基于18f4550ICD2、16F877的PIC单片机烧写器仿真器ICD2制作源码 错误更正：877的RA4口要上拉一个5K电阻,R11<4R7,74hc07不行必须用74LS07 如果想重烧IC，4550的CONFIG请参考BMP文件 1。调试时最好有一个有保护的HUB，分步进行 2。焊好后，电位器旋到0，不插队IC，通电测各点电压，并调好12V 3。只插4550，连PC，应能发现新硬件，重点查晶体，USB电压， 4。插好所有I

高速USB HUB IC!HUB专用!呵呵,不过是小日本的产品,如不抵制日货的工程朋友,可以选用!-Hight speed USB HUB IC!

The good news is you don’t even need to bother reading the entire USB standard. Some chapters were churned out by marketing, others aimed at the lower link layer normally taken care off by your USB controller IC and a couple aimed at host and hub