本文给出了一种以STC12C5408AD超低功耗单片机为控制核心的自动电阻测试仪的设计。电路通过继电器实现量程的自动改变，从而实现对电阻参数的测量。系统采用高精密的电阻作为参考电阻，通过电压比例计算的方法推算出电阻值。利用STC12C5408AD控制测量和计算结果，再加入自校准电路提高测量精度，同时用差压法消除了电源波动对结果的影响。本系统完成了电阻和电位器的测量并相应实现LED实时显示和RS232在上位机上实时显示电位器阻值随旋转角度变化曲线。另外，通过上位机设计电阻值，系统便能在被测电阻中筛选出与之相稳合的电阻元件。%This paper presents a design of automatic resistance tester that takes STC12C5408AD ultra-low power microcontroller as control core. Circuit through the relay to achieve the automatic change of range, so as to achieve the measurement of the resistance parameters. System uses high-precision resistors as a reference resistor, through voltage proportional calculation method to calculate the resistor values, uses STC12C5408AD to control measure and calculate results, then add the self-calibration circuitry to improve measurement accuracy, simultaneously uses differential pressure method to eliminate the effects of power fluctuations on the results. The system completes the measure of resistors and potentiometers, accordingly achieve LED real-time display and RS232 real-timely displays the potentiometer resistance curve with the rotation angle on the host computer. In addition, through the host computer to design resistance value, the system will be able to filter out the relative stability resistive element in the measured resistance.
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