We have some version 0.001 firmware running on a Cypress EZ-USB FX2LP
prototyping system. I'm trying to write Mac OS X code to talk to it. I'm
following the sample code in USB Device Interface Guide, 2005-11-09, fairly
slavishly.
I was encountering some very weird semi-reproducible problems. What I
eventually found was that these problems were associated with my attempts to
configure the device, a la Listing 2-5. If I simply omitted this step,
everything works perfectly.
So, our firmware engineer is saying, "I haven't paid much attention to that.
I've assumed that the Cypress-provided code was taking care of it automatically
but now I'm not so sure."
The question I have is this. Our device is only going to have one
configuration, and it's going to be vendor-specific. As a matter of good
practice, if you know that a device with device ID so-and-so, product ID
so-and-so has only one configuration, would you bother to go through the
configuration steps anyway, or would you skip them?
Second, neither the Cypress book nor "USB Complete" explains very clearly just
what would be some real-world examples of multiple configurations, or how they
would be used. What are some real-world examples? Do end user typically select
a configuration in some utility? Does a system typically configure the USB
device as soon as it's connected, or does it get switched from one to another
while it's running, or what? What are they for, and how are they typically used?
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