Design of Straw Moisture Detector based on AC Impedance Method

In this paper, a corn straw moisture detector with single-chip microcomputer as the core was designed based on the AC impedance method. The hardware uses the stm32 microcontroller as the controller, and the DDS sine wave generator generates a 100kHZ sinusoidal signal, converts the output constant current as the excitation signal through the constant current circuit, and then collects the ADC signal and the temperature signal. The software used FFT for detection, and the test data were fitted by least squares method. It is verified that the absolute measurement error of moisture content of the moisture detector designed in this paper is -2.0%~1.5%, and the response time is less than 1.5 s.