| The BLE technology has been widely researched and applied in many areas because of low power consumption,low cost and strong compatibility,such as message push,indoor positioning and wireless sensor network.It's often necessary to deploy a plurality of battery-powered BLE devices to implement specific functions within an area such as indoor positioning.However,there are some issues to often occur in practice,including BLE devices damage,loss,battery exhaustion and so on,which result in the work of BLE devices on-site maintenance to be done regularly,but the method is inefficient and to increase the maintenance costs.Moreover,when the user is out of the coverage areas of BLE signal,they can't communicate with each other.To solve the above problems,a Bluetooth gateway for the communication of the Internet of Things(Io T)is designed.The Bluetooth gateway can manage and communicate with the BLE devices remotely and centrally.The main research and development work are as follows:Firstly,the overall design of Bluetooth gateway system is completed.A design proposal of Bluetooth gateway which supports multiple network interfaces and MQTT protocol is implemented in this thesis.The Bluetooth gateway not only supports three common network interfaces,namely Ethernet,WiFi and GPRS,but also supports NB-IoT network interface.A scheme of adaptive connection to the Internet for Bluetooth gateway is designed for the communication scenarios where multiple network access methods coexist.The gateway would select the available network interface with the highest priority to connect to the Internet.In order to improve the work efficiency of the Bluetooth gateway,two different data scanning and processing methods for BLE devices broadcast data are designed for different application scenarios,and the scheme for data update is designed.Besides,the data packet formats of the Bluetooth gateway are designed by using JSON data interchange format so as to provide convenience for the design of client software.Secondly,the hardware development of the Bluetooth gateway is completed.The STM32F407 which is a micro controller unit with ARM kernel is used as the main controller of the Bluetooth gateway,and the communication interface circuits are designed base on STM32F407 including BLE,Serial Port,Ethernet,WiFi,GPRS and NB-IoT communication interface circuits.In order to make the Bluetooth gateway support Bluetooth 5.0 and increase BLE communication range,the Bluetooth chip CC2640R2 F which supports Bluetooth 5.0 and the Rod Antenna are used in BLE communication interface circuits.Furthermore,two power supply methods which are USB power supply and external power supply are designed to provide convenience for the user.Thirdly,the software development of the Bluetooth gateway is completed.The main software development work is to transplant tool software such as TCP/IP protocols stack and to develop software programs including Bluetooth gateway management programs and BLE devices management programs.The parameter setup program and initialization program are designed in the design of Bluetooth gateway management programs.The gateway only needs to be setup once and gateway parameters can be setup automatically when the gateway is rebooted.In addition,the Bluetooth gateway memory management program is designed to improve memory utilization.The BLE devices state information synchronization program is designed to improve the management efficiency of the BLE devices by using objects counting algorithm.Meanwhile,the BLE devices RSSI filtering program is designed to increase the ability of anti-interference of the BLE devises' RSSI signal by using hybrid filtering algorithm.Moreover,the amount of data is reduced by using digital ID instead of Bluetooth address when the user communicates with the BLE devices.Finally,the key functions of the Bluetooth gateway are tested.The test results show that the Bluetooth gateway is stable and reliable,and the Bluetooth gateway can manage and communicate with the BLE devices remotely and centrally. |
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