便携式微小电容测试仪的设计

Design of portable miniature capacitance tester

为了便于测量液体火箭发动机试验台贮箱中电容式液位计的电容值,设计了一种便携式电容测量仪。该系统是一款基于MSP430F449微控制器的数字便携式测试仪表,通过利用单片机内嵌的12位高速A/D转换器,实现高精度数据采集,通过LCD12864实现电容值的显示。分别从电容检测原理、系统硬件电路设计和微控制器软件编程三个方面详细阐述了该智能测量仪器的设计原理和实现方法。该仪表具有三端测量功能,可测量带长线缆的电容式传感器的电容值。电容测量范围为10～9 999 pF,精度可达1 pF。

In order to conveniently measure the capacitance value of the capacitance level gauge in the tank of the liquid rocket engine test bench, a portable capacitance measuring instrument was designed.The system is a digital portable test instrument based on MSP430F449 microcontroller.It realizes high-precision data acquisition by using 12-bit high-speed A/D converter embedded in the single-chip microcomputer, and displays the capacitance value through LCD12864.In this paper, the design principle and implementation method of the intelligent measuring instrument were elaborated from three aspects: capacitance detection principle, system hardware circuit design and microcontroller software programming.The instrument has a three-terminal measuring function that can measure the capacitance of a capacitive sensor with a long cable.The capacitance measurement range is from 10~9 999 pF with accuracy of 1 pF.