Design of Wireless Sensor Network Bidirectional Nodes for Intelligent Monitoring System of Micro-irrigation in Litchi Orchards

摘要

Wireless sensor network (WSN) bidirectional nodes, including the sensing node and the solenoid valve control node, were developed for information collection and micro-irrigation monitoring system in a litchi orchard, aimed at improving the problem of wireless communication barriers and the micro-irrigation management efficiency. The sensing node was composed of an MCU8051, a CC2530 RF chip for communication, a RFX2401for amplification. This node is supposed to collect data from a DHT22 air temperature and humidity sensor, a GY-30 light intensity sensor and a TDR-3 soil moisture sensor. The control node includes an MCU8051, a CC2530 RF chip for communication, and peripheral drive circuits for adapting the bi-stable pulse solenoid valve. The application software and backstage management software were written with these two nodes as the hardware platform, based on ZStack agreement. The maximum effective bidirectional communication distance of the designed nodes reached 1205m in unoccupied regions and 122m in litchi orchards. Within a 30 min working cycle, it could be estimated that two 3.7 V battery with a rated capacity of 3000 mA?h can power the sensing node for time up to 500d. Test results in litchi orchards show that the average packet loss rate is 0.75%. The system was processing smoothly with the above nodes for information acquisition and controlling micro-irrigation in litchi orchards.