FFT在单片机上的实现

精品文档---下载后可任意编辑摘 要音频信号分析仪是一种可广泛见于各种音响、调音和录音设备上的，能实时地采样及分析输入的音频信号的频谱，并将其显示在显示屏上的设备，使人在倾听音乐时能对音乐的高低频能有直观的了解。本文所介绍的即是这样一个音频信号分析系统。系统的硬件由信号调理、控制处理器、显示模块三部分组成。信号调理电路使信号可输入 300mV~3V 的沟通音频信号。这里只对单路信号处理：当电压较低时使用 LM324 运放获得增益，对超过 12800Hz 的信号进行滤波处理。另外设置输出音频接口以便监听。控制处理器采纳 51 内核 1T 单片机 STC12C60A5S2，晶振频率为 32.768MHz。该单片机自带 8 路 10 位高速 ADC，这里只用 1 路 ADC 的高 8 位。对信号连续采 32 个点进行浮点型 FFT运算。一次完整采样的时间为 1.25ms，最高采样频率为 25600Hz，分辨频率为800Hz~12800Hz，分 16 级。显示部分主体为 1602 液晶显示屏，其具有 2 行×16 列的 8×5 点显示点阵。16 分频谱将分别以柱高形式显示在显示屏上。程序中设置了频率下落效果以使观感更好。另设置了对比度调节电阻，使屏幕对比度可调。关 键 词：FFT 单片机 音频 频谱THEREALIZATIONOF FFT INTHEMICROCONTROALERABSTRACTAudio signal analyzer is a kind of device which can be widely found in various of audio, mixing and recording devices, and can sampling and analysis of the spectrum of the input have an intuitive audio signal and displays it on the display in real-time, people can are listening to Music for music when high frequency understanding. What presented in this article is just such an audio signal analysis system. The hardware of the system are formed with three parts: the signal conditioner, the control processor and the display module.Signal conditioning circuit makes the signal of 300mV ~ 3V AC audio signal available for inputting. In this system,we only process with single-channel signal: When the voltage is lower the system uses LM324 op amp to gain voltage, and as to signals more than 12800Hz it filt...