USB总线高速数据采集系统的设计误区及解决方案

摘要

Despite the USB specification has reached high transmission speed, but a lot of USB devices actually worked in the data transmission quite different from it, and the transmission speed is not stable. Many designers do not realize this situation when they design high speed data sample system. So the system has to result in losting data. This paper reveals the designing mistake of the system, and a resolving method is also introduced which is based on decimating and avoiding wasting bits and data compression as well. Experiments show that the method is correct and suit for USB Bus.%USB总线的实际传输速率与理论传输速率相差甚远,且不能保证其稳定性,一般在15MB/s～25MB/s左右;然而很多设计者在设计基于USB总线的高速数据采集系统时却并没有考虑到这一点,所设计的系统建立在USB具有稳定的高速率的基础上,必然会造成缓存溢出而丢失数据;指出了这类系统的设计误区,在分析了高速采集数据特点的基础上,提出了一种基于数据抽取、消除零空位、数据压缩的整套解决方案;在给出的实例中,该方案具有19:1的压缩比,其USB总线传输速率约为4.5MB/s,适用于USB总线实际传输带宽.