基于边缘电场效应和PCB技术水含量测量仪设计

摘要

In view of the market application deficiency of the water content detection method and the instrument,a measure-ment system based on capacitive fringing field effect and PCB technology was designed,consisting of self-designed detection probe,capacitance detection circuit,embedded processor,external SRAM,SD card memory,RS485 communication module,LCD touch screen,keyboard,power supply module and other components.The design of oil-water capacitance detection probe was made by the fringing field effect of the capacitor plate&PCB technology.Capacitance detection circuit was designed in using the up to 28-bit accuracy capacitance detection chip and the side stick SMA shielding head,which could improve the anti-jamming per-formance of the circuit.The system control hardware utilized embedded processor STM32F407ZGT6 and ran uCOSIII real-time embedded multi-tasking operating system.External SRAM and SD card memory provided the system operation and storage space. LCD touch screen and keyboard for users provided good interaction experience.Experimental data showed that the oil-water meas-urement system was a successful implementation of the prototype,which detection error was less than 3% and sensitivity could be achieved in 3.3 pF/%,given the oil-water ranged from 0 to 80%.%鉴于市场应用的油中水含量检测方法和仪器的不足,设计了一种基于边缘电场效应和PCB技术的水含量测量仪.仪器由检测探头、探头电容检测电路、嵌入式处理器、外置SRAM、SD卡存储器、RS485通信模块、触摸屏、键盘、电源模块等组成.检测探头利用电容极板的边缘电场效应,并通过PCB技术制造;探头电容检测采用精度高达28位的电容检测芯片和侧贴SMA屏蔽头以提高抗干扰性能;主控采用嵌入式处理器STM32F407ZGT6,运行μCOSIII多任务操作系统;外置SRAM和SD卡提供运行和存储空间;触摸屏和键盘为用户提供交互体验.实验测试:大豆油中水含量在0%~80%范围内,检测误差小于3%,灵敏度为3.3 pF/%.