IBM Z50 LCD Control

pete hilton <sarumanruvolo-hilton.org> wrote:

> Having got netbsd working satisfactorily on my Z50, I
have been
> looking into how to control the brightness/contrast on
the LCD.
>
> Having looked at the ITE8181 specs that I have and the
VR4171
> chipset specs I cannot see any registers which would
allow anything
> other than backlight on or off.  Obviously there is
SOME way to
> handle brightness/contrast because WINCE does it, but
does anyone
> know (or have a pointer to) how this works.  I dont
care about the
> buttons on the LCD panel because we can always use an
ioctl or some
> such once we know what the hardware mechanism is and
how it is
> accessed.
>
> If there is anyone from IBM out there watching this
group who has a
> detailed schematic or programming spec for the Z50, it
would be very
> nice to hear from them) ... my
guess in all this is that there is
> another control on the LCD that is not documented
publicly which
> handles the brightness/contrast.

One strategy might be to disassemble the WinCE ROM and stare
at it for
a while.

Another (a complementary one) - is to make the bootloader or
kernel
dump contents of all "interesting" hw registers
at the boot time and
then boot repeatedly with different brightness/contrast
settings and
watch for changed values.

PS: I had to do just that for hpcsh Jornadas to discover
that
brightness is controlled via DAC, and contrast via GPIO
pins.

SY, Uwe
-- 
uweptc.spbu.ru                         |       Zu Grunde
kommen
http://snark.ptc.spbu.
ru/~uwe/          |       Ist zu Grunde gehen