A Low-power Sensor Design Based On NB-IOT

With the progress of society and the development of science and technology,human society has entered a new century and new era of rapid development of information technology.At this important moment,the sensor played an irreplaceable role.Sensors are developing in the direction of intelligence,mobility,miniaturization and integration to adapt to different application scenarios.Sensor nodes are usually battery-powered.The number of sensors is increasing,and the application scenarios are becoming more and more complicated.Especially in some scenarios where it is not convenient to replace the battery or cannot be charged,the power supply of the sensor becomes an inevitable difficult problem.The dual-energy sensor node powered by lithium battery and energy harvesting greatly prolongs the service time of the sensor node and solves the energy supply problem of the node.NB-IOT is an emerging wireless communication technology that can be applied nationwide.It has the characteristics of wide coverage,large number of connections,low node cost,low power consumption,and excellent architecture.NB-IOT supports low power consumption and high efficiency connection of devices with high network connection requirements,and is the preferred technology for low power consumption and long-distance wireless communication.Based on the above analysis,this thesis designs a wireless sensor node based on NB-IOT,and transmits the data to the cloud platform to achieve cloud storage.The thesis first introduces the background and significance of the basic knowledge of sensor technology;analyzes the characteristics and applications of several energy harvesting methods,and according to the characteristics of the application scenarios,solar energy capture is selected as the energy harvesting method for the energy source of sensor;the thesis also analyzes several wireless communication methods,and selects the NB-IOT that is specifically designed for low power consumption,long distance transmission,and a large number of connections as the communication method designed for this thesis.In the thesis,the design process of the sensor node is introduced from two aspects of hardware and software.In terms of hardware,components are selected based on the principle of low power consumption.The overall framework of node is divided into five modules:energy capture module,power module,MCU control module,data acquisition module and NB-IOT communication module.MCU selectes stm321L series of low-power products from STMicroelectronics' STM32 series,and the communication module selectes NB-IOT module BC95 chip of Shanghai Yiyuan Communication Co.,Ltd,the energy capture module selects Linear Technology's LT3652 chip;.Designed for low transmission rate and delay-insensitive characteristics,some high-speed and low-latency features were abandoned in software.The overall software framework is divided into three modules:main function module,NB-IOT module and data acquisition module.Finally,the communication function of the sensor node is tested and analyze the power consumption of the node.The test selects the AM2320 temperature and humidity sensor as the test sensor,cloud platform selects China Telecom IoT open platform,registers and logs in to the cloud account,activates the NB-IOT node,and successfully transmits the test data to the cloud platform to achieve cloud storage.