矩阵键盘实验1：向用户介绍矩阵键盘扫描实现的方法，没有考虑去抖和判断键弹起的问题；把相应的键值显示在数码管上-Matrix Keyboard Lab 1: Introduction to the user to achieve the keyboard scan matrix approach, not considered to shake and bounce to determine key issues the corresponding keys on the display in