Example applications are developed in three Microsoft Visual Studio.NET languages: Visual C#, Visual C++, and Visual BASIC using the Cypress USB Suite C# library, CyUSB.dll. This application note also explains the companion firmware used with FX2LP™ and FX3™.
The host application is built on the Microsoft Visual Studio.NET 2010 platform. The host application writes to BULK IN and BULK OUT endpoints of FX2LP and FX3 using the interfaces provided by CyUsb.dll. CyUsb.dll, in turn, communicates internally with the Cypress USB driver CyUsb3.sys to access these endpoints.
Firmware residing on FX2LP and FX3 transfers the data sent from the host application on the BULK OUT endpoint to the BULK IN endpoint. The PC retrieves the same data using IN transfers. This is called "loopback".