程序员：钱树勇 采用定时中断检测4*4按键；识别长按短按，按压按键3秒默认为长按模式；具有松手检测功能。采用定时扫描模式，无死循环代码，所以更少占用Cpu资源-Timer interrupt to detect 4* 4 buttons　identify long press short press, press the button for 3 seconds by default long press mode　let go of detection. Timing scan mode, no infinite loop code, so the less occupied Cpu resources