CN202276343U - Near field communication module - Google Patents

Abstract

The utility model discloses a near field communication module, which comprises a radio frequency unit, a control unit, a baseband processing unit and a regulated power supply unit, wherein the radio frequency unit comprises a radio frequency chip subunit and an RC (resistor-capacitor) resonance circuit, the control unit and the baseband processing unit are integrated in the radio frequency chip subunit, the regulated power supply unit supplies power voltage to the radio frequency chip subunit, and the RC resonance circuit is connected with the radio frequency chip subunit, and is used for providing an outward antenna interface. The near field communication module modularizes and subminiaturizes the NFC (near field communication) function, the radio frequency chip subunit which carries out the payment function of an NFC mobile phone, a peripheral circuit, a crystal oscillator unit, the RC resonance circuit and the like can be integrated in one module,a power interface, the antenna interface and a communication interface are provided in terms of outward hardware, an application programming interface (API) is provided in terms of software, and thereby the near field communication module can be transplanted into the mobile phone or other hand-held devices after corresponding software and hardware are connected.

Description

A near field communication module

technical field

The utility model belongs to the technical field of radio frequency identification, in particular to a miniature embedded near-field communication module.

Background technique

Near Field Communication (NFC), also known as short-range wireless communication, is a short-range high-frequency wireless communication technology that allows non-contact point-to-point data transmission (within ten centimeters) and exchange between electronic devices. . This technology evolved from contactless radio frequency identification (Radio Frequency Identification, RFID) and is backward compatible with RFID. It was first promoted by Philips, Nokia and Sony, and is mainly used in handheld devices such as mobile phones. Due to the natural security of near-field communication, NFC technology is considered to have great application prospects in fields such as mobile payment.

The built-in NFC module of the mobile phone constitutes a part of the RFID module, which can be used as an RFID passive tag for payment; it can also be used as an RFID reader for data exchange and collection. NFC technology supports a variety of applications, including mobile payment and transactions, peer-to-peer communication, and information access on the move. Through the mobile phone with the NFC module, people can connect with the entertainment services and transactions they want at any place, any time, and through any device, so as to complete payment, obtain poster information and other functions. NFC devices can be used as contactless smart cards, smart card reader terminals, and device-to-device data transmission links. Their applications can be divided into the following four basic types: for payment and ticket purchase, for electronic tickets, For smart media and for exchanging and transmitting data.

According to the NFC technology architecture diagram officially announced by the NFC Forum in June 2006, the specific figure is shown in Figure 1. Wherein, the microprocessor is the processor part of the mobile phone or other terminals, and realizes the control of the NFC module through the interface. However, most of the existing NFC modules use the dual-chip solution of the combination of the NFC chip PN544 and its auxiliary security chip SmartMx, and there are many chips and circuits that implement various additional functions outside the chip, so that the NFC module is too large and inconvenient use.

Utility model content

The purpose of the utility model is to solve the above-mentioned problems existing in the existing NFC module, and propose a near field communication module.

The specific technical solution is: a near-field communication module, including a radio frequency unit, a control unit, a baseband processing unit, and a stabilized power supply unit, wherein the radio frequency unit includes a radio frequency chip subunit and an RC resonant circuit, and the control unit and the baseband The processing unit is integrated in the radio frequency chip subunit, the stabilized power supply unit provides power supply voltage for the radio frequency chip subunit, and the RC resonant circuit is connected with the radio frequency chip subunit to provide an external antenna interface.

Further, the near field communication module further includes a crystal oscillator unit, which provides an external clock for the radio frequency chip sub-unit.

Further, the radio frequency chip sub-unit is specifically implemented by a PN65N chip.

Furthermore, the stabilized power supply unit is specifically realized by the PAM3013DAB33 chip.

Beneficial effects of the utility model: the near-field communication module of the utility model modularizes and miniaturizes the NFC function, and can integrate the radio frequency chip subunit and its peripheral circuit, crystal oscillator unit, RC resonant circuit, etc. that realize the NFC mobile phone payment function In one module, the external hardware provides power interface, antenna interface and communication interface, and the software provides API interface, so that it can be transplanted to mobile phones or other handheld devices after corresponding software and hardware connections, so that the module is installed The equipment realizes NFC-based payment function, card simulation function and peer-to-peer communication function.

Description of drawings

Figure 1 is a technical architecture diagram of NFC.

Fig. 2 is a schematic diagram of the principle of the NFC module of the present invention.

Fig. 3 is a structural block diagram of the NFC module of the present invention.

Fig. 4 is a schematic diagram of the circuit principle of the stabilized power supply unit of the present invention.

Fig. 5 is a schematic diagram of the circuit principle of the radio frequency chip subunit of the present invention.

FIG. 6 is a schematic diagram of the principles of the RC resonant circuit and the antenna circuit of the present invention.

FIG. 7 is a schematic diagram of the basic peripheral circuit of the crystal oscillator unit of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the utility model is described further.

