在一块板上编写矩阵键盘扫描程序，当扫描到有键被按下时，将建通过串口发送出去，另一块板上单片机接收到串口发送来的键值后，将对应键值以0~F方式显示在数码管上。-A board to write the matrix keyboard scanner, when scanning to a key is pressed, will be built through the serial port to send out for an on-board microcontroller receives