[sane-devel] buttons-daemon for SANE genesys scanner

[m. allan noah]

On Sat, Jan 10, 2009 at 2:55 PM, Pierre Willenbrock
<pierre at pirsoft.dnsalias.org> wrote:
> m. allan noah schrieb:
>> On Sat, Jan 10, 2009 at 1:11 PM, Pierre Willenbrock
>> <pierre at pirsoft.dnsalias.org> wrote:
>>> m. allan noah schrieb:
>>>> On Fri, Jan 9, 2009 at 5:02 PM, Pierre Willenbrock
>>>> <pierre at pirsoft.dnsalias.org> wrote:
>>> [...]
>>>>> Another question: Is it okay to only look at the hardware state if the
>>>>> frontend asks for the state of the option? That way shorter presses can
>>>>> be lost, if the frontend does not poll often enough.
>>>> In my case, the scanners are smart enough to buffer the button presses
>>>> for 3 seconds, and I effectively read the status of all the buttons
>>>> from the scanner every time you ask for the value of the first option.
>>>> So, as long as the front-end reads within that 3 second window, no
>>>> presses are lost.
>>>>
>>>> If your machines dont buffer, then you might need a thread just to
>>>> read the status really quickly? Do you know how frequently the windows
>>>> driver reads the buttons?
>>> The genesys chips don't help at detecting hardware buttons. The only
>>> sensor logic in the chip is for the home-sensor. The rest is GPIO.
>>
>> Is it possible for a user to press and release the button and have the
>> driver 'lose' it if you dont read the GPIO pins during the 'pressed'
>> inteval?
>
> Exactly like that. And the windows driver has the same problem.

Ahh, I love cheap scanners :) How fast would you have to poll the
scanner to get short presses? 10Hz?

allan
-- 
"The truth is an offense, but not a sin"