用AT89C51单片机定时/计数器0的定时功能可构成一简单的方波发生器，实现周期为2s的方波，并能在虚拟示波器上直观地显示波形。-AT89C51 microcontroller with a timer/counter 0 timing functions may constitute a simple square wave generator, to achieve a period of 2s of the square wave, and can be visually displaye