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OpenCores.Org USB1.1 Function Controller Success Story

As part of the undergraduate program in Computer Engineering at the

University of Waterloo, all students must participate in a fourth year

design project. Our team created a PC Oscilloscope, since we had

frequently encountered problems with a lack of access to oscilloscopes

when working on our own personal projects. Real oscilloscopes are

expensive, and definitely outside our student budgets. Our concept was

to create a cheap, full featured oscilloscope by harnessing a PC’s

computing power and display ability.

When designing the oscilloscope, we quickly concluded that we needed a

relatively high bandwidth, common and affordable connection between a

PC and our device. USB was the natural choice. Our school had provided

us with an Altera Excalibur FPGA development kit, so we began by

searching for USB Core IP. After a few promising leads, none of the

companies were willing to donate a USB function controller to our

project.

At this point, Evan Jones remembered hearing about OpenCores, and

immediately discovered the USB1.1 function controller. We began by

reading the little documentation that was available. Since the author

of the component used a Phillips USB tranceiver and Philips does not

provide samples of that particular part, we ordered samples of a

nearly pin USB tranceiver from Fairchild Semiconductor. Meanwhile, we

compiled the component with the Altera Quartus tools.

Once the trancievers arrived, we soldered up a quick circuit to connect

the USB cable to our prototype board. The very first time we connected

the device to our PC, the PC crashed. We assumed that this was a good

sign, as at least the PC was seeing the USB device. After some more

debugging using another computer running Linux, we determined that

while the device and the PC were communicating, something was going

wrong. The PC was reporting that the device was sending “babble”.

We spent the next few days debugging. First we resoldered our USB

interface circuit to reduce noise. We manually decoded the signals on

the USB bus using an oscilloscope. We were stumped. It looked like the

beginning of the USB enumeration was working correctly, but it would

still fail and reset the bus.

We took a break and returned to it in a few days and redid absolutely

everything from scratch. This time the PC detected an unknown USB

device. It turns out that our problem was that we set an incorrect

setting in the VHDL header for our particular FPGA. With the default

settings and a recompile, the device worked.

It took us a few more weeks until we worked out our software device

driver and the remainder of the device logic, but that was all

relatively straightforward. The OpenCores USB function controller

worked as advertised. If we were to do the project again, we would

easily be able to get it up and running in a few hours.

Evan Jones                    http://www.eng.uwaterloo.ca/~ejones/

Mauro Loconsolo               4ydp_waterloo@rogers.com

Evan Robinson                 e2robins@uwaterloo.ca

Sahand Sojoodi                sahands@hotmail.com