Re: [lcd4linux] backlight Control

[Michael R. <re...@eu...>]

Hi Stefan,

>>> My LCD runs under WinXP with jaLCD really good. backlight is on. 
>>> But if i use lcd4linux i can make screens but the backlight can't
>>> be turned on. My lcd is connected like this : 
>>> http://www.jalcds.de/images/4x20backlight.gif

>> I see. They control the backlight with the SELECT signal and a
>> transistor.
>> 
>> lcd4linux does not support this.
>> 
>> You could hardwire your backlight so it stays on all the time.
>> there are several possibilities: either connect the base of the
>> transistor to +5V (including the resistor 150 ohm!!!), or shortcut
>> collector-emiiter.

> Ok i connected the backlight directly it runs. Thx a lot Would be
> nice if in next version i can control this port.
Good Idea. I will add it to my ToDo-List. But there are so many other, 
more important items, so it will take its time...

On the other hand, if you have some spare time, are you willing to write 
a patch? I will support you as much as I can. There are other display 
drivers which have software-controlled backlight, so sample code is 
available.

> But can you tell me
> how i can display different rows on after the other. I mean like
> first a screen for CPU than after 30 sec  a Screen for Ram and....

At the moment lcd4linux does not really support such "screens", but this 
will change. I planned to get a lot of this rework done over the 
christmas holidays, but unfortunately I got "SpellForce" as a christmas 
present. I spent about 100 hours on playing the last days :-)

There are two possible workarounds:

1. the ugly one: provide more than one config file, each containing one 
screen. use a shellscript which rotates the config file (symlink?) every 
30 seconds, and send a SIGHUP to lcd4linux so it rereads its config.

2. the not-so-ugly one: Use "virtual rows" for this. See the doc on the 
web page.


bye, Michael

-- 
Michael Reinelt                                   Tel: +43 676 3079941
Geisslergasse 4                                   Fax: +43 316  692343
A-8045 Graz, Austria                          e-mail: re...@eu...