说明：  本程序使用P89V51单片机利用起PCA功能对脉冲宽度可调，实现两路输出，加LED显示和按键功能，详细请看程序注释，编程风格自认可以
(This procedure since the use of PCA use P89V51 Singlechip feature adjustable pulse width to achieve two-way output, plus LED display and button functions, see the detailed program notes, programming styles can themselves)