Design Of Wireless Grain Monitoring System

China is a populous country as well as a large agricultural country.Food security is a major aspect of people's life safety,especially the security of grain storage.In the process of grain storage,a great deal of heat is generated due to respiration.If the heat is not dissipated in time,the grain will deteriorate,which brings great challenges to the work of safe storage.However,traditional grain monitoring system simply uses temperature measuring cables to connect large numbers of sensors,and they are often intertwined with each other in use,which brings inconvenience to the operation in the warehouse.In this paper,we introduced a wireless grain monitoring system based on wireless sensor network,aiming at the above problem.This system uses NB-IOT,wireless network,sensors and other technologies,and are made up of the design of grain monitoring extension,temperature measuring node,and the connection between the equipment and OneNet platform.The main work of this paper is as follows:1)We analyzed the shortcomings of traditional grain condition monitoring system.Moreover,based on the problems existing in the work of safe grain storage and the actual situation of our country,we proposed a grain condition monitoring system model which has the advantage of low power consumption,low cost,high reliability and easy installation and maintenance of equipment.2)In view of the existing problems in the use and maintenance of temperature measuring cables in grain depots,we introduced a single mobile wireless temperature measuring node.The temperature measuring node uses CC1101 micro-power RF circuit as communication module,STM32L031F6P6 ultra-low power MCU as controller,single-bus digital sensor DS18B20 for temperature measurement and large capacity lithium battery power supply.3)After deeply studied the indoor positioning model of sensor network,combining with the deployment characteristics of temperature measurement nodes in grain depots,we proposed a differential positioning model based on RSSI dynamic beacon nodes.This model effectively solves the problem that the wireless sensor network is difficult to accurately locate in the grain condition monitoring system.At the same time,the positioning scheme reduced the requirement for additional beacon nodes,thus reducing the hardware cost of the system.4)According to the design objective of grain condition monitoring system,we calculated the current consumption of each part of the working circuit of temperature measuring nodes.Then,we analyzed the power consumption of temperature measuring nodes,expecting to reduce the power consumption of nodes as much as possible through the improvement of hardware and software.At last,we introduced the mechanism of periodic wake-up,centralized reporting and active anomaly reporting of temperature measuring nodes.The anomaly number can be reported in real time while the power consumption of temperature measuring nodes is low.