[sane-devel] Re: How to link the Scan Button of CX3100 to a
m. allan noah
Tue, 27 Jan 2004 11:27:19 -0500 (EST)
On Tue, 27 Jan 2004, Bruce Bertrand wrote:
> Till Kamppeter wrote:
> > I recommend that you post this on the SANE mailing list
> > (http://www.sane-project.org/), as this is a scanning problem. I am
> > CCing this posting to there.
> > AFAIK noone has written a driver for scanner buttons yet (also not for
> > other scanner models). The scanner probably sends a certain signal
> > through the USB which is caught by a background process under Windows.
> > This process then starts a program to do the scan. The best way to
> > write a similar program under Linux is to use a USB sniffer to analyze
> > how the signal looks like and then write a daemon which listens for
> > such signals.
> > Till
> If this is the case, then it would only take one sniffer for all
> scanners that operate in this manner. Sort of like those universal
> "learning" remotes, where you hold up an existing remote to the learning
> remote, hit a "listen" button and then press a button on the old one,
> assigning whatever signal it receives to some function on the learning
not so simple as that. for machines with adf, you will usually have a
couple other sensors like paper thickness, input or output hopper
empty/full, cover open, lamp warm, etc. if the scanner sends all those as
a bitmask in one packet, then the user doing a button-press might show up
as a dozen different codes, based on those other flags. your 'generic'
button monitor would have to know a whole lot more about each individual
model than you would want (esp when things like which usb endpoint to use
and bulk v/s interrupt are taken into account)
all-in-all this sort of thing (reading the raw output from the scanner)
belongs in the backend, with suitable abstraction that a frontend could
use. finding that abstraction is more problematic...
"so don't tell us it can't be done, putting down what you don't know.
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