Using the Due, I need to communicate with a USB isochronous type device such as a GPS receiver. I would like to use the onboard USB Host port built into the SAM3X8E rather than a USB Host Shield that uses the MAX3421E. I have examined the curcuits@home website and the work done by Oleg that supports the MAX chip set. I have utilized the Due sketches that communicate with a keyboard and mouse and those work fine for HID devices. What I need is an I/O library or the knowledge of how to communicate with the SAM3X8E chip so I can build a device driver on top of it and then my application code on top of the driver. Has anybody done this level of code development and how was it accomplished for an isochronous device? Is there any existing low-level I/O libraries, etc. that I can use? In other words, I would like to avoid having to write the code to set and clear register bits, etc. if a library with a higher level interface already exists. Thanks for your insight!