[sane-devel] Libusb - reads and writes?

René Kjellerup webmaster at keenan.dk
Fri Dec 8 21:51:26 CET 2006


On Fri, 8 Dec 2006, m. allan noah

> On Thu, 7 Dec 2006, René Kjellerup wrote:
> > So the primary question is, which endpoint does one write to, and 
> > which does one read from?
> the in/out identifiers are written from the perspective of the host, not
the device. so you read in and write out. just as a check, the IN endpoint
will > have its high bit set (0x80).

> it is not unusual to get timeout errors and other weirdness on your first
command to the device, some fujitsu scanners require you to call TEST UNIT
READY several times with a really short timeout and ignore the errors before
they will play.

:) well being used to TCP connections, I'd never expected USB communication
to be so inconsistent.

Should I fill the scanner's endpoint buffer before reading? Or will a few
one byte writes do?
Anyone know how Canon's scanners like it? [:)]

Best regards
René Kjellerup
-- as life grows older, I gain experience. 

> allan
> --
> "so don't tell us it can't be done, putting down what you don't know.
> money isn't our god, integrity will free our souls" - Max Cavalera

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