Research On Multi-link Bidirectional Communication Mechanism Of Air Quality Monitoring Wireless Sensor

With the improvement of people's awareness of environmental protection in the 21 st century,the demand for environmental information has increased.In this paper,a multi-link bidirectional communication mechanism of air quality monitoring wireless sensor is designed for mobile platform and high-density on-line monitoring of ambient air.At present,the quality of air quality monitor products varies,which usually has a single monitoring gas,has no communication function,and is not portable enough.Aiming at the above problems,this paper designs a wireless sensor system for air quality monitoring based on STM32,and makes an in-depth study on the data communication protocol and communication mechanism.In order to ensure the controllability and security of the system,the network delay is predicted,and the data transmitted is encrypted.Finally,the network cost is discussed,in order to provide scientific and systematic technical support for designing a multi-link air quality monitoring system.Throughout the full text,the main research contents of this paper are:The hardware platform is builded.The STM32F103RCT6 is used as the main control chip to collect data through the multi-in-one sensor.The data is displayed in real time on the TFT-type screen,and uploaded through 4G,Wi-Fi,NB-IoT,and Lora modules respectively.Embedded software is designed by using the C language on the hardware platform.The FreeRTOS operating system is transplanted on the STM32 platform,the priorities of tasks are assigned according to system functions,making the system has air quality monitoring functions.The data packets with calibration time based on RTC function are uploaded to realize the air quality data real-time uploading.In this paper,design of the communication characteristics of various communication modules and the key details of software will be researched in depth.According to the requirements of the data content collected by the wireless sensor terminal of ambient air quality monitoring,and the integrity requirements of data transmission.The data communication protocol is customized,according to national standard communication protocol and data format,including the login communication protocol,the equipment timing communication protocol,the data upload communication protocol and the Wi-Fi distribution communication protocol.Moreover,the handshake protocol,response mechanism and supplementary transmission mechanism is designed to ensure the stability and integrity of the data link.The network delay is predicted by using time series.AES-128 algorithm is adopted to ensure the security of the link.Finally,the optimal network cost is calculated.The final experimental results show that the prediction of network delay by using time series method is accurate.The network data transmission under multilink is stable,and the data with calibration time based on RTC function can be uploaded stably.Even if the network is abnormal,the system will upload the data stably after the network is recovered.The data transmission is complete,and the system performance is stable and good.