一个简单实用的单片机键盘扫描程序。键盘为4*4扫描的键盘，通过行列扫描进行键码判断，并通过串行口或者485信号输出键码。应用于银行系统。-A simple and practical single-chip microcomputer keyboard scanner. 4* 4 keyboard for keyboard scanning, scan through the ranks to determine the key code and, through the serial port