说明：  51单片机的C语言教程，划时代的东西。里面包括的东西很丰富。包括LED，独立按键，矩阵按键，数码管，定时器，外部中断，步进电机，串口通信，USB通信，等所有内容的详细的工作原理，以及所有的详细的C语言代码。是学习单片机的不可缺少的东西。
(C-51 microcontroller tutorials, epoch-making thing. Which includes what is very rich. Including LED, independent keys, matrix keys, digital control, timer, external interrupt, step motor, serial communication, USB communication, so all the working principle of detail, and all of the details of the C language code. SCM is essential to learn something.)