利用DAC0832产生的正斜率斜波接到运放的正输入端，可调电位器的输出电压接到运放的负输入端，运放输出端信号引到CPLD器件所对应的输入检测管脚。最后通过CPLD将被测电压显示到数码管上-DAC0832 to produce a positive slope ramp receiving the output voltage of the op amp positive input terminal of the adjustable potentiometer received negativ