[sane-devel] how to fill values in Genesys_Frontend structure from usb log?

[Pierre Willenbrock]

Parag N(पराग़) schrieb:
>       I have usb log captured on windows just after powering up
> scanner HP 2400. I am checking Genesys_Frontend,Genesys_Motor
> structure values in genesys_devices.c. I want to know how to calculate
> values for Genesys_Frontend structure. Also how to calculate maximum
> start speed ,maximum end speed of scanner motor?

I assume you can already interpret register reads/writes.

Genesys_Frontend contains the setting of the analog frontend:
  AFE   |Genesys_Frontend
Register|    member
--------+----------------
0x00    |.reg[0]
0x01    |.reg[1]
0x02    |.reg[2]
0x03    |.reg[3]
0x04    |(reset)
0x06    |.reg2[0]
0x08    |.reg2[1]
0x09    |.reg2[2]
0x20    |.offset[0]
0x21    |.offset[1]
0x22    |.offset[2]
0x24    |.sign[0]
0x25    |.sign[1]
0x26    |.sign[2]
0x28    |.gain[0]
0x29    |.gain[1]
0x2a    |.gain[2]

AFE Registers a written by setting register FEWDA(0x50) to the register
number and then writing to registers FEWRDATA(0x3a,0x3b), so you will
see these three register writes repeat in your log(Register numbers for
gl646).

Genesys_Motor is not used in the gl646 part, but we want to move over to
parametrized slope generation not depending on hard-coded settings.

Each Genesys_Motor_Slope contains a slope description for a specific
stepping mode. The described slope should lead to the fastest final
speed possible.

The needed numbers can be directly derived from the slope tables(bulk
writes of maximum 256/512 bytes, to be interpreted as usigned short.
Each entry is the time between the corresponding steps). Take the
maximum starting speed you can find, and the maximum ending
speed(minimum value).

The motor can be actuated in different step modes, so there will be
slope tables using half steps and tables using full steps. Half step
tables will contain values half as large as full step tables. Currently
the values in Genesys_Motor are the time for a full step, even if used
for half step mode. They will be devided accordingly.

The 'g' entry can be set to 1, resulting in a linear acceleration.

I see that 'minimum_steps' is misleading, it contains the number of
steps used for the slope, which is more of an upper limit for the number
of steps.

In Genesys_Motor the 'base_ydpi' member is the motor resolution for full
step mode. 'optical_ydpi' is the maximum stepping resolution possible.
'max_step_type' is the smallest step type: 0->full step, 1->half step,
2->quarter step. Actually there is redundant information here, as
optical_ydpi=base_ydpi*2^max_step_type

If you got your scanner to work and you are not afraid to damage it, you
can try to finetune the acceleration slopes. I could speed them up for
my scanner. But that will only improve low quality scan time and head
moving home time.

Regards,
  Pierre