gnupic: Traffic lights as extreme feedback device controlled by a PIC via USB
Subject:
Re: Traffic lights as extreme feedback device controlled by a PIC
via USB
From:
Holger Oehm ####@####.####
Date:
5 Aug 2012 17:04:48 -0000
Message-Id: <501EA773.4050305@holger-oehm.de>
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Hi Peter,
thank you for your long answer and also thanks for the hint with
openmoko.org. Actually, I am already waiting for their answer to my
application... :-). (I also applied at Microchip for a PID, but got no
answer from them either.) And special thanks for calling it awesome, of
course! :-)))
> I have reservations against using the HID bDeviceClass however.
Yes, you are right, of course I did this because of Windows only. But
when I looked into the HID specification I saw that there were at least
usages that were not such a bad fit for the device: There is this "LED
Page (0x08)" in the "HID Usage Tables" which describes the device (apart
from the exact colors) quite nicely. So I wrote the HID descriptor for
my device using that page. It's not as if anything would really make use
of the description, but it works for me. And it is fairly easy to use:
(step 1: plug-in the device, step 2: download the jar file, step 3: run
java with the jar file and the url of the build server as arguments (on
Linux I added a udev rule for the device to get the permissions right)).
The only drawback is that this HID stuff is a little bit bloated for no
real benefit (other than enabling the device to run on Windows out of
the box).
I have to admit though, that I completely forgot about Macs. It looks to
me, that changing the device class would involve quite some effort and,
frankly, I am not sure if it is worth that. I just published the project
and I cant know if there will be any demand at all from Mac users for
it. Everybody else should be just fine (as long as HID.DLL or libusb.so
are present in their systems), or am I missing something here?
Also I am not sure if I understood the libwdi project pages correctly,
but it seems that I would need to cross-compile the stuff there and ship
shared libraries on windows together with the java application, right? I
doubt that I can manage to make this as easy to use as it is right now.
Additionally Windows 8 is not that wide spread at the moment that I
could assume that this WinUSB driver was already present, right?
So, at this time I would rather leave the HID description in the
firmware as it is and wait a bit (either until Macintosh users demand to
be able to use the device or Windows 8 being present on my PC at work or
a Mac being present at home). Would that be all right with you?
BTW: The need for permissions on Linux would not go away when I no
longer need libusb to disconnect the kernel HID driver, or would it?
Best Regards,
Holger.
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