[Libusb-devel] OT HID advice sought

[Kustaa N. <Kus...@pl...>]

Sorry for the OT intrusion, but since I know many people well versed in
HID 
hang around this list and I'm a member of this list I thought I'd try and
take advantage of it.

I'm working with an third party, that has a simple composite device with
some buttons and functions and we are co-operating in specifying the
requirements for the firmware.

Any solution that requires installation of any kind on the host
(Windows/Mac) 
side is out of the question.

Sorry can't be more explicit here.

The problem is that neither party is an expert on USB.

Anyway the device is going to represent itself as a HID keyboard and the
buttons

on the device will be treated as key presses on a keyboard (ALT -
something).

The question is how to best control the functions on the device through
the HID interface. These are simple on/off functions with very infrequent
state changes. 

Something like what is used to control the NUMLOCK-etc LEDs on
the keyboard comes to mind, but obviously can't use exactly those.

So I'm looking for ideas/pointers what would be the simplest way to
accomplish
this and which would not cause 'compatibility' issues with the way host OS
handles keyboards.

Can I, for example,simply define an output report to control those
functions?

What else is involved?

br Kusti