NFC Bluetooth Quick Connect

Research on Realizing Bluetooth Fast Connection Using NFC Technology

In recent years, as people have put forward higher requirements for the intelligent experience of automobiles, the development of automotive electronics has accelerated, further promoting the application of electronics, communication and other technologies in the automotive field. Bluetooth communication technology has always been the main wireless technology for vehicle communication. The traditional car bluetooth relies on the mobile phone to manually connect with the car bluetooth. The steps are cumbersome, and there are often situations such as being stuck or failing to connect, which greatly reduces the interactive experience. In recent years, Near Field Communication (NFC) technology has been greatly developed and matured. NFC technology is an interconnection technology jointly researched and developed by Philips and Sony for non-contact identification. As a standardized short-distance high-frequency wireless communication technology, the working frequency of NFC technology is l3.56MHz, and the communication distance is 5-10cm.

Compared with other radio frequency identification (RFID) technologies, NFC has the characteristics of extremely short reading and writing distances. However, this seemingly disadvantage itself limits the monitoring and attack of potential hackers, and has higher security. If the characteristics of these two communication technologies can be cleverly used, it will bring better user experience and communication security, and improve the competitiveness of automotive electronics in the market. Therefore, applying NFC technology to the field of mobile payment has become a research hotspot.

1. NFC technical solution

1.1 NFC working mode

NFC works in three modes: card emulation mode, reader-writer mode, and peer-to-peer communication mode.

(1) Card emulation mode. NFC is equivalent to a non-contact IC card in the card simulation mode. It writes some information into a mobile device with an NFC device. After the information is read by an external device, it returns instructions to guide the next operation. Therefore, the NFC mobile device can be used for activities such as mobile payment without changing existing devices.

(2) Reader mode. NFC is equivalent to a tag that can be read and written in the reader-writer mode, such as electronic posters, scenic spot maps, etc., and the advertising data and map data are written into the NFC tag, and the handheld NFC mobile device can read it to obtain the required information. Information.

(3) Point-to-point mode. In point-to-point mode, NFC can realize data transmission and communication between two mobile devices with NFC. For example, two devices exchange business cards or help the connection between two Bluetooth devices, by exchanging the data necessary for Bluetooth connection, to avoid the tedious operation process of Bluetooth connection.

1.2 NFC communication mode

(1) Active communication mode. In the active communication mode of NFC, the initiator and receiver alternately generate radio frequency fields. The initiator communicates at a preset transmission speed, and the receiver also needs to respond with load modulation data at the same transmission speed.

(2) Passive communication mode. In NFC passive communication mode, the sender generates a radio frequency field. This radio frequency field excites the receiver device. At this point, the sender starts communicating at the agreed speed, and the receiver responds with load-modulated data at the same speed.

1.3 NFC architecture

NFC technology is based on non-contact technology and is compatible with non-contact Ic card standard (ISO 14443 protocol) wireless communication technology. This technology has become a formal international standard, the ISO 18092 standard (NFC IP-1). The architecture of NFC technology includes the physical layer, data exchange layer, and application layer from bottom to top. The lowest physical layer standards include ISO 14443, ISO 18092, and ISO 15693, as shown in Figure 1. The data exchange layer mainly includes protocol standards for NFC devices to exchange data in three modes.

2. Android-based NFC terminal

Due to the expansion of the demand for NFC in the field of electronic consumption, the voice of combining NFC technology with mobile phones has gradually increased. This combination not only enables the application of smart phones in the field of electronic consumption, but also will invisibly increase the importance of such smart devices in life. Smart mobile devices with NFC can replace credit cards and electronic smart cards when applied to contactless payment. In addition, the smart mobile device can also be used in real life such as identification, social networking, and bus cards. The NFC terminal is basically similar to the ordinary Android device terminal, but the NFC module is added to realize its functions. System hardware block diagram shown in Figure 2. The NFC module has a communication interface and a control interface. It communicates with the baseband chip through the UART, and realizes the start-up control of the NFC module through the GPIO of the baseband chip. The NFC chip is connected to the SIM card of the mobile phone through the SWP interface, and the SIM card of the mobile phone is used as a security guarantee for the NFC module, storing user information in the SIM card, and the NFC module can read the information through the SWP interface.

The baseband chip is the basic module of a standard mobile phone, which can send, receive and process data communication, and provides interfaces with memory modules, power modules, SD cards, WiFi modules, Bluetooth modules, NFC modules, SIM cards, etc. The NFC module mainly includes a power module, a radio frequency module, and a baseband processor module. The power supply module supplies power to the NFC module and controls the power supply; the radio frequency module modulates the baseband information and transmits it, and receives the radio frequency information returned by demodulation; the baseband processor module is responsible for encoding the information and decoding the received data information.

