, but is received in the order of 01, 00, 10, and 11 during transmission. Upon receiving the carrier wave, the frequency divider circuit 102 divides the 106KHz short-range wireless communication clock signal according to the short-range wireless communication carrier wave of the first end of the short-range wireless communication LC resonant circuit, and transmits it to the clock input end SCK of the serial interface microcontroller 104 as the serial peripheral interface clock signal SPI CLK. After receiving the start of frame, the serial peripheral interface is triggered, and the serial data input terminal SIN of the serial interface microcontroller 104 sequentially receives 11101111, 10111111, 11111011, and 11111110 from the output terminal of the envelope detection circuit 103, and temporarily stores the received signals in the memory of the serial interface microcontroller 104 by the direct memory access (DMA) method.

[0038] Then, the serial interface microcontroller 104 decodes the received raw data into 01, 00, 10, and 11 based on the above-mentioned pulse-position modulation (PPM), thereby decoding the data 0xE1 transmitted by the near field communication reader to the near field communication tag device.

[0039] Fig. 10 is a schematic diagram showing a signal during transmission of the uplink transmission link (Uplink) of the ISO 15693 of the present invention. As shown in the figure, when transmitting the uplink transmission link (Uplink), Manchester code is adopted, which is executed on a subcarrier of 847KHz, and the modulation method is on-off keying (OOK), which mainly includes two symbols (see Fig. 10). When transmitting logic 0, the serial data output terminal SOUT of the serial interface microcontroller 104 outputs 0101010101010000000000000000 to the switching circuit 105 according to the subcarrier of 847KHz. When a logical 1 is transmitted, the serial data output terminal SOUT of the serial interface microcontroller 104 outputs 1111111111111111010101010101 based on the 847KHz subcarrier to the switching circuit 105. Similarly, data to be transmitted is first stored in memory and then transmitted to the serial data output terminal SOUT of the serial interface microcontroller 104 by a direct memory access (DMA) method.

[0040] In the above embodiment, the serial interface microcontroller 104 receives an envelope signal based on a serial peripheral interface bus (SPI) transmission protocol, but those skilled in the art will understand that the serial interface microcontroller can receive an envelope signal based on an integrated interchip sound (I2S) transmission protocol. Therefore, the present invention is not limited to using the serial peripheral interface transmission protocol. In addition, the short-range wireless communication LC resonant circuit 101 in the above embodiment is a short-range wireless communication resonant coil and a resonant capacitance connected in parallel, but those skilled in the art will understand that the short-range wireless communication LC resonant circuit 101 can also adopt a series resonance, so the present invention is not limited thereto.

[0041] FIG. 11 is a block diagram showing a more detailed circuit of a short-range wireless communication tag device according to a preferred embodiment of the present invention. Comparing FIG. 1 with FIG. 11, in the embodiment of FIG. 11, a DC blocking circuit 1101 and a bias circuit 1102 are added to the short-range wireless communication tag device. The DC blocking circuit 1101 is composed of a capacitance including a first end and a second end, the first end of the DC blocking circuit 1101 is connected to the first end of the short-range wireless communication LC resonant circuit 101, and the second end of the DC blocking circuit 1101 is connected to the input end of the frequency divider circuit, and is used to block the DC component of the short-range wireless communication carrier wave and pass the AC component of the 13.56 MHz short-range wireless communication carrier wave. The bias circuit 1102 is composed of two resistors R1 and R2. The resistor R1 is connected between the DC blocking circuit 1101 and the power supply voltage VDD, and the resistor R2 is connected between the DC blocking circuit 1101 and the common voltage VSS. The bias circuit 1102 is used to steer the short-range wireless communication carrier between a power supply voltage VDD and a common voltage VSS.

[0042] 12 is a circuit diagram showing an envelope detection circuit 103 of a near field communication tag device according to a preferred embodiment of the present invention. As shown in the figure, the envelope detection circuit 103 includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first unidirectional conductive element D1, a second unidirectional conductive element D2, a first transistor B1, a first capacitance C1, and a second capacitance C2. A first end of the third resistor R3 is connected to a power supply voltage VDD. A first end of the first unidirectional conductive element D1 is connected to a second end of the third resistor R3, and a second end of the first unidirectional conductive element D1 is connected to an input terminal IN of the envelope detection circuit 103, and the first unidirectional conductive element D1 is implemented as a diode in this embodiment. The emitter terminal of the first transistor B1 is connected to the common voltage VSS, the collector terminal of the first transistor B1 is connected to the first terminal of the first unidirectional conductive element D1, and the base terminal of the first transistor B1 is connected to the second terminal of the first unidirectional conductive element D1.

