[sane-devel] Trying to understand GL640

[Robert Brijder]

Hello,

I am trying to understand the GL640USB IEEE-1284 to USB Bridge. I have
looked at a few implementations of this bridge. Each time the
following registers are used (this code is from the canon630u
backend):

/* Register codes for the bridge.  These are NOT the registers for the
   scanner chip on the other side of the bridge. */
typedef enum
{
  GL640_BULK_SETUP = 0x82,
  GL640_EPP_ADDR = 0x83,
  GL640_EPP_DATA_READ = 0x84,
  GL640_EPP_DATA_WRITE = 0x85,
  GL640_SPP_STATUS = 0x86,
  GL640_SPP_CONTROL = 0x87,
  GL640_SPP_DATA = 0x88,
  GL640_GPIO_OE = 0x89,
  GL640_GPIO_READ = 0x8a,
  GL640_GPIO_WRITE = 0x8b
}
GL640_Request;

However, I have gone through the official datasheet supplied by
Genesys and could not find any documentation on these register
addresses. In fact, according to page 10 in the datasheet, the
registers on the above addresses have different meanings. What am I
missing here??

Thanks,
Robert