[Lcdproc] LCD 40x4 (HD44780 winamp) with backlight switch?

[Peter Marschall]

Hi Stefan,

On Wednesday, 4. July 2007 17:45, Stefan Hu=C3=9Ffeldt wrote:
> is it possible, to run a LCD 40x4 with HD44780 (Samsung chip) and winamp
> wiring with a backlight switch? The wiring uses pin 17 for EN2 which is
> also used for backlight.
>
> hd44780-winamp.c:
> ...
>
> |* Backlight
> |* SEL  (17)      backlight (optional, see documentation)
>
> I've tried to change the backlight pin to number 14, 'cause i don't use n=
RW
> at the LCD (it's grounded).
>
>          p->backlight_bit =3D (state?0:nLF);
>
> but that doesn't work. ;) I must say, that i'm not a coder...

A 40x4 HD44780 display has 2 HD44780s on it:
one for the upper 2 lines, one for the lower 2 lines.

Both need to be driven to be able to make full use of the LCD.
The HD44780 driver has support for this situation using the vspan
parameter.

Unfrotunately I do not own a HD44780 display for the parallel port,
so I cannot help with the wiring.

But maybe others on the list can jump in.

Peter
=2D-=20
Peter Marschall
peter@adpm.de