键盘扫描结束了，寄存器R1的值就直接表示了是那个键按下的，根据不同的键值去执行不同的程序，从而实现了十六个矩阵键盘扫描，同样原理，最多可以识别255个按键的矩阵扫描。

　　我们可以每次键盘扫描开始时检查R0的值是否为0，只有在为0才扫描键盘，不为0就证明刚刚扫描过键值，相应的按键工作还没有完成。但是必须记得，每个按键命令执行完成后，要给R0写上0，表示可以扫描键盘。-The end of the keyboard scanning, registers the value of R1 expressed on the direct button is pressed that, based on different keys to perform different procedures in order to achieve a 16 keyboard matrix scanning, the same principle can be identified up to 255 keys scanning the matrix. We can be the beginning of each keyboard scan to check whether the value of R0 to 0, only for the 0 to scan the keyboard, not just to 0 on the proven key scanned, the corresponding button has not yet completed the work. However, it must be remembered that the implementation of each key command is completed, give R0 write 0, that can scan the keyboard.