状态1：个人电脑键盘发送任意数量的0

状态1：PC机键盘发送0-9任一个数字，单片机接收发送的数字，并在数码管上显示。 状态2：单片机将接收到的数字回送到PC机，并在屏幕上显示。 -Status 1: PC Keyboard to send any number of 0-9, sending the number of single-chip receivers, and digital tube display. Status 2: Single-chip will receive the figures back to the PC, and displayed on the screen.