摘  要

本文设计并实现了一种基于STM32G031微控制器的简易信号失真度测量装置。该装置利用STM32G031的PWM功能结合板上低通滤波器（LPF）电路，生成频率可调（DC∼20KHz）且幅度可调（10mV∼500mV）的正弦波信号作为测试源。通过运算放大器将该信号输入至ADC进行量化处理，采样过程采用DMA传输以提高效率。利用快速傅里叶变换（FFT）计算信号的频谱，进而求得总谐波失真度（THD）。系统通过SPI接口的OLED显示屏实时展示采样波形、归一化幅值谱及失真度曲线（支持线性与对数坐标显示）。用户交互通过按键与光电旋转编码器实现，支持频率与幅度的调节、采样率的变更以及显示模式的切换。

实验结果表明，该装置能够准确生成并测量低失真度正弦波信号，但在小幅度输出时存在一定偏差。通过优化PWM占空比调节算法与FFT计算精度，系统性能得到显著提升。本设计不仅展示了STM32G031在信号处理领域的强大能力，也为便携式信号分析仪器的开发提供了有价值的参考。

关键词：STM32G031；信号失真度；PWM；FFT；OLED显示

Abstract

This paper designs and implements a simple signal distortion measurement device based on the STM32G031 microcontroller. The device utilizes the PWM functionality of the STM32G031 combined with an on-board low-pass filter (LPF) circuit to generate a sine wave signal with adjustable frequency (DC∼20KHz) and amplitude (10mV∼500mV) as the test source. The signal is input to an ADC for quantization through an operational amplifier, with DMA transmission employed during the sampling process to enhance efficiency. The frequency spectrum of the signal is computed using the Fast Fourier Transform (FFT), enabling the determination of Total Harmonic Distortion (THD). The system displays the sampled waveform, normalized amplitude spectrum, and distortion curve (supporting both linear and logarithmic coordinate displays) in real-time on an SPI-interfaced OLED display. User interaction is facilitated through push buttons and a photoelectric rotary encoder, allowing for adjustments in frequency and amplitude, changes in sampling rate, and switches in display mode.

Experimental results demonstrate the device's capability to accurately generate and measure low-distortion sine wave signals, albeit with some deviations at small amplitude outputs. System performance is significantly enhanced by optimizing the PWM duty cycle adjustment algorithm and FFT computation accuracy. This design not only showcases the powerful signal processing capabilities of the STM32G031 but also provides valuable insights for the development of portable signal analysis instruments.

Keywords：STM32G031; Signal Distortion; PWM; FFT; OLED Display