如何给嵌入式系统添加USB

现在许多嵌入式设备都要加usb接口，为什么要加，怎么加，这篇文章有简单的讲述。不过是英文的，幸好不长，大家不要怕，很快就看完了，希望您能有点收获
Designing USB
Into Embedded Systems
Issues and Answers


Overview
The interoperability, performance, and ease-of-use of USB has led to its overwhelming
acceptance in the marketplace. It is the interface of choice for all but the highest performance and
lowest cost applications. This near-ubiquity has led many companies to investigate adding USB
to existing embedded designs, thus providing compatibility with a wide variety of devices with a
minimum of development effort.

However, the ease-of-use of USB from a consumer standpoint belies the serious complexity of
the software and hardware design. Making poor decisio