The USB data transfer model between a source or destination on the host and an endpoint on a device is called a pipe. Pipe comes into existence once the device has been configured successfully. The number pipes that show up are a result of the number of endpoints defined in the descriptor file. Please see the Dscr.a51 file in the firmware where the endpoints are defined. The pipe number assigned to an endpoint is in the order in which it is described in the Dscr.a51 file. Note that the first endpoint is designated with pipe number 0.