Design of Automatic Resistance Tester Based on MC9S12DG128

MC9S12DG128 microcontroller as the core, designed a simple automatic resistance tester. Measuring range is 100Ω, 1KΩ, 10KΩ, 10MΩ four gears, accuracy ± (1% reading +2 word); From big to small scanning way, performing the basic measurement and automatic switching function, At the same time, automatically display a decimal point and unit. Key input module to complete the setup by screening resistance and errors, the microcontroller output PWM control servo rotation speed, in order to achieve different potentiometer speed control; Curve display module real-time displays the measured data, and the rotation angle of the potentiometer is displayed in graph form. Using the powerful function of LCD, display Chinese characters, to increase readability, improve the usability of tester. The system is cost-effective, high reliability, has a good application prospect.