说明：  arduino学习笔记 arduino学习笔记1 - 什么是arduino？ 要了解arduino就先要了解什么是单片机，arduino平台的基础就是AVR指令集的单片机。
(Arduino study notes Arduino study Note 1-what is Arduino? In order to understand arduino, we must first understand what is the basis of the single chip microcomputer (SCM), which is based on the AVR instruction set.)