键盘扫描程序，可以通过4*4键盘扫描。一般在做单片机设计时可以用到，这是一个4*4简易计算器的程序-Keyboard scanner, you can scan through the 4* 4 keyboard. Generally can be used when doing single-chip design. This is a 4* 4 Simple calculator program

系统由单片机、显示器、键盘等部分组成，利用显示器来显示密码锁输入的相关信息，系统上电时内部默认两组数字密码（4位或4位以上）；设置其他另外密码，或进行密码校验，密码输入正确则模拟打开密码锁(The system is composed of MCU, LCD, keyboard and other components, using the display to display information related to input password lock, when power on i