2.1NFC module is connected with the baseband chip

The baseband chip realizes complete control of the NFC module, and the UART communication only needs to pass through two transmission lines to complete the sending and receiving of data. Since the UART interface design method is more flexible and convenient, the transmission rate can also be defined by software. Therefore, using the UART interface to connect the NFC module to the baseband chip facilitates the control of the NFC module by the baseband chip without hindering other functions of the mobile phone.

2.2 NFC module is connected with SIM card

As an important security module, the SIM card is connected to the NFC module through the SWP interface, and the NFC reads the pre-stored security information in the SIM card through the SWP interface. Connect with the NFC controller through the C pin (ie swp) on the SIM card to realize full-duplex communication. The RST, CLK, and I/O of the SIM card are directly connected to the baseband chip, and the SWP is connected to the NFC module.

3. Combination of NFC and Bluetooth technology

Based on NFC and Bluetooth technology, the main function of vehicle-mounted applications is to use the characteristics of safety, convenience and speed of NFC short-distance communication to replace complex operations such as searching for devices and pairing in the process of Bluetooth transmission and connection. On the basis of NFC, the encryption mechanism that comes with the Bluetooth specification is not used. Before transmitting data, the sender device first sends the Bluetooth MAC address to the receiver device through NFC touch to avoid the generation of a PIN code; After pairing, send data to the other party using Bluetooth non-secure mode.

3.1 NFC and Bluetooth hardware connection

The Bluetooth terminal can quickly pair and connect through NFC, mainly based on the simple security pairing protocol (bluetooth secure simple pairing, SSP) proposed by the NFC alliance. Since the SSP protocol enables out-of-frequency pairing, the NFC link can complete information exchange and participate in the process of out-of-frequency pairing. Therefore, the pairing of the Bluetooth terminal no longer requires cumbersome search connections and PIN code authentication.

Due to the establishment of the Bluetooth Advanced Audio Broadcasting Protocol (A2DP) in the current Android 4.0 version, it is more convenient to use NFC to accelerate the Bluetooth pairing process. The pairing process includes the following two steps: first, read the NFC data exchange format (NFC data exchange format, NDEF) record from the external memory, and then perform connection pairing between two Bluetooth terminals.

3.2 Fast connection based on NFC car Bluetooth

The advantages and disadvantages of NFC technology and Bluetooth technology complement each other, which can accelerate the connection speed of Bluetooth in the car. The simple secure pairing (securesimpleprotocol, ssP) protocol in the Bluetooth technology used by the connection terminal is an NFC-based Bluetooth connection protocol recommended by the SIG and the NFC Forum in 2011. When the SSP protocol uses out-of-frequency pairing, the NFC link can participate in out-of-frequency pairing and complete information exchange. Therefore, the pairing of the Bluetooth terminal does not need to search for connection and PIN code authentication, which can greatly shorten the connection time. It mainly includes the following steps.

(1) The Bluetooth OOB data packet specified in the SSP protocol is generated by the processing chip. The data packet contains 2 bytes of OOB data length, 6 bytes of Bluetooth device address and OOB operation data. Among them, the OOB operation data includes the Bluetooth module name, HASHC code, R code, UUID (the globally unique identity code of each service and its attributes in Bluetooth, and the UUID of the Bluetooth connection process service is used here) and the device level code.

(2) After the data is generated, the processor packages the OOB data packet into a complete NDEF record according to the NFC data exchange format (NDEF), and sends it by the NFC module of the handheld terminal A.

(3) After the transmission is completed, the handheld terminal A controls the listen function of the Bluetooth Socket to enter the listening waiting state.

(4) The Bluetooth module of the handheld terminal receives the connection request of the vehicle terminal through the accept function, registers the program UUID with the system, and starts the thread for sending data. In order to strengthen system security, the elliptic curve encryption algorithm is added to the connection pairing process. Using this encryption algorithm, the handheld terminal transmits the ECC key to the receiving device through NFC touch before transmitting OOB data. After the vehicle-mounted terminal decrypts correctly according to the received ECC key, it analyzes the OOB information contained in the record of the handheld terminal, and according to the Bluetooth name, address and unique UUID data in the OOB information, through the connect function in the Bluetooth Socket, it sends data to the handheld terminal. Apply for a connection request. The transmitted data can be encrypted with a key, and then the encrypted information is sent to the other party using the Bluetooth non-secure mode. After receiving it, the receiver decrypts and restores the data, thus completing the data transmission between the two devices. This will greatly improve the security of data transmission while increasing the speed of Bluetooth connection.

Summarize

This paper implements the NFC function based on Android, and proposes a solution to apply it to automotive electronics, and compares the connection time-consuming analysis results of its pairing with traditional Bluetooth through testing. Adding the NFC function module to the Android system is an increasingly strong demand for modern intelligent devices. And then apply it to automotive electronics, whether it is a car phone, Bluetooth audio or electronic key, it simplifies people's life, improves safety during driving, and provides users with a good experience.

The above is the method of using NFC technology to realize Bluetooth fast connection introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.