声音是由震动所产生的， 一定频率的震动就产生了一定频率的声音。这个实验是喇叭里发出

滴答一长一短的报警声音,送出的端口是p1.2(即D2)输出如1khz,2khz、3khz变频信号报警,频率不一样发出的声音就不一样。

R54可以为10欧到100欧的电阻。

实验目的： 通过设置不同延时时间（延时时间不一样对应的频率就不一样）蜂鸣器将发出不动的声音。从而理解单片机中用位控制外围设备的方法。

-Sound is produced by the vibration, a certain frequency vibration to generate a certain frequency of sound. This experiment is ticking speaker, a long, one short of the alarm sound, send the port is p1.2 (ie D2) output as 1khz, 2khz, 3khz frequency signal alarm, not the same as the sound frequency is not the same. R54 for 10 euro to 100 ohm resistor. Purpose: By setting different delay time (delay time is not not the same as the corresponding frequency) will issue fixed buzzer sound. To understand the microcontroller peripherals using digital control methods.