Re: [lcd4linux] GPO circuitry

[Aragon G. <ar...@ph...>]

| By Martin Hejl <ma...@he...>
|                                          [ 2004-02-16 01:59 +0200 ]
> No, it isn't - at least not on the displays I have here. One kind seems 
> to have two "brightnesses" (low and _pretty_ high, to the point where I 
> think that "pretty high" may burn out the display soon - since it gets 
> somewhat warm) and the other kind simply has "on" if no resistor is 
> attached between pins 15 and 16 (I never attached anything to A and K 
> directly) and "off" if there's a resistor > 10 Ohm. Found this out 
> simply by attaching a pot to pins 15 and 16 and seeing what happens when 
> I turn the knob.

I think others with different modules will probably have different
experiences too, to make matters more difficult. :)


> But there are different kinds of backlights (electro luminescent, cold 
> cathode flourescent lamps and light emitting diode - and the LED type 
> might be implemented as a "Lightbox" or as a "Light-Pipe", or so I 
> gather from the various specs) and each will probably behave 
> differently. So, I guess you'll have to try to be sure.

EL and CCFL backlights I'm sure are very different from LED when it comes to
adjusting light intensity level.  I have experience only with LED
backlights.  Can anyone using EL and/or CCFL comment on the process of
adjusting brightness?

I'm leaning toward my design idea with a 4514 based decoder because it'll
allow the most flexibilty in choosing resistance values precisely for each
desired brightness level.  (at the cost of having to wire lots of resistors)


Regards,
Aragon