[libhid-discuss] Digital Arts & Crafts Studio - HID help needed

[Bill Kendrick]

On Tue, Nov 06, 2007 at 08:00:35PM -0500, Charles Lepple wrote:
> 
> As a developer, I'm sure this is second nature to you, but thank you  
> for giving us a good idea about what system you are working with.

You're welcome! :)


<snip>
> Also, if you were just doing a simple read() on /dev/usb/hiddev0, it  
> was probably doing interrupt transfers, and hid_get_input_report()  
> uses control transfers.

Ah, I see.  Obviously, I haven't had time to properly learn about USB,
and was struggling from the top-down with libraries first. :)
(Currently, the main time I have to work on the device is during a 3hr
train ride I take 2x per week.  BTW, I'll be doing so on 2007-11-09 from
7am to 10am Pacific time, and will be online.  Find me in #tux4kids on
irc.freenode.net if you'd like! :^) )


> In theory, the only difference is that interrupt reads will get  
> whatever report is available next, and a control transfer will allow  
> you to select a specific report.
<snip
> 
> But then again, you don't actually need usage paths for interrupt  
> reads. (With a report structure this simple, I will admit that libhid  
> is overkill, and you can just use the code as a guide for how to call  
> libusb directly.)

Indeed.  I've decided to start using libusb directly, but currently have
two problems:

(1) Reads fail :)
(2) I have not successfully detatched the device from the kernel.
  libhid did this for me via the 'force' open call.
  For now, I need to use the 'libhid-detatch-device' (I think?) tool first. :(

I'm guessing this list wouldn't be the appropriate place to ask libusb-related
questions, if I'm not using libhid at all, would it?

Thx!

-- 
-bill!
bill at newbreedsoftware.com
http://www.newbreedsoftware.com/