The near-field communication module of the present utility model includes a radio frequency unit, a control unit, a baseband processing unit and a stabilized power supply unit, wherein the radio frequency unit includes a radio frequency chip subunit and an RC resonant circuit, and the control unit and the baseband processing unit are integrated in the radio frequency In the chip subunit, the stabilized power supply unit provides a power supply voltage for the radio frequency chip subunit, and the RC resonant circuit is connected with the radio frequency chip subunit to provide an external antenna interface.

Wherein, the control unit and the baseband processing unit are integrated in the radio frequency chip sub-unit, which will not be described in detail here. Here we mainly introduce the radio frequency unit and the regulated power supply unit.

The near field communication module also includes a crystal oscillator unit, which provides an external clock for the radio frequency chip sub-unit.

The radio frequency chip sub-unit here is specifically implemented by a PN65N chip.

Figure 3 shows a structural block diagram of a near field communication module. A detailed description is given below.

Regulated power supply unit: Figure 4 shows the regulated power supply unit U2 (namely PAM3013DAB33). The regulated power supply unit provides the required voltage value for each unit. It belongs to the low dropout (LDO) voltage regulator chip, and the cost of the LDO voltage regulator chip Low noise, low quiescent current. At the same time, it requires few external components, usually only one or two bypass capacitors, which greatly simplifies the peripheral circuit of the chip. In addition, the utility model adopts a single power supply design, and the volume of the whole design is further reduced. Pin 1 of U2 (that is, PAM3013DAB33) is the chip enable terminal, connected to 5V voltage, and C5 is the filter capacitor. R9 and R10 are voltage divider resistors to control the output voltage, C7 is a filter capacitor, pin 5 is an output pin of the chip, and the working voltage of each subunit in the radio frequency unit is 3.3V.

Radio frequency unit: including radio frequency chip subunit, RC resonant circuit and antenna, as shown in Figure 5 and Figure 6.

Fig. 5 shows the radio frequency chip sub-unit in the radio frequency unit, where the radio frequency chip sub-unit is specifically implemented by a PN65N chip. The PN65N chip is the second generation NFC chip produced by NXP. It integrates the NFC chip PN544 and the security chip SmartMx. Card reader mode: supports reading cards of ISO 15693, ISO14443TypeA, ISO14443TypeB, Sony Felica and Mifare Classic protocols; virtual card mode: simulated as a MIFARE card (integrated with SmartMx), and can also be connected to an external UICC; NFC-IP1 mode (i.e. realize point-to-point communication mode): Transmission rate 106kbps, 212kbps or 424kbps. The crystal oscillator in the module provides a 27.12Mhz crystal oscillator, and the regulated power supply unit provides a stable voltage of 3.3V. Under the control of the external interface, PN65N realizes the processing of the baseband signal, and the signal is sent out by the antenna after being processed by the RC resonant circuit. When receiving, the antenna processes the received signal into a baseband signal through the radio frequency unit, and sends it to the baseband processing unit for processing. The baseband processing unit converts the baseband signal into control information that can be recognized by the control unit and sends it to the control unit through an external interface.

The RF chip sub-unit integrates a control unit (HT80C51MX) and a baseband processing unit. Among them, VEN is the chip enable pin; VEN_MON is the voltage monitoring enable pin; TXD and RXD are the sending and receiving pins of the UART port respectively; SIMVCC is the chip when the chip is working in Powered-by-Field mode. Take the mobile SIM card as an example) the pin for power supply of the card; SWP is the pin for communication between the chip and the SIM card; TX1, TX2, RX, VMID are used for sending and receiving radio frequency signals between the chip and the RC matching circuit; Provide RF receiving voltage reference; PF1 and PF2 are card analog interfaces of the chip; IRQ is the chip interrupt request pin; RESET is the chip reset pin.

Figure 6 shows the RC resonant circuit and antenna in the radio frequency unit. Among them, the pins TX1 and TX2 are differential output, and RX is receiving. The radio frequency transmitting part and the radio frequency receiving part are described below.

(1) RF transmission part: TX1 and TX2 differential signals pass through inductors L1 and L2, and the resonance of capacitors C10 and C11 raises the TX square wave signal from a low voltage to a sine wave of nearly 50V. C12 and C13 are DC blocking capacitors, and C18 and The antenna achieves parallel resonance, so that the antenna can obtain the maximum current and provide energy to the card. Generally, the middle point of the antenna is grounded, which is beneficial to improve the anti-static, stray and other indicators.

(2) RF receiving part: the received signal enters the RX pin through C14 and R1, VMID is the received bias voltage, the external C9 filter improves stability, RX is biased through R2, and the RX pin level is at the power supply The middle point, improve the receiving sensitivity.