[0043] The first end of the second unidirectional conductive element D2 is connected to the second end of the second capacitance C2, and the second end of the second unidirectional conductive element D2 is connected to the collector end of the first transistor B1, and the second unidirectional conductive element D2 is implemented as a diode in this embodiment. The first end of the first capacitance C1 is connected to the first end of the second unidirectional conductive element D2, and the second end of the first capacitance is connected to the common voltage VSS. The first end of the fourth resistor R4 is connected to the power supply voltage VDD, and the second end of the fourth resistor R4 is connected to the first end of the second unidirectional conductive element D2. The first end of the second capacitance C2 is connected to the output end OUT of the envelope detection circuit, and the second end of the second capacitance C2 is connected to the first end of the second unidirectional conductive element D2. The first end of the fifth resistor R5 is connected to the power supply voltage VDD, and the second end of the fifth resistor R5 is connected to the first end of the second capacitance C2. A first end of the sixth resistor R6 is connected to a first end of the second capacitance C2, and a second end of the sixth resistor R6 is connected to the common voltage VSS.

[0044] This embodiment is an envelope detector based on an operational amplifier, which has higher sensitivity and wider dynamic range. Bipolar transistor B1 and first unidirectional conductive element D1 are used to bias and make bipolar transistor B1 permanently operate in the forward active region. Load resistor R4 is connected to power supply voltage VDD and provides a small bias current to second unidirectional conductive element D2. Second unidirectional conductive element D2 rectifies the positive half-wave of collector voltage of bipolar transistor B1, and the potential of the plate of capacitance C2 follows the fluctuation of the envelope of the signal. Second capacitance C2 mainly captures the AC part of the envelope and filters the DC part, and fifth resistor R5 and sixth resistor R6 bias the AC part of the envelope. Second capacitance C2, fifth resistor R5 and sixth resistor R6 do not need any circuit and can be eliminated according to the situation and design. However, the present invention is not limited thereto.

[0045] The first unidirectional conductive element D1 and the second unidirectional conductive element D2 together restrict the current to flow from the first end of the unidirectional conductive element to the second end of the unidirectional conductive element. A person skilled in the art will appreciate that the unidirectional conductive element can be implemented by connecting a diode of a transistor or in other ways, other than using a diode, but the present invention is not limited thereto.

[0046] 13 is a flowchart showing data reception by a short-range wireless communication tag device using the short-range wireless communication method by a serial interface microcontroller according to a preferred embodiment of the present invention. As shown in the figure, in the short-range wireless communication method by a serial interface microcontroller, a method for receiving data by a short-range wireless communication tag device includes the following steps:

[0047] Step S1301 provides a serial interface microcontroller (see the serial interface microcontroller 104 of FIG. 1), and the serial interface microcontroller 104 has a serial interface, such as the above-mentioned Serial Peripheral Interface Bus (SPI) transmission protocol or I2S transmission protocol (Integrated Interchip Sound).

[0048] Step S1302: detecting a short-range wireless communication carrier wave by the short-range wireless communication LC resonant circuit. In this embodiment, a short-range wireless communication carrier wave of 13.56 MHz is detected.

[0049] Step S1303: divide the short-range wireless communication carrier wave to obtain a short-range wireless communication clock signal. As in the above-mentioned embodiment, the frequency of the frequency divider circuit 102 divides the short-range wireless communication carrier wave according to the type of short-range wireless communication protocol used.

[0050] In step S1304, an envelope signal is obtained by performing envelope detection on the short-range wireless communication carrier of the short-range wireless communication LC resonant circuit. As in the above-described embodiments of Figs. 1 to 10, the envelope detection circuit 103 performs envelope detection on the short-range wireless communication carrier.

