Design of Paper Counting Device Based on the Method of Bridge Free Axis

The STM32H743 processor is the core of this device, and it adopts the method of the bridge free axis to measure the impedance of the paper between two plates, by 16 bit high precision AD accurate sampling impedance under test and the reference phase shift and amplitude value of the voltage on both ends of the impedance, the paper between the value calculated plates corresponding capacitance value, according to the capacitance between the plate and the thickness of the paper assumes the inverse relationship, finally realizes the pad paper for precise measurement. The device has the functions of capacitance acquisition, processing, self-calibration and judging the plate short circuit. Through testing, the device can detect the number of papers between plates and the test status (plate short circuit, in the testing, self-calibration, test completion) according to the actual situation and display it on LCD in real time.