农田信息采集无线传感器网络节点设计

Design of wireless sensor network node for field information acquisition

农田信息的及时准确获取是精准农业实施的基础。该文分析了几种典型无线传感器网络技术应用实例,基于当前无线传感器网络在农田信息采集中的应用现状,提出了设计体积小、工作持续时间长的农田信息采集无线传感器网络节点的必要性。基于ATmega128L单片机和CC1000射频芯片设计了无线传感器网络节点通信电路,并给出了土壤温湿度、电导率传感器、空气温湿度传感器及光照度传感器的选型和指标参数。设计了节点软件系统,描述了一种基于优先级的静态任务调度机制的实现方法,将S-MAC中的SYNC帧和RTS/CTS帧融合并加入了睡眠周期动态调度机制,并实现了全网的长周期睡眠。最后对节点进行了验证试验,给出了节点吞吐能力曲线和系统电压变化曲线,并进行了分析。试验表明,在论文给出的低功耗机制控制下,节点每秒具有6个数据包处理能力;在20个节点容量的全覆盖网络中,10min采样周期下,节点可有效持续工作150d以上,可以满足精准农业信息采集需求。

Timely and correct getting field information is the foundation of implementation of precision agriculture. Four typical wireless sensor network （WSN） nodes for field information acquisition were analyzed. Necessity of designing small-size and long-life field information acquisition WSN node was proposed. Node hardware structure was presented. The RF communication circuit was designed based on ATmega128L and CC1000. The choice and index parameters of sensor for soil moisture/temperature/conductivity, air moisture/temperature and illuminance were listed. Design of software was described. A priority-based static task scheduling mechanism was realized on the node. SYNC frame of S-MAC was integrated with RTS/CTS frame, and a dynamic scheduling mechanism in the sleeping period was added in the integration. A networked long period sleeping mechanism was completed in the communication protocols. Curve of node system voltage change and curve of handling capacity were given after experimental study. The experiment results demonstrated that the node could handle 6 packets per second and can work 150 days continuously, under the conditions of 20 nodes full-coverage networks and 10 minutes sampling cycle. Therefore, the nodes can meet the demand of field information collecting in precision agriculture.