[0051] Step S1305 of sequentially receiving the digital sequence of envelope signals according to the serial transmission protocol and the triggering order of the near field communication clock signal, as in the above-mentioned embodiments of Figs.

[0052] S1306: decoding short-range wireless communication data from the digital sequence of the envelope signal based on a short-range wireless communication protocol.

[0053] 14 is a flowchart showing data transmission by a short-range wireless communication tag device using the short-range wireless communication method by a serial interface microcontroller according to a preferred embodiment of the present invention. Referring to FIG. 13 and FIG. 14, in the short-range wireless communication method by a serial interface microcontroller, a method of transmitting data by a short-range wireless communication tag device includes the following steps:

[0054] Step S1401: providing a switching circuit connected between a first end of the near field communication LC resonant circuit and a second end of the near field communication LC resonant circuit.

[0055] Steps S1301 to S1303 are the same as in the above-described embodiment.

[0056] Step S1402: controlling the first end and the second end of the switching circuit to be conductive and disconnected according to a short-range wireless communication protocol so as to output short-range wireless communication output data.

[0057] In summary, the spirit of the preferred embodiment of the present invention is to detect the carrier signal from the short-range wireless communication coil, generate a clock signal corresponding to the modulation frequency of the short-range wireless communication by frequency division, and transmit it to the serial interface microcontroller; and detect the modulated signal from the short-range wireless communication coil, demodulate the short-range wireless communication binary digital signal sequence by the envelope detection circuit, and sequentially transmit it to the serial interface microcontroller according to the above-mentioned clock signal. Then, the serial interface microcontroller decodes the short-range wireless communication data from the short-range wireless communication binary signal. In this way, the present invention does not adopt an integrated circuit dedicated to short-range wireless communication to decode the short-range wireless communication data, thereby saving costs.

[0058] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is clear to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the description of the claims that such modifications and improvements can also be included in the technical scope of the present invention. [Explanation of symbols]

[0059] 101 Near field wireless communication LC resonant circuit 102 Frequency divider circuit 103 Envelope detection circuit 104 Serial Interface Microcontroller 105 Switching Circuits SCK Clock input terminal SIN Serial data input terminal SOUT Serial data output terminal 1101 DC interruption circuit 1102 Bias circuit R1 resistor R2 resistor R3 resistor R4 resistor R5 resistor R6 resistor VDD Power supply voltage VSS Common voltage D1 First unidirectional conductive element D2 Second unidirectional conductive element B1 First transistor C1 Capacitance C2 Capacitance S1301~S1306 Flowchart S1401~S1402 Flowchart

Claims

1. a near field communication LC resonant circuit including a first end and a second end; a frequency divider circuit including an input terminal and an output terminal, the input terminal of the frequency divider circuit being connected to a first terminal of the short-range wireless communication LC resonant circuit; an envelope detection circuit including an input terminal and an output terminal, the input terminal of the envelope detection circuit being connected to a first terminal of the short-range wireless communication LC resonant circuit; a serial interface microcontroller including a clock input and a serial data input, the clock input of the serial interface microcontroller being connected to the output of the frequency divider circuit, and the serial data input of the serial interface microcontroller being connected to the output of the envelope detector circuit; The frequency divider circuit divides a frequency of a near field communication clock signal from a near field communication carrier wave of the first end of the near field communication LC resonant circuit according to a near field communication protocol; The envelope detection circuit converts the received signal into an envelope signal based on the received signal, A near field communication tag device, characterized in that a clock input terminal of the serial interface microcontroller receives the near field communication clock signal, and a serial data input terminal of the serial interface microcontroller receives the envelope signal, and is used to decode near field communication data from the envelope signal according to the near field communication protocol, The envelope detection circuit includes: a third resistor having a first end and a second end, the first end of the third resistor being coupled to a power supply voltage; a first unidirectional conductive element including a first end and a second end, the first end of the first unidirectional conductive element being connected to the second end of the third resistor and the second end of the first unidirectional conductive element being connected to an input end of the envelope detection circuit, the first unidirectional conductive element restricting a current to flow from the first end of the first unidirectional conductive element to the second end of the first unidirectional conductive element; a first transistor including an emitter terminal, a collector terminal, and a base terminal, the emitter terminal of the first transistor being connected to a common voltage, the collector terminal of the first transistor being connected to a first terminal of the first unidirectional conductive element, and the base terminal of the first transistor being connected to a second terminal of the first unidirectional conductive element; a second unidirectional conductive element including a first end and a second end, the first end of the second unidirectional conductive element being connected to an output end of the envelope detection circuit and the second end of the second unidirectional conductive element being connected to a collector end of the first transistor, the second unidirectional conductive element restricting a current to flow from the first end of the second unidirectional conductive element to the second end of the second unidirectional conductive element; a first capacitance having a first end and a second end, the first end of the first capacitance being connected to the first end of the second unidirectional conductive element and the second end of the first capacitance being connected to the common voltage; a fourth resistor including a first end and a second end, the first end of the fourth resistor being connected to the power supply voltage and the second end of the fourth resistor being connected to the first end of the second unidirectional conductive element.

