[sane-devel] add a Canon scanner to scanbuttond

[Thomas Rechberger]

still there is something missing, i guess in the backend there needs to 
be a special way in how to get the data from USB.

When i fire up wireshark in Linux i dont see any communication between 
scanner and host when the button is pressed.

When i watch it under XP i see that every second a packet is sent:

  Setup Packet

Offset 	Field 		Size 	Value 		Description
0 	bmRequestType 	1 	C0h
  	4..0: Recipient 	...00000  	Device
  	6..5: Type  		.10.....  	Vendor
  	7: Direction  		1.......  	Device-to-Host
1 bRequest 		1 	0Ch
2 wValue 		2 	008Ah
4 wIndex 		2 	00E4h
6 wLength 		2 	0001h

When the button is pressed, the data is 04, otherwise 00.

Not much clue what to do with it.