Author(s)

Jian Huang

Corresponding Author

Jian Huang

Abstract

In order to effectively measure low frequency signals, this paper proposes a new method and theory. The low-frequency signal is input to the A/D acquisition pin of the embedded microprocessor STM32F103ZET6, five hundred data are continuously collected in DMA mode.Five hundred data can be processed by software, it can measure the input signal frequency, period，amplitude, peak to peak value； calculate the slope can determine the input wave form.For the square wave signal, the duty cycle can be calculated by counting the data of the high and low level in a period.Compared with the traditional measurement method, the method has no complicated analog circuit, and has the advantages of simple interface circuit, powerful function and high precision.The test results show that this method can accurately measure and identify sine wave, triangle wave and rectangular wave signal with peak amplitude at 1~5V and 100Hz~10kHz in frequency range.Frequency error is less than 1%.The peak to peak error is less than 1%, and the square wave duty is accurate, almost without error.

Keywords

A/D Acquisition; Direct Memory Access; Peak to Peak Value; Identify the Wave Form