说明：  在这个实验中最重要的是时序，因为要精确到us，所以找到合适的延时函数很重要。之前网上有一些关于51的和PIC的精确延时函数，我试了下，还要去仿真，很不方便，后面搞了很久发现了一个很好的延时函数，我已经把它用红色标注出来了，抓好了延时，这程序基本没什么问题了。
(In this experiment is the most important thing in sequence, because want to us, so it s very important to find a suitable time delay function. Before there are some about 51 and precise time delay function of PIC, I tried, but also to the simulation, is not very convenient, back to for a long time found a very good time delay function, I have marked out in red, it pays special attention to the time delay, this basically no problem. )