I am involved with a project to create some custom microcontroller
code and associated userland applications. The connection from the
chips to the computer utilizes USB. Although my project is actually
Windows-specific, I wanted to do some work to get it up and running
on my personal computer. I have been playing with IOKitLib and
getting some basics down, and can get as far as detecting device
attach/detach.
My next logical step was to start inspecting the configuration
headers of my devices. However, I get errors basically telling me
that the configuration is invalid. I opened up USB Prober and System
Profiler. USB Prober's logging showed me the following errors:
IOUSBDevice[0x3514600]: Error (0xe0004002) getting device device
descriptor
IOUSBDevice[0x3514600]::GetFullConfigurationDescriptor - Error
(e0004001) getting full 32 bytes of config descriptor
IOUSBCompositeDriver[0x351e880](IOUSBDevice) GetFullConfigDescriptor
(0) returned NULL
AppleUSBOHCI[0x2620800]::Found a transaction which hasn't moved in 5
seconds on bus 8, timing out!
And these errors only occur occasionally; other times it simply says:
The IOUSBFamily was not able to enumerate a device.
The IOUSBFamily is having trouble enumerating a USB device that has
been plugged in. It will keep retrying.
So, my question, finally, is this:
Are there any major differences that I need to take into account
between the Windows and Mac USB stacks? The only major difference I
know of, physically, is that the Windows machines have USB 2.0,
whereas my G4 only has USB 1.1. However, occasionally, the System
Profiler correctly reports my (made-up) vendor and product IDs, and
my test program detects attaches/detaches.
Please note that I pretty much have complete control of the
microcontroller code, so it is possible that it may be the problem.
It is just the fact that the Windows implementation works well that
leads me to think that it shouldn't matter that much.
Thanks all!
-jake goulding
georgia institute of technology
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