送4X4矩阵键盘的键值C语言程序，打开串口调试助手，正确设置通信格式，按动4X4矩阵键盘任意一个按键，观察屏幕显示的按键键值。-Send 4 x4 matrix keyboard key values of C language program, open the serial debugging assistants, set communication format correctly, press 4 x4 matrix keyboard any keys, watch screen button key values.