Research And Development Of Soilless Substrate Multi-Parameter Detector Based On Android Platform

In agricultural production, the moisture content, conductivity, and temperature of the soil/substrate are important factors for crop growth. Testing these parameters timely and expediently is very important to guide agricultural production and increase crop yield. Development and application of wireless communication technology provide a new enlightenment to the modern agricultural direction. In this-dissertation, the wireless sensor nodes combined with the compound sensor of soil water content, conductivity, and temperature are developed according to the characteristics of the soilless culture technology, and a soil/substrate multi-parameter wireless detector based on Android platform is developed.First of all, the current situation of detection method of soil substrate parameters, monitoring system, portable instrument and wireless communication technology were analyzed. Through the analysis, the moisture content, conductivity, and temperature detection methods were determined and the research technical route was formulated. According to the characteristics of the soil substrate, the soil substrate compound sensor structure and detection circuit were designed. Through the analysis of the problems of the reflection, crosstalk between main devices, PCB was designed based on the optimization of layout and wiring.Secondly, compound wireless sensor nodes were designed based on Ad Hoc communication mode combined with the soil substrate compound sensor, wireless single chip CC2430, HLK-RM04 WiFi module and other electronic devices. The data collected by the compound sensors were processed by wireless single chip CC2430 and transmitted to WiFi module through serial port, then sent out. According to the problems of complicated wiring connection and brittle, auxiliary PCB was designed based on the idea of modularization. Every module was connected mechanically, enhancing the capacity of puncture and accelerating the promotion of wireless sensor nodes.Thirdly, the App of soil substrate detector was developed based on Android technology. The user interface was designed based on the interface design principles according to function analysis, and the function program was designed. What’s more, the different tests were carried out on different version and different phone models to ensure that the software can work accurately, stably, safely and reliably.Finally, performance analysis was carried out to verify the performance of the wireless detector. The results of detector calibration in greenhouse substrate shows that the maximum deviation of moisture measuring is 1.8% relative to drying method, the relative error is less than 8.5%; maximum deviation of electrical conductivity measuring is 0.201 mS/cm relative to HI98331 soil conductivity meter, the relative error is less than 6.2%; maximum deviation of temperature measuring is 1.33?C relative to JM222 high precision digital thermometer, the relative error is less than 3.1%. The cost is about 30% to HI98331 soil conductivity meter expect the phone. The measuring error of detector is small enough to match the detection precision of agricultural production.