[sane-devel] Weirdness with Canon FS2720U
tkelly-sane-devel at taborandtashell.net
Thu Aug 3 19:07:42 UTC 2006
m. Allan Noah wrote:
> sometimes you write a stupid loop and you dont wory about it. othertimes
> it is trying to reserve all the LUNs. with the fujitsu's, i just leave
> those two commands out, and it works. (there is only one master on the
> USB anyway)
Well, in the part I was talking about they reserved LUN = 0 eleven
times. I just used to work as a software quality assurance engineer and
this sort of thing is like fingernails on a blackboard to me. Maybe it
is a personal problem :-)'.
> opcode 0x2a, data type code 3 == send gamma table, in this case 10 bits.
> notice bytes 4 & 5 of the command before the table are 00 00, then 00
> 01, then 00 02 ... those are the 'id' of the table being loaded. later,
> in the set window command, that id will be used to tell the scanner how
> to munge the scan. these default ramps are linear, you may be able to
> leave them out.
Thanks for catching this, I was reading the SCSI spec wrong and thinking
it was the WRITE opcode (also 2Ah). This makes a lot more sense now.
>> I think next I am going to write some libusb code (my first) and try
>> cutting out some of these steps. The scanner has flash memory on the
>> mainboard, I don't understand why it would need its firmware upgraded
>> every time. Maybe Canon didn't build in a facility to actually upgrade
>> the firmware and they are writing over active memory every time you
>> turn it on?
> have you tried just adding usb support to the existing canon scsi backend?
Not yet, I will probably do that eventually. Right now I just want to
get data back on a *nix box.
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