学会使用USART和电脑的串口高度助手通信，通过设置外部中断0，由按键PD2触发向电脑发送字符，字符由一个数组储存，在串口助手上显示。

通过串口助手可以向单片机发送字符，并在LCD屏幕上显示，每次只能显示一位，设置delay函数延迟0.5秒显示-USART and learn to use the computer' s serial communications assistant height by setting the external interrupt 0, send characters, characters　an array of storage to the computer by PD2 trigger button is displayed on the serial assistant. Can be sent to the microcontroller through the serial port assistant character, and displayed on the LCD screen, you can only display one set delay 0.5 seconds delay function display