Generally, CSQuickUSB is a library that exposes access to USB hardware manufactured by Bitwise Systems (http://www.bitwisesys.com). Essentially allowing full featured interop with a USB 2.0 port and hardware of an external device, all from an easy to use C#/managed landscape.
DownloadTo download the latest release, go to the Downloads Page. For nightly builds see the SVN repository.
BackgroundBitwise Systems manufactures a USB module called QuickUSB which provides all the features of a full USB 2.0 system, but is very easy to integrate with existing hardware. However, at the time, the API to access the device is poorly designed and sparsely documented. In short, I wish I had went with the Cypress solutions instead.
Out of the box it comes with an unmanaged wrapper library called quickusb.dll, which wraps all the necessary Windows API calls to successfully preform USB 2.0 communication with the hardware. With that in mind, all CSQuickUSB is, is a wrapper of quickusb.dll, that is much easier to use and performs all the necessary win32 marshaling for full managed environment access to the hardware on the other side of the USB cable.
For examples on how to use the CsQuickUSB library see the UsageExamples wiki page