[libhid-discuss] Misunderstanding input and output paths

[Gary Briggs]

On Tue, Apr 20, 2010 at 07:49:50AM -0400, Charles Lepple wrote:
> >I've written some code [mainly copied outright from the libhid test
> >example], here:
> >http://icculus.org/~chunky/stuff/dcdcusb/main.c
> >
> >The output from that program is:
> >http://icculus.org/~chunky/stuff/dcdcusb/set_output_report_output.txt
> 
> The only thing to note is that there is a bug in the printing routine,  
> and if you see a "0x00000000" path element, it is just the 2nd or  
> later element of a range. The parser knows what to do internally,  
> though.

I'm still just having a hard time understanding the overall "how to get a
path out, given a lsusb listing".

I started reading this:
http://www.networkupstools.org/doc/2.2.0/hid-subdrivers.html
Is this actually relevant to me? It seems that if someone else has done
most of the work for HID power supplies, I'll have more luck beginning
with that?

> >Overall, I'm just confused as to what's going on or how to progress  
> >and
> >make this work. If anyone has any suggestions as to what I should do
> >from here, I'd greatly appreciate it.
> 
> What are your goals? Shutting down the power supply? Monitoring  
> certain parameters? If possible, I would start with something  
> innocuous like changing the state of an LED, but if you can power the  
> test machine from another power source, that would be best.

At least to start, I just want to read the current state of the PSU.
Saliently, at least to start, I just want to be able to figure out
whether the ignition is connected or not, and if not, how long until it
actually shuts the whole system down.

I figure that once I see *something* everything else is in the realm of
figuring out the device-specific hoojimajiggery. I'm still just at the
point where I want to see *something*.

Thank-you so much for your time and explanations, they've really been
helping me.

Gary (-;