[chuck-users] odd hid issue (touchpad)

Kassen signal.automatique at gmail.com
Fri Jul 17 17:49:51 EDT 2009


Sorry, I was thinking about a graphics tablet.

I suspected a misunderstanding like that. I'm well aware that graphics
tablets are currently unsupported. I was avoiding the word "scratchpad" as
on this evening I was experimenting with a mouse-based DIY turtable so I
imagined that might result in confusion later on and the word "trackpad"
eluded me. Sorry, my fault.

> I'm looking on
>  http://en.wikipedia.org/wiki/USB_human_interface_device_class
> The HID protocols are evidently only for USB connections.

Well, yes, strictly speaking. However I have been using PS/2 keyboards with
ChucK for quite a while (because my favourite keyboards pre-date the USB
standard) and have never had a issue with those under ChucK. I'd also like
to point out that if this device were completely unlike a HID device the
ChucK HID abstraction should be unable to open it. Instead it dutifully
reports it's a PS/2 device. My issue is that it does get opened as a mouse
but that it doesn't give any data. If ChucK would say "Hey, I see no USB
mouse so you can't have a HID abstraction of any mouse at all." it'd have to
admit that that would be inconvenient yet fair.

I'm not familiar with the Mac situation, having never owned one, but this is
a bog-standard  setup for non-Mac laptops. I believe it even makes sense as
supposedly PS/2 has some advantages over USB for mice in how it uses system
bus bandwith. We'd need to consult a hardware expert to verify that; I
certainly don't know that much about motherboard architecture or OS design.
This might also be limited by factors like maximum poll-rate and resolution;
I'm not sure but I don't think trackpad makers are very concerned with those
factors; these are hardly expensive high-performance interface devices.

Interestingly; according to ChucK there is a second mouse device here that
can be opened which looks like a emulation layer for macintosh mice. I have
no idea what that's doing there and why but it's not giving me any useful
signals either. I could look up the exact name if that would be relevant but
I would suspect it's simply there in case Ubuntu would be installed on a
Macbook. Maybe Apple instead uses a internal USB bus or something else

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