The communication distance of this module is small, so a coil-type near-field antenna with simple process and low cost is used. Due to the small shape of the mobile phone, the corresponding coil area is also small, so the mutual inductance M of the antenna coil between the NFC and the reader cannot meet the actual use. Therefore, ferrite with high magnetic permeability u can be inserted inside the NFC antenna coil. body material to increase the mutual inductance and compensate for the reduction of the coil cross-section. The coil antenna can be designed with PCB (Printed Circuit Board) or FPC (Flexible Print Circuit) circuit board materials.

C18 and the antenna resonate at 13.56MHz. The area of the antenna should be as large as possible, such as 1 square decimeter. The distance is very good. The number of turns is 1 or 2. If the area is relatively small, the number of turns should be slightly more, such as 6 square centimeters. , then the number of turns will be 6 turns, and the center of the coil can be grounded, which is to improve the antistatic ability.

Adjust C18 to maximize the peak-to-peak value of the two points of C18, which can generally reach more than 30V. Note that when debugging, the final environment must be taken into consideration, rather than a separate debugging antenna. The environment includes cards, casings, metal parts, etc., especially Cards and metal parts have a great impact on the performance of the antenna, which can be understood as reducing the inductance of the antenna.

After the resonance of the antenna is adjusted, the previous boost resonance has a certain change, and it is adjusted again. Through this, generally satisfactory results can be obtained.

Be careful not to adjust the voltage too high. First, the power consumption is too large. Second, because the Q value is too high, the frequency band is too narrow and the reception is affected. At this time, the voltage should be lowered appropriately. Third, the capacitor heat is too high. Generally, it is recommended to use 0805 package capacitor.

Specific design and debugging:

a. The design of the antenna is generally considered to be larger in size. For example, the diameter of the antenna of the subway gate machine reaches 10CM, and the number of winding coils is generally 2 or 3 coils. If the antenna area is not large, the number of coils can be increased appropriately. The inductance is controlled at the uH level, generally between 1 and 5uH.

b. For matching adjustment, generally L1 and L2 use 1uH inductance, preferably wire-wound inductance. Using Japanese SAGAMI wire-wound inductance, small size and good performance, the values of C10 and C11 remain unchanged, adjust the antenna resonant capacitance of C18 or adjust the values of C12 and C13, so that the voltage at both ends of the antenna reaches around 50V (peak-to-peak value can reach 50V, generally It is recommended to be above 30V), the general voltage is higher, and the distance of reading the card will be longer.

c. C6 and C16 are when the chip works in the card mode, an external card reader provides energy to the antenna and couples to the inside of the chip for the card chip to work.

The specific peripheral circuit of the crystal oscillator unit that provides an external clock for the RF chip sub-unit is shown in Figure 7 above, and the clock is specifically 27.12MHz.

The module of the utility model has the characteristics of small size (10mm*11mm), low power consumption, and the working frequency is 13.56Mhz. Due to its small size, it can be directly embedded into the mobile phone to realize the NFC function. When the battery of the mobile phone can provide the working voltage of the module, the module works in Polling loop mode (in this mode, the working state of the PN65N chip is between various functions. cycle), which can realize the functions of mobile payment, point-to-point communication, and card simulation. When the mobile phone is powered off, this module can work in Powered-by-Field mode, and the energy required for chip operation is provided by the radio frequency field. In this mode, this module can realize the function of card simulation.

In summary, it can be seen that the near field communication module of the present invention modularizes and miniaturizes the NFC function, and can integrate the radio frequency chip subunit and its peripheral circuit, crystal oscillator unit, RC resonant circuit, etc. that realize the NFC mobile phone payment function In one module, the external hardware provides power interface, antenna interface and communication interface, and the software provides API interface, so that it can be transplanted to mobile phones or other handheld devices after corresponding software and hardware connections, so that the module equipped with The device realizes NFC-based payment function, card simulation function and peer-to-peer communication function.

Those skilled in the art will appreciate that the embodiments described here are to help readers understand the principle of the utility model, and it should be understood that the protection scope of the utility model is not limited to such specific statements and examples. Those skilled in the art can make various other specific modifications and combinations based on the technical revelations disclosed in the utility model without departing from the essence of the utility model, and these variations and combinations are still within the protection scope of the utility model.

Claims (4)

1. A near-field communication module, comprising a radio frequency unit, a control unit, a baseband processing unit and a stabilized power supply unit, wherein the radio frequency unit comprises a radio frequency chip subunit and an RC resonant circuit, and the control unit and the baseband processing unit are integrated In the radio frequency chip subunit, the stabilized power supply unit provides a power supply voltage for the radio frequency chip subunit, and the RC resonant circuit is connected with the radio frequency chip subunit to provide an external antenna interface. 2. The near field communication module according to claim 1, wherein the near field communication module further comprises a crystal oscillator unit, which provides an external clock for the radio frequency chip sub-unit. 3. The near field communication module according to claim 1 or 2, characterized in that, the radio frequency chip sub-unit is specifically implemented by a PN65N chip. 4. The near field communication module according to claim 1 or 2, characterized in that, the voltage stabilized power supply unit is implemented by a PAM3013DAB33 chip.

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