计算方波信号的频率5Hz到500KHz可测，需要的可以下载(The frequency of the calculated square wave signal is 5Hz to 500KHz, which can be downloaded)

实现信号发生器.以单片机LPC2148为控制核心，主要由键盘与LCD显示模块、正弦波和方波发生模块(DDS)、三角波发生模块(CPLD与高速D／A)、增益控制和放大模块组成。(Implementation of signal generator)

无源蜂鸣器内部不带震荡源，所以如果用直流信号无法令其鸣叫，必须用2K~5K的方波去驱动它。在树莓派上实现无源蜂鸣器的鸣响(The passive buzzer does not have a shock source inside, so if the signal can not be called with a DC signal, it is necessary to drive it with the square wave of 2K~5K. The sounding of a pas

msp430单片机产生两类声音频率信号，根据实际每类信号的单个周期内包含两种不同频率的方波信号。并且可以通过机械按键切换两类音频信号。(The MSP430 singlechip produces two kinds of sound frequency signals, including two square wave signals of different frequencies in a single period of each class of signals.)