2. 2. The short-range wireless communication tag device of claim 1, further comprising a DC blocking circuit including a first end and a second end, the first end of the DC blocking circuit being connected to a first end of the short-range wireless communication LC resonant circuit and the second end of the DC blocking circuit being connected to an input end of the frequency divider circuit, the DC blocking circuit being used to pass the short-range wireless communication carrier wave.

3. The near-field wireless communication tag device according to claim 2, further comprising a bias circuit connected between the DC blocking circuit and the input terminal of the frequency divider circuit and used to operate the near-field wireless communication carrier wave between a power supply voltage and a common voltage.

4. The bias circuit includes: a first resistor including a first end and a second end, the first end of the first resistor being connected to the power supply voltage and the second end of the first resistor being connected to the second end of the DC blocking circuit; and a second resistor having a first end and a second end, the first end of the second resistor being connected to the second end of the DC blocking circuit and the second end of the second resistor being connected to the common voltage.

5. The envelope detection circuit includes: a second capacitance having a first end and a second end, the first end of the second capacitance being connected to the output end of the envelope detection circuit and the second end of the second capacitance being connected to the first end of the second unidirectional conductive element; a fifth resistor having a first end and a second end, the first end of the fifth resistor being coupled to the power supply voltage and the second end of the fifth resistor being coupled to the first end of the second capacitance; 2. The near-field wireless communication tag device of claim 1, further comprising: a sixth resistor having a first end and a second end, the first end of the sixth resistor being connected to the first end of the second capacitance and the second end of the sixth resistor being connected to the common voltage.

6. The serial interface microcontroller further includes a serial data output terminal, and the short-range wireless communication tag device includes: A switching circuit including a first end, a second end and a control end, the control end of the switching circuit being connected to a serial data output end of the serial interface microcontroller, the first end of the switching circuit being connected to a first end of the short-range wireless communication LC resonant circuit, and the second end of the switching circuit being connected to a second end of the short-range wireless communication LC resonant circuit; The near-field wireless communication tag device according to claim 1, characterized in that the clock input terminal of the serial interface microcontroller is used to receive the near-field wireless communication clock signal and control the conduction and disconnection of the first terminal and the second terminal of the switching circuit so as to output near-field wireless communication output data based on the near-field wireless communication protocol.

7. The short-range wireless communication LC resonant circuit includes: a short-range wireless communication resonant coil including a first end and a second end, the first end of the short-range wireless communication resonant coil being connected to a first end of the short-range wireless communication LC resonant circuit, and the second end of the short-range wireless communication resonant coil being connected to a second end of the short-range wireless communication LC resonant circuit; The near-field wireless communication tag device of claim 1, further comprising: a resonant capacitance having a first end and a second end, the first end of the resonant capacitance being connected to a first end of the near-field wireless communication LC resonant circuit, and the second end of the resonant capacitance being connected to the second end of the near-field wireless communication LC resonant circuit.

8. 2. The near field wireless communication tag device according to claim 1, wherein the serial interface microcontroller receives the envelope signal based on a Serial Peripheral Interface Bus (SPI) transmission protocol.

9. 2. The short-range wireless communication tag device according to claim 1, wherein the serial interface microcontroller receives the envelope signal based on an I2S (Integrated Interchip Sound) transmission protocol.

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