Bluetooth Smart Access Control System Development

The access control system is a system that controls entrances and exits. It is developed on the basis of traditional door locks. The current access control system has already surpassed simple door locks and key management. It has gradually developed into a complete set of access control systems. management system. In modern residential quarters, office buildings and other buildings or buildings, the access control system sets a personal identification code for each user, and the user needs to rely on the personal identification code to pass through the access control system. Therefore, the access control system is to protect the life and security of users in the building. An important facility for property safety.

The early stage of the development of the access control system is called the "electronic lock" stage. The emergence of electronic locks has improved people's management level for entrance and exit passages to a certain extent. Due to its high failure rate, it is not widely used. In recent years, with the development of proximity card technology and biometric technology, the access control system has developed by leaps and bounds, and there have been proximity card access control systems, fingerprint access control systems, iris access control systems, facial recognition access control systems, and random keypad access control systems. And other technical systems, they all have their own specialties in terms of safety, convenience, and ease of management, and the application fields of access control systems are becoming wider and wider.

Wherein the proximity card unlocking relies on the user to carry the proximity card, and the user is often easy to forget when going out, and the IC card is not easy to keep and is easy to lose. Fingerprint unlocking has high security, but the current fingerprint recognition module has the problem of low recognition rate, and fingerprint collection involves hygiene issues and user privacy, and the convenience is low. The processing speed of the iris recognition system is slow, which is not conducive to occasions with too many people, and the biological characteristics of the human body will change with the environment and time, thus affecting its rejection rate.

With the development and maturity of Bluetooth technology, the wireless intelligent access control system using Bluetooth 4.0 technology can interact with the centralized control management system, and perform centralized security management on the unlocker's data, voice, etc., thereby improving the security and reliability of the access control system sex.

1. Introduction to Bluetooth technology

Bluetooth technology first began in 1994 and was developed by Ericsson in Sweden. It uses frequency modulation technology, the frequency range is 2.402 ~ 2.480GHz. Its significant advantage lies in low power consumption and short distance to realize two-way wireless communication of various devices. In Bluetooth communication, no fixed infrastructure is required, only electronic products equipped with Bluetooth technology can automatically check the available profiles, connect it to another Bluetooth device using the same profile, and achieve a distance of about 10m. Communicate with each other within a certain distance, and the transmission speed can reach 1MB/s. A Bluetooth device has two possible roles, a master device and a slave device, and the same Bluetooth device can switch between these two roles. A Bluetooth master device can communicate with up to 7 slave devices at the same time. At any time, the master unit can send information to any one of the slave units, and can also send information to multiple slave devices at the same time by broadcasting. Compared with WiFi wireless technology, although Bluetooth technology is slightly inferior in speed, it is more power-saving, resource-saving, more environmentally friendly, and the harm of electromagnetic radiation harmful to human body is also smaller. Bluetooth technology is an effective means to realize lightweight interconnection, so it has been widely used.

2. Hardware design of intelligent access control system

The hardware design of the intelligent access control system is divided into three modules: the central control module, the Bluetooth communication module, and the door lock controller.

The central control module is the core module of the whole system, which completes the comparative certification and controls other modules. The central processing unit uses STM32F107VCT6 as the processing chip. STM32F107VCT6 is a product with strong performance in the new STM32 interconnected series microcontrollers launched by STMicroelectronics. The chip has 256KB Flash, up to 64KB SRAM, and integrates various high-performance industry standard interfaces, which can easily adapt to more applications. Its standard peripherals include 10 timers, two 12-bit analog-to-digital converters, two 12-bit analog-to-digital converters, two I2C interfaces, 5 USART interfaces and 3 SPI ports and high-quality digital audio interface IIS , In addition, STM32F107VCT6 has a full-speed USB (OTG) interface, two CAN2.0B interfaces, and an Ethernet 10/100MMAC module.

The Bluetooth communication module uses the Bluetooth 4.0 chip nRF8001 of Nordic Company. nRF8001 only needs a small number of peripheral devices to achieve stable wireless communication, its peak current is less than 12.5mA, and the average current in the connected state is very small, less than 12μA. The nRF8001 is a highly integrated wireless connectivity solution in a compact 32-pin QFN package measuring 5×5mm. In addition, the chip also integrates a DC/DC voltage regulator, which can further reduce the peak current and average current by 20% when powered by a button battery. Therefore, it is ideal for applications with space constraints and low power requirements.

The door lock controller is the executive component of the intelligent access control system, mainly composed of a drive circuit and an electric control lock. Under the control of STM32F107, the driving circuit drives the opening and closing of the electromagnetic lock, so as to achieve the purpose of opening and closing the door. Figure 1 is a hardware system structure diagram of an intelligent access control system.

3. Software design of Bluetooth smart access control system

The smart access control system uses a mobile phone with Bluetooth function as the key to open the door, and its software is divided into two parts: controller software and mobile phone APP software. The function of the controller software is bluetooth wireless communication, user identity authentication, control switch of electromagnetic lock, etc. After the system is powered on, the controller first initializes the device, and then starts polling to detect whether there is input on the access control code pad and search for nearby Bluetooth devices that can be connected. When the password keyboard is input, the controller will perform a verification operation. If the password is correct, the electromagnetic lock will be opened. If the password is wrong, the password receiving program will be reset and the password will be received again.

The mobile APP program needs the support of Bluetooth 4.0 and above, and the current mainstream smart phones can meet this requirement. Users need to first register with their name, room number, and mobile phone number to obtain a unique and corresponding door opening password. When using the mobile phone to open the door, the user opens the APP program, and the mobile phone will automatically match and connect with the Bluetooth communication module of the access controller.

After the connection is successfully established, the user enters the password to open the door and the mobile APP program sends the password to the access controller. When the password is stored and sent, it is encrypted with an encryption algorithm, and after being received by the access control controller, it is decrypted by the corresponding decryption algorithm, thereby improving the security of the system. The access control controller checks the decrypted plaintext password, and if the password is correct, the electromagnetic lock is opened and the door opening information is recorded. If the password is wrong, the door opening operation will not be performed, and the same device will be disconnected if the wrong password is entered multiple times. The system blacklists this device and blocks its connection request temporarily to prevent it from occupying the channel illegally. Figure 2 is a flow chart of software design.

Summarize

This paper designs an intelligent access control system based on Bluetooth technology, which is an improvement and innovative development of the traditional access control system. After testing, this system can realize the function of intelligent mobile terminal Bluetooth remote unlocking, making unlocking more convenient and safe, and has high practical value.

The above is the development example of the intelligent access control system based on Bluetooth technology introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have the development needs of intelligent access control module solutions, you can trust us. We represent a variety of single-chip microcomputers, voice chips, dual-mode Bluetooth ICs, and wifi chips. Brands include Songhan MCU, Yingguang MCU, Jerry Bluetooth, Ankai Bluetooth, Allwinner, and Realtek. Our technical services include: PCB design, microcontroller development, Bluetooth solutions, software and hardware custom development, APP development, small program development, WeChat official account development, etc. It can also undertake the design of intelligent electronic products, the development of living appliances, the research and development of beauty equipment, the application of Internet of things platform, the smart home control system, the development of TWS earphones, Bluetooth earphone speakers, the development of children's educational toys, the design of electronic education products, etc.