[libhid-discuss] libhid_interrupt_read returns same value for three keys

[Charles Lepple]

On Sep 23, 2009, at 7:38 AM, Alexander Juling wrote:

> Alexander Juling schrieb:
>> Charles Lepple schrieb:
>>> On Sep 16, 2009, at 4:42 AM, Alexander Juling wrote:
>>>
>>>> Unfortunately I got stuck now with a major problem. The keyboard  
>>>> is not in a standard keyboard body, so the labeling of the keys  
>>>> differs from a standard one. This won't be a problem unless three  
>>>> of the keys return the same result for the interrupt read  
>>>> function. Is there any way to differ the three key from each  
>>>> other? Unfortunately I cannot figure out, which keys they are  
>>>> originally.
>>>
>>> Is it possible that you need to send some additional information  
>>> to put the keyboard into a different mode?
>>>
>>> I don't know much about it, but HID keyboards have a "boot  
>>> protocol mode" which is supposed to be a simplified version of the  
>>> HID protocol.
>>

It does seem to have this mode:
"    bInterfaceSubClass      1 Boot Interface Subclass"

I don't think we have any functions in libhid for dealing with this,  
especially since the OS keyboard drivers may have initialized the  
keyboard already.

>>> What does 'lsusb -v' say for this keyboard?
>>>
>>>
>> I just need to know, which key is pressed and additional would send  
>> some information to the keyboard that will enable the caps-lock  
>> light or the num-lock light, but that seems to be another topic  
>> (even though it would be nice to receive an answer if you know it  
>> right now). The important part is, that three of the keys send back  
>> the same information back as it seems.
>>
>> I'm right now not at the office to send the lsusb -v, will do it  
>> tomorrow
>>
> I haven't done the hid_set_input_report(...) command before doing  
> hid_interrupt read. Could that be the problem?

Actually it's "hid_get_input_report()" and "hid_set_output_report()",  
but they get and set specific reports, whereas hid_interrupt_read()  
simply grabs whatever is next.

I haven't really done much with keyboards and mice, but you may need  
to look at hid_set_idle() and the corresponding "Set Idle" section of  
the HID Class spec (at usb.org).

The HID Class spec should also cover the Boot Protocol (in an  
appendix, IIRC).